JP3942973B2 - Seismic control structure of concrete structure with fiber reinforced cementitious material - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fiber reinforced structure in which various parts of a concrete structure having a short span beam can be controlled by controlling the seismic response of the structure by forming a central part or all of the short span beam member with a fiber reinforced cement material. It belongs to the technical field of damping structures for concrete structures made of cement-based materials.
[0002]
[Prior art]
As one type of concrete-based structure, many concrete-based structures including short-span beams having a short span have been implemented.
For example, the short-span beam 1 included in the concrete-based rigid frame structure illustrated in FIG. 6, the boundary beam 1 in the structure formed by the concrete-based earthquake-resistant wall 2 illustrated in FIGS. 7 and 8, or the concrete illustrated in FIG. 9. The short-span beam 1 constituting the outer peripheral part and the core part in the steel tube frame structure, or the short-span beam 1 constituting the balcony part (or the lower part of the corridor) of the concrete plate-like apartment house illustrated in FIG. .
[0003]
Incidentally, the short span beam referred to in the present invention refers to a short beam whose ratio between the total length of the beam and the height dimension in the cross section of the beam (shear span ratio under earthquake load) is about 1.5. Say. In the concrete structure including the short span beam 1, the seismic energy input to the structure at the time of a large earthquake acts on the short span beam 1 in a form in which shearing force is dominant, and shear failure tends to concentrate. . However, the problem is that short-span beams have brittle shear failure and almost no deformation capability unless sufficient shear reinforcement is provided.
[0004]
In the case of ordinary reinforced concrete short-span beams made of ordinary concrete, there is a limit to the dispersibility of cracks even if the shear reinforcement bars and strips are densely arranged, and it is difficult to control the damage.
[0005]
Measures are also being implemented to place braces on concrete structures or place studs as seismic control devices. However, since these seismic control devices are installed between the upper and lower beam members, it is a troublesome solution to both the plan for securing entrances and passages and the plan for arranging braces and studs. Exists. It is also a problem that a large number of studs need to be placed in order to expect a seismic control effect in ordinary buildings.
[0006]
As a different conventional technique, the vibration control structure of a building described in Japanese Patent No. 3171902 is constructed by joining a low yield point steel to the middle part of the beam and concentrating deformation on the low yield point steel part to absorb energy. This is a configuration that achieves a squeeze damping effect. However, the beam is an example of a steel structure building made of H-shaped steel.
[0007]
[Problems to be solved by the present invention]
As described above, when a concrete structure including a short span beam is subjected to a large repetitive load during a large earthquake, it can be said that the design is determined by the shear strength of the short span beam. Therefore, it is necessary to accurately estimate the maximum shear force and to properly design reinforcement and concrete strength.
Even so, the deformation capacity of the short span beam is inherently small, and the energy absorption capacity cannot be expected, and if it is sheared, it is difficult to repair and use it.
[0008]
As a countermeasure against the above problems, the vibration control structure described in Japanese Patent No. 3171902 is ineffective. This is because it is impossible to perform energy absorption by joining a low yield point steel to a short span beam of a concrete structure and concentrating deformation on the low yield point steel portion.
[0009]
By the way, a so-called fiber-reinforced cement-based material (or fiber-reinforced mortar) in which short fibers such as carbon fiber, aramid fiber, glass fiber, vinylon fiber, polypropylene fiber, and steel fiber are mixed as a reinforcing material for concrete is used in conventional ordinary concrete. In comparison, it is known that the cracks at the time of tension are dispersed and that the width of the cracks is restricted by the fibers, so that it has excellent apparent tensile strength and tensile toughness. As explained in the technical section, it is already used as a part of concrete structure.
[0010]
Therefore, when the fiber-reinforced cement material is applied to a short span beam of a concrete structure, bending cracks and shear cracks are dispersed at the portion of the short span beam and the width of the crack is restricted by the fibers. So-called concrete peeling or the like does not occur and the yield strength does not drop rapidly. Moreover, since the adhesion strength between the reinforcing bar and the concrete is improved and the plastic rotational deformation ability is increased, a larger energy absorption ability can be expected.
Accordingly, the present invention has been made with a focus on the fact that the seismic response of the entire building can be controlled by appropriately grasping and designing the energy absorption amount.
Another problem to be solved is that fiber-reinforced cement-based materials are difficult to perform on-site due to their properties.
[0011]
The object of the present invention is to form the center part or all of a short span beam of a concrete structure with a fiber-reinforced cement-based material, thereby increasing the plastic deformation rotation capability and enabling seismic response control of the entire building, The purpose is to provide a seismic control structure that gives a seismic control effect to the structure while eliminating the need to install a seismic control device that affects the plan of the opening.
[0012]
The next object of the present invention is to form the central part or the whole of the short span beam with a fiber reinforced cementitious material, thereby increasing the deformation capacity while reducing the amount of shear reinforcement, resulting in a large seismic energy absorption capacity as a whole. The aim is to provide a seismic control structure that exhibits excellent crack dispersibility, reduces the degree of damage, and enables the reuse of the structure by simple repair after an earthquake.
[0013]
[Means for Solving the Problems]
As a means for solving the above-described problems of the prior art, the vibration control structure of a concrete structure using the fiber-reinforced cement material according to the invention of claim 1 is:
In concrete structures,
The short-span beam has a short-span beam in which the center of shear deformation is concentrated as a precast beam member made of fiber-reinforced cement-based material, and the other parts are made of ordinary concrete. It is characterized by being.
[0015]
Seismic structure of Concrete Structures by fiber-reinforced cement-based material according to the invention described in claim 2, in Concrete Structure,
The area where shear deformation concentrates at the center of a short span beam with a short span is formed as a precast beam member with a fiber reinforced cementitious material, and the other part is a U-shaped cross section that also serves as a beam form frame with the same fiber reinforced cementitious material A short-span beam is constructed by a precast beam member formed in series with the central portion, and ordinary concrete is cast on a U-shaped cross-sectional portion that also serves as the beam form frame.
[0016]
Seismic structure of Concrete Structures by fiber-reinforced cement-based material according to the invention described in claim 3, in Concrete Structure,
The area where shear deformation concentrates at the center of a short span beam with a short span is formed by integrating steel sheets on the bottom surface as a precast beam block made of fiber reinforced cementitious material, and steel plates are integrated on the bottom surface using other ordinary concrete. The part formed by construction and the beam block are characterized in that a short-span beam is constructed in which the steel plate on each bottom surface is integrally joined together and the beam block is arranged in the center. .
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Below, the damping structure of the concrete structure by the fiber reinforced cementitious material which concerns on the invention described in Claims 1-3 is demonstrated based on embodiment shown in FIGS.
[0018]
First, FIG. 1 shows a fiber-reinforced cement-based material in which the central portion 1A where shear deformation and shear fracture are concentrated in the short-span beam 1... Joined to the columns 3 and 3 in the concrete ramen structure illustrated in FIG. (See FIG. 1C), and the other side parts 1B are made of ordinary concrete (FIG. 1B). A precast beam member is manufactured in the factory in advance, and it is carried to the site between the columns 3 and 3. short span beam 1 and erection by known techniques shows an embodiment which is built (the invention of claim 1 Symbol placement) to. This is because fiber-reinforced cement-based materials are difficult to perform on-site due to their properties.
The short-span beam 1 shown in FIG. 1 is a known half precast beam that exposes a part of the beam main reinforcement 5 and the hoop reinforcement 6 on its upper surface and facilitates the integrated construction with the slab concrete to be struck later. What is comprised as a member is shown.
[0019]
Next, in the embodiment of FIG. 2, as in FIG. 1, the central portion 1 </ b> A where shear deformation and shear fracture concentrate in the short span beam 1 is formed of a fiber reinforced cementitious material (see FIG. 2B). In addition, as shown in FIG. 2C, both side portions 1B other than the central portion 1A also have a U-shaped cross section that also serves as a beam form frame formed in series (integrally) from a fiber-reinforced cement material. Further, a precast beam member having a structure in which a beam reinforcing bar composed of a beam main reinforcing bar 5 and a hoop reinforcing bar 6 is preliminarily stored in the grooves of the both side portions 1B is manufactured in advance in the factory, and this is carried to the work site. FIG. 2A shows a stage in which it is erected by a known technique. After that, the short-span beam 1 is constructed by placing ordinary concrete into the groove of the U-shaped cross-sectional portion 1B that also serves as the beam form frame with the placement of the slab concrete (the invention according to claim 2 ).
[0020]
The U-shaped cross-sectional structure that also serves as the beam form of the both side portions 1B is also implemented in a configuration in which the lower half of the beam rebar is embedded in a fiber-reinforced cement material as in the embodiment shown in FIG. 2D. .
In any case, after laying the precast beam member between the columns 3 and 3, when placing the slab concrete, the ordinary concrete is cast into the groove of the U-shaped cross section which also serves as the beam formwork. The span beam 1 and the slab are completed at once (the invention according to claim 2 ).
According to this embodiment, the both side portions 1B are cut into a U-shaped cross section that also serves as a beam form and are carried into the field. Therefore, compared with the embodiment of FIG. It can reduce the time and effort of transportation and installation. As a result, there is an advantage that the cost can be reduced.
[0021]
Next, FIG. 3 shows a precast concrete in which a beam-column joint block 4 formed of ordinary concrete as a beam joint portion of the column 3 and both side portions 1B excluding the central portion of the short span beam 1 are integrally made of ordinary concrete. An embodiment in which a member is manufactured in advance in a factory, is carried into the field, and is installed on a pillar 3 is shown.
In the beam-column joining block 4, a sheath hole through which each main reinforcing bar 7 of the column 3 passes is provided in the vertical direction. Further, on both side portions 1B of the short span beam, the main reinforcing bars 5 constituting the beam reinforcing bars are also laid through the column beam joining block 4, and the hoop bars 6 are also arranged. The upper main bars 5 and the hoop bars are also arranged. 6 is configured as a half precast member in which the upper half of 6 is exposed.
[0022]
FIG. 3 also shows how the main beam 7 of the column 3 is passed through the column-beam joint block 4 having the above configuration to the upper portion (beam mounting position) of the column 3 together with both side portions 1B of the short span beam and to the sheath hole of the block 4. After installation, the beam formwork of the central part 1A of the short span beam is assembled on-site, and the assembly of the beam rebar is completed, and the central part 1A is integrated with the both side parts 1B in series using fiber reinforced cementitious material. to build the structure, it shows a status which was completed a short span beam 1.
[0023]
Next, in FIG. 4, both side portions 1B except the central portion 1A of the short span beam 1 are installed in advance to the beam mounting position of the column 3 by a field casting method using ordinary concrete or as a precast concrete member manufactured by a factory. Yes. On the other hand, the central portion 1A of the short span beam 1 is manufactured in advance as a precast concrete member made of a fiber-reinforced cement material at a factory, carried into the site, and previously installed on the column 3 of the both side portions 1B and 1B. It is inserted in between. And the embodiment which integrated the joint part 11 of the steel plates 9 and 10 which were integratedly constructed in the bottom face of the center part 1A and the both side parts 1B in advance so as to be able to transmit a bending moment by means such as welding is shown. ing.
[0024]
In the embodiment of FIG. 4, a cover plate 13 is placed on the upper surface of the central portion 1 </ b> A for the purpose of cutting the central portion 1 </ b> A with the slab concrete 12.
The main point of this embodiment is that the central portion 1A where the shear deformation during the earthquake is concentrated and destroyed is repaired after the joint 11 of the steel plates 9 and 10 is separated and replaced with a newly manufactured central portion 1A. Is to make it possible.
[0025]
[Effects of the present invention]
The damping structure of the concrete structure by the fiber reinforced cement material according to the invention described in claims 1 to 3 is made of the fiber reinforced cement material at the central part or the whole where the shearing force and shear deformation are concentrated in the short span beam. Since they are formed, bending cracks and shear cracks within the above range are dispersed, the apparent adhesion strength is increased, and the plastic rotational deformation performance is increased, so that a greater seismic energy absorption capability can be expected. Therefore, by properly grasping and designing this seismic energy absorption performance, it is possible to provide a seismic control structure that controls the seismic response of the entire concrete structure.
In addition, it is not necessary to use a seismic control device such as another expensive damper, and the seismic performance can be imparted to the concrete structure. Therefore, it can be implemented at low cost and without any influence on the floor plan of the building.
Therefore, since it is not necessary to arrange bars that are more dense than necessary for short span beams, the workability is greatly improved.
In addition, the fiber reinforced cementitious material has the effect of dispersing cracks, and damage is less likely to occur in a single location, which reduces visual damage and is advantageous for reuse after an earthquake.
Furthermore, as a result of the advancement of precasting of the structure, it contributes to labor saving and quality improvement of field work.
[Brief description of the drawings]
FIG. 1A is a front view showing a structure of a short span beam, and B and C are sectional views taken along lines bb and cc in FIG.
FIG. 2A is a front view showing different structures of a short span beam, and B, C, and D are bb and cc cross-sectional views of FIG.
FIG. 3 is an elevational view showing a different structure of a short span beam.
FIG. 4 is an elevational view showing a further different structure of the short span beam.
FIG. 5 is a plan view of FIG. 4;
FIG. 6 is an elevation view showing a short span beam of a concrete-based rigid frame structure.
FIG. 7 is a front view showing a short span beam of a concrete structure by a seismic wall.
FIG. 8 is a side view showing a short-span beam of a concrete seismic wall structure.
FIG. 9 is a plan view showing a short span beam of a concrete tube frame structure.
FIG. 10 is a plan view showing a short span beam of a concrete plate-like apartment house.
[Explanation of symbols]
1 Short span beam 3 Column 1A Center part of short span beam (fiber reinforced cement material)
1B Both sides of short span beam (ordinary concrete)

Claims (3)

In concrete structures,
The short-span beam has a short-span beam in which the center of shear deformation is concentrated as a precast beam member made of fiber-reinforced cement-based material, and the other parts are made of ordinary concrete. It is characterized in that is, vibration control structure of concrete structures by fiber維補strong cementitious material. In concrete structures,
The area where shear deformation concentrates at the center of a short span beam with a short span is formed as a precast beam member with a fiber reinforced cementitious material, and the other part is a U-shaped cross section that also serves as a beam form frame with the same fiber reinforced cementitious material the precast beam members formed in series with the central portion, the short span beams are frames, usually concrete U-shaped cross section that serves as the beam-type frame, characterized in that formed by pouring, fiber維補strong cement Damping structure for concrete structures using steel materials. In concrete structures,
The area where shear deformation concentrates at the center of a short span beam with a short span is formed by integrating steel sheets on the bottom surface as a precast beam block made of fiber reinforced cementitious material, and steel plates are integrated on the bottom surface using other ordinary concrete. The part formed by construction and the beam block are characterized in that a short-span beam is constructed in which the steel plate on each bottom surface is integrally joined together and the beam block is arranged in the center. , the seismic structure of concrete-based structures by fiber維補strong cement-based material.

Images