中文摘要：

对一组不锈钢空间预应力钢桁架模型开展了火灾下的结构响应试验研究及数值模拟分析．试验模型用奥氏体304无缝不锈钢管制作，通过置于模型下端的伸缩小立柱施加预应力．抗火试验测定了桁架弦杆和腹杆的温度响应及上弦节点位移．利用试验结果检验了数值模型的正确性，并对不同参数的不锈钢预应力钢桁架火灾响应进行了数值分析．结果表明，预应力度对不锈钢预应力钢桁架火灾下的位移响应有较大影响．当施加的预应力值较大，且所产生的反向位移接近荷载所引起的正向位移时，火灾下结构的位移响应将出现跳跃及明显的波动，且冷却后的变形恢复也比较明显．数值模拟分析进一步表明，在同样火灾条件和预应力条件下，索张拉预应力不锈钢桁架跨度越大，越容易产生变形，而且挠度比总是大于尺度比．

英文摘要：

The experimental study and numerical analysis of fire behavior of a set of spatial pre-stressed stainless steel truss models was finished and presented. The Austenite 304 seamless stainless steel tubes was selected and used for making the bars of truss of the test model. A short rotatable steel tube which can be elongated and retracted was set at the center of the truss right below the bottom chord of the truss to realize application of pre-stresses. The correctness of the numerical model established here was checked, and fire response of the pre-stressed stainless steel trusses considering the different parameters based on the numerical model was numerical simulated. The results show that degree of prestressing has great effect on the displacement response of the pre-stressed stainless steel trusses under fire. The displacement of the pre-stressed steel truss in fire will jump up and has obvious wave while the pre-stress applied to the structure is larger. The reverse displacement caused by the pre-stress is close to the positive displacement resulted from the load applied to the structure, and recovery of deformation of the structure after cooling is also evident. It is concluded from the numerical analysis results that the deformation of the structure with larger span in fire is prestress structures.