基于双向渐进结构优化法的钢桥系统失效模式识别  

Identification of System Failure Modes of Steel Bridges Based on Bi-directional Evolutionary Structural Optimization

作　　者：罗晓瑜[1,2] 王春生[1,2] 姚书奎 寇婷苇 王茜[1,2] 

机构地区：[1]长安大学公路学院,陕西西安710064 [2]长安大学公路大型结构安全教育部工程研究中心,陕西西安710064

出　　处：《中国公路学报》2017年第3期31-39,共9页China Journal of Highway and Transport

基　　金：国家重点基础研究发展计划("九七三"计划)项目(2015CB057706);国家自然科学基金项目(211021140372);中央高校基本科研业务费专项资金项目(10821153501;310821153401;310821161021;310821151020)

摘　　要：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。The accurate simulation and transfer of the structural failure status was the key issue of the identification algorithm for system failure modes of the steel bridges.Aimed at the accurate simulation of the possible stress redistribution of the yielded failure members under a strengthening or unloading state,and refinement of the simplified method of changing the structural status by deleting and replaying the disabled elements with a fictitious force in the structural performance analysis process,a tensile elastic-plastic material constitutive mode wasproposed firstly for a better reveal of the characteristics of the steel elements in the elastic,yielding,strengthening and unloading stage.A compressive elastic-plastic material constitutive mode was considered for the reduction of yield stress. Furthermore,the bi-directional evolutionary structural optimization method was introduced to realize the automatic transfer of structural analysis state.Then,the elasticity of the tension and compressive members and the occurrence of partial unloading phenomenon were estimated by the judging criteria of stress.The material constitutive modes of the elements were converted to corresponding modes automatically in the process of identification of system failure modes,and these elements were deleted when reaching the ultimate strength.The results show that the interaction effect and the phenomenon of stress redistribution of the steel bridge components are fully considered by this method.The main failure modes of the steel bridges are identified by precise simulation and automatic transfer of structural analysis.Combined with the phase critical strength branch and bound criterion,the automatic identification program for the structural failure modes is developed,the trunk and main branch of the failure tree of the steel bridges are identified and generated rapidly.An example of a steel truss bridge is given to show that the system failure modes and the fake failure modes of the structure can be identified successfully.

关 键 词：桥梁工程 钢桥 双向渐近结构优化法 系统失效模式 结构可靠度 分枝-约界法 

分 类 号：U448.36[建筑科学—桥梁与隧道工程]