冷弯薄壁型钢屋架受力性能及杆件计算长度研究

为研究低层冷弯薄壁型钢结构屋架的受力性能，对两个不同构造形式的屋架足尺试件进行了受弯性能试验研究，考察了冷弯薄壁型钢结构屋架的工作原理和破坏模式。试验结果表明：钢桁架的破坏主要是支座处节点连接的破坏，而杆件没有发生屈曲，不属于强度破坏。采用非线性有限元分析方法对钢结构屋架进行了变参数分析，结果表明：钢材强度、截面形式以及钢材厚度对桁架承载力都有较大的影响。采用柱挠度曲线(CDC)法分析了节点连接半刚性对冷弯薄壁型钢桁架压杆计算长度的影响，研究表明,冷弯薄壁型钢桁架压杆半刚性连接的计算长度与节点转动刚度和构件自身刚度有关，建议受压弦杆、端斜腹杆以及端竖腹杆平面内计算长度系数取为1.0，受压腹杆平面内计算长度系数取为0.9。

Study on mechanical behavior and effective length of cold-formed thin-walled steel roof truss

In order to investigate the mechanical performance of low-rise cold-formed thin-walled steel roof truss, two full scale specimens of roof truss with different structural forms were tested under flexural loading condition. The working mechanism and failure mode of cold-formed thin-walled steel roof truss were investigated. The study shows that the damage of steel truss happens at the connection of supports, and no buckling can be observed in cold-formed thin-walled members. Hence, the specimens do not encounter the damage of strength. The nonlinear finite element analysis method was used to conduct parameters analysis of steel roof truss, and the results showed that steel strength, section forms and steel thickness had great effect on the bearing capacity of cold-formed thin-walled steel roof truss. Using the column deflection curve (CDC) method, this paper analyzed the effect of semi-rigid connection on the effective length of compressed members in the cold-formed thin-walled steel truss. The method shows that the effective length of semi-rigid connection depended on connection rotational stiffness and member rigidity. The in-plane effective length were suggested to be 1.0 for compressed chord, end strut and end web, and it was suggested to be 0.9 for compressed web.