中文摘要：

对一组不锈钢空间预应力钢桁架模型进行了火灾下的结构响应及火灾后力学性能试验研究。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,并对火灾后的结构模型开展了卸载及加载试验。结果表明,不锈钢空间预应力钢桁架模型在受火过程中,即使产生较大的位移和扭曲变形,结构模型仍未出现整体坍塌。钢桁架上、下弦杆有一定的温差,且上弦杆响应温度沿模型纵向变化幅度较下弦杆更大。对于具有同样几何尺寸和材料性能的索张拉钢桁架,受火前是否施加预应力对其火灾下的位移响应、残余变形及火灾后的受力性能均有较大影响。桁架自身刚度对预应力钢桁架的抗火性能也有一定的影响,刚度较大的结构模型,其火灾后承载时易出现扭曲变形。

英文摘要：

The experimental study of fire behavior and post-fire performance of a set of spatial pre-stressed stainless steel truss models was conducted in this study. The Austenite 304 seamless stainless steel tubes were selected and used for making the bars of truss of the structure model. A short rotatable steel tube which can be elongated and retracted was set below the bottom chord of the truss to realize application of pre-stresses. The response temperatures of the chords and web bars of the truss of the model and typical displacements of the upper nodes of the truss were measured, and the unloading and loading experiments were further conducted for the structure model which was not out of work after exposure to fire. The results show that the whole collapse of the structure models did not take place even when large displacement and torsion deformation had appeared in the spatial stainless pre-stressed steel truss model under fire. Certain difference exists between the response temperatures of the top and bottom chords of the truss, and along the longitudinal direction of the truss model, the temperatures of the top chords vary greater than those of the bottom chords. For stainless pre-stressed steel trusses with the same geometrical dimension and material properties, whether pretension was applied before ignition is of great influence on the displacement response and residual deformation under fire, and the post-fire performance. Result also shows that, stiffness of the truss itself also has obvious effect on the fire-resistant performance of the pre-stressed steel truss： the torsion deformation of the test model in fire is easier to be produced if stiffness of the truss of the model is larger.