残余应力对单轴对称工字梁稳定承载力的影响

对单轴对称工字形悬伸梁、连续梁进行整体稳定试验前,通过截面法测量了截面中的残余应力分布.根据测量结果和简化分布模型,编写了能描述残余应力大小和分布的ANSYS初应力文件,在非线性分析中以此来考虑残余应力对构件整体稳定性的影响.通过比较试验和有限元分析结果发现,考虑残余应力所得的计算结果与试验结果吻合良好,不考虑残余应力所得到的极限荷载与试验值差别较大.试验结果表明:当梁截面中的窄翼缘尺寸较小时,翼缘中残余应力以受拉为主,其端部残余压应力较小,焊接残余应力对单轴对称工字形悬伸梁和连续梁的整体稳定承载力影响很大,主要是提高作用,有限元计算时应该考虑残余应力.对比分析结果表明,文中所用的残余应力分布模型能够模拟试验梁的真实情况.

Effects of welding residual stresses on the stability capacity of the monosymmetric Ⅰ- beams

The residual stress distribution was measured by the sectioning method before the overall stability tests of monosymmetric Isection overhanging beams and continuous beams were conducted.According to the measured results and simplified pattern,the initial stress files of ANSYS which can describe the magnitude and distribution of the residual stress were compiled.Through inputting the initial stress into the nonlinear analysis,the effects of the residual stresses on the overall stability were considered.Comparing the tests results with the FEA(finite element analysis) results,it is found that the FEA results taking into account the residual stresses agree well with the tests results,but the discrepancies were obviously observed between the ultimate loads neglected the residual stress and the test results.The test results indicate that when the width of the narrow flange is small,the residual stress in this flange is mainly tensile,the compressive residual stresses in tips of flange are little.The welding residual stresses significantly affect the stability capacity of the monosymmetric I-section overhanging beams and continuous beams.So the residual stresses should be considered in the FEA.The results of the comparing analysis show that,the residual stress pattern adopted herein can simulate the real case of the test beams.