Space frame structure selection principle

The selection of the space frame structure is based on the plane shape of the building, the span size, the support situation, the load size, the roof structure, the building requirements, the manufacturing and installation methods, and the material supply situation, combined with the principles of applicability and economy. For example, when the roof load is large, it is not suitable to choose a square pyramid with favorable placement, and when the side length is relatively large, it is not suitable to choose an inclined space frame, but a square pyramid with positive placement and two-way favorable placement should be considered. For another example, the peripheral support span is When the distance is 30m, the checkerboard-shaped quadrangular pyramid and the evacuated quadrangular pyramid cannot be selected, because the number of modules in the length and width direction of these two frames can only be odd: the span of more than 100 meters should use a three-layer space frame. Two layers are not only uneconomical but also difficult to manufacture due to the large size of the ball joint rod. From the perspective of the amount of material, when the plane is close to a square, it is the most economical to place the quadrangular pyramid frame, followed by the positive quadrangular pyramid space frame and the two-way orthogonal cross two-series space frame (orthogonal or oblique). The most expensive material is the three-way cross beam system. However, when the span and load are large, the three-way cross beam system network frame is more economical and reasonable, and the rigidity is also large. When the plane is rectangular, it is economical to place the quadrangular pyramid space frame at an orthogonal angle in two directions.

The “Space Frame Structure Design and Construction Regulations” (JGJ7-91) recommend the following selection regulations:

1. The peripheral support frame with a rectangular plane shape, when its side-to-length ratio (long side to short side) is less than or equal to 1.5, it is advisable to use an inclined quadrangular pyramid modular, a checkerboard-shaped quadrangular pyramid space frame, and an upright evacuated four-corner space frame. Cone space frame, two-way orthogonal inclined space frame, two-way orthogonal positive space frame, and positive quadrangular pyramid space frame. When the span is small, the honeycomb triangular pyramid space frame can also be used. When the building requires unequal support distances in the two directions of length and width, two-way oblique space frames can be used.

2. For the peripheral support space frame with a rectangular plane shape, when its side-to-length ratio is greater than 1.5, it is advisable to use a two-way orthogonal positive space frame, a positive quadrangular pyramid or a positive evacuated quadrangular space frame. When the side-length ratio is less than 2, the oblique quadrangular pyramid space frame can also be used. A one-way fold-line space frame can be used when the plane is long and narrow.

3. The selection of the space frame with a rectangular plane shape and an opening on one side supported by three sides can be carried out according to Article 1, and the opening side can be increased by increasing the number of layers of the space frame or appropriately increasing the height of the entire space frame. The open sides of the space frame must form vertical or inclined side trusses.

4. The plane shape is a rectangular, multi-point support space frame, which can be selected according to the specific situation: a positive quadrangular pyramid space frame, a positive evacuated quadrangular pyramid space frame, and a two-way orthogonal positive space frame. For multi-span modulars combined with multi-point supports, two-way orthogonally inclined space frames or slanted quadrangular pyramid space frames can also be selected.

5. The plane shape is circular. For the hexagonal space frame supported by the periphery, a three-way space frame, triangular cone space frame or evacuated triangular cone space frame can be selected according to specific conditions. When the span is small, the honeycomb triangular pyramid space frame can also be used.

6. For the floors of multi-story buildings and roofs with a span of not more than 50m, a combined space frame structure with reinforced concrete slabs instead of online can be used. The combined space frame should be selected from the positive quadrangular pyramid space frame, the positive evacuated quadrangular pyramid space frame, the two-way orthogonal positive space frame, and the inclined quadrangular pyramid space frame, and the honeycomb triangular pyramid space frame.