焊接加固热作用对工形截面压弯钢构件承载性能的影响

为研究焊接加固热作用及不同初始负载对工字形压弯钢柱承载性能的影响,基于考虑热影响的热结构耦合分析方法进行了热源模型热输入改进,并考虑初始几何缺陷、初始残余应力及摩擦等,完成了不同负载下焊接加固的3个工字形压弯钢柱的模拟分析。研究了焊接位移时程、腹板应力应变重分布及荷载位移关系,通过有限元分析与相应试验结果对比验证,进而获得了试验无法获得的焊接温度场、翼缘与加固板间的焊接应力应变重分布以及翼缘边缘屈服承载力等结果,并将承载力结果与规范计算结果对比,考察了现有设计方法。结果表明,焊接顺序决定焊接变形的发展过程,焊接热输入和初始负载共同决定持载焊接的位移变化范围和焊接残余变形的大小;初始负载越大,应力应变重分布往偏心受力方向发展更多,承载力越低,而初始残余应力不影响极限承载力;采用考虑热影响的有限元方法具有一定可行性和总体安全性,规范设计方法仍有可提升空间。

Analysis of welding heat effect on load-carrying behavior of I section steel beam-columns strengthened by welding

In order to investigate the influence of reinforcement welding heat effect and different initial load on load-carrying behavior of I section steel beam-columns, three specimens strengthened by welding while under different load were simulated. Based on the thermal-structural coupling method considering heat effect, the analysis improved thermal input of heat source model and also considered initial geometric imperfection, initial residual stress and friction. Time history of displacement during welding, web stress-strain redistribution and load-displacement relationship were discussed, and meanwhile the effectiveness of the finite element analyses(FEA) were verified by comparing the FEA results and test results. Furthermore, welding temperature field, stress-strain redistribution between flange and strengthening plate and flange margin yield capacity, which could not be measured by test, were acquired. And by comparison of bearing capacity results and code calculation results, the present design methods were discussed. The results showed that welding strengthening procedure decided the development of welding residual deformation, while thermal input and initial load effected the range of displacement change during welding under load and magnitude of welding residual deformation. Higher initial load propelled the development of stress-strain redistribution toward the eccentric loading direction, thus leading to lower bearing capacity. However, initial residual stress had little effect on ultimate capacity. FEA method considering heat effect showed certain practicability and overall security, and code design method remained space for improvement still.