JPH0127225B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to an earthquake-resistant structure in which earthquake-resistant walls are of a type that is prone to bending and failure.

(Conventional technology) Conventionally, as an earthquake-resistant structure for multi-story buildings,
Column 1a located in the center of the building as shown in Figure 4
There is an example of a multi-layered wall surrounded by a quake-resistant wall 2a, and a pile foundation 4a has piles 5a driven opposite each column.

(Problem to be solved by the invention) However, according to the conventional earthquake-resistant structure, the shear rigidity of multi-layered earthquake-resistant walls is large and it is difficult to deform due to horizontal force, so excessive stress is concentrated on the earthquake-resistant walls, and It is easy to cause shear failure, which is a curved failure mode. For this reason, the challenge is to design a structure that prevents shear failure and allows bending failure, which is rich in tenacity, to occur first. Further, in the conventional example, the number of piles is required in accordance with the number of columns, but if the number of piles can be reduced, it is desirable from the viewpoint of construction efficiency and economy. Of course, it is possible to reduce the number of piles in small-scale buildings by using large-diameter piles, but this has the disadvantage of increasing the burden on the foundation and increasing the amount of concrete and reinforcing bars. .

(Means for solving the problem) In the earthquake-resistant structure of the present invention, the pillars 11, 11 of the lowest layer of the pillars 1, 1 located parallel to each other in a multi-story building
The cross-sectional area of the column 1 is made smaller than that of the column 1 on the upper floor, and the column 11 bears only the overturning moment during an earthquake, and the column 11 is made of RC construction, S construction, etc.
In the present invention, the lowermost shear wall 12 of the multi-layer shear wall 2 surrounded by the columns 1 and 11 is a triangular wall with V-shaped pillars 3 arranged, and this triangular wall It bears the axial force. A triangular wall does not necessarily mean that the outer shape of the wall is triangular, but refers to a wall that has a configuration that allows the vertical axial force of the column 1 to flow through the center of the lower surface of the shear wall 12 to the foundation 4. The diagonal members 3 include, for example, a V-shaped steel frame or reinforcing bars arranged in a V-shape.

(Function) By reducing the cross-sectional area of the pillars 11 in the lowest layer, the bending rigidity of the shear wall is reduced, the shear rigidity of the multi-layer shear wall is reduced, and the wall is given stiffness, reducing the structural characteristic coefficient Ds value. , it is possible to prevent excessive stress concentration on the shear walls.

(Example) In Fig. 1, among the pillars 1, 1 located in the center of a multi-story building and parallel to each other, the pillar 1 on the lowest floor
1 and 11 have a cross-sectional area smaller than that of the pillars on the upper layer. The walls surrounded by pillars 1, 1 and 11, 11 are all earthquake-resistant walls. In the lowermost shear wall 12, a V-shaped diagonal member 3 is arranged on a line connecting the intersection of the columns and beams and the lower surface of the center of the shear wall. Therefore, the vertical axial force can flow from the columns 1, 1 through the diagonal member 3 and reach the pile foundation 4 as shown by the arrow. A pile 15 driven in the center of the piles 5 in the pile foundation is located opposite to the top of the lower end of the V-shaped diagonal member 3.

Comparative Example Below, we will compare the horizontal rigidity of the proposed shear wall and the conventional shear wall, as well as the bearing capacity in the single layer section.

First, let's compare the horizontal stiffness.

For the frame with the proposed shear wall shown in Figure 2A and the frame with the conventional shear wall shown in Figure 2B, elastic stress analysis was performed by applying an external force corresponding to the Ai distribution, and the horizontal rigidity of the shear wall was I asked for Table 1 shows the assumed cross section, and Table 2 shows the stress analysis results.

As is clear from the analysis results in Table 2, the proposed shear wall was able to reduce the horizontal stiffness to approximately 1/2 of that of the conventional example.

Next, we will compare the holding strength.

The yield strength of the present invention shown in FIG. 3A and that of the conventional example shown in FIG. 3B were determined, and Table 3 is a comparison table.

First, a conventional example will be explained.

The moment due to external force (1st floor column base) is M=1.44P×7.2+P×3.6=14.0P It is.

The moment due to the boundary beam is H _G = 113 × 4 + 180 + 2 = 812 t・m.

The overturning moment at foundation uplift is M=151×6+812=1718t・m The overturning moment at bending yield of the shear wall is M≒1501t・m ΣM=1501+113×4=1953t・m Therefore, the moment at bending yield (=1953× t
m) > Moment at foundation uplift (=1718t・m), so the bearing capacity of the shear wall is determined by the uplift of the foundation.

M=1718=14.0P P=123t Q=2.44×123=300t The shear strength is A=60×60×2+15×(600−60)=15300cm ² be=15300/600=25.5 Pte=5.07×8/15300 ×170=0.265% Pwh=1.27/20×25.5=0.00249 σ ₀ =188000/15300=12.3Kg/cm ² , so ∴Qwsu={0.053Pte ^0.23 (210+180)/1
+0.12+(2.7√3000+0.1×σ ₀ }be×600×7/
8 = 297t < 300t (value for shear failure).

On the other hand, in this case, the overturning moment due to external force, the moment due to the boundary beam, and the overturning moment when the foundation is lifted are the same as the conventional example: M = 14P, H _G = 812t・m, M = 1718t・m .

The overturning moment at bending yield of the shear wall is M≒1389t・m, and the moment at bending yield (=1389t・m)<
Since this is the moment when the foundation is uplifted (=1718t・m), the bearing capacity of the shear wall is determined by bending yield.

P = 99.2t Qw = 242t The shear wall shall be designed to have a bearing capacity of 242t or more.

Assuming that the holding capacity is equal to the required holding capacity (Qun), find the maximum horizontal force that can be borne (Qud).

Qun＝Ds Fes Qud ∴Qud＝Qun／Ds・Fes＝Qun／Ds (assuming Fes＝1.0) As is clear from Table 3, conventional shear walls are expected to undergo shear failure, so deformation is expected. I can't do it,
It has a large value of Ds=0.55. On the other hand, the proposed shear wall can be expected to undergo deformation because bending failure occurs first, and the value of Ds is small at 0.4.

Therefore, although the carrying capacity (Qun) is smaller in this case, 370t (conventional example) > 315t (main proposal), the maximum horizontal force that can be borne (Qud) is 673t (conventional example) < 788t ( This value is larger for the original plan), which shows that the original plan is a structurally advantageous seismic wall.

(Effects of the Invention) The present invention has a structure in which the cross-sectional area of the column on the lowest floor is reduced and this column bears only the overturning moment during an earthquake, so the shear rigidity of the multi-story shear wall is reduced, and the shear stiffness of the shear wall is reduced. This type of earthquake-resistant structure can prevent excessive stress concentration, give resilience to shear walls, and has a small overturning moment, making it easy to create bend-first earthquake-resistant structures in medium- and low-rise buildings where bending failure is relatively unlikely to occur. Structural characteristic coefficient Ds in buildings
The value can be reduced. Since the diagonal members of the lowermost shear wall are configured to direct the vertical axial force to the center, the number of piles can be reduced compared to conventional examples, and the burden on the foundation can be reduced, improving workability and economy. Desirable from a sexual standpoint.

[Brief explanation of drawings]

Figure 1 is an explanatory diagram, Figure 2A is a diagram of the framework of the present invention,
FIG. 2B is a frame diagram of a conventional example, FIG. 3A is a stress diagram of the present invention, FIG. 3B is a stress diagram of a conventional example, and FIG. 4 is a diagram showing an earthquake-resistant structure of a conventional example. 1,11...Column, 2,12...Shear wall, 3...
Diagonal material.

[Table] ※※ Replacement of shear rigidity of shear walls with braces.

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Claims (1)

[Claims] 1 The cross-sectional area of the lowest layer of columns located parallel to each other is made smaller than that of the upper layer column, and the lowest layer of the multi-layer shear wall surrounded by the columns is made to meet the intersection of the columns and beams. This earthquake-resistant structure is characterized by a triangular wall with a V-shaped diagonal member connecting the center of the lower surface of the earthquake-resistant wall.