基于累积荷载效应分析刚架结构极限承载力

Ultimate bearing capacities analysis of frame structures based on accumulated load effects

传统极限承载力分析的塑性铰法(PHM)及其修正格式(mPHM)没有考虑加载历史累积荷载效应对刚架失效的影响,不能正确处理内力反向问题,由此导致刚架结构极限承载力和失效模式分析结果出现错误。为此,首先研究了前序失效阶段累积荷载效应的影响,据此分析结构迭代计算中相邻迭代步出现内力反向时PHM和mPHM发生错误的原因;然后通过合理修改构件截面强度,以反映结构强度损伤演化规律,据此计算刚架结构极限承载力,并识别结构潜在失效模式,提出了刚架结构的失效判据,建立了刚架结构分析的改进塑性铰法(iPHM);最后,进一步通过iPHM与PHM、mPHM、弹塑性增量加载法对比分析,验证了iPHM的适用性、计算精度和效率。

Load effects accumulated in the loading history are not taken into account in traditional plastic hinge method(PHM)and its modified form(mPHM),so that either PHM or m PHM could not handle properly the problem of internal force reversal in iterative analysis,which leads to error estimation of ultimate bearing capacities and failure modes of frame structures.In order to overcome this drawback,the reasons that the PHM and the m PHM may get erroneous estimations are investigated at first,then the total load effects accumulated in the preorder iterative steps are presented to modify the sectional bending strengths of structural members to simulate the damage evolution of the frames,based on which the ultimate bearing capacities and potential failure modes of frames are determined.Finally,a criterion is proposed for determination of failure of frame structures,thereafter the improved plastic hinge method(iPHM)is developed.Examples are provided to demonstrate the applicability,higher efficiency and accuracy of the proposed i PHM,compared with those of the PHM,m PHM and the elasto-plastic incremental analysis.