JP7826638B2 - Reinforced wall and wall reinforcement method - Google Patents

Description

The present invention relates to a reinforced wall and a wall reinforcement method.

Patent Document 1 discloses a technique for reinforcing a reinforced concrete wall by anchoring steel plates to the wall surface of the wall, which is constructed in an area surrounded by reinforced concrete columns and beams.

Japanese Patent Application Publication No. 11-324337

However, reinforcing reinforced concrete walls with steel plates does not significantly improve their strength. Also, the load at which the steel plates begin to buckle is not high enough, so the steel plates may buckle or peel off from the reinforced concrete wall during an earthquake.
Therefore, the present invention has been made in consideration of the above circumstances, and an object of the present invention is to prevent buckling of steel plates reinforcing existing walls and to improve the strength of the existing walls.

A reinforcing wall for solving the above problem comprises an existing wall made of reinforced concrete surrounded by existing reinforced concrete columns and beams, steel plates and thickened reinforced concrete sections stacked on the existing wall in order out of the plane of the existing wall , and post-installed anchors for fixing the steel plates to the existing wall, wherein the post-installed anchors are composed of an anchor bolt that penetrates the steel plates, one end of which is driven into the existing wall and the other end of which is embedded in the thickened section, and a plurality of nuts that are screwed onto the anchor bolt and embedded in the thickened section, and the plurality of nuts are arranged at intervals.

A wall reinforcement method for solving the above-mentioned problems involves attaching a steel plate to an existing reinforced concrete wall surrounded by existing reinforced concrete columns and beams, fixing the steel plate to the existing wall with post-installed anchors, and then driving in additional reinforced concrete so that a thickened section of the reinforced concrete is layered on top of the steel plate. The post-installed anchor is composed of an anchor bolt whose one end is driven into the existing wall and a plurality of nuts screwed at intervals to the other end of the anchor bolt , and the other end of the anchor bolt and the plurality of nuts screwed at intervals to the other end of the anchor bolt are embedded in the thickened section.

According to the above, since the reinforced wall becomes thicker by providing the thickened portion, and the existing wall is reinforced by the steel plate and the thickened portion, the strength and earthquake resistance of the reinforced wall are improved.
Because the steel plates and thickened sections are stacked on the existing wall in order out of the plane of the existing wall, the load at which buckling begins to occur in the steel plates is increased, suppressing buckling and peeling of the steel plates during an earthquake. As a result, the reinforced wall has high strength and earthquake resistance.

Preferably, the reinforcing wall further comprises an anchor that is driven into the existing wall to fix the steel plate to the existing wall and is partially embedded in the thickened portion.
According to the above, the steel plate is less likely to peel off from the existing wall, and buckling of the steel plate is prevented.

This invention improves the strength of existing walls and prevents buckling and peeling of steel plates.

FIG. 1 is a front view of a seismic reinforcement wall and a column-beam frame. II-II cross-sectional view. III-III cross-sectional view. FIG. 1 is a front view of an existing wall. FIG. 10 is an explanatory diagram of the process of attaching steel plates to an existing wall. FIG. 1 is an explanatory diagram of the process of driving a post-installed anchor. This is an explanatory diagram of the process of pouring additional concrete into thicker sections of reinforced concrete structures. 10 is a graph showing the relationship between member angle and horizontal shear force obtained by simulation. FIG. 10 is a front view of the earthquake-resistant reinforcement wall of the modified example (1). FIG. 10 is a cross-sectional view of a seismic reinforcement wall according to modified example (2). FIG. 10 is a front view of the earthquake-resistant reinforcement wall of the modified example (3). FIG. 10 is a front view of the earthquake-resistant reinforcement wall of the modified example (4). FIG. 10 is a front view of the earthquake-resistant reinforcement wall of the modified example (5).

Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are subject to various limitations that are technically preferable for implementing the present invention, but the scope of the present invention is not limited to the following embodiments and illustrated examples.

1. Earthquake-resistant reinforcement wall Figure 1 is a front view showing an earthquake-resistant reinforcement wall and a column-beam frame of a building. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is a cross-sectional view taken along line III-III in Figure 1.

The column-beam structure 1 consists of adjacent columns 2, 2 and adjacent beams 3, 3 of the existing building frame. The columns 2, 2 are erected vertically, and the beams 3, 3 are erected horizontally between the columns 2, 2, creating a rectangular frame-like structure for the column-beam structure 1. The columns 2, 2 and beams 3, 3 are made of reinforced concrete or steel-reinforced concrete.

The seismic reinforcement wall 10 is constructed inside the beam-column structure 1. The seismic reinforcement wall 10 comprises an existing wall 20 made of reinforced concrete, an adhesive layer 38, a steel plate 30, multiple post-installed anchors 40, and a thickened section 50 made of reinforced concrete. The seismic reinforcement wall 10 is constructed by joining a steel plate 30 to one surface 21 of an existing wall 20 with an adhesive layer 38, fixing the steel plate 30 to the existing wall 20 with post-installed anchors 40, and then installing a thickened section 50 on the surface 21 and the steel plate 30. Therefore, the adhesive layer 38, steel plate 30, and thickened section 50 are layered on the existing wall 20 in this order outward from the surface of the existing wall 20, thereby reinforcing the existing wall 20.

The existing wall 20 is a seismic wall constructed inside the column-beam frame 1. The wall reinforcement of the existing wall 20 is either double reinforcement or single reinforcement. Double reinforcement means that there are two sets of vertical and horizontal reinforcement bars arranged in a grid pattern across the thickness of the existing wall 20, while single reinforcement means that there is one set of vertical and horizontal reinforcement bars. The ends of the vertical reinforcement are fixed to the beams 3, and the ends of the horizontal reinforcement are fixed to the columns 2.

The existing wall 20 has a rectangular opening 22 in its center. Here, as shown in the front view of Figure 4, the portion 23 of the existing wall 20 above the opening 22 is called the hanging wall portion 23, the portion 24 below the opening 22 is called the waist wall portion 24, and the portions 25 on both sides of the opening 22 are called the sleeve wall portions 25. The portions 26 on both sides of the hanging wall portion 23 and above the sleeve wall portion 25 are called the upper sleeve wall portions 26, and the portions 27 on both sides of the waist wall portion 24 and below the sleeve wall portion 25 are called the lower sleeve wall portions 27.

As shown in Figures 1 to 3, the steel plate 30 is attached to the sleeve wall portion 25 of the existing wall 20 by an adhesive layer 38. The adhesive layer 38 is made of a hardened resin-based adhesive or cement-based adhesive.

Multiple post-installed anchors 40 are arranged in a grid pattern within the plane. The post-installed anchors 40 fasten the steel plate 30 to the sleeve wall portion 25 of the existing wall 20. These post-installed anchors 40 prevent the steel plate 30 from peeling off from the sleeve wall portion 25 and also prevent the steel plate 30 from buckling.

The post-installed anchor 40 has an anchor bolt 41 and a nut 42. The anchor bolt 41 penetrates the steel plate 30, and a portion of the anchor bolt 41 is embedded in and fixed to the sleeve wall portion 25. The anchor bolt 41 is a metal anchor bolt or an adhesive anchor bolt. The nut 42 is screwed onto the anchor bolt 41 to fasten the steel plate 30 to the sleeve wall portion 25. Note that the number of nuts 42 screwed onto the anchor bolt 41 may be two or more. When there are two or more nuts 42, these nuts 42 may be spaced apart or stacked. If there are two or more nuts 42, the area around the post-installed anchor 40 where the steel plate 30 is less likely to peel off from the existing wall 20 expands, improving the effectiveness of preventing buckling of the steel plate 30.

The thickened portion 50 is thickened so as to be layered on the steel plate 30, and is also thickened so as to be layered on the areas protruding from the steel plate 30, i.e., the upper sleeve wall portion 26, the lower sleeve wall portion 27, the hanging wall portion 23, and the waist wall portion 24. The wall reinforcement of the thickened portion 50 is arranged in a lattice pattern and is embedded in the concrete of the thickened portion 50. The wall reinforcement of the thickened portion 50 is single-reinforced or double-reinforced. Of the wall reinforcement of the thickened portion 50, the ends of the vertical reinforcement are fixed to the beam 3 with anchors or the like, and the ends of the horizontal reinforcement are fixed to the column 2 with anchors or the like.
The portion of the post-installed anchor 40 that protrudes from the steel plate 30 is embedded in the concrete of the thickened portion 50.

The thickened portion 50 is not driven into the opening 22 in the existing wall 20. The thickened portion 50 has an opening in the center that overlaps with the opening 22 in the existing wall 20.

2. Reinforcement Method of Existing Wall Next, a reinforcement method of the existing wall 20, that is, a construction method of the seismic reinforcement wall 10, will be described.
First, adhesive is applied to one or both of the steel plate 30 and the sleeve wall portion 25, and the steel plate 30 is attached to the sleeve wall portion 25 with the adhesive, as shown in Figure 5. Note that a grid-like arrangement of through holes 31 is formed in advance in the steel plate 30. The through holes 31 are holes through which anchor bolts 41 of post-installed anchors 40 are passed.

Next, as shown in Fig. 6, a plurality of post-installed anchors 40 are driven into the sleeve wall portion 25, and the steel plate 30 is fastened to the sleeve wall portion 25 by these post-installed anchors 40. The driving of the post-installed anchors 40 will be described in detail below.
First, an embedding hole is opened in the sleeve wall portion 25 using a drill or the like through the through hole 31. Next, the anchor bolt 41 is inserted into the through hole 31 and embedded in the embedding hole, thereby fixing the anchor bolt 41 to the sleeve wall portion 25. Next, the nut 42 is screwed onto the anchor bolt 41, and the steel plate 30 is fastened to the sleeve wall portion 25 by the nut 42.

After the post-installed anchor 40 is driven, the thickened portion 50 is driven in as shown in Fig. 7. The driving of the thickened portion 50 will be described in detail below.
First, the vertical reinforcement and bar arrangement are placed. When placing the vertical reinforcement, the ends of the vertical reinforcement are fixed to the beams 3. When placing the horizontal reinforcement, the ends of the horizontal reinforcement are fixed to the columns 2. Next, a formwork is constructed within the area surrounded by the columns 2, 2 and the beams 3, 3. Next, concrete is poured inside the formwork, embedding the vertical reinforcement and the horizontal reinforcement in the concrete, and the parts of the post-installed anchors 40 that protrude from the steel plate 30 are also embedded in the concrete. Once the poured concrete has hardened, the formwork is dismantled to expose the thickened portion 50.

3. Advantageous Effects of the Earthquake-Resistant Reinforcement Wall (1) The provision of the thickened portion 50 increases the thickness of the earthquake-resistant reinforcing wall 10, thereby improving the strength and earthquake resistance of the earthquake-resistant reinforcing wall 10. Furthermore, the improvement in the strength and earthquake resistance of the earthquake-resistant reinforcing wall 10 due to the thickened portion 50 allows the steel plate 30 to be made thinner, which leads to a reduction in the material cost of the steel plate 30.

(2) Because the steel plates 30 reinforce the sleeve wall portions 25 of the existing wall 20, the strength and seismic resistance of the seismic reinforcement wall 10 are improved. Furthermore, the improved strength and seismic resistance of the seismic reinforcement wall 10 due to the steel plates 30 leads to a thinner thickened portion 50 and reduced material costs for the thickened portion 50.

(3) Because the steel plate 30 is sandwiched between the existing reinforced concrete wall 20 and the thickened portion 50, the load at which buckling begins to occur in the steel plate 30 is increased, preventing buckling of the steel plate 30.

(4) Because the steel plate 30 is fixed to the existing wall 20 by the post-installed anchors 40, the steel plate 30 is prevented from peeling off from the existing wall 20 and buckling of the steel plate 30 is also prevented. In particular, because the post-installed anchors 40 fasten the steel plate 30 to the existing wall 20, peeling of the concrete in the existing wall 20 near the interface between the adhesive layer 38 and the existing wall 20 is prevented, and as a result, peeling and buckling of the steel plate 30 are prevented.

(5) An adhesive layer 38 is interposed between the steel plate 30 and the existing wall 20, and the steel plate 30 is joined to the existing wall 20 by the adhesive layer 38. This makes it difficult for the steel plate 30 to peel off from the existing wall 20, preventing buckling of the steel plate 30.

4. Verification by Simulation A simulation was performed using the finite element method to determine the relationship between the member angle and horizontal shear force when the upper beam 3 was displaced horizontally.

There are four types of simulation models:
(1) Earthquake-resistant reinforcement wall 10
(2) Existing wall 20 only (i.e., without steel plate 30, adhesive layer 38, post-installed anchor 40, and thickened portion 50)
(3) Only the existing wall 20 and the thickened portion 50 (i.e., without the steel plate 30, adhesive layer 38, and post-installed anchors 40)
(4) Only the existing wall 20, the steel plate 30, the adhesive layer 38, and the post-installed anchors 40 (i.e., no thickened portion 50)

All models are scaled down to approximately one-third the size of the actual wall. In the model, the interior height of the existing wall 20 is 0.9 m, the interior width of the existing wall 20 is 1.48 m, the vertical dimension of the opening 22 is 0.3 m, the horizontal dimension of the opening 22 is 0.5 m, the thickness of the existing wall 20 is 40 mm, the thickness of the steel plate 30 is 6 mm, the thickness of the adhesive layer 38 is approximately 1 mm, and the thickness of the thickened portion 50 is 40 mm.

The simulation results are shown in Figure 8. In the graph of Figure 8, the horizontal axis represents the member angle, and the vertical axis represents the shear stress. The member angle is the horizontal displacement of the upper beam 3 divided by the wall height. Comparing the maximum horizontal shear force, or shear strength, for models (1) to (4), model (1) has the highest shear strength, model (3) has the second highest shear strength, model (4) has the third highest shear strength, and model (2) has the lowest shear strength. Simply reinforcing the existing wall 20 with either the thickened section 50 or the steel plate 30, as in models (3) or (4), does not significantly improve the strength and seismic resistance of the existing wall 20. It can be seen that reinforcing the existing wall 20 with both the steel plate 30 and the thickened section 50, as in model (1), improves the strength and seismic resistance of the seismically reinforced wall 10.

5. Modifications Each component of the seismic reinforcement wall 10 may be modified from the above embodiment. Modifications from the above embodiment are described below. At least two of the modifications (1) to (6) described below may be applied in combination whenever possible.

(1) As shown in Figure 9, the steel plate 30 and adhesive layer 38 may extend from the sleeve wall portion 25 (see Figure 4) into the upper sleeve wall portion 26 (see Figure 4) and the lower sleeve wall portion 27 (see Figure 4), and the steel plate 30 may be attached to the sleeve wall portion 25, the upper sleeve wall portion 26, and the lower sleeve wall portion 27 by the adhesive layer 38. In this case, the grid-like arrangement of the post-installed anchors 40 extends to the upper sleeve wall portion 26 and the lower sleeve wall portion 27, and the steel plate 30 is fixed to the upper sleeve wall portion 26 and the lower sleeve wall portion 27 by the post-installed anchors 40.

(2) As shown in Fig. 10, ribs 40A may be provided instead of the post-installed anchors 40. The ribs 40A are welded to the steel plate 30 so as to protrude out of the plane of the steel plate 30, and are embedded in the concrete of the thickened portion 50. The ribs 40A extend in the vertical direction and are arranged at intervals in the horizontal direction. Angle steel or a strip plate is used as the ribs 40A.
The rib 40A may be installed before the steel plate 30 is attached to the existing wall 20, or after the steel plate 30 is attached to the existing wall 20 and before the thickened portion 50 is added.
Such ribs 40A reinforce the steel plate 30 and suppress buckling of the steel plate 30 during an earthquake, which in turn suppresses peeling of the steel plate 30 from the existing wall 20 and the thickened portion 50 during an earthquake.
The ribs 40A may extend in the horizontal direction and be arranged at intervals in the vertical direction.Furthermore, the ribs 40A may be arranged in a lattice pattern.

(3) As shown in Figure 11, the existing wall 20 does not have to have an opening. In this case, the steel plate 30 is affixed to the entire existing wall 20 with an adhesive layer 38. In addition, post-installed anchors 40 are arranged in a grid pattern throughout the entire existing wall 20, and the steel plate 30 is fixed to the entire existing wall 20 by these post-installed anchors 40.

(4) As shown in FIG. 12, the steel plate 30 may be divided into multiple steel plate pieces 32, and these steel plate pieces 32 may be attached to the existing wall 20. In this case, the steel plate pieces 32 may be joined to each other by welding, or may be in contact with each other without being welded. The process of welding the steel plate pieces 32 to each other may be performed before or after the process of attaching the steel plate pieces 32 to the existing wall 20 with the adhesive layer 38. Note that even in the above cases (1) and (3), the steel plate 30 may be divided into multiple steel plate pieces 32.

(5) As shown in Figure 13, the steel plate 30 may be divided into multiple steel strips 33, and these steel strips 33 may be attached to the existing wall 20. These steel strips 33 extend longitudinally and are arranged at intervals in the horizontal direction. In addition, the steel strips 33 may also extend longitudinally in the horizontal direction and be arranged at intervals in the vertical direction. In addition, even in the cases of (1) and (3) above, the steel plate 30 may be divided into multiple steel strips 33.

(6) In the above embodiment, the steel plate 30 is adhered to the existing wall 20 by the adhesive layer 38. Alternatively, the steel plate 30 may be attached directly to the existing wall 20 without using adhesive, and the steel plate 30 may be fixed to the existing wall 20 by post-installed anchors 40.

REFERENCE SIGNS LIST 1... Column-beam frame 2... Column 3... Beam 10... Earthquake-resistant reinforced wall 20... Existing wall 30... Steel plate 38... Adhesive layer 40... Post-installed anchor 50... Thickened portion

Claims (2)

An existing reinforced concrete wall surrounded by existing reinforced concrete columns and beams,
a thickened portion of steel plates and reinforced concrete laminated on the existing wall in the out-of-plane direction of the existing wall;
and a post-installed anchor for fixing the steel plate to the existing wall,
The post-installed anchor is an anchor bolt that penetrates the steel plate, has one end driven into the existing wall, and has the other end embedded in the thickened portion;
a plurality of nuts that are screwed onto the anchor bolts and embedded in the thickened portion,
A reinforcing wall characterized in that the plurality of nuts are arranged at intervals. Steel plates were attached to the existing reinforced concrete walls surrounded by existing reinforced concrete columns and beams.
After fixing the steel plate to the existing wall with post-installed anchors,
A wall reinforcement method in which an increased thickness portion of a reinforced concrete structure is laminated on the steel plate,
The post-installed anchor is composed of an anchor bolt having one end driven into the existing wall and a plurality of nuts screwed at intervals to the other end of the anchor bolt,
A wall reinforcement method characterized by embedding the other end side of the anchor bolt and a plurality of the nuts screwed to the other end side of the anchor bolt at intervals in the thickened portion.