钢管混凝土拱面外稳定的可靠度与灵敏度分析

Reliability and sensitivity analysis for lateral stability of concrete filled steel tubular arches

为研究不确定性对钢管混凝土(concrete filled steel tubular,CFST)拱面外稳定承载能力的影响,建立了面外失稳的极限状态函数.利用有限元软件ABAQUS,分别考虑和不考虑非线性影响计算了CFST拱的极限承载力和临界力;基于一次可靠度方法(first order reliability method,FORM),通过MATLAB自编程和有限元软件的协同工作得到了可靠指标随初始荷载的变化曲线以及随机变量的灵敏度指标.对比分析表明:CFST拱的面外稳定承载力介于临界力和极限承载力之间,且临界力为上限值;不同随机变量对可靠指标的灵敏度差异明显,其中几何尺寸的影响较大,弹性模量次之,材料强度的影响较小,而初始几何缺陷在规范规定的限值以内时,影响最小;然而,随着横向力的增加,材料强度的灵敏度指标逐渐增大,而弹性模量的灵敏度指标逐渐减小.

To investigate the influences of uncertainties on stable bearing capacity of CFST arches,the limit state function for lateral instability is established.The software ABAQUS is used to calculate the ultimate bearing capacity or critical load for stability with or without considering nonlinearities.Based on the FORM,the cooperative work of self programming with MATLAB and finite element software is adopted to obtain reliability and sensitivity indices for different initial loads.The results show that the real bearing capacities of CFST arches for lateral stability lie between critical load and ultimate bearing capacity,and the critical load is the upper limit.The geometric size has the most important influences on reliability index and it is followed by the elastic modulus and the material strength.The initial geometric imperfection has little effect within the limit of code.However,with the increasing of lateral load,the sensitivity indices of material strength increase,while the sensitivity indices of elastic modulus decrease.