JP2014101662A - Reinforcement structure and reinforcement method of existing beam member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcement structure and a reinforcement method of an existing beam member capable of performing reinforcement work without disturbing indoor use of a structure to be reinforced and obtaining appropriate reinforcement effects on the structure while securing shear resistance required for a target shear displacement amount of the existing beam member.SOLUTION: Only on an outdoor-side surface 2a of an existing beam member 2 bridging a column member 5 and a column member 5, a reinforcement member 7 is disposed so as to cover the outdoor-side surface 2a. In the state where a predetermined gap (g) is kept between both ends of the reinforcement member 7 and the column members 5 opposing both the ends, the reinforcement member 7 is integrated with the existing beam member 2 and fixed.

Description

  The present invention relates to a reinforcing structure and a reinforcing method for an existing beam member. More specifically, the present invention can be reinforced without obstructing indoor use of a structure to be reinforced, and at a target shear displacement amount of the existing beam member. The present invention relates to a reinforcing structure and a reinforcing method for an existing beam member that can secure a necessary shear strength and obtain an appropriate reinforcing effect for a structure.

  Various methods for seismic reinforcement of existing structures have been proposed. As illustrated in FIGS. 16 and 17, when the seismic resistance of the structure 11 is improved, the surface of the existing beam member 2 made of reinforced concrete in which the main reinforcement 3 and the shear reinforcement 4 are embedded in the concrete C (outdoor side) A method is known in which a reinforcing member 12 such as a steel plate is wound around and integrated with the surface 2a, the indoor surface 2b and the lower surface 2c). Such a conventional reinforcing method focuses on increasing the shear strength of the existing beam member 2 to be reinforced, and the shear strength of the reinforced existing beam member 2 is often more than necessary (over spec). In addition, even if the shear strength of the reinforced existing beam member 2 is improved, if the existing member (column member 5) in the vicinity thereof is not reinforced, the structure 11 between the existing beam member 2 and the column member 5 has an external force. Load balance will be unbalanced. Therefore, the load burden on the column member 5 that is not reinforced increases, and the structure 11 as a whole may not have a sufficient reinforcing effect.

  In addition, in the reinforcing method in which a reinforcing member is wound around the surface of an existing member, it is necessary to perform reinforcement work from the inside and outside of the structure, and the structure cannot be used indoors during the reinforcement work, or indoor use is significantly restricted. There is a problem that. Therefore, it is not suitable for reinforcement intended for structures such as apartment houses where people live daily.

  In order to solve this problem, various reinforcing methods capable of performing construction only from the outside of the structure have been proposed (see, for example, Patent Document 1). Patent Document 1 proposes a reinforcing method in which a steel-concrete composite structural member (reinforcing member) made of reinforcing steel and fiber-reinforced concrete is integrated with an outer wall surface of an existing building. In this reinforcing method, since it is required to use a shape steel and fiber reinforced concrete as the reinforcing member, there is little room for selection of a material to be used. In addition, when a reinforcing member is integrated and reinforced only on the outdoor surface of the beam body, when both ends of the reinforcing member are connected to the column body, the column body is separated from the beam body via the reinforcement member. Since the shearing force acts directly, it is necessary to reinforce the column body.

JP 2006-312859 A

  The purpose of the present invention is to enable reinforcement work without hindering the indoor use of the structure to be reinforced, and to ensure the necessary shear strength at the target shear displacement of the existing beam member, and to ensure that the structure is appropriate. An object of the present invention is to provide a reinforcing structure and a reinforcing method for an existing beam member that can provide a sufficient reinforcing effect.

  In order to achieve the above object, the reinforcement structure for an existing beam member of the present invention is a reinforcement structure for an existing beam member including a reinforcement member fixed to an existing beam member spanned between a column member and a column member. The reinforcing member is fixed to only the outdoor side surface of the existing beam member so as to cover the outdoor side surface, and is integrated and fixed with the existing beam member, and both ends of the reinforcing member and the column members facing the both ends are respectively fixed. A predetermined gap is formed between the two.

  Further, the reinforcing method of the existing beam member according to the present invention is the reinforcing method of the existing beam member spanned between the column member and the outdoor side surface only on the outdoor side surface of the existing beam member. The reinforcing member is arranged so as to cover, and the reinforcing member is integrated and fixed with the existing beam member with both ends of the reinforcing member and each of the column members facing the both ends being provided with a predetermined gap. It is characterized by that.

  According to the present invention, since the reinforcing member is fixed to only the outdoor surface of the existing beam member so as to cover the outdoor side surface, the reinforcing work can be performed only from the outside of the structure. be able to. Therefore, indoor use of the structure to be reinforced is not restricted during the reinforcement work, and the structure can be positively applied to reinforcement for structures such as apartment houses. The effect of the present invention "without interfering with the indoor use of the structure to be reinforced" does not prevent indoor use of the room to be reinforced when reinforcing the inside of the structure. The meaning is included.

  In addition, by providing the reinforcing member only on the outdoor surface of the existing beam member, the shear strength of the existing beam member is not excessively increased until the target shear displacement is exceeded. In addition, since a predetermined gap is formed between both ends of the reinforcing member fixed integrally with the existing beam member and each of the column members facing the both ends, the existing beam is connected to the column member via the reinforcing member. The shearing force from the member does not act directly, and the balance of the load burden between the existing beam member and the column member when the structure receives an external force does not change greatly. Thereby, it is possible to secure a necessary shear strength at the target shear displacement amount of the existing beam member and obtain an appropriate reinforcing effect for the structure.

It is a front view which illustrates the structure which has a reinforcement structure of the present invention. It is explanatory drawing which illustrates the internal structure of the existing beam member of FIG. 1 by a front view. It is AA sectional drawing of FIG. It is BB sectional drawing of FIG. It is explanatory drawing which illustrates the process of constructing the reinforcement structure of FIG. 1 by planar view. It is explanatory drawing which illustrates the process of constructing the reinforcement structure of FIG. 1 by sectional view. It is a graph which illustrates the relationship between the shear displacement amount and shear force of the existing beam member before reinforcement and the existing beam member reinforced by this invention. It is a graph which illustrates the relationship between the amount of shear displacement and the shear force of the existing beam member before reinforcement, and the existing beam member reinforced by the conventional method. It is explanatory drawing which shows the modification of the structure which has a reinforcement structure of this invention by planar view. It is explanatory drawing which illustrates typically the static loading experiment with respect to a test sample. It is a perspective view which illustrates the test sample of FIG. It is a graph which illustrates the static loading experiment result of a comparative example. FIG. 6 is a graph illustrating the static loading test result of Example 1. FIG. 10 is a graph illustrating the static loading test result of Example 2. FIG. 10 is a graph illustrating the static loading experiment result of Example 3. It is a front view which illustrates the structure which has the reinforcement structure by a conventional method. It is CC sectional drawing of FIG.

  Hereinafter, the reinforcement structure and reinforcement method of the existing beam member of this invention are demonstrated based on embodiment shown in the figure.

  The reinforcing structure of the existing beam member of the present invention illustrated in FIGS. 1 to 4 is a target shear displacement amount of the existing beam member 2 by reinforcing the existing beam member 2 constituting the structure 1 with the reinforcing member 7. This ensures the necessary shear strength. Thereby, the appropriate reinforcement effect with respect to the structure 1 is acquired, and the whole seismic strength of the structure 1 is improved. The structure 1 to be reinforced is, for example, a reinforced concrete building, an apartment house, or the like.

  In this structure 1, the existing beam member 2 is bridged between the existing column member 5 and the column member 5. A wall member or the like is appropriately provided in a portion surrounded by the column member 5 or the existing beam member 2. In the existing beam member 2, main bars 3 extending to the column members 5 at both ends and penetrating in the longitudinal direction are arranged vertically, and shear reinforcing bars 4 are arranged at a predetermined pitch in the longitudinal direction. Is integrated with concrete C. The column member 5 is laid with vertical bars 6a at a predetermined pitch in the vertical direction, main bars 6b extending in the vertical direction, and auxiliary bars 6c as required, which are concrete. Integrated with C.

  The reinforcing structure of the present invention includes a reinforcing member 7 that is fixed to an existing beam member 2 that is bridged between the existing column member 5 and the column member 5. The reinforcing member 7 of this embodiment is a reinforced concrete plate. In the reinforcing member 7, axial bars 9 extending in the longitudinal direction are vertically arranged, and ribs 8 are arranged at a predetermined pitch in the longitudinal direction, and these are integrated with the concrete C. The bar arrangement is not limited to the one shown in this embodiment, and an arrangement appropriately arranged such as using a wire mesh in place of the reinforcing bar can be adopted.

  The reinforcing member 7 is disposed only on the outdoor-side surface 2a of the existing beam member 2, and is fixed integrally with the existing beam member 2 so as to cover substantially the entire range of the outdoor-side surface 2a. The reinforcing member 7 and the existing beam member 2 are fixed so that they can be integrally deformed without being displaced at the boundary when subjected to an external force (shearing force). If the reinforcing member 7 is made of reinforced concrete as in this embodiment, the connecting anchor bars 10 that connect the reinforcing member 7 and the existing beam member 2 are embedded in each other, and the reinforcing member 7 is connected via the connecting anchor bars 10. And the existing beam member 2 are firmly integrated and fixed. As the connection anchor bar 10, for example, a deformed bar is used.

  As the reinforcing member 7, in addition to the reinforced concrete plate, for example, a precast concrete plate, a fiber-containing concrete plate, a metal plate such as a steel plate, a hard resin plate, or the like can be used. The reinforcing member 7 and the existing beam member 2 are integrally fixed by solidifying materials such as anchor bolts and nuts, concrete, mortar, grout (cement paste) or other appropriate means according to the respective materials. .

  A predetermined gap g is formed between both ends of the reinforcing member 7 integrated with the existing beam member 2 in the longitudinal direction and the column members 5 facing the both ends. The size of the predetermined gap g is, for example, not less than 10 mm and not more than ½ of the beam of the existing beam member 2, preferably about 50 mm.

  In order to construct this reinforcing structure, as illustrated in FIGS. 5 and 6, the connection anchor bars 10 are projected from the outdoor-side surface 2 a of the existing beam member 2. Further, the outdoor side surface 2a is provided with necessary reinforcing bars such as the stirrup 8 and the axis 9. The outdoor surface 2a may be roughened.

  Next, a mold 13 is installed with a gap in the front-rear direction with respect to the outdoor side surface 2 a, and the outdoor side surface 2 a is covered with the mold 13. 5 and 6, the formwork 13 is indicated by hatched portions. Concrete C is placed between the mold 13 and the outdoor side surface 2a. When the placed concrete C is solidified, a reinforcing member 7 made of reinforced concrete is formed, and the connecting anchor bars 10 are embedded in the reinforcing member 7 and the existing beam member 2 in communication. Thereby, the reinforcing member 7 is integrated and fixed with the existing beam member 2. Thereafter, by removing the mold 13, a predetermined gap g is formed between both ends of the reinforcing member 7 and each of the column members 5 facing the both ends.

  In order to determine the specification of the reinforcing member 7 in the present invention, for example, based on the allowable shear displacement amount of the existing beam member 2 to be reinforced, the target shear displacement amount (design target value) of the existing beam member 2 is determined. Set. Next, until the shear displacement amount of the existing beam member 2 reaches the design target value, the strength (shear strength) at which the existing beam member 2 does not undergo shear failure is calculated based on simulation calculation. Then, the specification of the reinforcing member 7 is determined so that the reinforced existing beam member 2 has the calculated shear strength at the shear displacement amount of the design target value. That is, without considering the case where the existing beam member 2 undergoes shear deformation exceeding the design target value, a shear displacement amount that is considered to be practically appropriate is set as the design target value.

  FIG. 7 shows the relationship between the shear displacement amount (shear deformation angle) and shear force of the existing beam member 2 adopting the reinforcement structure of the present invention, and FIG. 8 shows the conventional reinforcement structure (structures illustrated in FIGS. 15 and 16). The relationship between the shear displacement amount (shear deformation angle) of the adopted existing beam member 2 and the shear force will be exemplified. 7 and 8, the solid line is the test data of the existing beam member 2 reinforced, and the broken line is the test data of the existing beam member 2 before reinforcement.

  As illustrated in FIG. 7, in the reinforcing structure of the present invention, until the shear deformation amount of the design target value is reached by the reinforcement by the reinforcing member 7, the shear force is maintained at a high level and the existing beam member 2 is sheared and broken. do not do. On the other hand, when the shear deformation exceeds the design target value, a shear failure occurs in the existing beam member 2, and the shearing force (proof strength) is reduced brittlely. As illustrated in FIG. 8, in the conventional reinforcing structure, even when the shearing deformation greatly exceeds the design target value due to reinforcement, the existing beam member 2 does not undergo shear failure, and the shearing force (proof strength) is Maintained at a high level.

  As described above, according to the present invention, the existing beam member 2 is reinforced by the reinforcing member 7 fixed only to the outdoor surface 2a of the existing beam member 2 until the shear displacement amount that is the design target value is reached. Do not secure shear strength. Therefore, as in the conventional reinforcing structure illustrated in FIGS. 12 and 13, when the reinforced existing beam member 2 exceeds the shear displacement amount that is the design target value, a specification that exhibits excessive shear strength more than necessary. Instead, economic design becomes possible.

  Further, according to the present invention, the reinforcing member 7 is attached only to the outdoor-side surface 2a of the existing beam member 2, and is fixed integrally with the existing beam member 2, so that the reinforcement work from the outside of the structure 1 is completed. Can be made. Therefore, since the indoor use of the structure 1 to be reinforced is not restricted during the reinforcement work, the structure 1 such as an apartment house can be actively applied to the reinforcement. When the reinforcing member 7 is attached to the outdoor side surface of the column member 5, the effective space such as a veranda may be narrowed. However, when the reinforcing member 7 is attached to the outdoor side surface 2a of the existing beam member 2, such a problem also occurs. Absent.

  In addition, the reinforcement structure of this invention is applicable also when reinforcing the inner side of the structure 1 so that it may illustrate in FIG. This reinforcement structure is intended to reinforce the room 1A inside the structure 1. The reinforcing member 7 is integrally fixed to the existing beam member 2 so as to cover the outer surface 2a only on the outer surface 2a of the existing beam member 2 forming the inner chamber 1A. And the predetermined clearance g is formed between the both ends of this reinforcement member 7, and each of the column member 5 which opposes this both ends.

  In the case of this embodiment, the reinforcement work can be completed only from the outside of the inside room 1A. Therefore, the indoor use of the inner room 1A is not restricted during the reinforcement work.

  Furthermore, in the present invention, the predetermined gap g is formed between both ends of the reinforcing member 7 that is integrally fixed with the existing beam member 2 and each of the column members 5 that are opposed to the both ends. The shearing force from the existing beam member 2 does not act directly on the reinforcing member 7. Therefore, the load balance between the existing beam member 2 and the column member 5 when the structure 1 receives an external force does not change significantly. That is, it is possible to avoid an additional load burden on the column member 5. Therefore, an appropriate reinforcing effect for the structure 1 can be obtained.

  The thickness of the reinforcing member 7 varies depending on the material, specifications, and the like, but in the case of the reinforcing member 7 made of reinforced concrete, it is preferably 50 mm or more in consideration of workability and the like, for example, about 150 mm to 250 mm.

  The burying length of the connection anchor bars 10 with respect to the existing beam member 2 is set to 30 mm or more, for example. If the embedment length is less than 30 mm, it is difficult to sufficiently integrate the reinforcing member 7 and the existing beam member 2. Further, if the buried length exceeds 200 mm, the time for drilling the buried hole for projecting the connecting anchor bars 10 on the outdoor side surface 2a becomes excessive, so this buried length is preferably 30 mm to 300 mm. Is 100 mm to 200 mm. For example, the embedment length of the connection anchor bars 10 with respect to the reinforcing member 7 is preferably 30 mm or more, and is set to about 50 mm to 200 mm.

  The thickness of the connecting anchor muscle 10 is, for example, about 9 mm to 25 mm in outer diameter. The arrangement density of the connecting anchor bars 10 is appropriately determined so that the reinforcing member 7 and the existing beam member 2 can be integrally fixed.

  The test sample S (Examples 1, 2, and 3) of the beam member having the reinforcing structure illustrated in FIGS. 1 to 4 and the test sample S that is not reinforced by the reinforcing member with respect to Examples 1 to 3 (Comparison) Example) was prepared, and the shear displacement amount and the shear force of each test sample S were measured using the loading device 14 as illustrated in FIGS. 10 and 11.

  The specifications of each member are as follows.

Column member: height H1 = 1400 mm, thickness H2 = 800 mm, width H3 = 500 mm
Beam member: height h1 = 650 mm, thickness h2 = 350 mm, inner length L = 1600 mm, main bar 3-D25 / 2-D22, main bar amount pt = 1.16%, shear reinforcement bar □ -D10 @ 300 , Shear reinforcement ratio pw = 0.14%
Reinforcing member: height h1 = 650 mm, inner length 1500 mm (predetermined gap g = 50 mm), axial muscle 2-D10, loose muscle □ -D10 @ 150
Connection anchor bar: D13, buried length of 91 mm for beam member

  The individual specifications of the test samples S of Examples 1 to 3 and Comparative Example are shown in Table 1.

  Each test sample S has the upper and lower column members 5 fixed to the reaction force frame 16 and the base B with a PC steel rod, and the hydraulic actuator 15 attached to the reaction force wall 18 through the reaction force frame 16. Positive and negative horizontal forces were repeatedly loaded on the beam member 2. By controlling the expansion and contraction of the vertical oil jacks 17 attached to both ends of the reaction force frame 16, an axial force (a vertical force in the figure) is always generated in the beam member 2 that undergoes shear deformation due to the loaded horizontal force. I tried not to.

The horizontal displacement δ at the top of the test sample S was divided by the inner length L of the test sample S, and the relative member angle R = δ / L was controlled with the north direction being positive. The loading cycle is performed for R = 0.125 × 10 ⁻² (rad.), 0.25 × 10 ⁻² (rad.) One cycle at a time, 0.50 × 10 ⁻² (rad.), 0.75 × 10 ⁻² (rad.), 1.0 × 10 ⁻² (rad.), 1.5 × 10 ⁻² (rad.), 2.0 × 10 ⁻² (rad.), 2.5 × 10 ^-2 (rad.) And 3.0 × 10 ^-2 (rad.) Were performed two cycles at a time, and the last load up to 4.0 × 10 ^-2 (rad.) Was limited to the plus direction. The measurement results for the test samples S of Comparative Example, Example 1, Example 2, and Example 3 were as shown in FIGS. 12, 13, 14, and 15, respectively.

From the results of FIGS. 12 to 15, R = 0.75 × 10 ⁻² rad. It can be seen that the maximum shear strength Qmax of the beam member is improved by about 1.3 to 1.5 times in the region of the shear displacement amount which is practically important. A comparison between Example 1 (FIG. 13) and Example 3 (FIG. 15) shows that the thickness of the reinforcing member hardly affects the maximum shear strength Qmax of the beam member.

DESCRIPTION OF SYMBOLS 1 Structure 1A Inside room 2 Existing beam member 2a Outdoor side surface (outside surface)
2b Indoor side surface 2c Lower side surface 3 Main bar 4 Shear reinforcement bar 5 Column member 6a Band bar 6b Main bar 6c Auxiliary bar 7 Reinforcement member 8 Axial bar 10 Axial bar 10 Connection anchor bar 11 Structure 12 Reinforcement member 13 Formwork 14 Loading device 15 Hydraulic actuator 16 Reaction force frame 17 Vertical oil jack 18 Reaction force wall B Base C Concrete g Clearance S Test sample

Claims (8)

  In the reinforcing structure of an existing beam member provided with a reinforcing member fixed to the existing beam member spanned between the column member, the reinforcing member is provided only on the outdoor surface of the existing beam member. The existing beam member is integrated and fixed so as to cover the outer surface, and a predetermined gap is formed between both ends of the reinforcing member and each of the column members facing the both ends. Reinforcement structure for beam members.   The reinforcing structure for an existing beam member according to claim 1, wherein the reinforcing member is made of reinforced concrete, and a connection anchor bar that connects the reinforcing member and the existing beam member is embedded.   The reinforcement structure for an existing beam member according to claim 1 or 2, wherein the predetermined gap is 10 mm or more and 1/2 or less of a beam claw of the existing beam member.   The reinforcement structure of the existing beam member according to any one of claims 1 to 3, wherein an embedded length of the connection anchor bar with respect to the existing beam member is 30 mm or more.   In the method of reinforcing an existing beam member spanned between a column member and a column member, a reinforcing member is disposed only on the outdoor side surface of the existing beam member so as to cover the outdoor side surface, and the reinforcing member A reinforcing method for an existing beam member, characterized in that a predetermined gap is formed between both ends and each of the pillar members facing both ends, and the reinforcing member is integrated and fixed with the existing beam member.   Connecting anchor bars are projected from the outdoor surface of the existing beam member, the outdoor surface is covered with a mold, and concrete is placed between the mold and the outdoor surface, and the concrete is solidified. The reinforcing method of the existing beam member according to claim 5, wherein the reinforcing member is formed of reinforced concrete, and the connection anchor bars are communicated with and embedded in the reinforcing member and the existing beam member.   The method for reinforcing an existing beam member according to claim 5 or 6, wherein the predetermined gap is set to be 10 mm or more and 1/2 or less of a beam length of the existing beam member.   The reinforcement method of the existing beam member in any one of Claims 5-7 which sets the embedding length of the said connection anchor reinforcement with respect to the outdoor side surface of the said existing beam member to 30 mm or more.

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