高强钢焊接薄壁箱形截面双向压弯构件的稳定承载力

The Stability of High-Strength Steel Welded Thin-Walled Box Beam-Columns Under Biaxial Bending

采用ANSYS软件建立有限元模型分析了Q460钢焊接薄壁箱形截面双向弯曲压弯构件的极限承载力。分析中考虑几何缺陷和材料缺陷,以及几何非线性和材料非线性的影响。同时,研究了构件长细比和板件宽厚比对极限承载力的影响;探明构件达到极限承载力时真实的应力分布状态;提出了采用毛截面计算其承载力的简单计算公式;收集可获得的试验结果以验证提出的计算公式。研究表明,建立的有限元模型能够很好地模拟焊接箱形截面双向偏心压弯构件的局部-整体相关屈曲性能;在大部分情况下,无量纲极限承载力与构件长细比和板件宽厚比近似为线性关系;构件达到极限承载力时还处于弹性阶段;轴力和双向弯矩之间的相关曲线也近似为线性;引入屈服强度修正系数后,基于线性相关关系的计算公式能够很好地预测Q460钢薄壁双向压弯构件的极限承载力;该公式还可推广到普通钢构件和更高强度的钢构件。

In this paper,ageometric and material nonlinear finite element model is developed using ANSYS software,which can take account of both geometric and material imperfections,to investigate the ultimate strength of Q460steel welded thin-walled box columns under biaxial loading.Furthermore,the influences of slenderness ratio and width-tothickness ratio to the ultimate load carrying capacity are investigated.The actual stress distributions are also studied when the beam-columns reach ultimate capacities.Based on these results,simplified calculation formulas,which use the gross cross-section properties,for predicting the maximum strength of Q460steel beam-columns with slender plates under biaxial bending,are proposed.The proposed formulas are verified by available experimental results.It shows that the developed finite element model can simulate the local-overall interaction buckling behavior of the bidirectional eccentrically loaded welded box-section compression members.In most cases,the non-dimensional ultimate bearing capacity is approximately linear with slenderness ratio and width-to-thickness ratio,respectively.The beamcolumns are still in the elastic stage when reaching ultimate capacities.The interaction curves between axial force and bi-axial flexural moments,for Q460steel thin-walled box section beam-columns,are nearly linear.After introducing a steel yield strength modification factor,the formula based on a linear interaction relationship can accurately evaluate the local-overall interactive buckling strength of Q460steel beam-columns subjected to biaxial bending.This formula also can be applied to beam-columns fabricated from ordinary-strength steel and high-strength steel with a nominal yield stress greater than 460MPa.