US20050076596A1

US20050076596A1 - Reinforcement material and reinforcement structure of structure and method of designing reinforcement material

Info

Publication number: US20050076596A1
Application number: US10/490,017
Authority: US
Inventors: Shunichi Igarashi
Original assignee: Structural Quality Assurance Inc
Current assignee: Structural Quality Assurance Inc
Priority date: 2001-09-25
Filing date: 2002-09-25
Publication date: 2005-04-14
Also published as: WO2003027417A1; MA26287A1; CN1558980A

Abstract

Disclosed is a reinforcing member, which comprises a woven body formed by a weaving process, or a tape-shaped or sheet-shaped body, having a high ductility and high bendability. The reinforcing member is adapted to be installed on a surface of a structure member or a boundary portion of the structure member, or inside a structure member, to reinforce the structure member. The woven body, or a tape-shaped or sheet-shaped body, has a Young's modulus equal to or less than that of the structure member, and a tensile fracture strain of 10% or more. The Young's modulus of the reinforcing member is preferably in the range of 1/2 to 1/20, more preferably 1/5 to 1/10, of that of the structure member. Specifically, the Young's modulus of the woven body is preferably in the range of 500 to 50000 MPa, more preferably 1000 to 10000 MPa. The present invention also provides a reinforced structure using the above reinforcing member.

Description

TECHNICAL FIELD

The present invention relates to a reinforcing member for a structural body, a reinforced structure using the reinforcing member, and a method for designing the reinforcing member.

BACKGROUND ART

Heretofore, there have been known various techniques (reinforced structures, reinforcing members and reinforcing methods) for reinforcing a member of a structural body (hereinafter referred to as “structure member”). Among them, a conventional technique characterized by installing a reinforcing member on the surface of or inside a structure member subject to reinforcement includes (1) a technique of embedding a reinforcing bar in concrete as a substrate, or so-called reinforced concrete technique, (2) a technique of driving a bolt or nail into a substrate, (3) a technique of incorporating a high-strength steel rod inside concrete as a substrate and introducing a tensile force to the steel rod, (4) a technique of wrapping a steel plate around a structure member, or so-called steel-plate wrapping technique, and (5) a technique of using a so-called continuous-fiber reinforcing member made of carbon or aramid fibers and resin, such as epoxy resin, impregnated therein.
Another conventional technique characterized by installing a reinforcing member between the respective outer surfaces of adjacent structure members includes (6) a technique of forming a space, such as hole or slit, in the structure members, and penetratingly inserting a reinforcing member into the space, and (7) a technique of forming a space in the structure members, penetratingly inserting bundled fibers of a continuous-fiber reinforcing member into the space, and then spreading out the fibers.
Still another conventional technique characterized by installing a reinforcing member on the surface of a flat structure member, such as wall, includes (8) a technique of constraining a reinforcing member by a metal plate formed with a hole, and a bar, such as a metal bar, penetrating the structure member, and (9) a technique of bundling the fibers of a continuous-fiber reinforcing member at the edge of the structure member, and anchoring the bundled fibers to the edge of the structure member or another member adjacent to the structure member.
Yet another conventional technique characterized by forming a reinforcing member in a cylindrical shape and filling the inner space of the cylindrical reinforcing member with filler includes (10) a technique of forming an iron reinforcing member in a cylindrical shape, and filling the inner space of the cylindrical reinforcing member with concrete to use the obtained reinforcing member as a column.
Yet still another conventional technique characterized by installing a plurality of reinforcing members on the outer surface of a structure member in a superimposed manner includes (11) a technique of providing a plurality of continuous-fiber reinforcing members on the outer surface of a structure member in its vertical and horizontal directions in a superimposed manner.
Another further conventional technique characterized by providing a strip-shaped reinforcing member on the outer surface of a structure member includes (12) a technique of providing a strip-shaped (tape-shaped) steel plate or continuous-fiber reinforcing member around a structure member, (13) a technique of filling epoxy resin along a crack of a substrate in a strip shape, and (14) a technique of fixing a strip-shaped steel plate on the surface of a structure member by use of epoxy resin or an anchor bolt.
Still a further conventional technique characterized by installing a reinforcing member on the outer surface of a junction of structure members includes (15) a technique of providing a steel jacket or attaching a continuous-fiber reinforcing member on the outer surface of a junction of structure members.
An additional conventional technique characterized by using a resin-impregnated reinforcing member includes (16) a technique of using a so-called continuous-fiber reinforcing member made of carbon or aramid fibers and epoxy resin impregnated therein.
The above techniques (4) to (14) are intended to transmit a shear stress directly to a reinforcing member without causing any displacement or peeling between a substrate and the reinforcing member. For example, the shear reinforcement effect of a reinforced concrete member is said to have the same mechanism as that of a shear-reinforcing bar, and the reinforced concrete member is designed by assigning a reinforcement amount and coefficients expressing the property and reinforcement effect of a reinforcing member to a design formula of the shear-reinforcing bar. Most of the techniques (3) and (15) also include the step of injecting a grouting or resin material between a reinforcing member and a substrate to transmit a shear stress directly to the reinforcing member. The term “substrate” herein means a material constituting a structure member, and a physical object to which a reinforcing member is to be fixed.
Therefore, an intended reinforcement effect can be obtained only if a substrate is maintained in its proper state, and no displacement or peeling is caused between the substrate and the reinforcing member. This prerequisite must be guaranteed by the design technique and construction management.
The reinforcing member, such as the reinforcing bar, the steel rod and the steel plate, used in the techniques (1) to (4), (6), (8), (10), (12), (14) and (15), has the flexural rigidity and shear rigidity of its own. Thus, if a substrate is locally subjected to a large strain, the reinforcing member cannot follow the local strain, resulting in loss of the reinforcement effect due to the occurrence of local fracture in the substrate or local buckling or cracks in the reinforcing member.
In the techniques (12) and (16), the reinforcing member made of resin-impregnated continuous fibers has the same problem as described above due to the flexural and shear rigidities resulting from the effect of resin impregnation in addition to the flexural and shear rigidities of the continuous fibers themselves. Further, while this reinforcing member is designed using a formula based on the assumption that it has only tensile rigidity, an intended reinforcement effect is actually likely to be lost due to occurrence of bending or local buckling in consequence of the flexural rigidity and shear rigidity of its own.
The material, such as carbon or aramid fibers, used in the techniques (5), (7), (11) and (16), has a fracture strain of 2% to several %, which is liable to cause damages by the corners of a substrate or the unevenness of the surface of a substrate. Thus, an appropriate construction management is essentially required. Further, if the substrate has some cracks due to a certain external force, the reinforcing member will be locally broken, which leads to significant deterioration or disappearance of the reinforcement effect.
In the techniques (1) to (15), if a structure member contacting with another structure member or having a flat shape or a concavo-convex or irregular surface is reinforced by forming a through-hole therein and penetratingly inserting a reinforcing member into the through-hole, such a construction work will involve a problem of high cost and/or extended period, and a particular technology or tool will be required to fix the edge of the reinforcing member or insert the reinforcing member.
In the above technique, a plate, a rod or a bundle of continuous fibers which serves as an anchor portion of the reinforcing member (hereinafter referred to as “anchor member”) has a structure and rigidity different from those of the remaining portion of the reinforcing member. Thus, the threshold value of the reinforcement effect is undesirably defined by the threshold values of stress transmission between the reinforcing and anchor members and between the anchor member and the substrate.
Further, the substrate is requited to bear the stress occurring at the fixed portion of the anchor member. Therefore, if the strength of the substrate is lowered due to aged deterioration or such an aged deterioration is calculated, the above technique cannot be applied.
In the technique of introducing a tensile force to a steel rod, if it is applied to a substrate exhibiting significant creep, such as concrete, the tensile force of the steel rod will be reduced due to the creep, and the reinforcement effect will be lost across the ages. Further, if the anchor portion of the steel rod is broken by a sudden external force due to earthquake or the like, the steel rod suddenly freed from the tensile force will be likely to jump out of the concrete and damage the surroundings.
Thus, the techniques (1) to (16) are required to install the reinforcing member by spending an extended time in association with professional engineers, which involves a high construction cost. The application of these techniques is also limited to a specific substrate which can be formed to have a smooth surface as in reinforced concrete, and allows a reinforcing member to be brought into close contact therewith so as to form a structure capable of locally transmitting a shear force.
In the so-called continuous-fiber reinforcing member composed of epoxy-resin-impregnated carbon or aramid fibers in the technique (16), material constants, such as strength and Young's modulus, important in reinforcement design are defined in the state after the fibers are impregnated with the resin. This reinforcing member is fixed to a structural body, for example, according to the following process as disclosed in Japanese Patent Laid-Open Publication No. 8-260715.

- (i) Pre-cleaning the surface of a structural body by removing/repairing stains and damages, such as cracks, thereon,
- (ii) Applying a primer on the surface,
- (iii) Uniformly applying a powerful adhesive, such as epoxy resin, on the surface,
- (iv) Wrapping the reinforcing member around the structural body to cover over the surface while stretching the reinforcing member and keeping it from loosing,
- (v) Re-applying the adhesive on the surface of the reinforcing member and impregnating the reinforcing member with the adhesive, and
- (vi) Curing the adhesive for given days, and applying on the surface of the reinforcing member an appropriate coating material for protecting the reinforcing member from ultraviolet light or the like.

The reinforcing member is fixed through the many steps as described above, and the adhesive in the step (v) can be applied only after the adhesive applied in the step (iii) is completely cured or hardened by chemical action (if the adhesive in the step (v) is prematurely applied, gas bubbles generated during the chemical action will be confined in the reinforcing member to cause the deterioration in strength of the reinforcing member. Thus, the above process has to be completed by taking a great number of days.
The impregnating step has to be carried out in the working site under a strict construction management. If an external force acts to cause the peeling between the resin and the continuous fibers, or the resin is defective in curing or deteriorated due to environmental conditions, the design performance of the reinforcing member will be significantly degraded.
Generally, if a structure member has a non-flat or irregular surface, such as a wall-mounted column, or is joined to or located very close to another member or non-structural material, such as a column having a window frame attached thereto, it is difficult to obtain a sufficient reinforcement effect. Further, the interactions between a structure member and a reinforcing member and between the reinforcing member and the surrounding are likely to cause deterioration of the reinforcing member. Furthermore, there is the need for obtaining a sufficient reinforcement effect in a wide range from a small deformation to a large deformation.

DISCRIPTION OF THE INVENTION

According to a first aspect of the present invention, there is provided a reinforcing member comprising a woven body formed by a weaving process to have a high ductility and high bendability. The reinforcing member is adapted to be installed on a surface of or inside a structure member to reinforce the structure member. The woven body has a Young's modulus equal to or less than that of the structure member, and a tensile fracture strain of 10% or more.
In the reinforcing member set forth in the first aspect of the present invention, the Young's modulus of the woven body may be in the range of 1/2 to 1/20, preferably 1/5 to 1/10, of that of the structure member. Specifically, the Young's modulus of the woven body may be in the range of 500 to 50000 MPa, preferably 1000 to 10000 MPa.
The woven body may have a thickness in the range of 0.2 to 20 mm, preferably 0.5 to 15 mm, more preferably 1 to 10 mm.
The woven body may include yarns made of polyester.
The woven body may have a bending deformation angle of 90-degree or more, and a shear deformation angle of 2-degree or more.
The reinforcing member set forth in the first aspect of the present invention may be heat-set to allow a Young's modulus in a limit state to be greater than a Young's modulus immediately before fracture. The heat setting process comprises the steps of heating the reinforcing member to apply a tensile force thereto, and then cooling the reinforcing member while maintaining the tensile force, so as to provide enhanced initial rigidity and Young's modulus to the reinforcing member. In addition, a resin impregnation process may be performed to impregnate the reinforcing member with resin.
This reinforcing member may have an elongation strain in the range of 0.1% to 10% in the limit state.
According to a second aspect of the present invention, there is provided a reinforcing member comprising a tape-shaped or sheet-shaped body made of a rubber-based or resin-based elastic material having a high ductility and high bendability. The reinforcing member is adapted to be installed on a surface of or inside a structure member to reinforce the structure member. The tape-shaped or sheet-shaped body has a Young's modulus equal to or less than that of the structure member, and a tensile fracture strain of 10% or more.
In the reinforcing member set forth in the second aspect of the present invention, the Young's modulus of the tape-shaped or sheet-shaped body may be in the range of 1/2 to 1/20, preferably 1/5 to 1/10, of that of the structure member. Specifically, the Young's modulus of the tape-shaped or sheet-shaped body may be in the range of 500 to 50000 MPa, preferably 1000 to 10000 MPa.
The tape-shaped or sheet-shaped body may have a thickness in the range of 0.2 to 20 mm, preferably 0.5 to 15 mm, more preferably 1 to 10 mm.
The tape-shaped or sheet-shaped body may have a bending deformation angle of 90-degree or more, and a shear deformation angle of 2-degree or more.
As long as meeting the aforementioned requirement, the reinforcing member set forth in the second aspect of the present invention may be formed by spraying or applying a rubber-based or resin-based material or fiber-reinforced mortar to the structure member in the working site. While the material cost in this case is higher than the polyester woven fabric, it is often the case that such a reinforcing member is advantageous in terms of the ratio of reinforcement effect to cost as compared to conventional techniques. A Young's modulus in a limit state such as a design ultimate state, a fracture strain and a fracture stress can be calculated based on the stress-strain relationship of the reinforcing member to determine a required reinforcement amount (the thickness of the reinforcing member) and the performance of the structure member according to an after-mentioned calculation method.
According to third and fourth aspects of the present invention, there are provided two types of reinforced structures for a structural body. The reinforced structures comprise the reinforcing members set forth in the first and second aspects of the present invention, respectively. In these reinforced structures, the reinforcing member is fixed on a surface of or inside a substrate which constitutes a structure member of the structural body and consists of at least one material, or on a surface of a boundary portion of the structure member or inside the structure member, to reinforce the structure member.
In the reinforced structures set forth in third and fourth aspects of the present invention, the reinforcing member may be fixed to the structure member in such a manner that an effective constraint range of the reinforcing member covers the pre-calculated width and length of a gap to be generated in the structure member in future.
The substrate may be made of at least one material selected from the group consisting of (1) concrete, (2) steel frame, (3) brick, (4) block, (5) gypsum board or plaster board, (6) wood, (7) rock, (8) earth or soil, (9) sand, (10) resin and (11) metal.
The fixation may be performed by means of an adhesive. The layer of the adhesive applied to the reinforcing member or the structure member may have a thickness in the range of 5 to 90%, preferably 20 to 40%, of the thickness of the reinforcing member.
The fixation may be performed by placing the reinforcing member on the structure member through the layer of the adhesive and then applying a pressing force or a beating force to the reinforcing member while allowing a part of the adhesive to be infiltrated into the reinforcing member. In case of the woven body, the fixed portion of the reinforcing member may have a void ratio of 1.1 or more. In case of the tape-shaped or sheet-shaped body, the fixed portion of the reinforcing member may have a void ratio of 1.4 or more.
The bonding strength of the fixation may be less than the peeling/shear fracture strength between the structure member and the reinforcing member. This prevents the reinforcement effect from disappearing due to fracture in the structure member and the reinforcing member before the occurrence of peeling in the fixed portion. Specifically, the bonding strength may be in the range of 10 to 80% of peeling/shear fracture strength in the surface of the structure member applied with the adhesive.
The adhesive may be a one-component, non-solvent adhesive.
The fixation of the reinforcing member to the structure member may be performed without chamfering the structure member and adjusting the unevenness of the surface of the structure member.
In the reinforced structures set forth in third and fourth aspects of the present invention, even after the structure member has a gap, the reinforcing member holds or constrains the structure member in such a manner that it forms an envelope surface covering a surface of the structure member adjacent to the gap to serve as a medium for transmitting a stress acting on the structure member on both sides of the gap (bridge for transmitting the stress). The envelope surface serving as the transmission medium is formed by elongation in the reinforcing member adjacent to the gap and/or peeling in the fixed portion adjacent to the gap. In other words, the envelope surface serving as the transmission medium is formed by the elastic elongation of the reinforcing member in a free zone where the fixation is released due to the generation of the gap.
The term “substrate” means a material constitutes a structure member subject to reinforcement, and a physical object to which a reinforcing member is to be fixed. The shape and material of the substrate are appropriately selected depending on a desired performance or function of the structure member. The material of the substrate is not limited to a specific form or type, and may be any conventional structural material, any conventional non-structural material or any filler material. For example, the substrate may be concrete, steel frame, brick, block, gypsum or plaster board, precast concrete, wood, rock, earth or soil, sand, metal, or granular resin. The substrate may include plural kinds of materials. For example, when a filler material such as resin is filled in a space between a structure member and a reinforcing member, the combination of the filler material and the material of the structure member may be defined as the substrate. The term “gap” herein means a chap or crack generated in a structure member. When a structure member has a deformation inducing a gap therein, the resulting displacement between the structure member and a reinforcing member adjacent to the gap forms an envelope surface in a portion of the reinforcing member around the gap of the structure member without any fracture of the reinforcing member. The enveloped surface serves as a bridge allowing a stress of the structure member to be transmitted across the gap. That is, a shear stress is transmitted through the boundary surface between the reinforcing member and a portion of the structure member having no gap or through a fixed portion. The envelope surface of the reinforcing member is formed based on a plurality of factors including as the elongation of the reinforcing member adjacent to the gap, the release (peeling-or another factor) of the fixation adjacent to the gap, and the fixation around the gap.
The fixation of a reinforcing member to a structure member is performed by applying an adhesive a part or all of the boundary surface between the structure member and the reinforcing member, or by closingly looping a reinforcing members in an adhesive or mechanical manner while enclosing and deforming a portion of the structure member, so as to provide a tensile force in the reinforcing members to generate a frictional or bearing force between the reinforcing member and the structure members.
The adhesive to be applied to the boundary between a structure member and a reinforcing member is required to maintain an adhesion strength required for fixing the reinforcing member to the structure member, for the period of use of the structure member under environmental conditions of the structure member. In this case, there is no need to set the required adhesion strength at a value higher than the fracture strength of the structure member or the reinforcing member. Thus, the adhesive may be one-component adhesive. The adhesive may also be applied to the reinforcing member in advance, and stored together with the reinforcing member. In this case, an operation of fixing the reinforcing member can be quickly completed.
The term “fixation zone” herein means a zone where the reinforcing member is fixed. The term “free zone” means a zone where the fixation of the reinforcing member is released (due to peeling or another factor). In an after-mentioned design method, the ratio of the size of the fixation zone to the size of the free zone is expressed by a numerical value of “constraint ratio”.
The terms “fixation strength” and “fixation range” herein mean a strength and a range capable of causing the displacement in a specific finite areas (free zone) of reinforcing and structure members when the structure member has a local fracture inducing a gap, so as to allow a stress of the structure member to be transmitted through the reinforcing member across the gap without any fracture of the reinforcing member.
The relationship between load and deformation of the structure member after the generation of the gap is expressed as the functions of the dimensions of the structure member, the boundary condition of the structure member, the position and size of the gap, the Young's modulus and thickness of the reinforcing member, and the size of a free zone caused by the gap. Thus, a required strength, required Young's modulus, required amount (required installation range, required thickness etc.) and required fixation strength of the reinforcing member can be calculated based on a value in a limit state (tolerance or threshold value) of the size (width etc.) of a gap to be generated in the structure member, the size of a zone where the elongation of the reinforcing member can be neglected (fixation zone), and the size of a zone where the reinforcing member is to be elongated (free zone).
A Young's modulus for use in the calculation of the required amount etc. of the reinforcing member is a value (limit state value) corresponding to a strain to be generated in the reinforcing member in a limit state where the size of the gap reaches the threshold value. Therefore, in view of the elastic property of the reinforcing member, the design of setting a Young's modulus in the limit state to be greater than a Young's modulus corresponding to another strain such as a strain immediately before fracture can advantageously reduce the reinforcement amount.
The installation range of the reinforcing member is not necessarily the entire surface of the structure member, but may be a portion of the structure member. In this case, the reinforcing member is installed to form an envelope surface in the circumferential direction of the structure member or to form a surface capable of being in contact with the portion of the surface of the structure member smoothly from the outside.
The installation range of the reinforcing member is selectively determined depending on a desired performance, shape or configuration of a structure member, or a method of fixing a reinforcing member. For example, if a plurality of structure members are located adjacent to each other, the reinforcing member may be installed such that an envelope surface is formed to cover the junction between the adjacent structure members, or it is penetratingly inserted into a hole or slit formed in the adjacent structure members. Further, if the structure member is a flat member such as a wall, a reinforcing member may be installed on only one of the opposite surfaces thereof, or a reinforcing member may be installed on the respective opposite surfaces thereof and closingly looped through a through-hole formed in the structure member.
The aforementioned reinforced structure may be formed by providing a reinforcing member to a structure member of an existing structural body, or may be formed by installing a reinforcing member to a structure member of a structural body to be newly constructed. When the reinforced structure is applied to a new structural body, the size and weight of the structure member can be reduced as compared to the conventional techniques to provide reduced seismic load. This makes it possible to achieve drastically reduced construction cost of the structural body, and significantly enlarged utilizable space of a living room or the like.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a structure member 1 with a reinforcing member 5.
FIG. 2 is a sectional view taken along line A-A of FIG. 1.
FIG. 3 is a perspective view of a structure member 1 with a reinforcing member 5.
FIG. 4 is a perspective view of a structure member 1 with a reinforcing member 5.
FIG. 5 is a graph showing the relationship between load and deformation in a structure member 1.
FIG. 6 is a graph showing the relationship between circumferential strain and deformation in a structure member 1.
FIG. 7 is a perspective view of a structure member divided by a gap.
FIG. 8 is a sectional perspective view of a structure member sliced perpendicular to the axis thereof in FIG. 7.
FIG. 9 is a graph showing a stress-stain relationship of a reinforcing member.
FIG. 10 is a graph showing the relationship between load and deformation in a non-reinforced model column.
FIG. 11 is a graph showing the relationship between load and deformation in a SRF-reinforced model column.
FIG. 12 is a graph showing the relationship peak load in a normal direction and deformation.
FIG. 13 is a graph showing the relationship elongation strain in the circumferential length of a structure member and deformation.
FIG. 14 is a perspective view of a wall-mounted column with a reinforcing member.
FIG. 15 is a sectional view of the wall-mounted column in FIG. 14.
FIG. 16 is a sectional view of the wall-mounted column in FIG. 14.
FIG. 17 is a perspective view of an H-section structure member 143 after reinforcement.
FIG. 18 is a perspective view of a hollow structure member 149 after reinforcement.
FIG. 19 is a partial sectional view of a reinforced member 181.
FIG. 20 is a graph showing the relationship between load and deformation with respect to the member 181.
FIG. 21 is a plan view of a polyester belt 199.
FIG. 22 is a perspective view showing an example of a column 205 reinforced by use of a beltlike reinforcement 201.
FIG. 23 is a perspective view showing an example of a column 205 reinforced by use of a beltlike reinforcement 201.
FIG. 24 an elevation of the column 205 shown in FIG. 23.
FIG. 25 is a sectional view of a surface portion of the column 205 shown in FIGS. 22 to 24.
FIG. 26 is a view showing an effective bond length between the beltlike reinforcement 201 and a crack 215.
FIG. 27 is a schematic view of the column 205 subjected to an axial force, bending, and a shear force.
FIG. 28 is a view showing a force which attempts to expand the crack 215 formed in the column 205.
FIG. 29 is a view showing the deformation of the column 205.
FIG. 30 is a view showing horizontal force Q applied to the column 205 and an envelope indicative of displacement hysteresis of the column 205.
FIG. 31 is a view showing the relationship among the horizontal displacement of the column 205, the vertical displacement of the column 205, and a horizontal force applied to the column 205.
FIG. 32 is a view showing restoring-force characteristics of the column 205.
FIG. 33 is a view showing the relationship between cumulative horizontal displacement Σδ_hand hysteretic absorbed energy W in the column 205.
FIG. 34 is a detailed view of FIG. 33.
FIG. 35 is a view showing the relationship between cumulative horizontal displacement Σδ_hand vertical displacement δ_v.
FIG. 36 is a perspective view showing a state in which connecting reinforcements 269 a and 269 b are disposed on the joint between a column 261 and a beam 263.
FIG. 37 is a perspective view showing a state in which a beltlike reinforcements 271 a and 271 b are disposed on the joint between the column 261 and the beam 263.
FIG. 38 is a sectional view of the joint between the column 261 and the beam 263 on which the connecting reinforcements 269 b, etc. are disposed.
FIG. 39 is a design flowchart for determining the amount of reinforcement.
FIG. 40 is a design flowchart for determining the amount of reinforcement.
FIG. 41 is a diagram showing the relationship between cumulative deformation and hysteretic absorbed energy with respect to a reinforced member.
FIG. 42 is a diagram showing the relationship between tensile stress and strain with respect to a reinforcement material impregnated with resin and a reinforcement material unimpregnated with resin.
FIG. 43 is a diagram showing properties (test specifications) of the tested columns, loading conditions, test results, and SRF reinforcement effects etc.
FIG. 44 is an explanatory diagram of the relationship between the width of a gap and the elongation of a reinforcing member.
FIG. 43 is a diagram showing the relationship between the tensile force of a reinforcing member and the relative displacement of a structure member in a SRF-reinforced structure.

BEST MODE FOR CARRYING OUT THE INVENTION

With reference to the drawings, various embodiment of the present invention will now be described in detail.
FIG. 1 is a perspective view of a structure member (or a member of a structural body) with a reinforcement member according to an embodiment of the present invention. FIG. 2 is a sectional view taken along the line A-A in FIG. 1. As shown in FIGS. I to 3, a structure member 1 comprises a substrate 3 with a reinforcing member 5. The reinforcing member 5 is installed, for example, in such a manner that it envelops a portion of the surface of the substrate 3 (see FIG. 1), or it encloses a given portion (periphery etc.) of the substrate (FIG. 3). The substrate 3 is principally a material constituting the structure member 1 subject to reinforcement, and a physical object to which the reinforcing member 5 is to be fixed. The shape and material of the substrate 3 are appropriately selected depending on a desired performance or function of the structure member 1. The substrate 3 is a structural material such as reinforced concrete, a non-structural material such as block or brick, or a filler material such as sand or granular resin. The reinforcing member 5 installed on the surface the substrate 3 acts to bear a stress of the substrate 3 while bridging between both sides of a fractured surface such as chap or crack (or gap) generated in the substrate.
In addition to the above function, a reinforcing member 5 according to a first mode of embodiment is composed of a woven body having all of extensibility (high ductility and high bendability), strength and elasticity, and adapted to be installed on the surface of or inside a substrate of a structural body to reinforce the substrate. The woven body characteristically has a Young's modulus equal to or less than that of the structure member (substrate), and a tensile fracture strain of 10% or more.
When the structure member includes plural kinds of primary substrates (materials), the term “Young's modulus of the structure member (substrate)” herein means the lowest one in the respective Young's moduluses of the materials.
As above, the reinforcing member has high ductility and high bendability, or extensibility. The term “high ductility” means to have a large fracture strain. The term “high bendability” means to readily cause a large bending deformation and shear deformation (high flexibility) without fracture.
Even if a substrate is deformed to have a gap or irregular surface, the reinforcing member having high ductility can constrain the substrate without fracture to maintain a desired reinforcement effect.
The reinforcing member having high bendability can be readily bent at an acute angle. Thus, the reinforcement can be installed along an irregular circumferential surface of a structure member, and can be deformed under load to have a fixed portion formed in conformity to the curvature or corner angle of a substrate.
The reinforcing member is required to have elasticity for generating a tensile force in response to change in the circumferential length of a substrate to bring out a geometrical constraint effect and coping with a repeated alternate load or the like. Preferably, the rigidity of the reinforcing member is greater at the initial stage of the generation of strain than immediately before fracture.
In the present invention, the Young's modulus of the woven body constituting the reinforcing member 5 is set to be equal to or less that that of the structure member. This is intended to reduce a stress acting on the boundary surface the reinforcing member and the substrate 3 when the reinforcing member starts deforming in response to the occurrence of deformation or crack in the structure member 1 due to a load acting on the substrate 3, so as to increase a limit deformation causing peeling in the boundary surface. Further, the tensile fracture strain of the woven body is set at 10% or more. Because in the design of structural bodies for an accidental load due to earthquake or the like, a design limit is generally about 2 to 4% of deformation in a structure member. Additionally considering a local-strain-concentration coefficient of 5, the reinforcing member would be not fractured in the design limit if the fracture strain is 10% or more. According to the results of loading tests of a structure member, in case where a reinforcing member including aramid fibers having several % of fracture strain was bonded on a surface of a structure member, the fracture of the reinforcing member was observed. On the other hand, in case where the structure member was reinforced by a SRF reinforcing member having 10% or more of fracture strain, no fracture was observed in the reinforcing member
By contrast, in the reinforcing member disclosed in the aforementioned Japanese Patent Laid-Open Publication No. 8-260715, the Young's modulus and fracture strain of aromatic polyamide fibers used therein are directly applicable. Thus, the Young's modulus is in the range of 80000 to 120000 MPa, and the tensile fracture strain is in the range of 2.5 to 4.5%. Further, when the aromatic polyamide fibers act as an actual reinforcing member, it will be an aromatic-polyamide-fiber-reinforced epoxy resin having higher bending and shear rigidities than those of the elemental fibers. As a result, the reinforcing member is likely to peel off over a wide range at the same time due to inability of following the deformation of a substrate. In this connection, the Young's modulus of concrete is about 20000 MPa, and the Young's modulus of hard wood such as oak is about 10000 MPa.
The Young's modulus of the woven body is preferably in the range of 1/2 to 1/20, more preferably 1/5 to 1/10, of that of the substrate. If the Young's modulus is less than the lower limit of the range (or the value of Young's modulus is excessively small), the reinforcing member has to be designed to have an increased thickness to obtain a desired reinforcement amount. This is economically inefficient. Further, as described later, a peeling-limit elongation (δ1: FIGS. 44 and 45) is increased, resulting in delayed response of the reinforcement effect and increased damage of the structure member.
Specifically, the Young's modulus of the reinforcing member is preferably in the range of about 500 to 5000 MPa, more preferably about 1000 to 1000 MPa.
Preferably, the tensile fracture strength of the woven body is in the range of 3 to 5 times of that of the structure member. Any local fracture of the structure member can be avoided by setting a stress concentration coefficient in the range of 3 to 5.
The thickness of the woven body is preferably in the range of 0.2 to 20 mm, more preferably 0.5 to 15 mm, particularly 1 to 10 mm. This range is desired to obtain an intended performance and facilitate handling.
Preferably, the material of strings constituting the woven body is polyester (fiber).
Preferably, the woven body has a bending deformation angle of 90-degree or more, and a shear deformation angle of 2-degree or more.
Preferably, the woven body is heat-set to allow a Young's modulus in a limit state to be greater than a Young's modulus immediately before fracture.
Preferably, the reinforcing member has an elongation strain in the range of 0.1% to 10% in the limit state.
A reinforcing member according to a second mode of embodiment is a tape-shape or sheet-shaped body made of a rubber-based or resin-based elastic material, and adapted to be installed on a surface of or inside a substrate of a structural body to reinforce the substrate. Further, the tape-shaped or sheet-shaped body has a Young's modulus equal to or less than that of the structure member, and a tensile fracture strain of 10% or more.
The Young's modulus of the tape-shaped or sheet-shaped body is preferably in the range of 1/2 to 1/20, more preferably 1/5 to 1/10, of that of the substrate. Specifically, the Young's modulus of the reinforcing member composed of the tape-shaped or sheet-shaped body is also preferably in the range of about 500 to 5000 MPa, more preferably about 1000 to 1000 MPa.
The thickness of the tape-shaped or sheet-shaped body is preferably in the range of 0.2 to 20 mm, more preferably 0.5 to 15 mm, particularly 1 to 10 mm.
Preferably, the tape-shaped or sheet-shaped body has a bending deformation angle of 90-degree or more, and a shear deformation angle of 2-degree or more.
The above factors of the reinforcing member according to the second mode of embodiment have been selectively determined in the same way as that in the reinforcing member according to the first mode of embodiment.
Two types of reinforced structures for a structural body according to third and fourth modes embodiment of the present invention comprise the reinforcing members according to the first and second modes of embodiment, respectively. Further, the reinforcing member is fixed on a surface of or inside a substrate constituting a structure member and including at least one material to reinforce the substrate.
In the reinforced structures, the reinforcing member is preferably fixed to the substrate in such a manner that an effective constraint range of the reinforcing member covers the pre-calculated width and length of a gap to be generated in the substrate in future.
In other words, the reinforcing member 5 is fixed to the substrate 3 in the structure member 1. More specifically, the reinforcing member 5 and the substrate 3 are constrained to one another. The mechanism of this constraint is roughly classified into two types. A first mechanism is a bonding constraint, and a second mechanism is a geometrical constraint.
The first mechanism or bonding constraint is achieved by bonding the reinforcing member 5 to the substrate 3. In this case, even after a gap is generate to create a zone where the bond is separate (herein after referred to as “free zone”), as long as a bonded portion exists around the free zone, the bonding constraint can be maintained.
The thickness of the layer of an adhesive applied to the reinforcing member or the substrate is preferably in the range of 5 to 90%, more preferably 20 to 40%, of the thickness of the reinforcing member.
The fixation is performed by placing the reinforcing member on the substrate through the layer of the adhesive and then applying a pressing force or a beating force to the reinforcing member while allowing a part of the adhesive to be infiltrated into the reinforcing member. In case of the woven body, the fixed portion of the reinforcing member preferably has a void ratio of 1.1 or more. In case of the tape-shaped or sheet-shaped body, the fixed portion of the reinforcing member preferably has a void ratio of 1.4 or more. In this way, gas generated during the curing reaction of the adhesive can be adequately released from the adhesive layer or the reinforcing member. Thus, an initial bonding ability can be achieved without generation of gas bubbles in the adhesive layer, defective bonding, and swollenness and float of the adhesive layer. The upper limit of the void ratio is not limited to a specific value, but preferably in the range of about 2 to 3.
Preferably, the bonding strength is less than the strength of the substrate. If the bonding strength is equal to or greater than the strength of the substrate, the fracture of the structure member causes the generation of a tensile force in the reinforcing member and the release of the bonding to annul the reinforcement effect in a wide range at the same time. The bonding strength is preferably in the range of 10 to 80% of peeling/shear fracture strength in the surface of the substrate applied with the adhesive. If the bonding strength is higher than the upper limit of the range, the structure member will be damaged in an operation of detaching the reinforcement. If the bonding strength is lower than the lower limit of the range, a desired reinforcement effect cannot be obtained. Specifically, the bonding strength is preferably in the range of about 1 to 2 N/mm². In this connection, the peeling/shear fracture strength of concrete is about in the range of 3 to 5 N/mm².
By contrast, in the reinforcing member disclosed in the aforementioned Japanese Patent Laid-Open Publication No. 8-260715, the epoxy resin to be impregnated also serves as an adhesive. Thus, if a structural body made of concrete is reinforced by this reinforcing member, the bonding strength will become higher than the strength of the substrate to cause the aforementioned problems.
While any suitable adhesive satisfying the above condition may be used, the adhesive is preferably a one-component, non-solvent adhesive. This one-component, non-solvent adhesive may include an epoxy-urethane-based, non-solvent, moisture-setting type adhesive. This type of adhesive advantageously has no odor, no open time and long lifetime.
The fixation of the reinforcing member to the structure member or the substrate can be performed without chamfering the structure member or the substrate and adjusting the unevenness of the surface of the structure member or the substrate. By contrast, in the reinforcing member disclosed in the aforementioned Japanese Patent Laid-Open Publication No. 8-260715, it is practically required to chamfer the substrate at R=10 mm or more due to aramid fibers as a primary component of the reinforcing member. If carbon fibers are used, R=20 mm or more of chamfering will be required.
In the reinforced structures according to the third and fourth modes of embodiment, the fixation can be achieved without the large bonding strength as described above. Thus, there is no need for any primer treatment and any anchoring operation after the fixation. For example, only by winding the reinforcing member around the structure member, even after peeling, the reinforcement effect can be maintained by the geometrical constraint.
The adhesive 11 may be applied to the reinforcing member 5 at a working site of the bonding operation. Alternatively, the adhesive 11 may be applied to the reinforcing member 5 in advance, and stored until the bonding operation. In these reinforced structures, in an operation of detaching or peeling the adhesive, the substrate 3 or the reinforcing member is never damaged while leaving the adhesive layer thereon.
When it is required to achieve the bonding constraint, as shown in FIG. 1, the reinforcing member 5 is installed in a range (reinforcing-member installation range 9) extending outward from a range (effective bonding constraint range 7) for reinforcing the structure member 1. The effective bonding constraint range 7 is selectively determined depending on a required performance or function of the structure member 1. The effective bonding constraint range 7 may be a portion of the surface of the structure member 1. In this case, the reinforcing member 5 is installed to form an envelope surface in the circumferential direction of the structure member 1 or to form a surface capable of being in contact with the portion of the surface of the structure member smoothly from the outside.
The second mechanism or geometrical constraint is achieved, for example, by bonding both ends of a reinforcing member and installing the reinforcing member in such a manner that it encloses a given portion (periphery etc.) of a substrate 3, as shown in FIG. 3. In this case, the substrate 3 and the reinforcing member 5 is geometrically connected together, and constrained to one another.
More specifically, in conjunction with the deformation of the substrate, the length of the closed or looped reinforcing member is changed to generate a tensile force in the reinforcing member. If the reinforcing member is installed in conformity to the curvature or corner angle of the substrate, the tensile force will cause the frictional force or bearing force between the reinforcing member and the substrate so that the substrate and the reinforcing member exert a constraint force against deformation to one another. In case where a reinforcing member is bonded in conformity with the corner angle of a substrate, it can be expected to have a geometrical constraint-like effect such that the bearing force of the bonded surface at the corner is increased by the tensile force of the reinforcing member to provide enhanced bonding strength.
While the geometrical constraint is changed depending on the shape of the substrate 3, the relative positional relationship between the reinforcing member 5 and the substrate 3, it can be maintained until the reinforcing member 5 is fractured even if the substrate 3 is fractured. On the other hand, the bonding constraint disappears when the substrate 3 is fractured, and the bonding strength becomes lower than a given value as described later.
The quantification of the effect of the reinforcing member (reinforcement effect model) will be described below. FIG. 4 is a perspective view showing a portion of a structure member 1 having the reinforcing member 5 installed thereon, wherein the reinforcing member 5 elastically constrains a substrate 3 having a gap 13. The gap is a crack or chap generated in the substrate 3. A gap width 15 (d) means the width of the gap 13.
Upon deformation of the structure member 1, a stress is concentrated on the reinforcing member and the surface of the structure member 1 adjacent to the gap 13 to cause the peeling of the reinforcing member 5 from the surface of the structure member 1. In the following description, this peeled area is referred to as “free zone 19”, and the length of the free zone 19 associated with the region having a width 23 (Δw) of the reinforcing member 5 is referred to as “free length (a)”. In the area where the bonding or geometrical constraint is achieved, the reinforcing member 5 and the structure member are constrained to one another.
In the following description, this constrained area is referred to as “constraint zone 21”, and the length of the constraint zone 21 associated with the region having the width 23 (Δw) of the reinforcing member 5 is referred to as “constraint length (a)”. When a free zone is generated, a fixation length (s) is reduced from a constraint length (b) by a factor of a free length (a). In this case, a certain shear force, such as a bonding or frictional force, acts between the reinforcing member 5 and the substrate 3 in a zone (fixation zone) of the fixation length (s=b−a). While it can be technically said that the constrained area is enlarged as the free length is increased, this hypothesis will be ignored in the following calculation in view of a risk-free approximate calculation.
Given that in a portion of the reinforcing member 5 of the width 23 (Δw)×the constrained zone 21 (constrained length (b)), an average value of shear stresses 18 acting between the surface of the substrate 3 and the non-peeled reinforcing member 5 is Tf, and a tensile force, Young's modulus and thickness in the free zone 19 of the reinforcing member 5 being q, E_fand t, respectively. The tensile force 17 and the resultant of the shear stresses 18 are balanced in the fixation zone, and thus the following relational expression is formulated. In the following relational expression, the reinforcing member is presupposed as an elastic body, and the elongation in the region of the fixation length is ignored because it is small as compared to the elongation in the free zone. $\begin{matrix} q = \frac{{dE}_{f} t Δ w}{a} = (b - a) τ_{f} Δ w & [1] \end{matrix}$
The following relational expression can be obtained by eliminating “a” from the expression [1], dividing by tΔw, and giving that a tensile stress of the reinforcing member 5 is σ_f. $\begin{matrix} σ_{f}^{2} - \frac{b}{t} τ_{f} σ_{f} + \frac{d}{t} E_{f} τ_{f} = 0 & [2] \end{matrix}$
From the condition of the real root of σ_f, it can be proved that a gap width d is between 0 (zero) and $\begin{matrix} d_{\max} = \frac{b^{2} τ_{f}}{4 E_{f} t} . & [3] \end{matrix}$
For a certain gap width d, two of σ_fwill be derived as a solution. Given that larger one of them is achieved, a maximum value σ_fmaxand a minimum value σ_fminof σ_fare expressed as follows: $\begin{matrix} σ_{f \max} = \frac{b}{t} τ_{f}, σ_{f \min} = 0.5 σ_{f \max} & [4] \end{matrix}$
σ_fmaxis a stress in the condition of the gap width d=0 or at the time when the gap 13 is just generated on the surface of the structure member 1. σ_fminis a stress at the time when the gap 13 is enlarged, and the gap width d reaches a value d_maxin the expression [3]. According to the expressions [1] to [3], when the tensile stress of the reinforcing member 5 is σ_fmin, the free length (a) is calculated as ½ of the constraint length (b). If the gap width d is increased at a value larger than dmax, the expression [1] will be invalid in view of dynamical theories, the free length (a) will be sharply increased until a certain constraint such as geometrical constraint is given again.
The change in the length (hereinafter referred to as “circumferential length”) L of the envelope (the circumference of the envelope surface) can be presupposed as the change in the total value d of the gap width across the circumference. Thus, the following formula is satisfied between a circumferential strain φ and the total value of the gap width measured along the circumference. In the following formula, L₀is the circumferential length before the generation of the gap.
d=φL₀ [5]
Further, given that the reinforcing member 5 is elongated only in the free zone (free length a) where the fixation between the reinforcing member 5 and the structure member 1 is separated, the following relational expression of the circumferential strain φ and the strain E_fof the reinforcing member by focusing on the elongation of the reinforcing member 5 installed to form the envelope surface: $\begin{matrix} \frac{a}{L_{0}} = \frac{Φ}{ɛ_{f}} & [6] \end{matrix}$
wherein a/L₀is an index indicating the level of the constraint, and thus hereinafter referred to as “constraint rate”.
The tensile force 17 (σ_f) of the reinforcing member 5 can be calculated as follows in accordance with the strain (ε_f) and Young's modulus (E_f) of the reinforcing member 5. In the following formula, a secant Young's modulus will be used if the Young's modulus of the reinforcing member is changed dependent on the strain thereof.
σ_f=ε_fE_f [7]
Given that after the structure member 1 is fractured by the action of repeated load, it can be approximated as a granular body, the following relational expression is satisfied: $\begin{matrix} σ_{f} = \frac{B}{2 t} σ_{3} & [8] \end{matrix}$
wherein B is the distance (sectional width) between the reinforcing members, and σ₃is a constraint pressure of the granular body.
The following relational expression can be obtained by applying the relationship between the primary stress σ_fand constraint pressure σ₃of the granular body to the expression [8]: $\begin{matrix} σ_{f} = \frac{B (1 - \sin φ)}{2 t (1 + \sin φ)} σ_{1} & [9] \end{matrix}$
In the state of axial compression, the value of the primary stress s₁can be approximated as a value derived from dividing a compressive force by a pressure-receiving sectional-area. On the other hand, under the condition of receiving a shear force, it is required to calculate with the inclusion of the influence of the shear force.
The relationship of the tensile force of the reinforcing member, the deformation causing a gap of the structure member and the fixation force is obtained from the expressions [3] to [7] and [9]. Further, since the deformation causing a gap would represent the level of the damage of the substrate, the relationship between the damage of the substrate and the tensile force (or strain) of the reinforcing member can also be obtained.
The above model is unconfined by the type of the gap 13. Specifically, the model is applicable to any gap 13 caused by any factor including a dynamical factor, such as bending or shear, and a material factor, such as temperature, dryness, expansion or deterioration. According to the model, particularly when the reinforcing member 5 is installed in a direction crossing to a gap 13 caused by shear (shear chap, shear fracture surface, etc.), it can elastically constrain the surrounding of the gap 13 to control a shear deformation at a finite value and maintain the toughness of the structure member 1.
Further, the above model is unconfined by the type of the substrate 3. The substrate 3 may be any construction material, such as reinforced concrete, steel framed reinforced concrete, steel frame, brick, block, gypsum or plaster board, precast concrete product, wood, rock, sand or resin. The substrate 3 may be an existing structural or non-structural martial or a newly installed material.
The installation of the reinforcing member 5 may be a portion of the structure member as long as it is wider than an area (effective bonding constraint range 7) corresponding to the constraint zone 21 (constraint length (b)) for the crack or gap 13. Referring to FIG. 1, the area of the effective bonding constraint range 7 in the reinforcing-material installation range 9 is an effective range.
According to the expressions [3] and [4], the reinforcement effect is superficially increased in proportion to the bonding strength. However, if the bonding strength is set at a value close to the full strength of the substrate 3 or the reinforcing member 5, the substrate 3 or the reinforcing member 5 will be locally fractured before generation of a free length (a) to annul the reinforcement effect. Thus, the bonding strength is required to be set at a level causing no fracture in the substrate 3 and the reinforcing member 5 in the above process.
The aforementioned model can be achieved if the reinforcing member 5 is not fractured by a stress concentration arising around a crack or gap or at a corner of the structure member 1 in connection with the generation and enlargement of the gap 1 in the structure member 1. Thus, it is also required to provide extensibility (large fracture strain) to the reinforcing member 5. While carbon fibers or aramid fibers have a large elastic coefficient and fracture strength, any material having a small fracture strain is not suitable as the reinforcing member in the first mode of embodiment and another after-mentioned mode of embodiment.
The model can also be achieved if the reinforcing member brings out a sufficient performance even after the adhesive layer between the substrate and the reinforcing member is partly fractured. Thus, a continuous-fiber reinforcing member whose performance is defined under the condition of a structure in which a a shear yield strength is increased as the deformation of the structure member is increased. Therefore, a shear load-deformation relationship has two extreme values, as described later in conjunction with FIGS. 5, 12, etc.
FIG. 5 is a graph schematically showing the above relationship between load and deformation. The horizontal axis represents a deformation (deformation angle) in a structure member 1, and the horizontal axis represents a load acting on the structure member 1. The shape of the curve is described by ten parameters or Q_max1, α Q_max, Q_mid, Q_min, Q_max2and R₁to R₅. Q_max1is an initial maximum vale of the load, α Q_maxbeing the load in a limit state (design ultimate state etc.), Q_minbeing a minimum value of the load, Q_midbeing the load by which the bonding constraint is released and shifted to the geometrical constraint, and Q_max2being the load by which the reinforcing member 5 is fractured, or the deformation of the structure member 1 reaches at an extreme value and becomes unable to bear any load. R₁to R₅are the deformations corresponding to Q_max1, α Q_max, Q_mid, Q_min, Q_max2, respectively. The limiting point 27 (Q_min, R₄) is a point where the structure member 1 is fractured by load, and starts exhibiting behaviors of a granular body.
FIG. 6 is a graph showing the relationship between circumferential strain and deformation in the structure member. The horizontal axis represents a deformation (deformation angle) in the structure member 1, and the horizontal axis represents a circumferential strain in the structure member 1. The change in an apparent volume, or a volume associated with an envelope surface, of the structure member 1 is expressed by a circumferential strain (strain in the circumferential length of the section of the structure member 1 in a direction perpendicular to the axis thereof and an axial strain (strain in the axis of the structure member 1). The circumferential strain φ is changed as shown in the graph 29 in response to the carbon or another fibers bound by resin are bonded on the surface of a substrate without float and wrinkle is not suitable as the reinforcing member in the first mode of embodiment and another after-mentioned mode of embodiment.
Further, the reinforcing member 5 is also required to have elasticity to bring out a control effect to the phenomenon that the gap 13 is opened and closed by a repeated alternate load.
The quantification of the performance of a structure member 1 (structure-member performance model) will be described below. The dynamic performance and durability of the structure member can be quantified in consideration of the performance of a substrate and a desired reinforcement effect. The following description will be made in conjunction with one example in which a substrate 3 of the structure member 1 is a bar-shaped member made of reinforced concrete, and the substrate 3 is reinforced by the reinforcing member 5 and subjected to repeated shear.
As mentioned in connection with the reinforcement effect model, even after a shear gap is generated in a structure member 1 due to a repeated shear force applied thereto, a shear force will be transmitted through the reinforcing member 5 across the gap to cause a bending deformation and maintain the toughness of the structure member 1. The reaction force of the reinforcing member 5 is borne by the bonding constraint until the tensile force of the reinforcing member 5 is increased up to σ_fminin the expression [4], and subsequently borne by the geometrically constraint.
Then, when the substrate 3 is increasingly fractured by the work of repeated load action to have dynamic characteristics such that they can be approximated as those of a granular body (dense sands) having a surface covered by an elastic body, change of the relationship between the load and the deformation in FIG. 5.
(R₁, φ₁), (R₂, φ₂), (R₃, φ₃), (R₄, φ₄) and (R₅, φ₅) in FIG. 6 correspond (R₁, Q_max1), (R₂, α Q_max), (R₃, Q_mid), (R₄, Q_min) and (R₅, Q_max2), respectively.
The circumferential strain is gradually increased as the bonding is separated to increase a free zone 19. In the range of R₃to R₄, the circumferential strain is kept approximately constant by the geometrical constraint. When the deformation goes beyond R₄, the circumferential strain will be increased again because the structure member 1 behaves as a granular body. The axial strain is changed in the same manner as that of the circumferential strain.
The result of an experimental verification will be described below. While the structure member is described as a column in the following description, it is not limited to such a column.
FIG. 7 shows the state when a region having the width 39 (H) of a structure member 31 reinforced by a reinforcing member 37 is divided into a first segmental member 33 a second segmental member 35 by a structural gap 41 (gap width 43 (d)), and the opposite ends of the divided structure member receive the action of a shear force 45 (Q). The reinforcing member 37 is installed to form an envelope surface in the circumferential direction of the structure member 31 or to form a surface capable of being in contact with the portion of the surface of the structure member smoothly from the outside. The shear force 45 is being transmitted between the first and second segmental members 33, 35 through the reinforcing member 37 in each section.
FIG. 8 is a perspective view of the section (thickness 47 (ΔH)) perpendicular to the axis of the structure member in FIG. 7. Each of shear forces, reinforcing-member tensile stresses 51 (σ_f), and tensile forces 53 (σ_cs) of concrete from the shear force 45(Q). Given that the Young's modulus of the reinforcing member 37 is E_f, a reinforcing-member strain ε_fcan be expressed by the following expression. $\begin{matrix} ɛ_{f} = \frac{σ_{f}}{E_{f}} = \frac{Q_{f}}{2 E_{f} Ht} & [11] \end{matrix}$
The result of an experimental test on the effect of the above reinforcing member, and the performance of a structure member having the reinforcing member installed thereon will be described below. The test was carried out using an RC column (SRF-reinforced model column) having the above reinforcing member installed thereon and a non-reinforced RC column (non-reinforced model column) (SRF: Soft Retrofitting for Failure). The outline of the test is shown as follows.
An axial force and a repeated shear force are applied to the column while constraining the rotation of the capital and base of the column.
A horizontal force is applied to the capital through a rigid frame having a loading point at the center of the column.
Under a displacement control, deformation angles of 1/400 to 4/400 are applied in the positive and negative displacements two times, and then deformation angles of 6/400, 8/400, 16/400, 24/400, 32/400, 48/400 and 64/400 are applied in the positive and negative displacements one time, and finally, a deformation angle of 200/900 as a limit of a pressure device is applied.
Fourteen cases were tested under a variable axial force and a constant axial force. Among these cases, the results of nine cases under a constant axial force were used to quantitatively evaluate the performance of the above SRF reinforcing member. and reinforcing bar acts on the structure member 31 (first and second segmental members 33, 35) and the reinforcing member 37. Among the shear forces, a first shear force to be transmitted from the upper surface of the first segmental member 33 to the lower surface of the second segmental member 35 through the reinforcing member 37 is defined as a transmission shear force 49 (ΔQ_f). While not shown, there is a second shear force to be transmitted in the opposite direction of the first shear force or from the upper surface of the second segmental member 35 to the lower surface of the first segmental member 33 at the same value as that of the first shear force.
Given that the tensile force 53 (σ_cs) is 0 (zero) for the purpose of simplifying the description without losing universality, the difference between the shear forces in the upper and lower surfaces of the first segmental member 33 provides the transmission shear force 49 (ΔQ_f). The same goes for the second segmental member 35.
Given that the thickness 47 (ΔH) is infinitely small, and a body force and a moment with an arm having a length in the thickness direction are ignored. Further, given that there is no distributed load, and the reinforcing member 37 bears only the tensile stress 51 for the purpose of simplicity. Furthermore, given that the transmission shear force 49 (ΔQ_f) acts to the reinforcing member 37 such that the front-side and back-side tensile stresses 51 (σ_f) become equal to each other, and ΔQ/ΔH is constant, the following relation is satisfied in view of a balance expression: $\begin{matrix} σ_{f} = \frac{Q_{f}}{2 H_{t}} & [10] \end{matrix}$
wherein t is the thickness of the reinforcing member 37, and Q_fis a value derived by eliminating the shear forces transmitted through concrete and reinforcing bar
FIG. 43 is a chart showing properties (test specifications) of the tested columns, loading conditions, test results, and SRF reinforcement effects, on the nine cases under a constant axial force.
FIG. 10 is a graph showing the relationship between horizontal load and deformation (restoring force characteristic) on the non-reinforced model column (Case 8). The horizontal axis represents a deformation (δ (mm)), and the vertical axis represents a horizontal load (Q (kN)). In a deformation angle of 0.6% (1/166), a maximum load was increased up to 237 kH (Q_max), and the non-reinforced model column could not bear the axial force (η=0.3) in a cycle having a deformation angle of greater than 1.5%.
FIG. 11 a graph showing the relationship between horizontal load and deformation (restoring force characteristic) on the SRF-reinforced model column (Case 9). The horizontal axis represents a deformation (δ (mm)), and the vertical axis represents a horizontal load (Q (kN)). The model column was reinforced by bonding a reinforcing member formed of a polyester woven fabric having a thickness (t) of 4 mm, around the model column. The properties of the reinforcing member are shown in FIG. 43. The bonding strength is about 1 MPa.
In a deformation angle of 0.9%, a maximum load was increased up to 258 kH (Q_max), and the horizontal load is maintained at a value of 80% (0.8 Q_max) or more of a maximum horizontal load until the deformation angle goes beyond 4.0%. Given that 0.8 Q_maxis a design ultimate state, an ultimate toughness coefficient (p) is 6.
In the subsequent loading cycles, the peak load is gradually reduced, and minimized (61: minimum point of the peak load) at a deformation angle of 64/400. In the next cycle, the peak load is increased.
FIG. 12 is a graph showing the relationship between the peak value of the horizontal load and the deformation in each of the loading cycles, on the nine cases under a constant axial force in FIG. 43. The horizontal axis represents a deformation angle (R (%)), and the vertical axis represents a maximum horizontal load (peak load) in a positive direction in each of the loading cycles. Numerals in the figure indicate the case numbers illustrated in FIG. 43.
Referring to FIG. 11, in all of the reinforced cases ( Cases 2, 3, 5, 9 and 13), a maximum point (maximum value Q_max), a minimum point (minimum value Q_min) and an apparent gradientchange point (Q_mid: peak load at the change point) are observed. For example, in Case 9, a maximum point 63, a minimum point 65 and a gradient-change point 67 are observed. The Case 2 with a small reinforcement amount has a smaller R₄(deformation angle at the minimum point) than that of other cases.
For each of these cases, Q_mid/Q_maxand Q_min/Q_maxwere calculated based on the above maximum point, minimum point and gradient-change point. The result is shown in FIG. 62. Q_midQ_maxbecomes approximately equal to a theoretical value of 0.5 according to the expression [4]. Q_minis reduced from Q_midonly by about 10% thereof. This result supports the validity of the aforementioned quantification of the effect of the reinforcing member.
FIG. 13 is a graph showing the relation between structure-member circumferential-length elongation strain and deformation. The horizontal axis represents a deformation angle (R (%)), and the vertical axis of a structure-member circumferential-length elongation strain (4) (%)). The measurement was performed along five lines provided around the reinforced columns at even intervals. As a result, all of the lines were uniformly elongated, which supported the validity of the expression [10]. The average values of the test results was plotted to prepare FIG 13.
Referring to FIGS. 12 and 13, it is proved that the change of a peak load and the change of a circumferential strain in each of the cycles have an extremely strong correlation as with FIGS. 5 and 6 which have been schematically shown. That is, most of a shear force after the maximum load Q_maxis borne by the reinforcing member according to the mechanism which has been described in conjunction with FIGS. 7 and 8.
In this way, the design calculation can be performed according to the aforementioned quantification models of the reinforcement effect and the performance of a structure member having a reinforcing member installed thereon.
For the purpose of comparison, the index (reinforcement efficiency) K representing the reinforcement effect, which is defined by the following expression [12] according to a method of Japan Society of Civil Engineers, was calculated under the condition of a design ultimate state of 0.8 Q_max:
S=S _c +S _s +KS _s(A _f ,f _fud) [12]
wherein S is a shear strength after reinforcement, S_cbeing a shear strength calculated from a concrete strength etc., S_sbeing a shear strength calculated from a shear reinforcing bar etc., and S_s(A_f, f_fud) being a reinforcing-member section A_fand a reinforcing-member strength f_fudwhich are substituted with corresponding values in a SRF reinforcing member. FIG. 62 shows the calculated K (reinforcement efficiency).
Further, a design strength σ_fdof the reinforcing member was calculated back according to a method defined in the design/installation manual for continuous-fiber reinforcement of Architectural Institute of Japan. FIG. 43 shows the ratio (reinforcement efficiency: σ_fd/σ_fmax) of the design strength σ_fdto a fracture strength σ_fmaxof a SRF reinforcing member. In the above calculation, a shear strength S after reinforcement was calculated by determining a shear margin from a roughness coefficient. The calculation was also performed on the assumption that a yield deformation angle was 1/250 in all of the cases.
The reinforcement efficiencies in the both methods (K, σ_fd/σ_fmax) are an approximately the same value of about 0.2 in the case of F_c=3.5 MPa. In the case of F_c=18 MPa, it is observed that the value tends to be increased. In particular, this tendency is significant in the latter method (σ_fd/σ_fmax). This would result from evaluating the reinforcement effect as the square root of a reinforcement amount. On the reinforcement efficiency K, there have been reported experimental values in the range of 0.8 to 1.0 for carbon fibers, and about 0.4 for aramid fibers.
In the above test, a small value or about 0.2 less than that in the aforementioned conventional techniques and 1.0 in a reinforcing bar is obtained. This results from the difference in the material or a low Young's modulus of the reinforcing member, and the methodological or structural difference or a mechanism based on the peeling and displacement caused between the reinforcing member and a substrate.
The result obtained by calculating the circumferential strain in the design ultimate state (0.8 Q_max) from an actually measured circumferential length is shown in FIG. 62. An actually measured ultimate circumferential strain (φ₂) is in the range of 0.2 to 0.4%, and thus the damage level of the inside of the structure member is equivalent to that in the conventional techniques such as the reinforcement using carbon fibers.
A reinforcing-member strain (ε_f) was calculated from an actually measured shear load (Q) (see the expression [11]), and then a constraint rate (a/L₀) was calculated from the calculated reinforcing-member strain (ε_f) and an actually measured circumferential strain (φ)) (see the expression [6]). This constraint rate (a/L₀) is shown in FIG. 62. The constraint rate (a/L₀) is the ratio of a free length (a) to a circumferential length (L₀).
In this test, the tested reinforced column receives a shear force from one direction. For example, given that when a gap is generated in a surface parallel to a direction of the shear force and thereby a bonding constraint is completely released and shifted to a geometrical constraint, two surfaces of the circumference of a square section provide resistance, the constraint rate (a/L₀) is theoretically 0.5.
Referring to FIG. 43, the tested reinforced column has a constraint rate (a/L₀)<0.5 in Cases 3 and 5, and a constraint rate (a/L₀)>0.5 in Cases 9 and 13. Thus, it can be said that in the design ultimate state, while a bonding constraint in Cases 3 and 5 having a deformation angle R₂of 1 to 2% is still effective, a bonding constraint in Cases 9 and 13 having a deformation angle R₂of 4 to 6% is released and completely shifted to a geometrical constraint.
As in the above observation on the test results, the validity of the model for the effect of a reinforcing member (reinforcement effect model) and the model for the performance of a structure member with a reinforcing member installed thereon (structure-member performance model) has been verified. It is understood that the aforementioned numerical values are experimental values, and a safety factor coping with variations must be used in actual designs.
A method for determining the material, thickness, installation range and others (or for designing) of the reinforcing member of the present invention will be described below.
FIGS. 39 and 40 are design flowcharts for a reinforcement amount in a process of reinforcing a structure member through a method of the present invention. With reference to the flowcharts in FIGS. 39 and 40, a method of determining reinforcement parameters will be described below.
As shown in FIG. 39, limit conditions of the weight, shape, function and others of a structural body are first determined (Step 301). Concurrently, the amplitude, cycle or period, duration and energy of a sudden external force likely to act on the structural body are determined (Step 302). Among the sudden external force likely to act on the structural body, a burden share to be borne by a substrate of the structural body, such as reinforcing bar and concrete, is also determined (Step 303).
Then, in a design process (a) of determining parameters of a structure member when a structural body or a structure member is newly constructed, the parameters of the structure member are determined in consideration of the data determined in Steps 301 to 303 (Step 304). The parameters of the structure member may be determined using conventional structural design/calculation methods or any other suitable reinforcement manuals.
Then, Among each of a load in ordinary condition, such as the weight of the structure member itself, and the sudden external force, a burden share to be borne by a method of the present invention is determined (Step 305). Specifically, this step is intended to determine the type, property, and magnitude (amplitude, period, duration, and energy) of the sudden external force to be borne by the method, structure or material of the present invention. These data may be obtained by subtracting the energy of a sudden external force bearable with other factors than the reinforcement according to the method of the present invention (the burden share of the substrate etc. determined in Step 303) from the total energy of the sudden external force likely to act on the structural body in the durable term thereof, which has been determined in Step 301. Thus, if the reinforcement of the present invention is used in a structural design for a new construction, the materials and/or parameters of a structure member can be determined in an economically advantageous manner by a factor of the reinforcement of the present invention.
In a design process (b) involving no determination of any parameter of a structure member, for example, in a design process of reinforcing an existing structural body or structure member using the reinforcing member, the data in Step 305 are determined from the data determined in Steps 302 and 303. In this process, such data may be obtained by subtracting a sudden external force bearable with other factors than the reinforcement according to the method of the present invention from the total energy of the sudden external force likely to act on the structural body in the durable term thereof, as with the process (a).
Then, the amplitude and energy of a sectional force to act on the structure member are calculated (Step 306). Specifically, based of the type, property and magnitude of the sudden external force determined in Step 302, the amplitude and magnitude of a sectional force (shear force, axial force, bending moment, etc.) to act on a structure member including a reinforced structure member and other structure members, and a deformation (shear strain, axial strain, bending strain, etc.) of the structure member. Concurrently, the displacement amplitude and vibrational energy of the entire structure body to be induced by the sudden external force are calculated (Step 307).
The data in Step 306 or 307 may be rigorously calculated by performing a structural analysis calculation, such as a finite element method or frame analysis method taking account of a restoring force characteristic of a reinforced structure member and other structure members as shown in FIG. 51. Alternatively, the data in Step 306 or 307 may be calculated by simplifying a structural system and setting assumptions such as energy formulas, as in practical structural designs. Except that an associated deformation range is wider than that in a conventional calculation, the calculations in Steps 306 or 307 can be performed in the same manner as that in a structural design for a structure member having a known restoring force characteristic.
Then, the relationship of a reinforcement amount, a restoring force characteristic and an axial strain of the reinforced structure member is determined (Step 308). The data in Step 308 are determined by the calculations in Steps 306 and 307. In Step 308, it is generally required to perform a feedback from 310 to Steps 306 and 307 through Steps 308, as indicated by the dashed lines of FIG. 59.
Then, limit conditions of the function, usability, recoverability and others of the structural body after the action of the sudden external force such as a seismic force are determined (Step 309), and the determined limit conditions are compared with the displacement amplitude and vibration energy of the structural body calculated in Step 307 to determine reinforcement parameters (Step 310).
Specifically, the reinforcement parameters are determined by comparing the deformation of the structural body calculated in Steps 306 to 308 with an allowable deformation amount to be derived from the conditions determined in Step 309 or the use conditions of the structural body after the action of the sudden external force such as a seismic force. Step 310 is performed in consideration of the limit conditions of the weight, shape, function and others of the structural body which have been determined in Step 301.
If the conditions in Step 309 are determined based on the policy of simply preventing collapse against a large earthquake, the allowable deformation can be set at a large value. If a large deformation involves the risk of disaster such as derailment even immediately after occurrence of a large earthquake, as in an elevated railroad for the bullet train, the reinforcement amount will be determined in consideration of such a factor.
Further, if a design ultimate state is defined by a load-withstanding capacity (strength) corresponding to a given deformation angle of a structure member, the reinforcing member can be designed by the following process.
<1> Among a shear strength Q_uexpected to a structure member in a design ultimate state, a shear strength Q_futo be shared by the reinforcing member is determined.
<2> A allowable damage in the structure member is expressed by the total value du of a gap width on the circumference of the structure member, and the value du is converted into a reinforcing-member strain ε_fu.
<3> A reinforcement amount (thickness t) is calculated from Q_fu, ε_fu, a stress distribution in the inside of the structure member and a Young's modulus of the reinforcing member E_f.
In the above Steps <1> to <3>, the expressions [5] to [11] or modified expressions obtained by modifying the expressions [5] to [11] according to the conditions of the structure member. In this case, the reinforcement design has to be performed using a sufficient safety factor for a fracture strain because there is a possibility of causing a strain several times larger than the reinforcing-member strain ε_fin the expression [11]. Further, in the calculation of Q_f, a shear force transmitted by a substrate (a shear force transmitted by concrete, reinforcing bar or the like, etc.) may be subtracted, or the subtraction of this shear force may be set at 0 (zero) on the safe side.
A load-withstanding capacity of the structure member after the structure member goes beyond the above design ultimate state can also be calculated using the expressions [8] and [9]. However, in an actual design, the performance of the structure member and the reinforcement amount are experimentally checked as needed as in a conventional design for reinforced concrete members.
The expressions [5] to [11] are valid even if the substrate is not a structural material such as concrete. Therefore, a structure member can be produced using a substrate consisting of a material, such as brick or block, which has been considered as a non-structural material, However, if the rigidity of a substrate is less than that of the reinforcing member, the deformation of the substrate will be increased before development of a reinforcement effect, and a design process including a calculation required for taking account of the increase deformation will be complicated as compared to the above process. Thus, the material of the reinforcing member is selected such that the Young's modulus of the reinforcing member is less than that of the substrate, as described above. However, if the Young's modulus of the reinforcing member is excessive low, the thickness of the reinforcing member required for obtaining a desired reinforcement effect will be increased as shown in the expressions [3] and [11]. Specifically, the material of the reinforcing member is selected from one having a Young's modulus preferably in the range of about 1/2 to 1/20, more preferably about 1/5 to 1/10, of that of the substrate.
The bonding constraint mechanism becomes effective for a larger gap and can suppress the deformation (circumferential strain) of the substrate at a smaller value as the reinforcing member has a larger Young's modulus in the design ultimate state. This deformation (circumferential strain) of the substrate is quantified by the expressions [3] and [11].
FIG. 9 is a graph showing a stress-strain relationship of the reinforcing member. The horizontal axis represents a strain (ε) of the reinforcing member, and the vertical axis represents a stress (σ_f) of the reinforcing member. As described above, the reinforcing member is required to have extensibility (large fracture strain). In this regard, the design for the reinforcing member and others is preferably performed in consideration of the curve of the stress-strain relationship as shown in FIG. 9.
Preferably, on the curve of the stress-strain relationship in FIG. 9, the ratio 59 (σ_fu/ε_fu) of a stress a fu of the reinforcing member to ε_fuof the reinforcing member in a design ultimate state 57 of a structure member is defined as a Young's modulus E_fof the reinforcing member in the design ultimate state, and the design of the reinforcing member and others is performed using the Young's modulus E_f, and a fracture strain ε_maxand fracture stress (strength) σ_maxof the reinforcing member The reinforcing member is selected to satisfy a desired performance of the reinforced structural with reference to the expressions [1] to [9]. When a polyester woven fabric or the like is used as the reinforcing member, it may be heated to provide a tensile force thereto, and then cooled while maintaining the tensile force or subjected to a treatment for impregnating the reinforcing member with resin (resin impregnation treatment), to provide E_flarger than σ_fu/ε_fu. The reinforcing member subjected to the above treatment can have a higher reinforcement efficient (reinforcement effect per unit thickness) than that of the reinforcing member without the treatment, to achieve a reduced material cost.
A reinforced structure will be described below in conjunction with an example where a structure member is a walled column. FIG. 14 is a perspective view of a walled column with the reinforcing member installed thereon. The walled column comprises a column 71 and a wall 73. The reinforcing member 75 is installed in such a manner it is wound around the column 71 and bonded on a reinforcing-member installation range 79. The reinforcing-member installation range 79 has a larger area than that of an effective bonding constraint range 77. The effective bonding constraint range 77 corresponds to a given constraint length (b). The wall 73 is formed with no through-hole for installing the reinforcing member 75.
An epoxy-urethane based one-component adhesive (bonding strength T_f=1 MPa) is used for the bonding. A polyester sheet member (Young's modulus E_f=2100 MPa, thickness t=2 mm) is used as the reinforcing member 75.
Given that a shear force applied in X direction causes a gap in a surface parallel to X direction, a restraint length (b) allowing the bonding constraint to be effectively maintained until the total (d) of the gap width measured along a circumferential length parallel to X axis is increased up to 2 mm is calculated as b=1183 mm according to the expression [3]. Given the a safety factor is 2, a design constraint length (bd) is about 40 cm.
FIG. 15 is a sectional view of the walled column 69 in FIG. 14. The design constraint length (b_d) corresponds to the effective bonding constraint range 77 in FIGS. 14 and 15.
While a shear bearing force of the walled column 69 is obtained by assigning the dimensions of the column 71, the strength of the reinforcing member 75, the strength of the adhesive and others to the expressions [4] and [10], it is desired to experimentally check it as needed because the reinforcement effect and the geometrical restraint limit are different from those in case where the reinforcing member is fully wound around the column.
A restoring force characteristic in the state after the shear force goes beyond the design ultimate state to cause fracture of the walled column 69 and thereby the bonding restraint is completely released and shifted to the geometrical restraint can be calculated according to the expressions [8] an [9].
In this state, at the joint portion between the column 71 and the wall 73, the stress af of the reinforcing member 75 is transmitted through the inside of the substrate. Thus, the limit ((Q_max2, R₅): FIG. 5) of the validity of the geometrical restraint is determined by smaller one of the strength of the reinforcing member and the strength of the substrate at the joint portion. At any rate, the geometrical restraint can be maintained up until the limit (Q_max2, R₅) without forming a hole or the like in the walled column 69 and penetrating the reinforcing member therethrough.
FIG. 16 is a sectional view of the walled column 69 in FIG. 14. While the reinforcing member 75 installed around the column 71 is opened at the joint plane between the column 71 and the wall 73, a portion of the column 71 in this open zone 183 is constrained by the wall 73 having the reinforcing member 75 installed thereon. Thus, the entire circumferential of the column 71 is constrained by the reinforcing member 75 and the wall 73 having the reinforcing member 75 installed thereon. In this case, the geometrical constraint is achieved in an effective geometrical constraint range 81.
Alternatively, a given reinforcement effect can be obtained by installing the reinforcing member on only one of the surfaces of a structure member such as wall. Further, a earthquake-resisting wall may be formed by placing a pair of boards, such as precast concrete boards, in parallel with one another between two existing columns to form a wall, pouring concrete or filling sands or the like into the space between the boards, and installing the reinforcing member around the wall and/or the columns.
Thus, according to the above reinforced structure, the reinforcing member having a given rigidity and extensibility is installed a portion of the surface of a structure member to be reinforced, to reinforce the structure member. Thus, the reinforcement can be applied to a structure member having any shape such as a convexo-concave or irregular shape. In addition, the reinforcing member can be installed without forming any hole or the like in a structure member subject to reinforcement. Therefore, a reinforced structure excellent in toughness and load-withstanding capacity can be constructed quickly and readily at a low cost.
Further, the reinforcement effect of the reinforcing member and the performance of the reinforced structure with the reinforcing member can be quantified and/or evaluated according to the aforementioned reinforcement effect model and structure-member performance model. Thus, the reinforcing member can be adequately selected and designed depending on a structure member subject to reinforcement.
As seen in the reinforcement effect model and the structure-member performance model, the reinforcing member and the adhesive according to the first mode of embodiment can be effectively selected depending the material, category and type (existing or new construction, etc.) of a structure member. Thus, the labor load and cost for constructing the reinforced structure having a desired performance and preparing/installing the reinforcing member having a desired reinforcing effect or quake-resistance effect can be constructed can be reduced while shortening a construction period.
As a substitute for the reinforcing member 75, a strip-shaped polyester belt 199 as shown in FIG. 21 may be used. The material of the polyester belt 199 may be polyester-based fibers for use in bell rope or the like. While a reinforcing sheet such as a construction sheet has a strength in the range of 500 to 1000 kgf/3 cm width, the polyester belt 199 has a strength of about 15000 kgf/5 cm width.
Another reinforced structure will be described below in conjunction with an example where a structure member has an H shape. FIG. 17 is a perspective view of an H-shaped structure member 143 after reinforcement. As shown in FIG. 17, the H-shaped structure member 143 is reinforced using a reinforcing member 145 and a granular filler material 147.
The sheet-shaped reinforcing member 145 is shaped into a cylindrical shape and disposed around the H-shaped structure member 143 to form a space therebetween. The granular filler material 147 is filled in the space between the H-shaped structure member 143 and the reinforcing member 145. For example, a fiber or rubber-based sheet material may be used for the reinforcing member 145. For example, the filler material 147 may be a natural granular material, such as sands, or an artificial granular material, such as resin.
The glandular filler material 147 transmits a stress to the reinforcing member 145 while being deformed in connection with energy loss. Thus, differently from the conventional reinforcing techniques such as continuous fibers or steel-plate wrapping, there is no need for fixing the filler material with resin or adhesive. Even if the filler material is bonded or fixed for the reason of construction, the bonding or fixation may be performed in a temporary level allowing the shape of the filler material to be held under ordinary loading or in earth tremor.
This type of reinforced structure may be used to reinforce a structure member having a complicated sectional shape, as well as the H-shaped structure member 143. In this type of reinforced structure, when the structure member is deformed in connection with an apparent volume expansion, the granular filler material 147 transmits the apparent volume expansion to the reinforcing member to provide enhanced reinforcement effect. Further, the granular filler material may be formed of an inorganic noncombustible material having high heat capacity to have an additional effect of protecting the H-shaped structure member 143 from heat.
Still another reinforced structure will be described below in conjunction with an example where a structure member is hollow. FIG. 18 is a perspective view of a hollow structure member 149 after reinforcement. As shown in FIG. 18, the hollow structure member 149 is reinforced using a reinforcing member 145 and a granular filler material 147.
The sheet-shaped reinforcing member 145 is installed on and around the outer surface of the cylindrical hollow structure member 148. The inside of the hollow structure member 149 is filled with the granular filler material 145. For example, a fiber or rubber-based sheet material may be used for the reinforcing member 145. For example, the filler material 147 may be a natural granular material, such as sands, or an artificial granular material, such as resin.
The granular filling material 147 is installed to fill the space of the hollow structure member 149. In addition, the glandular filler material 147 transmits a stress to the reinforcing member 145 while being deformed in connection with energy loss. Thus, there is no need for solidifying the filler material filled in the inside of the structure member as in concrete used in a concrete-filling steel-pipe construction method.
In this reinforced structure, when a hollow structure member is reinforced, the granular filler material 147 is installed inside the structure member to provide enhanced reinforcement effect. The filler material acts to transmit to the reinforcing member 145 an apparent volume expansion cased when the hollow structure member 149 is fractured in connection with energy loss. While the hollow structure member in the above example has a circular sectional shape, the present invention is not limited to such a shape.
In addition, in order to reinforce the H-shaped structure member 143 or the hollow structure member 149 used the glandular filler material 147, compounding this reinforced structure and other reinforced structure can be applied.
Next, an example of the reinforced structure in case of using plurality of reinforcements will be described. FIG. 19 is a partial sectional view of a reinforced member 181. In FIG. 19, the member 181 is reinforced by use of a protective reinforcement 183, a reinforcement 185, a reinforcement 187, and a protective reinforcement 189.
The protective reinforcement 183, the reinforcement 185, the reinforcement 187, and the protective reinforcement 189 are sequentially, from inside to outside, disposed on the member 181. The protective reinforcement 183 is disposed in order to protect the reinforcements 185 and 187 and the protective reinforcement 189 from the action of the member 181. For example, when the member 181 is made of a material, such as concrete, from which alkali separate outs, and the reinforcements 185 and 187 and the protective reinforcement 189 are made of a material, such as polyester fiber, of low alkali resistance, the protective reinforcement 183 is made of a material, such as a resin, which has a function to prevent separation of alkali from the member 181.
The protective reinforcement 189 is disposed in order to prevent a deterioration in the function of the protective reinforcement 183 and the reinforcements 185 and 187 which would otherwise result from the action of substances in the external environment. For example, when the protective reinforcement 183 and the reinforcements 185 and 187 are polyester-fiber sheets or the like, these reinforcements are likely to be deteriorated by ultraviolet rays. Thus, the protective reinforcement 189 is made of epoxy, urethane, or a like resin to thereby prevent a deterioration of the reinforcements disposed inside the same. A fireproof belt can also be used as the protective reinforcement 189.
The reinforcement 185 and the reinforcement 187 differ in a reinforcement effect on the member 181. For example, the reinforcement 187 is made of polyester fiber or the like, and the reinforcement 185 is made of a resin or fiber impregnated with resin. In this case, the reinforcement 187 exhibits a reinforcement effect at up to a large strain (up to about 15%) of the member 181, whereas the reinforcement 185 exhibits a reinforcement effect at a low strain (not greater than 1%) of the member 181.
When the member 181 is to be reinforced merely by use of a polyester fiber reinforcement, the reinforcement must assume a large thickness in order to exhibit a reinforcement effect at the stage of a small strain of the member 181, since the reinforcement is smaller in Young's modulus than the member 181. However, through combined use of the polyester fiber reinforcement and a reinforcement made of a material, such as a resin or fiber impregnated with resin, having a large Young's modulus, the polyester fiber reinforcement thinner than that used solely for reinforcing the member 181 can exhibit a reinforcement effect even at a small strain (not greater than 1%) of the member 181. Also, being bonded directly to the surface of the member 181 or protective reinforcement 183, the reinforcement 185 can exhibit a reinforcement effect at small strain. The protective reinforcement 183 assumes, as needed, a function for transmitting a shear force induced between the surface of the member 181 and the reinforcement 185. For example, a resin primer is used as the protective reinforcement 183.
The reinforcement 185 and the reinforcement 187 may differ in a mechanism for yielding a reinforcement effect so as to exhibit a reinforcement effect under different load conditions and over the range of deformation. For example, there are combined a method in which part of a shear force imposed on the member 181 is directly borne by a reinforcement, and a method in which the expansion of an apparent volume of the member 181 is restrained.
Material and configuration of the reinforcement 187 can be such that a reinforcement effect is yielded through restraint of the expansion of an apparent volume. With the aim of enhancing the load bearing capacity of the member 181 through enhancement of shear fracture yield strength of the member 181, the reinforcement 185 is made of an iron plate, carbon fiber, aramid fiber or the like. Through direct transmission of a shear force between the member 181 and the reinforcement 185, the shear force is shared between the member 181 and the reinforcement 185, whereby the member 181 is reinforced. Also, a polyester sheet or belt or the like whose rigidity is enhanced through impregnation with resin or through application of adhesive to the entire surface thereof can be used as the reinforcement 185. This yields a merit in that the reinforcement 185 and the reinforcement 187 can be continuously laid.
FIG. 20 is a graph showing the relationship between load and deformation with respect to the member 181 which is reinforced by means of a multilayer configuration as shown in FIG. 19. In FIG. 20, the vertical axis represents load, and the horizontal axis represents deformation. The load represents section forces of the member 181, such as axial force, bending moment, shear force, etc. The deformation represents deformations corresponding to the section forces; specifically, axial contraction, flexural modulus, shearing strain, etc. A curve 193 which represents the case of reinforcement by means of multilayer configuration indicates that the member 181 has load bearing capacity over a wider range of deformation as compared to the case of no reinforcement employed as represented by a curve 191.
FIG. 20 shows an ordinary example in which the effective deformation range of the reinforcement 185 does not overlap with that of the reinforcement 187; i.e., a slight reduction in load bearing capacity occurs between an effective range 195 of the reinforcement 185 and an effective range 197 of the reinforcement 187. The reduction of load bearing capacity can be avoided by overlapping the effective deformation ranges of the reinforcements 185 and 187.
According to this reinforced structure, reinforcements of different characteristics are disposed in layers on the exterior of a member, to thereby exhibit a reinforcement effect over a wide range of load conditions of the member as well as over a wide range of conditions of the external environment. The member 181 is not limited to a concrete member or the like but may be the filler 147 shown in FIGS. 17 and 18. In this case, through employment of the filler 147 that yields an effect equivalent to that yielded by the protective reinforcement 183, the protective reinforcement 183 may be omitted.
Notably, a beltlike reinforcement of high strength and rigidity, such as the polyester belt 199, can be used as the reinforcement 185 to be bonded directly to the surface of the member 181 or protective reinforcement 183. Since the polyester belt 199 can be woven into texture that exhibits greater Young's modulus per unit width as compared with a polyester sheet, the polyester belt 199 can be used as the reinforcement 185, which exhibits a reinforcement effect at the stage of small strain. For example, according to the tensile test result of the polyester belt 199 having a width of 64 mm and a thickness of 4 mm, strain is 2% under a load of 2500 kgf.
When the polyester belt 199 is used as the reinforcement 185, a column 205 shown in FIGS. 22 to 25 corresponds to the member 181 of FIG. 19. A reinforcement method by use of the polyester belt 199 as shown in FIGS. 22 to 25 will be described in the subsequent section of an eighth embodiment.
FIG. 21 is a plan view of the polyester belt 199; FIGS. 22 and 23 are perspective views showing examples of the column 205 reinforced by use of a beltlike reinforcement 201; and FIG. 24 is an elevation of the column 205 shown in FIG. 23.
First, reinforcement shown in FIG. 22 will be described. In FIG. 22, a plurality of beltlike reinforcements 201 are disposed at predetermined intervals on the column 205 in such a manner as to be wound about the column 205. End portions of each of the beltlike reinforcements 201, which are wound about the column 205, can be connected together by means of bonding and/or a clasp, which are mechanical joints. Use of mechanical joints can implement reinforcement in a short period of time and is thus suited for urgent reinforcement to be performed immediately after an earthquake disaster. Beltlike reinforcements 203 bonded axially to the column 205 can be expected to yield the effect of controlling a crack(s) extending along a direction intersecting the same.
Next, reinforcement shown in FIGS. 23 and 24 will be described. The beltlike reinforcement 201 is compactly wound about the column 205 shown in FIGS. 23 and 24. While tension is imposed on the beltlike reinforcement 201 in the direction of arrow C, the beitlike reinforcement 201 is wound onto the column 205 in the direction of arrow D, thereby enhancing a reinforcement effect. The beltlike reinforcement 201 is bonded directly to the column 205. Comer portions of the column 205 are not particularly required to be chamfered or to undergo like processing in order to avoid breaking textile at the corner portions. However, a beltlike reinforcement (not shown) bonded to a corner portion of a member in parallel with the edge of the corner portion can be expected to yield the effect of easing stress concentration of an edge portion on a reinforcement.
As shown in FIG. 24, the beltlike reinforcement 201 is wound onto an upper end portion 207 and lower end portion 211 of the column 205 in parallel with the circumferential direction of the column 205 and is spirally wound onto a general portion 209 such that, as the beltlike reinforcement 201 is wound one turn, it axially advances by the width thereof, whereby the beltlike reinforcement 201 can be wound about the column 205 compactly and evenly. Also, the winding direction (clockwise or counterclockwise) can be altered so as to wind the beltlike reinforcement 201 onto the column 205 in two layers, three layers, etc., thereby enhancing a reinforcement effect. In this case, after winding of the first layer is completed, an adhesive is applied to the first layer, and then the second layer is formed through winding such that the winding pitch is shifted by half the width of the beltlike reinforcement 201 between the first and second layers, thereby preventing the potential move of the beltlike reinforcement 201.
In order to allow the reinforcing member to be in close contact with the substrate in the above winging manner, it is required that the reinforcing member can be bent at an angle equal to or greater than the corner angle of the column, and sheared at an angle equal to or greater than the displacement angle between the parallel winding and the spiral winding. In a typical column, the bending angle and the displacement angle are 90 degree or less and 2-degree or less, respectively. When a reinforcing member is installed in a crossed manner as described later in connection with FIG. 56, it is preferable that the reinforcing member can be sheared at a large angle.
FIG. 25 is a sectional view of a surface portion of the column 205 shown in FIGS. 22 to 24. As shown in FIG. 25, the beltlike reinforcement 201 is bonded directly to the column 205 by use of an adhesive 213.
The beltlike reinforcement 201 shown in FIGS. 22 to 25 is, for example, the polyester belt 199 shown in FIG. 21. As mentioned in the sections of the second and seventh embodiments, the polyester belt 199 is made of polyester fiber, which is a material for a strap or the like. The polyester belt 199 is used particularly in view of the following: being higher in rigidity and strength than a civil engineering sheet, the polyester belt 199 restrains an increase in the width of crack in the column 205 and controls the deformation of an apparent volume for the range of small strain.
Next will be described the method for calculating the amount of reinforcement in the case of reinforcement for restraining the width of crack for the range of small strain of the column 205. FIG. 26 is a view showing an effective bond length between the beltlike reinforcement 201 and a crack 215.
When a member is locally ruptured due to bending, axial force, shear force, or a like force imposed thereon, the crack 215 appears on the surface of the member. In FIG 126, the crack 215 is made on the surface of the column 205, to which the beltlike reinforcement 201 is bonded directly. The belt width 219 of the beltlike reinforcement 201 is w. A force which attempts to expand the crack 215; i.e., tension 221, is imposed on the beltlike reinforcement 201 in the amount of q per belt. In FIG 145, the beltlike reinforcement 201 restrains crack width 217 to d or less.
Stress concentration is present in the vicinity of the crack 215. Width 223 (a) extending in opposite directions from the crack 215 is the length of a region where a bonding effect is lost due to shear fracture of the adhesive 213 or member surface. Width 223 (a) is hereinafter called a free length. Restraint length 225 (b) is a natural restraint length of the column 205 and is measured from a free end. Accordingly, the beltlike reinforcement 201 is bonded to the column 205 along fixation length s=b−a.
Restraint length 225 is the length of a single side in the case a rectangular cross section, as in the column 205, and is the length of an arc corresponding to a central angle of about 90 degrees in the case of a circular cross section. When these lengths are significantly large as compared with belt width 219 (w) of the beltlike reinforcement 201, restraint length 225 is a length along which an effective bonding force is not zero.
When the crack 215 is located at around the center of a certain surface of a member having a rectangular cross section, restraint length 225 extends to another surface of the member.
When k represents the rigidity of the beltlike reinforcement 201, free length a; i.e., width 223, crack width 217 (d), and tension 221 (q) are related as expressed by
q=kd/a 21)
when τ represents the average shear force between the beltlike reinforcement 201 and the column 205 as measured within fixation length s=b−a, τ is expressed by
τ=q/(w·s) 22)
When free length a is eliminated from Eq. 21) and Eq. 22), tension 221 (q), average shear force T, and crack width 217 (d) hold quadratic relation as represented by
q=1/2[τwb±{(τwb)²−4τwkd} ^0.5] 23)
This relation has two solutions q at maximum crack width d_maxor less. Since a larger solution is first realized, the larger solution is employed. Then, q falls somewhere between maximum value q_maxand minimum value q_minaccording to crack width 217 (d).
q_max=τwb 24)
q_min=0.5τwb 25)
Crack width d_maxcorresponding to minimum value q_minis expressed by
d _max =τwb ²/(4k) 26)
When the crack width is in excess of d_max, Eq. 23) does not have a solution. That is, such a mechanism does not hold true. Maximum value q_maxand minimum value q_minwhen the beltlike reinforcement 201 bears part of a force attempting to expand the crack 215 are obtained from the above relations, thereby enabling design of structural reinforcement through utilization of the above-mentioned mechanism. Values obtained from Eq. 24) to Eq. 26) are proportional to bonding force T (average shear force) between a member, such as the column 205, and the beltlike reinforcement 201.
When a material which is inexpensive and has excellent stretchability, such as the polyester belt 199, is used as the beltlike reinforcement 201, since the Young's modulus of the material is about one-tenth that of concrete or one-hundredth that of iron, the following problem is involved. Even when the adhesive 213 having large average shear force τ is used for bonding, the material encounters difficulty in sharing with a member a force which is elastically imposed on the member, without formation of the crack 215. However, when a reinforcement effect is particularly needed at the stage of small deformation, a polyester belt or the like is impregnated with resin to thereby enhance the rigidity of the reinforcement. The thus-prepared reinforcement is used together with an epoxy resin adhesive.
The polyester belt 199 has a woven body of a weft double weave using a polyester-fiber yam with 1700 dtex (dcitex). The polyester belt 199 has a Young's modulus of 4676 MPa, a thickness of 4 mm, a fracture strain of 15%, and a specific gravity of 0.98. Since the polyester base yam has a specific gravity of 1.4, a void ratio of the polyester belt 199 is (1.4/0.98=) 1.43 when expressed by the ratio of specific gravity.
The column 205 is made of reinforced concrete. Concrete has a compression fracture strength of 13.8 MPa (135 kgf/cm²), a Young's modus of 19500 MPa, and a direct shear strength of about 2.6 MPa. The reinforcing member was installed without performing any chamfering and any adjustment of surface unevenness.
Rubiron 101 (one-component: available from Toyo Polymer Co.) was used as an adhesive. The layer of the adhesive is 1 mm. The adhesive has a bonding strength of about 1 MPa (10 kgf/cm²), and a specific gravity of 1.4. A part of the adhesive is infiltrated into the texture of the polyester belt 199, and cured. However, even if the entire adhesive of 1 mm thickness enters into the void of the polyester belt 199, it will occupy only about 70% of the void of the polyester belt 199, and the breathability or air-permeability of the reinforcing member can be maintained. While Rubiron 101 is not a non-solvent adhesive, it has been experimentally verified that the same reinforcement effect can be obtained even using a non-solvent adhesive having a bonding strength equivalent to that of Rubiron 101.
With respect to the effect of the reinforcement using the impregnated aramid fibers as disclosed in the aforementioned Japanese Patent Laid-Open Publication No. 8-260715, a test result of the same method as that in FIG. 29 is introduced in a number of publications. However, none of these publications reports the increase of load after Q min, as indicated by the load-deformation curve 243 b in FIGS. 30 and 50, and the test ends up with the fracture of the aramid-fiber reinforcing member before Q min or the peeling of the reinforcing member from a structure member.
A case study is conducted for the structure of FIG. 25 under, for example, the following conditions: the beltlike reinforcement 201 is the polyester belt 199 having a width of 64 mm and a thickness of 4 mm; the column 205 is a reinforced-concrete column having a restraint length 225 of b=30 cm; and the adhesive 213 is LUBIRON, which is the trade name of an epoxy urethane adhesive produced by Toyo Polymer Corp. In this study, calculation conditions are as follows: average shear force T=10 kgf/cm²; the beltlike reinforcement 201 (polyester belt 199) has a belt width 219 of w=6.4 cm and a restraint length 225 of b=30 cm; and the beltlike reinforcement 201 (polyester belt 199) has a rigidity of k=153000 kgf/cm².
Calculation of maximum value q_max, minimum value q_max, and maximum crack width d_maxby use of Eq. 4) to Eq. 6) gives the following results: maximum value q_max=1920 kgf; minimum value q_min=960 kgf; and maximum crack width d_max=0.12 cm.
Accordingly, when this reinforcement is carried out, cracking can be restrained up to maximum crack width d_max=1.2 mm. A single beltlike reinforcement 201 (polyester belt 199) bears a tension 221 of q=0.9 tf.
FIG. 27 is a schematic view of the column 205 subjected to an axial force, bending, and a shear force. FIG. 28 is a view showing a force which attempts to expand the crack 215 formed in the column 205. Described below is a reinforcement effect to be yielded in the case where the column 205 is reinforced by use of the polyester belt 199, which serves as the beltlike reinforcement 201, according to the method of FIG. 24; and the thus-reinforced column 205 is loaded in the following manner: while axial force 229 (P) is applied to the column 205, a horizontal force is applied to the column 205 so as to repeatedly generate bending moment 231 (M) and shear force Q.
The column 205 is assumed to be an ordinary structural column. Conditions of study are as follows: shear force 227 (Q) is horizontally imposed on the column 205 at the middle of height h; i.e., at height (h/2); and the upper and lower ends of the column 205 slide horizontally without involvement of rotation. As a result, a horizontally even shear force (resultant force Q) and an axial force (resultant force P) are generated in the column 205. A bending moment is M=Qh/2 at the upper end of the column 205, zero at the middle, and −M at the lower end.
When shear force 227 (Q) reaches maximum shear force Q_max, which depends on the conditions of reinforcing bars and concrete of the column 205, the crack 215 is generated in a direction of angle θ 237. A force which attempts to horizontally expand the crack 215 is shear force 227 (Q) imposed on the column 205. The force is considered to be borne by the beltlike reinforcement 201 which is present over the range represented by arrow c 233. Since a single belt of the beltlike reinforcement 201 has a width of w and exhibits a tension of q, a resultant force Q of the beltlike reinforcement 201 present over the range represented by arrow c 233 is represented by Q=q·2C/w.
Since the column 205 has a rectangular cross section, the beltlike reinforcement 201 on the near-side surface thereof and that on the far-side surface thereof are involved in reinforcement; therefore, a coefficient of 2 is used. As seen from FIG. 28, length C of arrow c 233 is represented by C=b tan τ. Generally, shear force Q is partially borne by a member. However, it is assumed that, when the deformation of the member exceeds a level corresponding to around Q_max, at which a belt becomes significantly effective, substantially the entire shear force is borne by belt tension.
When angle θ 237 is 45 degrees, width 235 of the column 205 is b (restraint length)=30 cm. Accordingly, horizontal forces Q_maxand Q_mincorresponding to maximum value q_max, and minimum value qmin which are previously calculated for the polyester belt 199 (width 64 mm and thickness 4 mm) by use of Eq. 24) to Eq. 26) are obtained as Q_max=q_min2b/w=18000 kgf and Q_min=q_min2b/w=9000 kgf. Thus, by virtue of the effect of the reinforcement, a horizontal resistance force of not less than 9 tf can be maintained when the width of the crack 215 is not in excess of d_max=1.2 mm.
Next will be described the results of a test conducted in the following manner: a horizontal force was repeatedly applied to an unreinforced column 205 and to a column 205 reinforced by use of the polyester belt 199 (width 64 mm and thickness 4 mm), which serves as the beltlike reinforcement 201 shown in FIG. 24, under the conditions of FIG. 27 while displacement was controlled. Other test conditions were as follows: the concrete strength of the column 205 is 135 kgf/cm²; the axial ratio of reinforcement is 0.56%; the ratio of shear reinforcing bar is 0.08%; an axial force is held constant at 37 tf (axial force ratio 0.3).
FIG. 29 is a schematic view showing the deformation of the column 205. FIGS. 30 to 35 show experiment results, in which horizontal displacement δ _h 239 represents the horizontal displacement of the column 205; and vertical displacement δ _v 241 represents the vertical displacement of the column 205. FIG. 30 is a graph showing the relationship between horizontal force Q of the column 205 and an envelope indicative of displacement hysteresis of the column 205. FIG. 31 is a graph showing the relationship among the horizontal displacement of the column 205, the vertical displacement of the column 205, and a horizontal force. FIG. 32 is a graph showing restoring-force characteristics of the column 205.
In FIG. 30, the horizontal axis represents horizontal displacement δ_h(239) of the column 205, and the vertical axis represents horizontal force Q (shear force 227). In FIG. 32, the horizontal axes represent horizontal displacement δ_h(239) of the column 205 and the angle of deformation, and the vertical axis represents horizontal force Q (shear force 227).
In FIG. 30, a reinforcement-absent curve 243 a is an envelope as observed when the column 205 is not reinforced with the beltlike reinforcement 201, and a reinforcement-present curve 243 b is an envelope as observed when the column 205 is reinforced. The reinforcement-present curve 243 b is an envelope along the following points on a hysteretic loop 253 shown in FIG. 32: a point corresponding to a level 255 a equivalent to the level of the Great Hanshin Earthquake Disaster, a point corresponding to a level 255 b equivalent to two times the level of the Great Hanshin Earthquake Disaster, a point corresponding to a level 255 c equivalent to three times the level of the Great Hanshin Earthquake Disaster, a point corresponding to a level 255 d equivalent to five times the level of the Great Hanshin Earthquake Disaster, etc.
In FIG. 31, the horizontal axis represents horizontal displacement δ_h(239); the upward vertical axis represents horizontal force Q (shear force 227); and the downward vertical axis represents vertical displacement δ_v(241). A reinforcement-absent curve 243 a and a reinforcement-present curve 243 b are envelopes similar to those shown in FIG. 30. The reinforcement-absent curve 245 a shows vertical displacement 6 of the column 205 which is not reinforced with a beltlike reinforcement. The reinforcement-present curve 245 b shows vertical displacement δ_vof the column 205 which is reinforced with the beltlike reinforcement 201 (polyester belt 199).
As shown in FIGS. 30 and 31, when Q_max1represents the maximum horizontal force in the case of no reinforcement being employed as represented by the reinforcement-absent curve 243 a; Q_max2represents the maximum horizontal force in the case of reinforcement being employed as represented by the reinforcement-present curve 243 b; and Q_minrepresents the minimum horizontal force in the case of reinforcement being employed as represented by the reinforcement-present curve 243 b, experiment data show Q_max1=17.5 tf, Q_max2=18 tf, and Q_min=7 tf.
In FIG. 31, the reinforcement-absent curve 243 a, which shows horizontal force Q of the unreinforced column 205, and the reinforcement-absent curve 245 a, which shows vertical displacement δ_vdrop sharply at and after the time when horizontal force Q becomes Q_max1. This supports the aforementioned assumption that, in the case of the reinforced column 205, the beltlike reinforcement 201 (polyester belt 199) exhibits a reinforcement effect; i.e., the beltlike reinforcement 201 bears substantially the entire shear force in a horizontal-displacement region ranging from a horizontal displacement corresponding to Q_max2to a horizontal displacement corresponding to Q_min.
The experimentally obtained value of minimum horizontal force Q_minappearing on the reinforcement-present curve 243 b is lower than a calculated value of 9 tf, which is obtained through calculation using the models of FIGS. 27 and 28. This can be said to be an experimental error and implies the occurrence of a drop in strength at the bond area between the concrete surface of the column 205 and the beltlike reinforcement 201 (polyester belt 199). The value of maximum shear force Q_max2is substantially equal to a calculated value of 18 tf.
As shown in FIG. 29, when horizontal displacement δ_hof the column 205 is displacement amplitude δ _hc 247, the reinforcement-present curve 243 b indicative of horizontal force Q has a horizontal-force inflection point 249, and the reinforcement-present curve 245 b indicative of vertical displacement δ_vhas a vertical-displacement inflection point 251. Displacement amplitude δ _hc 247 is horizontal displacement δ_hat around a point corresponding to the level 255 c equivalent to three times the level of the Hyogo-Ken Nanbu Earthquake on the hysteretic loop 253 shown in FIG. 32; i.e., about 140 mm (angle of deformation 0.15 rad).
FIG. 33 is a graph showing the relationship between cumulative horizontal displacement Σε_hand hysteretic absorbed energy W in the column 205. FIG. 34 is a detailed view of FIG. 33. In FIG. 33, the horizontal axis represents cumulative horizontal displacement Σε_h, and the vertical axis represents hysteretic absorbed energy W.
Cumulative horizontal displacement Σε_h, which is represented by the horizontal axis in FIGS. 33 and 34, was calculated by the equation shown below. In the equation, i is the number of steps in data recording, and n is the current number of steps. Cumulative horizontal displacement Σε_his calculated as an indicator of a position on the hysteretic loop 253 shown in FIG. 51. $\begin{matrix} \sum^{} δ_{h} = \sum_{i = 1}^{n} \langle δ_{hi + 1} - δ_{hi} \rangle & 27) \end{matrix}$
Cumulative absorbed energy W represented by the vertical axis was calculated by the following equation. Cumulative absorbed energy W is work done by horizontal force Q; i.e., by shear force 227.
W=∫Qdδ_h 28)
When a certain column 205 of a structure bears an axial force 229 of P, corresponding mass m can be represented by use of gravitational acceleration g as m=P/g. Thus, of energy which is input to the structure and consumed until completion of vibration, work E which is done by shear force 227 imposed on the column 205 is approximated by the following expression by use of velocity response spectrum δ_vof earthquake motion.
E=0.5(P/g)Sv ² 29)
The curve of hysteretic absorbed energy 257 shown in FIG. 33 shows hysteretic absorbed energy which is calculated from the experimentally obtained hysteretic loop 253 shown in FIG. 51, by use of Eq. 28). The straight lines indicative of a level 259 a equivalent to the level of the Great Hanshin Earthquake Disaster and a level 259 b equivalent to five times the level of the Great Hanshin Earthquake Disaster represent values which are calculated by Eq. 29) for comparison with the curve of hysteretic absorbed energy 257. FIG. 53 additionally show values which are calculated by Eq. 29) and represented by the straight lines indicative of a level 259 c equivalent to two times the level of the Great Hanshin Earthquake Disaster and a level 259 d equivalent to three times the level of the Great Hanshin Earthquake Disaster. Velocity response spectrum used in the calculation by Eq. 29) was Sv=90 cm/s at a natural period of 0.3 sec appearing in the record of Kobe Marine Meteorological Observatory.
FIG. 35 is a graph showing the relationship between calculated cumulative horizontal displacement Σε_hand vertical displacement δ_vby use of Eq. 27). In FIG. 35, the horizontal axis represents cumulative horizontal displacement Σδ_h, and the vertical axis represents vertical displacement δ_v(241). As mentioned previously in the description which was given with reference to FIG. 31, when horizontal displacement is horizontal amplitude δ _hc 247; i.e., about 140 mm, the vertical-displacement inflection point 251 appears. At this time, cumulative horizontal displacement Σδ_his about 1500 mm. As shown in FIG. 35, vertical displacement δ_vis not greater than 5 mm (strain 0.5%) until cumulative displacement reaches about 1500 mm at the vertical-displacement inflection point 251.
The above-described experiment demonstrated the following:

- {circle over (1)} A reinforcement effect was exhibited for low-strength concrete (135 kgf/cm²), which encounters difficulty in being reinforced by a conventional method.
- {circle over (2)} A reinforcement effect was exhibited continuously over a range from small strain to large deformation.
- {circle over (3)} It was confirmed that the reinforcement-present curve 243 b shown in FIG. 49 has two inflection points of horizontal force (a point of Q=Q_max2and a point of Q=Q_min; i.e., the horizontal-force inflection point 249).
- {circle over (4)} It was confirmed that the reinforcement-present curve 245 b shown in FIG. 31 has a single inflection point of vertical displacement δ_v(the vertical-displacement inflection point 251). This inflection point corresponds to the horizontal-force inflection point 249 (Q=Q_min) mentioned above in {circle over (3)}. The vertical-displacement inflection point 251 is a point at which a mechanism represented by Eq. 21) to Eq. 26) shifts to a mechanism in that the cross-sectional shape of the column 205 begins to be deformed, and great axial deformation arises, since the mechanism represented by the equations is disabled as a result of a series of events of cumulative damage to concrete due to repeated load; a drop in concrete strength; a drop in bonding strength τ between the beltlike reinforcement 201 (polyester belt 199) and the concrete surface of the column 205; and an increase in crack width 217 beyond limit d_max.
- {circle over (5)} Vertical displacement δ_v(axial contraction of the column 205) is not greater than 0.5% until the second inflection point of horizontal force Q; i.e., the horizontal inflection point 249 at which Q becomes Q_min, is reached; i.e., until vertical displacement δ_vreaches vertical-displacement inflection point 251. This range of vertical displacement δ_vis tolerable such that a structure can be practically reused after an earthquake.
- {circle over (6)} Conceivably, in the case of reinforcement being not carried out (as represented by the reinforcement- absent curves 243 a and 245 a in FIGS. 30 and 31), before hysteretic absorbed energy reaches the Great Hanshin Earthquake Disaster equivalent thereof, vertical displacement δ_vincreases abruptly with a resultant collapse of the structure.
- {circle over (7)} In the case of reinforcement being carried out, vertical displacement δ_vis not greater than 0.5% until hysteretic absorbed energy 257 shown in FIGS. 33 and 34 becomes about 2.5 times the hysteretic absorbed energy of the Great Hanshin Earthquake Disaster. This range of vertical displacement δ_vis tolerable such that a structure can be practically reused after an earthquake.
- {circle over (8)} In the case of reinforcement being carried out, as shown in FIG. 35, when hysteretic absorbed energy becomes greater than about 2.5 times that of the Great Hanshin Earthquake Disaster (when cumulative horizontal displacement Σδ_hbecomes greater than about 1500 mm), vertical displacement δ_vincreases gradually. However, as shown in FIGS. 50 and 32, horizontal yield strength increases, and absorbed energy per cycle increases, whereby a vibration-damping effect is enhanced, thereby yielding a great collapse prevention effect.

As seen from the results of experiment shown in FIGS. 30 to 35, in which the beltlike reinforcement 201, such as the polyester belt 199, is bonded directly to a member, such as the column 205, exhibits continuously a reinforcement effect on deformation ranging from a small one as observed after formation of the crack 215 to a large one.
A conventional reinforcement method in which a member is wrapped with reinforcement is characterized in that, in order to prevent formation of cracks, a reinforcement material, such as carbon fiber or wrapping iron plate, having rigidity equivalent to or greater than that of a major dynamic component of the member is bonded directly to the surface of the member by use of resin or the like. The beltlike reinforcement 201, such as the polyester belt 199, is bonded directly to a member, such as the column 205 is not adapted to suppress formation of the crack 215 on the member surface but is adapted to restrain crack width 217 to an effective value; for example, to about 2 mm, whereby the functional impairment of a member is controlled to thereby maintain usability and safety of a structure.
A method in which a high-rigidity material, such as the polyester belt 199, is bonded directly to the surface of a member is intended to enhance the effect of maintaining the shape of the member with respect to deformation accompanied by finite crack 215. As seen from Eq. 21) to Eq. 24), this effect is enhanced in proportion to the circumferential rigidity of a reinforcement, and the enhancement of the effect is limited by the magnitude of a shear force to be transmitted between the surface of the member and the reinforcement. Accordingly, through a high-rigidity reinforcement being bonded directly to a member, a reinforcement effect can be enhanced.
The beltlike reinforcement 201 used in the ninth embodiment is not limited to the polyester belt 199. Any material having strength and rigidity equivalent to those of the polyester belt 199 can be used.
The reinforcement method is such that, through control of an increase in crack width 217, the expansion of an apparent volume of a member is restrained. Thus, in principle, the method is identical to that of the previous application. However, the method employs the mechanism of restraining variation in shape and axial strain and is verified theoretically and experimentally, thereby indicating high practical viability thereof.
Next, a structure for enhancing a reinforcement effect for a member involving an irregular profile and a member-to-member joint of the present invention will be described. FIG. 36 is a perspective view showing a state in which connecting reinforcements 269 a and 269 b are disposed on the joint between a column 261 and a beam 263. The beam 263 is joined to the column 261 at right-hand and left-hand side surfaces 265 b.
The joint between the column 261 and the beam 263 is reinforced by use of two sheetlike connecting reinforcements 269 a and four connecting reinforcements 269 b. The connecting reinforcement 269 a assumes the form of a sheet and is bonded to the column 261 and the beam 263 in such a manner as to cover the joints between the side surfaces 265 b of the column 261 and the side surface 267 a of the beam 263. A central portion of the connecting reinforcement 269 a is bonded to a side surface 265 a of the column 261 and the right-hand and left-hand side surfaces 265 b adjacent to the side surface 265 a. Opposite end portions of the connecting reinforcement 269 a are bonded to the side surface 267 a of the beam 263.
The connecting reinforcement 269 a assumes the form of a sheet and is bonded to the column 261 and the beam 263 in such a manner as to cover the joint between the side surface 265 b of the column 261 and the side surface 267 b of the beam 263. The connecting reinforcements 269 a and 269 b are, for example, stretchable, fibrous or rubber sheet materials.
The connecting reinforcements 269 a and 269 b are not necessarily sheetlike reinforcements but may assume the form of a beltlike reinforcement, such as the polyester belt 199. The thickness, width, length, etc. of the connecting reinforcements 269 a and 269 b, either sheetlike or beltlike, are determined to provide a required amount of reinforcement.
The connecting reinforcements 269 a and 269 b may be bonded to the column 261 and the beam 263 in a tentative condition but may be bonded in such a manner as to yield strength. Generally, the displacement amplitude of a structure depends greatly on the deformation of a member-to-member joint. Thus, in view of the amount of reinforcement being determined by the method shown in step 309 of FIG. 40, which will be described later, use of the latter bonding is practical.
FIG. 37 is a perspective view showing a state in which a beltlike reinforcements 271 a and 271 b are disposed on the joint between the column 261 and the beam 263. In FIG. 37, a single beltlike reinforcement 271 a and two beltlike reinforcements 271 b are disposed in such a manner as to cover the connecting reinforcements 269 a and 269 b which are disposed as shown in FIG. 36. The beltlike reinforcement 271 a is disposed on the exterior of a bigger member; i.e., on the exterior of the column 261. The beltlike reinforcement 271 a is wound onto the column 261 in such a manner as to be continuously wound between a portion of the column 261 located above the joint between the column 261 and the beam 263 and a portion of the column 261 located below the joint while obliquely crossing the joint. The beltlike reinforcement 271 b is disposed on the exterior of a thinner member; i.e., on the exterior of the beam 263. The beltlike reinforcement 271 b is independently wound about the right-hand and left-hand beams 263 joined to the column 261.
The above-described method is repeatedly carried out until a required amount of reinforcement is obtained. In FIG. 37, the beltlike reinforcements 271 a and 271 b are disposed in two layers and cross-wound onto the joint between the column 261 and the beam 263.
The beltlike reinforcements 271 a and 271 b are bonded to the column 261 and the beam 263 in such a manner as to yield strength. FIG. 38 is a sectional view of the joint between the column 261 and the beam 263 on which the connecting reinforcements 269 b, etc. are disposed. The beltlike reinforcements 271 a and 271 b are disposed on the connecting reinforcement 269 b in a winding condition. The column 261 or the beam 263 and the sheetlike connecting reinforcement 269 b are bonded such that tension is mutually transmitted via shear resistance of a bond zone. Similarly are bonded the following combinations: the connecting reinforcement 269 b and the beltlike reinforcements 271 a and 271 b; the column 261 or the beam 263 and the connecting reinforcement 269 a; and the connecting reinforcement 269 a and the beltlike reinforcements 271 a and 271 b.
In case of need, a reinforcement 273 a is wound about the exterior of the column 261, and a reinforcement 273 b is wound about the exterior of the beam 263. The reinforcements 273 a and 273 b are stretchable sheetlike or beltlike materials.
As described above, according to the reinforced structure, the connecting reinforcements 269 a and 269 b are disposed on the joint between the column 261 and the beam 263 so as to enhance a member-to-member reinforcement effect. Furthermore, the beltlike reinforcement 271 a is cross-wound onto a joint of a bigger member; i.e., about a joint of the column 261, and the beltlike reinforcements 271 a and 271 b are wound about the exterior of the column 261 and that of the beam 263 in layers, to thereby obtain a required amount of reinforcement.
In FIGS. 36 and 37, the reinforcement is cross-wound onto the joint. However, the reinforcement can be wound about the joint in the form of the letter T or the like. Reinforcement is applicable not only to the joint between a column and a beam but also to the joint between other members. The method can be combined with the method using slits or bores. This combined method is particularly effective for reinforcing the joint between members of greatly different thicknesses or shapes, such as the joint between a slab and a beam or the joint between a wall and a beam.
When a sufficient amount of reinforcement can be obtained merely by use of the beltlike reinforcements 271 a and 271 b, the connecting reinforcements 269 a and 269 b can be omitted.
In the above reinforced structure of a structural body, the reinforcing member is made of a material having high ductility and high bendability, or extensibility, and installed on the surface of or inside a structure member or substrate through the fixation using an adhesive, so as to constrain the apparent volume expansion of the structure member to control the change in shape or the damage of the structure member.
A material which is inexpensive and facilitates working and bonding, such as a polyester sheet, is used as a reinforcement material. The Young's modulus of such a material is about one-tenth that of concrete or one-hundredth that of iron. Thus, the reinforcement material's effect of bearing part of a load imposed on a member during the elastic stage accompanied by very small strain as do reinforcing bars of reinforced concrete, is very weak; specifically, as weak as the above-mentioned Young's modulus ratios.
However, when repeated imposition of load induces yielding and cracking of main component materials, such as concrete and iron, of a column; i.e., when plastic deformation begins, the rigidity of the member drops; thus, the method of the previous application exhibits significant effectiveness. Even after concrete or a like component material of the column assumes a granular form and then a powder form, and iron undergoes significant plastic deformation or ruptures retains these component materials in a unitary shape, thereby exhibiting the capability of maintaining an axial force and the capability of resisting an external force, such as bending and shearing.
The reinforced member absorbs very large energy in the above-mentioned sequential repeated-deformation process while maintaining rigidity, thereby preventing the collapse of a structure which would otherwise result from reception of an abrupt external force, such as a seismic force.
FIG. 41 is a diagram showing the relationship between cumulative deformation and hysteretic absorbed energy with respect to a reinforced member on which a repeated load is imposed. The horizontal axis represents cumulative deformation, and the vertical axis represents hysteretic absorbed energy. As a result of a repeated external force being imposed on a member during the member being deformed with involvement of finite cracking, component materials of the member are partially ruptured. A shear force transmitted between the member and a reinforcement decreases accordingly. As a result, a reinforcement effect weakens, and the effect of retaining the shape of the member also weakens. The rupture of component materials of the member induced as a result of reception of a repeated load can be measured in terms of work done by the external force; i.e., in terms of hysteretic absorbed energy.
A certain limit (called a shape retainment limit energy 275) is present according to the type and amount of material. When this limit is exceeded, a material behaves in a granular fashion, and thus the shape of a member begins to vary significantly. A member reinforced according to a method of the present invention or the previous application is deformed such that the cross section assumes a circular shape, and the entire shape approaches to the shape of linked balls. Accordingly, the shape of a structure also varies significantly.
The method of the present application is characterized by being able to cope with a wide energy region and a wide deformation region, and an enhancement of an effect to be yielded as shown in FIG. 41. When the method of the present invention are applied to a seismic isolator, the seismic isolator can absorb energy in such an amount that a material having a volume equivalent to that of the seismic isolator is pulverized substantially completely, while variation in shape is minimized, and rigidity is retained. This is a very efficient behavior for a seismic isolator. When a special filler is mixed into a component material of a seismic isolator, the filler functions to internally reinforce the material through utilization of energy, such as heat, to be generated by work which is done by an external force in the above-mentioned process, thereby further enhancing a seismic isolation effect.
Next, the fibrous sheetlike reinforcements and beltlike reinforcements as mentioned above are impregnated with resin will be described. FIG. 42 is a graph showing the relationship between tensile stress and strain with respect to a reinforcement material impregnated with resin and a reinforcement material unimpregnated with resin. The vertical axis represents tension, and the horizontal axis represents extensional strain (%).
An impregnated-with-resin curve 277 shows the stress-strain relation obtained from a tensile test which was conducted on a polyester sheetlike textile impregnated with epoxy resin after the resin was cured. An unimpregnated-with-resin curve 279 shows the stress-strain relation obtained from a tensile test which was conducted on the same sheetlike textile unimpregnated with epoxy resin.
Comparison in FIG. 42 between the impregnated-with-resin curve 277 and the unimpregnated-with-resin curve 279 shows the following: as a result of impregnation with resin, rigidity; i.e., the gradient of the parting line of the graph, is significantly large at a strain of 0% to about 3%; and deformation can be maintained without rupture until large strain is reached. Similar test results are also obtained from a polyester beltlike material, such as the polyester belt 199 shown in FIG. 21.
The test results shown in FIG. 42 show the following: as a result of a sheet or beltlike material woven from polyester fiber being impregnated with resin, resin yields the effect of restraining deformation of fiber for the range of small strain; thus, the material represented by the impregnated-with-resin curve 277 exhibits increased rigidity as compared with the material represented by the unimpregnated-with-resin curve 279. When deformation increases, the material represented by the impregnated-with-resin curve 277 loses the above-mentioned effect without significant breakage of fiber. As a result, deformation can be maintained until a large strain of not less than 15% is reached.
Thus, through a reinforcement material impregnated with resin; i.e., a material of a single kind, enhances the effect of restraining deformation for the range of small strain as well as yields the effect of bearing a load for the range of large strain.
The aforementioned reinforcing member can be designed as follows.
As described above, the dynamic property (the relationship between external force and deformation) of the reinforced structure is defined by the following parameters. Thus, the reinforced structure can be designed by calculating the performance of a structural body subject to reinforcement, according to these parameters and data of the structural body.
1) Thickness of reinforcing member t
2) Young's modulus of reinforcing member E_f
3) Fracture strain of reinforcing member ε_fb
4) Reinforcing-member stress at yield of fixation structure τ_fmax
5) Reinforcing-member installation mode (Whether reinforcing-member is closingly looped (FIG. 1) or not (FIG. 3))
6) Reinforcing-member installation range (When not closingly looped) expressed by b
7) Peeling-limit elongation δ1
For determination of reinforcing-member stress at yield of fixation structure, the following 8) or 9) can be used.
8) Constraint length b and Average fixation strength τ_f
9) Peeling energy of boundary surface of fixation structure G_f
Further, the gap width and reinforcing-member tensile force in a SRF-reinforced structure has a relationship as shown in FIG. 44. Specifically, if the gap width is increased from zero, a reinforcing member will be elongated in a fixation zone, and thereby a reinforcing-member stress will be generate. When the elongation of the reinforcing member on the gap reaches δ1, the release of the fixation structure is initiated to generate a free length a (FIG. 44). If the fixation is based on bonding, and the reinforcing member is bonded even at a position sufficiently away from the gap, the fixation force will be kept at an approximately constant value as long as a constraint length (the distance between the gap and a position where the fixation force is not zero) can be increased in conjunction with the increase of the gap width (FIG. 4). This is the range from Point A to Point B in FIG. 44. Subsequently, a fixation length (s=b−a) is reduced, and thus the reinforcing-member stress is reduced. This is the range from Point B to Point C. According to the theory shown in the expressions [1] to [4], the bonding is released all at once when the reinforcing-member stress becomes half of its maximum value. If the reinforcing member is closingly looped, or a geometrical constraint exists at the corner of the structure member or the like, the fixation force will be maintained to increase a reinforcing-member tensile force in proportion to the gap width until the reinforcing member reaches a fracture stress (stress corresponding to the fracture strain ε_fb) (range from Point C to Point D).
For example, in case of a bar-shaped structure member, the relationship between reinforcing-member tensile force and restoring force can be determined from the theory as shown in the expressions [9] and [10], or an experimental test. Further, the reinforcing-member elongation δ₁providing the maximum value of the reinforcing-member tensile force is a value derived from integrating strains in the fixation zone of the reinforcing member at the time of the limit where the bonding is released (when the reinforcing-member tensile force reaches τ_fmax), and becomes smaller as the Young's modulus of the reinforcing member is increased. This factor is ignored in the theory shown in the expressions [1] to [4].
The maximum reinforcing-member tensile force may be derived from dividing the product of the restraint length and the average bonding strength by the reinforcing-member thickness from the expression [4]. However, if the reinforcing member is wounded around a structure member, and the structure member is installed over a wide range, the constraint length cannot be figured out in some cases. This problem can be solved by determining the maximum reinforcing-member tensile force using the boundary-surface peeling energy in the following expression [101]: $\begin{matrix} σ_{f \max} = \sqrt{\frac{2 E_{f} G_{f}}{t}} & [101] \end{matrix}$
The boundary-surface peeling energy is defined as energy required for peeling the bonding boundary-surface of unit area between a thin elastic body and a substrate as shown in FIG. 44, and can be calculated from the following expression [102] using the maximum tensile force σ_fmaxcaused in the elastic body and the thickness t and Young's modulus of the elastic body, which are obtained as the reinforcing bar. Further, while a maximum reinforcing-member tensile force σ_fmaxis calculated using the expression [101], it is given that the reinforcing-member stress does not go beyond a value corresponding a reinforcing-member strain of 1%.
The above apparent yield stress (σ_fmaxin the expressions [101] and [102]) is a maximum stress capable of being borne before the fixation of the reinforcing member is released (FIG. 45), and calculated from the Young's modulus of the reinforcing member, the boundary-surface peeling energy and the thickness of the reinforcing member using the expression [101]. In the expression [101], the apparent yield stress is reduced in reverse proportion to the square root of the thickness. Thus, the reinforcing-member thickness can be determined by a simple repeated calculation.
As above, while the present invention has been described in conjunction with preferred embodiments of a reinforced structure, reinforcing method, quake-absorbing structure, and reinforcing member for a structural body according to the present invention, the present invention is not limited to such embodiments. It is obvious to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the present invention. Therefore, it is intended that such changes and modifications are obviously encompassed within the scope of the present invention.

Industrial Applicability

As mentioned above, the present invention can provide a reinforcing material or member excellent in ductility and load-withstanding capacity, quickly at a low cost. result of a peeling test. $\begin{matrix} G_{f} = \frac{t}{2 E_{f}} σ_{f \max}^{2} & [102] \end{matrix}$
The expression [101] is obtained by resolving the formula [102] about σ_fmax.
In a design for SRF-reinforcing a reinforced concrete structure member, a conventional design formula for reinforced concrete structure members can be applied to the calculation of the reinforcement effect of a SRF reinforcing member by substituting the SRF reinforcing member with a reinforcing bar and calculating the reinforcement effect using the boundary-surface peeling energy etc. by use of the phenomenon that a SRF reinforcing member apparently yields at σ_fmaxas shown in FIG. 55 (expression [103]). However, there is possibility that the gap width in the design limit state does not reach the peeling-limit elongation δ1 illustrated in FIGS. 44 and 55 due to a small Young's modulus of the SRF reinforcing member as compared to that of reinforcing bar. Thus, it is required to take notice of checking whether δ₁is caused within the design limit, through an experimental test or the like, or putting a limit on the reinforcing-member stress.
For example, in a design for a SRF reinforcing member installed based on bonding in such a manner that it is wounded around a bar-shaped reinforced concrete structure member shown in FIG. 7, an equivalent shear reinforcing bar amount P_wfafter reinforcement is calculated as follows: $\begin{matrix} P_{wf} = P_{w} + \frac{2 t}{b_{m}} \frac{σ_{f \max}}{σ_{sy}} & [103] \end{matrix}$
wherein t is the thickness of the reinforcing member, bm being the width of the section of the structure member, pw being the ratio of the shear reinforcing bar to the structure member subject to reinforcement, and σ_sybeing a yield stress of the The effects of the reinforcing member according to the present invention is effective to repair, maintenance and reinforcement of existing structure bodies, and usable in new structural bodies. In either case, the cost, construction period etc. required for satisfying a desired performance can be reduced as compared to those in conventional techniques. The reinforcing material or member according to the present invention is useable as a safeguard against sudden external forces such as explosion, which have been untreatable by conventional techniques. In addition, the reinforcing member installed on the outer surface of a structure member as a primary element thereof makes it possible to provide a reinforced structure readily at a low cost and achieve enhanced reinforcement performance. Furthermore, the present invention facilitates reuse of decrepit or affected structural bodies to promote effective use of existing structural bodies and industrial resources and to allow industrial wastes to be reduced.
Moreover, a reinforcement configuration, a seismic isolator, and a reinforcement method for a structure according to the present invention can suitably be applied to, for example, the following cases: a member to be reinforced involves undulation or an irregular profile; a member is joined to or located in proximity to another member or a nonstructural member; a reinforcement is possibly deteriorated due to interaction between a member and the reinforcement or between the reinforcement and an external environment; a reinforcement effect must encompass a small deformation through a large deformation; and seismically isolating reinforcement is required.

Claims

1-64. (canceled)

65. A reinforcing member to be installed on a member or members of a structure to reinforce said member or members, having a high bendability to fit an edge or edges of said member or members, and to follow a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

66. The reinforcing member as defined in claim 65, which has a bending deformation angle of 90-degree or more.

67. The reinforcing member as defined in claim 65, which has a shear deformation angle of 2-degree or more.

68. A reinforcing member to be installed on a member or members of a structure to reinforce said member or members, having a high bendability and an elasticity, with a Young's modulus not greater than that of said member or members to follow a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

69. The reinforcing member as defined in claim 68, wherein the Young's modulus is to be a product specification value.

70. A reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing member a design size thereof is determined by the product of a Young's modulus and thickness.

71. The reinforcing member as defined in claim 65, which is formed by a weaving process.

72. A reinforcing member to be installed on a member or members of a structure to reinforce said member or members having an elasticity and a high ductility, with a tensile fracture strain thereof greater than that of said member or members to follow a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

73. The reinforcing member as defined in claim 72, wherein the tensile fracture strain is 10% or more.

74. A reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing member a tensile fracture strain is a product specification value.

75. A reinforcing member to be installed on a member or members of a structure to reinforce said member or members, said reinforcing member having an elasticity and a high ductility, with a Young's modulus in the range of 500 to 50,000 Mpa to follow a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

76. The reinforcing member as defined in claim 65, which comprises a woven body being heat-set to allow a Young's modulus in a design limit state to be greater.

77. The reinforcing member as defined in claim 65, which is made of a rubber-based or resin-based elastic material.

78. A fixation material to be used for a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said fixation material a strength thereof is lower than a fracture strength of said member or members.

79. An adhesive to be used for a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said adhesive a strength thereof is lower than a fracture strength of said member or members.

80. An adhesive to be used for a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein said adhesive boundary-surface peeling energy is to be a product specification value, thereby a breaking of said adhesive layer does not cause breaking said member or members.

81. An adhesive to be used for a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, said adhesive not applying a solvent, to thereby remove a harmful effect to a human body.

82. An adhesive to be used for a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, said adhesive being a one-component, to thereby simplify a fixation process.

83. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, said reinforcing structure having a high bendability to fit an edge or edges of said member or members, and to follow a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

84. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member has a high bendability and an elasticity, with a Young's modulus not greater than that of said member or members to follow a deformation of said member or members so as to maintain a reinforcement effect.

85. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member has a high bendability and an elasticity, with a Young's modulus in the range of 500 to 50,000 Mpa to follows a deformation of said member or members so as to maintain a reinforcement effect.

86. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member allows a flexural rigidity and shear rigidity to be low, to thereby prevent said reinforcing member breaking said member or members till after said member or members deformed.

87. The reinforcing structure as defined in claim 84, wherein a reinforcing member, which has a Young's modulus to be a product specification value, is installed.

88. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure a design size thereof is determined by the product of a Young's modulus and thickness of said reinforcing member.

89. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member has an elasticity and a high ductility, with a tensile fracture strain thereof not greater than that of said member or members, to thereby maintain practically a load of said member or members till after said member or members broken.

90. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member has a high ductility and elasticity, with a Young's modulus in the range of 500 to 50,000 Mpa, to thereby prevent said reinforcing member breaking said member or members till after said member or members deformed.

91. The reinforcing structure as defined in claim 89, wherein a tensile fracture strain of said reinforcing member is 10% or more.

92. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member has a tensile fracture strain to be a product specification value.

93. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member, which has a high bendability, is installed without chamfering of said member or members or grouting between spaces of said member or members, and follows a deformation of said member or members so as to maintain a reinforcement effect.

94. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member is installed on said member or members through a filler material in a space between the reinforcing member and said member or members, and a shear strength of said filler material is lower than said member or members and said reinforcing member, to thereby maintain a reinforcement effect by confining an apparent volume expansion till after said member or members deformed.

95. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure said reinforcing member, which comprises a plurality of materials having a variant Young's modulus and fracture strain, is installed, to thereby maintain a reinforcement effect from an early stage of said member or members deformed till after said member or members broken.

96. A reinforcing structure comprising a reinforcing member to be fixed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure a fixation strength is lower than a fracture strength of said member or members, thereby a breaking of a fixation part does not occur.

97. The reinforcing structure as defined in claim 96, wherein said fixation essentially consists of an adhesive.

98. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure by an adhesive to reinforce said member or members, wherein in said reinforcing structure said adhesive is a non-solvent adhesive, thereby no harmful effect is given to a human health.

99. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure by an adhesive to reinforce said member or members, wherein in said reinforcing structure said adhesive is a one-component, thereby a reinforcing structure forming process is simplified.

100. A reinforcing structure comprising a reinforcing member to be installed on a member or members of a structure by an adhesive to reinforce said member or members, wherein in said reinforcing structure said adhesive has a boundary-surface peeling energy to be a product specification value, thereby a breaking of said adhesive layer does not cause breaking said member or members.

101. A reinforcing structure comprising a reinforcing member to be fixed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing structure a size of said reinforcing member is determined so as to obtain a required reinforcement effect by fixation strength or boundary-surface peeling energy.

102. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member has a high bendability to fit an edge or edges of said member or members, and to follow a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

103. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member, which has a high bendability and an elasticity, with a Young's modulus equal to or less than that of said member or members, is installed, and follows a deformation of said member or members without breaking said member or members so as to maintain a reinforcement effect.

104. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method a design size thereof is determined by the product of a Young's modulus and thickness of said reinforcing member.

105. The reinforcing method as defined in claim 103, wherein said reinforcing member, which has a Young's modulus to be a product specification value, is installed.

106. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member, which has a tensile fracture strain to be a product specification value, is installed.

107. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member, which has an elasticity and a high ductility, with tensile fracture strain thereof equal to or more than that of said member or members, is installed, to thereby maintain practically a load of said member or members till after said member or members broken.

108. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member, which has a high ductility and an elasticity, with a Young's modulus in the range of 500 to 50,000 Mpa, is installed, and follows a deformation of said member or members so as to maintain a reinforcement effect.

109. The reinforcing method as defined in claim 104, wherein a tensile fracture strain of said reinforcing member is 10% or more.

110. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member, which has a high bendability, is installed without chamfering of said member or members or grouting between spaces of said member or members, to thereby maintain a reinforcement effect till after said member or members deformed.

111. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member is installed between spaces of said member or members through a filler material whose shear strength is lower than said member or members and said reinforcing member, to thereby maintain a reinforcement effect by confining an apparent volume expansion till after said member or members deformed.

112. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said reinforcing member, which comprises a plurality of materials having a variant Young's modulus and fracture strain, is installed, to thereby maintain a reinforcement effect from an early stage of said member or members deformed till after said member or members broken.

113. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method a fixation strength allows to be less than a fracture strength of said structural member, thereby breaking a fixation part does not occur.

114. The reinforcing method as defined in claim 114, wherein said fixation essentially consists of an adhesive.

115. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said adhesive is a non-solvent adhesive, thereby no harmful effect is given to a human health.

116. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method said adhesive is a one-component, thereby a reinforcing structure forming process is simplified.

117. A reinforcing method comprising a reinforcing member to be installed on a member or members of a structure to reinforce said member or members, wherein in said reinforcing method an adhesive, which has a boundary-surface peeling energy to be a product specification value, is applied.

118. The reinforcing structure as defined in claim 82, wherein said member or members is at least one selected from the group consisting of: concrete; steel frame; brick; block; gypsum board or plaster board; wood; rock; earth or soil; sand; resin; and metal.

119. The reinforcing method as defined in claim 83, wherein said member or members is at least one selected from the group consisting of: concrete; steel frame; brick; block; gypsum board or plaster board; wood; rock; earth or soil; sand; resin; and metal.