JPH0419355B2 - - Google Patents

Description

[Detailed description of the invention]

[Detailed Description of the Invention] In general, a shear wall in an earthquake-resistant structure has a main role of contributing to the strength of a building and preventing deformation of the building through the rigidity of the wall. Conventional shear walls made of reinforced concrete construction have the advantage of extremely high bearing capacity and high initial rigidity, but they have poor deformation performance, and in the rare event of a large earthquake, the frame parts may undergo small damage before reaching their maximum bearing capacity. Rapid deformation occurs due to interlaminar deformation of the skeleton,
It has the disadvantage of causing a decrease in proof strength. Therefore, in order to construct a shear wall that is effective during a major earthquake, it must be highly tough and able to maintain its strength even after reaching its maximum strength. The present invention has been proposed based on such a viewpoint, and the present invention has been proposed by incorporating a wall plate of a framed shear wall in reinforced concrete, steel reinforced concrete, or a steel structure frame into a wall plate surface material made of mortar or normal strength concrete. Compressive strength is 80~150
It is constructed of sand German trench-shaped reinforced concrete with a low-strength concrete wall board core material rich in compressive toughness of about Kg/cm ² interposed, and the columns and beams of the reinforced concrete or steel-framed reinforced concrete are constructed of ordinary or high-strength concrete, The wall plate resists seismic force by compressive drag in the diagonal direction of the wall plate, and has a shear strength within the elastic limit during normal and weak earthquakes, and functions as a highly rigid building, and during strong earthquakes, the wall plate resists earthquake force. Before the columns and beams around the wall plate undergo shear failure due to the compressive drag of the plate, the core material of the wall plate made of the low-strength concrete with high compressive toughness causes compression failure, and the wall plate gradually The structure is characterized in that it adapts to the deformation of the surrounding columns and beams while undergoing compressive fracture, and eventually the wall plate cooperates with the framework of the surrounding columns and beams to resist external forces. The purpose of the flexible shear wall is to increase the rigidity of the building against normal wind pressure and the small earthquakes that often occur, and to reduce the deformation of the building, and to reduce the deformation of the building during the rare occurrence of large earthquakes. Improved shear walls that maintain strength, reduce earthquake input by lowering the rigidity of the building in response to large deformations, and are structured so that the frame and wall plates work together to resist external forces. It is in the point of providing. In the present invention, as described above, the wall plate of a shear wall surrounded by reinforced concrete, steel reinforced concrete, or steel frame has a compressive strength of 80
It is composed of a sandwich-like reinforced concrete consisting of a low-strength reinforced concrete wall plate core material with a high compressive toughness of ~150 Kg/cm ² and a wall plate surface material made of mortar or normal strength concrete, and the above-mentioned reinforced concrete, steel-framed reinforced concrete columns and beams. Since it is constructed of ordinary or high strength concrete to prevent shear failure due to the compressive drag of the wall explained in FIGS. 12 and 13, which will be described later,
During normal times, it acts as a shear wall with relatively high rigidity, but during a major earthquake, compression failure gradually progresses from the low-strength concrete part of the wall plate core, and the walls around the wall plate gradually undergo compression failure. It adapts to the deformation of the columns and beams, causing a decrease in the stiffness of the building and reducing the seismic input, and ultimately the wall plates and surrounding columns,
The beam framework works together to resist external forces. In this case, since the frame around the wall plate is sound, the earthquake-resistant wall has strong mechanical properties with little decrease in yield strength, and the above-mentioned drawbacks are eliminated. In addition, by adjusting the cross-sectional thickness of the core material and surface material of the wall plate, the strength of the earthquake-resistant wall can be adjusted, and the watertightness and carbonation resistance properties are also higher than that of ordinary concrete. The core material is made of low-strength concrete, which has a slightly lower strength due to the surface of the core material, and its properties are improved by covering the surface material with a surface material of ordinary concrete or mortar. In the case of a steel frame structure, the columns and beams have sufficiently high strength that they will not undergo shear failure due to the compressive drag of the walls, but in this case the walls will be destroyed slowly. The present invention will be described below with reference to the illustrated embodiments. Figures 1 to 3 show reinforced concrete columns 1a, beams 2a, made of ordinary or high-strength concrete,
Compressive strength ≒
Wall board core material 3a made of low-strength concrete of 80 to 150 Kg/cm ² and mortar or compressive strength ≒ 200
This figure shows a frame in which a sandwich-like reinforced concrete wall board 3 is arranged, and the wall board surface material 3b is made of ordinary strength concrete of Kg/cm ² . Here, we will explain the flow of force between columns, beams, and wall plates. Figure 12 shows the state in which seismic force is applied to the seismic wall, and Figure 13 shows the flow of force at that time. Since the tensile strength of the concrete that makes up the wall plate is weaker than its compressive strength, tensile cracks occur when an earthquake force is applied to the concrete, and the main force is transmitted to the wall plate as a compressive force p. At that time, the compressive force p is transmitted to the columns and beams on the lower floor via the corners of the columns and beams. At this time, the restraining pressure q that attempts to resist the compressive force of the wall plate due to the reaction force generated in the pillars and beams at the corner
works on the wallboard. That is, the wall plate resists the seismic force by the diagonal (brace direction) compressive drag of the wall plate. If ordinary or high-strength concrete is used for the wall plate, a larger compressive force will be generated than if low-strength concrete is used, and the confining pressure at the corner will be larger. Therefore, the failure type of the shear wall is due to the confining pressure q,
Either the columns and beams fail in shear, or the wallboard fails in compression. In this embodiment, low-strength concrete was used as the core material 3a of the wall plate 3 to weaken the compression resistance of the wall plate 3 and to improve the corner portions around the joints between columns and beams. The restraining force q is weakened to prevent shear failure of beams and columns, and a further characteristic of low-strength concrete is that its strength decreases more slowly after compressive failure than normal or high-strength concrete. Low-strength concrete suitable for the wall component material obtained as a result of experiments by the present inventors will be mentioned.

[Table] Figure 9 is a chart showing the stress-strain curves of each of the above-mentioned concretes and normal strength concrete. Also, the reason why mortar or normal strength concrete is used as the surface material 3b of the wall board 3 is that the low strength concrete of the core material 3a has slightly lower watertightness and carbonation resistance characteristics than normal concrete. To improve this, and to further improve the core material 3a
The strength of the seismic wall can be adjusted by adjusting the cross-sectional thickness of the surface material 3b and the surface material 3b. 4 to 8 show each embodiment of the shear wall according to the present invention, and in FIGS. 4 and 5, sandwich-shaped reinforced concrete constructed as described above is installed inside the column 1a of the reinforced concrete frame and the beam 2a. An example is shown in which the wall board 3 is arranged, and Fig. 4 shows the case where the vertical reinforcement of the wall board 3 is not anchored to the beam 2a at the bottom of the wall board 3, and Fig. 5 shows the case where the vertical reinforcement is anchored to the beam 2a. Indicate the case. Note that the wall plate 3 may be made of precast or cast-in-place concrete. Note that 3' in FIG. 5 is post-cast concrete that is covered after the wall vertical reinforcements are connected to the reinforcing bars anchored to the beams 2a. Figures 6 and 7 show the case where the sandwiched reinforced concrete wall plate 3 is used in a reinforced concrete frame or a steel-framed reinforced concrete frame, and Figure 6 shows the case where the wall plate 3 made of precast reinforced concrete is simply inserted into the frame by 20 to 40 mm. Fig. 7 shows a case in which the wall plate 3 made of precast concrete is assembled into a frame, the joints 4 are tightened with bolts, welded, or joined with reinforcing bars, and the wall Concrete or mortar is later poured into the peripheral gap of the plate 3. In each of the above embodiments, each column and beam is a wall plate 3.
It is constructed of ordinary or high-strength concrete to prevent shear failure due to compressive drag, and is shear reinforced as necessary. In FIG. 8, the precast concrete wall plate 3 is assembled into a steel frame frame, and the peripheral joints 5 are constructed by tightening bolts, welding, etc. Next, regarding the mechanical properties of the present invention, the results of an experiment shown in FIG. 10, which was conducted to confirm its seismic effect, will be explained. Figure 10 shows a conventional one-piece shear wall in which columns, beams, and wall plates are integrally constructed of ordinary concrete, or a sandwich-like reinforced concrete wall plate in which the cross-sectional area of the ordinary-strength concrete surface material is larger than that of the low-strength concrete core material. Wall panels with opposite proportions,
The relationship between the horizontal load and the member angle for a wall plate with a ratio between 1 and 2 is shown, and a normal monolithic shear wall has a maximum load at an interstory deformation member angle (see Figure 11) R ≒ 5/1000 radians. This results in a sudden decrease in proof strength. Ordinary one-piece shear walls resist horizontal loads using the compressive drag force of the wall plate, and this reaction force is supported by the corners of columns and beams. often causes shear failure, resulting in a sudden drop in proof strength.Also, even if the wall plate concrete can be fully supported, the decline in proof strength will be rapid because the wall plate concrete lacks compressive toughness. In terms of structural design, such sudden fractures or rapid declines in yield strength should be avoided as much as possible, and for this purpose, load-bearing walls with high toughness are desirable even if the yield strength is somewhat reduced. As shown by , in Fig. 10, the rigidity of the load-bearing wall of the present invention is close to that of the conventional integral shear wall when the deformation is small, and as the deformation increases, the stiffness of the conventional shear wall is R=4/1000~5/10
On the contrary, the shear wall of the present invention maintains sufficient strength with almost no decrease in strength even under deformation of R = 10/1000 radian or more. There is. In this way, in the shear wall of the present invention, before the columns and beams undergo shear failure due to the compressive drag of the wall plate, the low-strength concrete material that is the core material of the wall plate causes compression failure, and at that time, the wall plate Because the core material, concrete, has high compressive toughness, the wall plates gradually undergo compressive failure and adapt to the deformation of the frame, eventually working together with the surrounding columns and beams to resist external forces. It is possible to change the strength and toughness by changing the thickness ratio between the core material and the surface material of the wall board. Although the present invention has been described above with reference to embodiments, the present invention is, of course, not limited to such embodiments, and can be modified in various ways without departing from the spirit of the present invention. .

[Brief explanation of drawings]

Figures 1A and 1B to Figures 3A and 3B are front views and vertical side views, respectively, and Figures 4A and 4B to 8A and 8B when the present invention is applied to reinforced concrete structures, reinforced steel concrete structures, and steel frame structures. The figures are a longitudinal front view and a longitudinal side view showing each embodiment of a shear wall according to the present invention, and Fig. 9 is a compressive stress-distortion curve of low-strength concrete and normal-strength concrete used in the present invention. Fig. 10 is a load deformation curve of each shear wall according to the conventional and the present invention, Fig. 11 is a diagram for explaining Fig. 10, and Fig. 12 is an explanatory diagram showing a state in which seismic force is applied to the shear wall. , FIG. 13 is an explanatory diagram showing the flow of force at that time. 1a, 1b, 1c...column, 2a, 2b, 2c...
...Beam, 3...Wallboard, 3a...Wallboard core material, 3b...
...Wallboard surface material.

Claims (1)

[Claims] 1. The wall of a framed shear wall in reinforced concrete, steel-framed reinforced concrete, or a steel structure frame is placed in a wall board surface material made of mortar or normal strength concrete, with a compressive strength of about 80 to 150 kg/cm ² and a low strength with high compressive toughness. The wall plate is constructed of sandwich-shaped reinforced concrete with a concrete wall plate core material interposed therebetween, and the columns and beams of the reinforced concrete or steel-framed reinforced concrete are made of ordinary or high-strength concrete, and the wall plate has the same resistance to earthquake force. It resists compressive drag in the diagonal direction of
During a strong earthquake, before the columns and beams surrounding the wall plate undergo shear failure due to the compressive drag of the wall plate, the core material of the wall plate made of the low-strength concrete with high compressive toughness causes compressive failure. The wall plate gradually undergoes compression failure and adapts to the deformation of the surrounding columns and beams, and eventually the wall plate and the frame of the surrounding columns and beams cooperate with each other to resist external forces. A flexible shear wall characterized by: