Selection requirements for steel roof trusses

Steel roof truss is a kind of flat truss composed of various straight rods connected to each other; Under the transverse joint load, each member generates axial pressure or axial tension, so the cross-sectional stress distribution of the member is uniform and the material is fully utilized. It has the characteristics of small amount of steel, light weight, large rigidity, easy processing and forming and wide application. Roof truss can be divided into three forms: triangular roof truss, trapezoidal roof truss and parallel chord roof trusses according to its shape.

The selection of steel roof truss should comply with the following principles:

First, to meet the requirements of use, mainly drainage slope, building clearance, skylights, ceilings and hanging cranes.

Second, the force is reasonable. The shape of the roof truss should be similar to the bending moment diagram, the member is uniformly stressed, the short rod is compressed, the long rod is tensile, and the load is arranged on the node to reduce the local bending moment of the chord, and the middle of the roof truss has enough height to meet the stiffness requirements.

Third, it is convenient for construction. The members and nodes of the roof truss should be reduced in number and variety, the structure should be simple, the size should be uniform, and the angle should be between 30° and 60°. The span and height should avoid ultra-wide and ultra-high. The design should be comprehensively analyzed and specifically handled, so as to determine the specific reasonable form.