高强钢焊接箱形柱受力性能研究(Ⅰ):残余应力统一分布模型

Study on mechanical properties of high strength steel welded box columns(Ⅰ):unified model of residual stress

现有高强钢焊接箱形截面残余应力分布模型仅适用于特定强度等级的高强钢,尚缺乏适用于不同强度等级高强钢的残余应力分布模型。为此,基于不同强度等级高强钢焊接箱形截面残余应力的已有试验,研究钢材的强度等级、板件厚度及宽厚比对残余应力分布和峰值的影响,提出不同强度等级高强钢焊接箱形截面的残余应力统一分布模型。该模型采用多重阶梯函数形状,适用于屈服强度460~960 MPa的焊接箱形截面,且满足每个板件自平衡条件和对称性。将残余应力统一分布模型的形状、数值和已有试验结果进行对比,证明该模型的准确性。在基于纤维模型的极限承载力数值分析中,分别采用残余应力统一分布模型和已有分布模型计算高强钢焊接箱形柱的受压承载力,并将各自得到的极限承载力与已有试验结果进行对比。研究结果表明,采用残余应力统一分布模型后,不同等级高强钢焊接箱形柱的纤维模型计算能更准确地预测其极限承载力。残余应力统一分布模型可为不同等级高强钢焊接箱形柱的二阶非弹性分析提供参考。

The existing residual stress model of high strength steel welded box sections are only applicable to specific grades of high strength steel.Therefore,there is a scarcity of residual stress models that are generally applicable to different strength grades of steel.Based on the existing experiments on the residual stress of welded box sections with different strength grades of steel,the effects of steel strength grade,plate thickness and width-thickness ratio on residual stress distribution and peak values were investigated,and a unified model of residual stress for welded box sections of high strength steel with different strength grades was proposed.The shape of the unified model is a multiple step function model which is suitable for welded box sections with yield strength of 460 MPa to 960 MPa,and each plate meets the condition of self-equilibrium and symmetry in this model.By comparing the shape and value of unified model of residual stress with experimental results,the unified model is verified to be accurate.In the numerical analysis using fiber model,the residual stress unified distribution model and the existing distribution model were used to calculate the bearing capacity of the high strength steel welded box column,and the obtained ultimate bearing capacity was compared with the existing test results.The research results show that the fiber model of the welded box column of different grades high strength steel could predict the ultimate bearing capacity more accurately after adopting the unified model of residual stress.The model provides a reference for the subsequent inelastic analysis of the second-order method.