Space frame steel structure

Space frame is made of multiple rods in accordance with a certain space form through the nodes connected to the space steel structure.

The basic units that constitute the space are triangular cone, triangular prism, square, truncated quadrangular cone, etc. These basic units can be combined into planar shapes of trilateral, quadrilateral, hexagonal, circular or any other shapes. It has the advantages of space force, light weight, high rigidity and good seismic performance. It can be used as the roof cover of gymnasiums, theaters, exhibition halls, waiting halls, stadium grandstand canopies, airplane hangars, and bidirectional large-column mesh-frame steel structure from workshops and other buildings. The disadvantage is that the number of rods converging on the nodes is more, and the production and installation is more complicated than the plane structure.

Different shapes

It can be divided into double-layer plate-type space frame steel structure, single-layer and double-layer shell-type space frame steel structure. The rods of plate-type space frame and double-layer shell-type space frame steel structure are divided into upper chord rod, lower chord rod and web rod, which mainly bear tensile force and pressure. The rods of single-layer shell-type space frame steel structure, in addition to bearing tensile force and pressure, also bear bending moment and shear force. The vast majority of China’s mesh frame steel structure adopts plate type mesh frame structure.

Forms of Composition

The first type is composed of plane truss system, and there are four forms of two-way orthogonal orthotropic space frame, two-way orthogonal diagonal space frame, two-way diagonal diagonal space frame and three-way space frame steel structure.

The second category consists of quadrangular cone unit, there are positive release quadrangular cone space frame, positive release of evacuation quadrangular cone space frame, oblique release quadrangular cone space frame, checkerboard quadrangular cone space frame and star-shaped quadrangular cone space frame five forms.

The third category consists of triangular cone unit, there are three forms of triangular cone space frame, pumping triangular cone space frame and honeycomb-shaped triangular cone space frame. Shell-type space frame structure according to the shell surface form mainly has column surface shell-type space frame, spherical shell-type space frame and hyperbolic parabolic surface shell-type space frame. Space frame structure according to the material used in steel space frame, reinforced concrete space frame and steel and reinforced concrete composed of a combination of space frame, in which the steel space frame used more.

Space frame structure is a high degree of super-static structure system. When analyzing the plate type space frame, it is generally assumed that the nodes are articulated, and the external load is acted on the nodes according to the principle of static equivalence, which can be calculated according to the space truss displacement method, i.e., the finite element method of articulated rod system. Simplified calculation method can also be used, such as cross beam system differential analysis method, proposed plate method, etc. for internal force and displacement calculation. The nodes of single-shell space frame are generally assumed to be rigidly connected, and should be calculated according to the finite element method of rigidly connected rod system. Double-shell space frame can be calculated according to the finite element method of articulated rod system. Single and double shell type space frame can also be used to simplify the calculation of the proposed shell method.

Design structure

The cross-section of the rods of the steel structure of the space frame should be determined according to the strength and stability calculation. In order to reduce the calculated length of the compression rod and increase its stability, measures such as additional re-split rods and support rods can be used. The nodes of plate type space frame and double shell type space frame made of steel mainly have three forms: cross plate node, welded hollow ball node and bolted ball node. The cross plate node is applicable to the steel structure of space frame with section steel rods, and the connection between rods and node plate adopts welding or high strength bolt connection. Hollow ball nodes and bolted ball nodes are applicable to the steel pipe rods of the space frame structure. The nodes of single-layer shell-type space frame should be able to withstand the bending internal force. In general, the steel consumption of the nodes accounts for 15-20% of the steel consumption of the whole steel space frame structure.