激光焊接不锈钢工字形截面中长柱受力性能研究

Global stability of laser-welded stainless steel I-section columns

为研究激光焊接奥氏体不锈钢工字形截面轴心受压中长柱的承载性能,对10根激光焊接不锈钢工字形薄柔截面中长柱进行轴心受压试验研究,结果表明,中长柱的破坏模式均为板件局部屈曲与构件整体弯曲屈曲的相关失稳。同时,基于残余应力试验,验证了已有激光焊接不锈钢工字形截面的残余应力分布模型。基于试验结果验证了有限元模型,对激光焊接不锈钢工字形截面轴心受压中长柱开展参数分析,研究了几何初始缺陷和残余应力对中长柱稳定承载力的影响,结果表明,残余应力是影响中长柱稳定承载力的主要因素。结合试验和有限元计算结果,对CECS 410:2015《不锈钢结构技术规程》中轴心受压构件稳定承载力设计公式的适用性进行评估,并考虑残余应力的影响修正了轴心受压构件整体稳定设计公式的计算系数。采用修正后计算系数的规范公式能准确计算激光焊接不锈钢工字形截面轴心受压构件的稳定承载力。

To investigate the global stability and load-carrying capacities of laser-welded austenitic stainless steel I-section columns, ten laser-welded stainless steel slender I-section specimens under axial compression were tested, and the failure mode and load-carrying performance were analyzed. The results showed that all the ten tested column specimens failed in a combination of local buckling and flexural buckling. Meanwhile, based on the residual stress test, the existing residual stress pattern of laser-welded stainless steel I-section was verified. The finite element model was validated against the test results and then employed to perform parametric studies, where the effects of initial geometric imperfections and residual stress on the behavior of laser-welded stainless steel I-section columns under axial compression were evaluated. The results revealed that the residual stress is the primary influencing factor on the behavior of the columns. The obtained test and FE results were then adopted to assess the accuracy of the relevant design rules given in the current Chinese standard CECS 410: 2105. Considering the influence of the residual stress pattern, the calculation coefficients of the global stability design formula for axial compression members in CECS 410: 2015 were revised. The CECS 410: 2015 design approach with the proposed calculation coefficients was shown to offer accurate resistance predictions for laser-welded stainless steel I-section columns under axial compression.