JPH0327708B2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to an air membrane structure roof.

The air membrane structure is made by crossing cables on the roof surface and stretching them in the shape of a sticky net, and then fixing the membrane material around the squares of the grid on all four sides. send the
Indoor air pressure 0.0025 atmospheres (25Kg/m ² ) below atmospheric pressure
It is an air support structure in which the roof surface is inflated by raising the roof, and the conventional technology for cable arrangement is often two-way arrangement.

In the United States, this two-way arrangement is the most convenient way to minimize bending stress on the compression ring as a boundary structure when the plan shape of the building is rectangular or super elliptical. This was adopted as a layout.

There are over 10 examples of this two-way cable in the United States.
Although improvements have been made gradually with each building, some problems remain.

Firstly, in an air support structure that obtains a balanced curved surface by internal pressure, the shape is easily changed by wind or snow after the shape is determined, as shown in Figure 1, so the membrane 1 and cable 2 may change. Geometric nonlinear analysis must be performed again under the condition of maintaining balance, but the membrane panels installed in the compartments made of these two-way cables are almost all manufactured in different shapes, making it difficult to mass-produce the same product. It cannot be manufactured in the same time frame, and the manufacturing cost is relatively high. The reason for this is that membrane sections made with a two-way cable arrangement
Although the dimensions are the same on the projected plane, because the roof is a curved surface, the dimensions of the membrane panels actually manufactured differ slightly.

In order to solve this problem, there is a case in the United States where the dimensions of membrane production were purposely standardized, but in this case the roof did not have the expected curved surface but instead became flat, and when it snowed, snow accumulated in the center and the roof fell down. There was an accident in which roof panels were damaged, and the ones built after that time again used the conventional method, and instead of standardizing the dimensions of the roof panels, they were manufactured one by one based on a predetermined size and shape.

Second, there were cases where two-way cables were placed on the entire roof surface, but the cable length was short in the peripheral area, and the cable tension did not increase.
There are many cases where peripheral cables are omitted to reduce the number of cables. This has the advantage of reducing roof construction costs and roof weight, but on the other hand, judging from the material strength of the membrane material, the diamond-shaped part in the center can bear the membrane stress in two directions. The rectangular portion at the periphery bears membrane stress in the short side direction.

Therefore, in the rectangular portion, the membrane material is designed based on the uniaxial allowable stress of the membrane material, and if the same membrane material is used, the membrane panel in the diamond-shaped portion will be over-designed.

Third, although this two-way cable arrangement is approximately spaced apart, in very large roof areas, the maximum wind load on the roof surface also varies from roof section to roof section, and the membrane panels cannot be equally stressed.
This results from the two-way equally spaced cable arrangement.

The present invention was made in view of the above problems.
The gist of this is that cables are arranged radially and concentrically, and the radial cables arranged at the periphery are thinned out in number as they move towards the center. When thinning out cables in a cable arrangement where membrane material is attached to a compartment, the cables are not cut off immediately at the intersection with the concentric cable;
Furthermore, the shape and dimensions of the membrane panel are made as much as possible by extending the concentric cable in the center in two parts without fixing it to the membrane material, and fixing the next adjacent radial cable at the part where it intersects with the concentric cable. In order to unify the number of membrane panels and reduce the number of membrane panels relative to the roof area, rationalizing and economical production, and making maximum use of the allowable stress of the membrane and cables, the membrane has a considerable amount of biaxial stress. The present invention is characterized in that the load cables are of the same size so that the tension can be shared equally, and this will be explained in detail below based on the drawings.

In other words, in the United States, there are many stadiums with roofs built for football games, etc., and the planar shape is often rectangular or super elliptical, but in Japan, since baseball is the main sport, stadiums with a roof are often built with a planar shape that is close to circular. I often have it.

Therefore, assuming this planar shape, the second
As shown in the figure, it is possible to use both the radial cable a arrangement and the concentric cable b arrangement. However, such concentric and radial cable b and a arrangements are difficult to use due to the allowable stress of the membrane material used in the circumferential part. The membrane panel dimensions can be set to maximize the use of the membrane, but as it approaches the center, the spacing between the radial cables a becomes narrower, the membrane area is smaller, and the existing stress of the membrane becomes smaller, making it possible to economically reduce the strength of the membrane material. In addition, the number of membrane panels increases, and the number of cables and attachment hardware for the membrane material increases unnecessarily, making it uneconomical.

For this reason, regarding the air membrane structure cable arrangement constituted by the concentric cable b and the radial cable a, the radial cable a is thinned out in the central part, and the cable section in the central part is set as an appropriate section.

Note that O in the figure indicates a compression ring as a boundary structure.

By adopting this method of configuring a multi-stage ring-shaped equally spaced zone, the allowable stress of the membrane material c can be maximized, and the number of membrane panels manufactured can be reduced by reducing the number of different types of panels. By standardizing panel manufacturing dimensions, it becomes possible to produce economically.

When implementing what is shown in FIG. 2, it may be necessary to provide a reinforcing method that meets each design condition for practical use.

The first reason is that among cables arranged radially and concentrically, in the case of radial cables, as the cables arranged at the periphery move toward the center, the distance between the cables becomes denser. However, when actually thinning out radial cables, in order to transmit the tension at the ends of the thinned-out cables to the concentric cables, it is necessary to use restraining hardware that has a considerably large binding force. The cable end cannot be restrained unless it is fixed to the concentric cable using a wire, and a joining method using such a large restraining metal fitting is impractical.

The second reason is that when the radial cable and concentric cable are joined in a T-shape, the stress state applied to the membrane material is different from the membrane stress of the two-way cable net method used in a normal air membrane structure. However, considerable concentrated stress acts on the membrane material on the opposite side of the thinned-out radial cable terminal, resulting in a result different from the initial intention, which was to equalize stress in the membrane material.

In order to solve this problem, it is necessary to rationally handle the tensile force generated at the end of the radial cable to be thinned out.

As this process, as shown in Figure 3, the thinned out radial cable a' is connected to two extension cables d and
Then, the next adjacent radial cable a or a' is fixed at the part where it intersects with the concentric cable b.

The purpose of the extension cable d is to process the cable tension in stages, and the extension cable d does not subdivide the membrane material c, but does not fix it to the membrane material c, but uses only the cable itself to separate the next part near the center. It extends to concentric cable b and is restrained.

By doing this, the stress treatment at the end of the thinned radial cable a' becomes smooth, and excessive concentrated stress does not act on the membrane stress.

Although not shown, the radial cable a connected from the outermost periphery to the innermost concentric cable may be further extended and brought together at the center point in order to manage stress at the center. .

[Brief explanation of drawings]

FIG. 1 is a roof curved surface diagram obtained by geometric nonlinear analysis, FIG. 2 is a plan view showing the basic configuration of the present invention, and FIG. 3 is a plan view showing the air membrane structure roof of the present invention. 1...Membrane, 2...Cable net, a...Radial cable, a'...Radial cable, b...Concentric cable, c...Membrane material, d...Extension cable.

Claims (1)

[Claims] 1 Arrange the cables radially and concentrically,
When thinning out the radial cables arranged at the periphery, the number of radial cables is thinned out toward the center, and the membrane material is attached to the square sections formed by these cables. Without immediately terminating at the intersection with the concentric cable, the concentric cable in the center is further extended in half without being fixed to the membrane material, and the next adjacent radial cable is fixed at the point where it intersects with the concentric cable. An air membrane structure roof that is characterized by the