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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.
The structural response of a group of stainless steel prestressed steel truss model under fire was studied and numerical simulation was carried out.The test model was made of 304 stainless steel austenitic stainless steel tube and the prestressing force was exerted by the telescopic small column placed at the lower end of the model. The fire response of the truss chord and the web and the displacement of the winding chord are measured. The correctness of the numerical model is verified by the test results and the numerical analysis of the fire response of the stainless steel prestressed steel truss with different parameters is carried out. The prestressing force has a great influence on the displacement response of the stainless steel prestressed steel truss fire.When the applied prestressing value is large and the resulting reverse displacement is close to the positive displacement caused by the load, the displacement of the structure under fire The response will jump and obviously fluctuate, and the deformation recovery after cooling is also obvious.Numerical simulation further shows that under the same fire conditions and prestressing conditions, the greater the span of cable prestressed stainless steel truss, the more prone to deformation , And the deflection ratio is always greater than the scale ratio.