AN ASYMPTOTIC-NUMERICAL ANALYSIS FOR THE LOWER BOUND DYNAMIC BUCKLING ESTIMATES

A finite element asymptotic analysis for determining the lower bound dynamic buckling estimates of imperfection-sensitive structures under step load of infinite duration is presented. The lower bound dynamic buckling loads and the corresponding displacements are sought in the form of asymptotic expansions based on the static stability criterion and they can be determined by solving numerically (FEM) several linear problems with a single nonsingular sub-stiffness matrix.

基于极限分析下限法的溶洞顶板承载力研究

在已有的极限分析下限法求解格式的基础上,直接以超载系数作为目标函数,将应力边界分为超载边界和不超载边界,建立求极限承载力下限法的非线性规划模型,并使用内点法求解最优解。通过模拟土体的三轴试验验证了本方法和程序的正确性,并将程序应用于溶洞顶板承载力的研究中,在已有极限分析下限法对溶洞顶板承载力研究的基础上,进一步考虑了水平向地应力对溶洞顶板承载力的影响。研究结果表明,在溶洞顶板厚度相同的前提下,溶洞跨高比l的值对溶洞顶板承载力影响非常显著;在溶洞尺寸相同的前提下,溶洞顶板厚度只在一定范围内对溶洞极限承载力有影响,超过这个范围后,其影响可不考虑;考虑水平向地应力在顶板厚度较大、跨高比较小时对承载力影响较大,在使用下限法计算溶洞顶板极限承载力时不能忽略水平向地应力的影响。