安定荷载上限近似解的数值分析方法及其应用

NUMERICAL PROCEDURES OF UPPER-BOUND APPROXIMATION OF SHAKEDOWN LOADS AND ITS APPLICATION IN ENGINEERING

弹塑性结构在变值荷载作用下具有交变塑性和增量破坏两种可能的破坏型式,安定性分析就是要确定荷载变动的最大范围。确定安定荷载上限的机动型安定性定理之关键在于构造运动许可的塑性应变增量场,而在实际问题求解中这一数值实施过程往往是很困难的。为此,nigoK&&放松了经典机动安定定理的某些条件,分别得到了在不发生交变塑性变形意义上的安定准则和在不发生累积塑性变形意义上的安定准则。本文以此为基础分别构造了相应的上限数值求解格式。并将其应用到土工安定性分析中,对海洋平台地基的安定性问题进行了数值分析。

There exist two types of failure modes including alternating plasticity and incremental collapse for elastoplastic structures subjected to varied loading. The purpose of shakedown analysis is to determine maximum range of load variation. The kinematical-type shakedown analysis is to assess an upper bound of shakedown load based on kinematically-admissible incremental plastic strain fields which are difficult to be constructed for actual structures. Hence, some constraint conditions in the kinematic shakedown theorem were released by Konig and two shakedown criteria respectively for alternating plasticity and incremental collapse were obtained. This simplification makes numerical solution for upper bound of shakedown loads possible. Based on kinematically-type shakedown criteria for incremental collapse and for alternating plasticity, computational procedures for avoiding incremental collapse and alternating plasticity are formulated and used to evaluate bearing capacity of structures and soil foundations under transient or cyclic loading pattern.