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准确模拟钢桥系统失效状态,实现结构失效状态的转移是钢桥结构系统主要失效模式识别算法的核心之一。针对钢桥中已屈服的失效杆件在继续强化或卸载情况下可能导致的结构内力重分布现象,以及通过删除失效单元并对失效单元所在节点外施加虚载实现结构拓扑状态转变的简化方法难以精确模拟结构实际受力性能的问题,提出了更全面反映钢材在弹性、屈服、强化、强化后卸载这4个阶段力学性能的受拉弹-塑性材料本构模型,钢材受压时采用考虑屈服应力折减的弹-塑性本构模型,并引入双向渐进结构优化法实现结构分析状态的自动转移;通过应力判断准则确定拉压杆件的弹塑性状态以及是否出现局部卸载现象,在钢桥系统失效模式搜寻过程中完成材料本构模型随单元受力状态的自动转换,直至达到材料极限强度后才予以删除这些杆件。结果表明:该方法充分考虑了钢桥构件间的相互影响关系与结构的内力重分布现象,通过精细化分析与结构状态自动转移,实现钢桥结构系统失效路径的搜寻;结合阶段临界强度分枝-约界法编制的识别钢桥主要失效模式的计算程序,实现了钢桥系统失效树主干和主枝的快速识别和生成,并成功识别出算例钢桁架桥的主要失效模式以及伪失效模式。
Accurately simulating the failure state of steel bridge system and realizing the transfer of structural failure state are the core of the main failure mode identification algorithm of steel bridge structural system. Aiming at the phenomenon of structural internal force redistribution which may have resulted from failure of the yielding bar in the steel bridge under continued strengthening or unloading, and a simplified method to realize the transition of the topology state of the structure by deleting the failed cell and applying the virtual load outside the node where the failed cell resides Accurately simulate the actual mechanical properties of the structure, put forward a more fully reflect the steel in the elastic, yield, strengthen, strengthen the mechanical properties of the four stages after the unloading of the tension elastic - plastic constitutive model of plastic materials used to consider yielding Stress-reduced elasto-plastic constitutive model, and introduced two-way progressive structure optimization method to achieve the automatic transfer of structural analysis state; through the stress judgment criteria to determine the elastic-plastic state of tension and compression elements and whether there is partial unloading phenomenon, Failure mode search process to complete the material constitutive model with the unit automatically converted state, until the ultimate strength of the material to be deleted after these rods. The results show that this method takes full account of the interaction between steel members and the redistribution of internal forces of the structure. Through the refinement analysis and the automatic transfer of structural state, this method realizes the search of the failure path of the steel bridge structural system. - The calculation program for identifying the main failure modes of steel bridges prepared by the approximation method to realize the rapid identification and generation of the main trunk and the main branch of the failed steel tree system and to successfully identify the main failure modes and pseudo-failure modes of the example steel truss bridges .