JPH0327709B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a pneumatic 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
This is an air support structure that inflates the roof surface by increasing the height of the air support structure, 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 shorter 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 placed at approximately the same spacing, in extremely large roof areas, the maximum wind load on the roof surface also varies depending on the roof area, and the membrane panels cannot be under the same stress. . 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 the cable arrangement for installing membrane material in a compartment, the shape and dimensions of the membrane panel should be kept as thin as possible by extending and fixing the cables further to the concentric circle cable in the center, without immediately terminating it at the intersection with the concentric circle cable. unified,
In order to reduce the number of membrane panels relative to the roof area and to rationalize and make production more economical, as well as to make maximum use of the allowable stress of the membrane and cables, the membranes bear considerable biaxial stress and the cables This feature is characterized in that the tension is distributed evenly by using the same dimensions, 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. often have.

Therefore, assuming this planar shape, the second
As shown in the figure, it is possible to use both the radial cable arrangement a and the concentric cable arrangement b.

However, with such a concentric and radial cable arrangement b and a, the membrane panel dimensions can be set so that the allowable stress of the membrane material used can be set to the maximum in the circumferential area, but in the central area As the distance between the radial cables a becomes narrower, the membrane area becomes smaller and the existing stress of the membrane becomes smaller, which means that the strength of the membrane material cannot be utilized economically, and the number of membrane panels increases, making it difficult to attach the cables and the membrane material. The amount of hardware, etc. 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, it is possible to maximize the allowable stress of the membrane material c, reduce the number of membrane panels manufactured by reducing the number of different types of panels, and reduce the number of membrane panels produced. By standardizing the 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 shown in Fig. 3, this process involves not immediately terminating the thinned out radial cable a' at the intersection with the concentric cable b, but extending it as an extension cable e to the concentric cable b in the center and fixing it. Try to disperse the tensile force.

The purpose of the extension cable e is to process the cable tension in stages, and the extension cable e does not subdivide the membrane material c, but instead of fixing it to the membrane material c, the extension cable e is used as a single cable to handle the next cable tension 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.

Incidentally, in order to manage the stress at the center, the radial cable a connected from the outermost circumference to the concentric cable at the innermost core may be further extended and brought together at the center point O.

[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, e... 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. A roof with an air membrane structure characterized in that the roof is not immediately terminated at the intersection with the concentric cable, but is further extended and fixed to the concentric cable in the center.