在役钢板组合梁桥的时变体系冗余性

Time-varying system redundancy of in-service steel platecomposite girder bridge

为研究多梁式钢板组合梁桥应对非对称极端作用的体系非线性冗余性能,沿着结构的传力路径和体系的再平衡过程,辨识了体系承载的3种弯曲失效模式,推导了体系弹性分配和塑性再分配能力的定量评价新指标,建立了考虑承载机制经时变异性的时变体系冗余性评估方法。基于MATLAB/OpenSEES编制了单元纤维的时变演化参数组管理程序,研究了材料劣化对体系再平衡和内力重分配性能的影响规律;采用数值增量算法,开展了结构在非对称荷载下的弹塑性全过程分析,并通过与构件-体系层次的破坏性试验对比验证了数值模型的准确性,进而建立了基于纤维宏单元的时变体系非线性冗余数值模拟方法。研究结果表明:材料劣化会导致体系从多梁协同承载机制向单梁承载机制转换,并引起构件延性、体系冗余性和可靠性发生不同程度的退化;更适应现场快速装配需求的少主梁或少横联形式容易在服役年限出现构件安全性和体系冗余性不足的情况。主梁、中部横联和端部横联的失效对体系承载性能影响较大,为钢板组合梁桥的关键构件,其他横联的敏感性较低,为非关键构件。

To investigate the system nonlinear redundancy performance of a multi-girder steel plate composite girder bridge under asymmetric extreme loads,three bending failure modes of the system were identified along the force transmission path of the structure and the rebalancing process of the system.A new performance indicator was derived for quantitatively evaluating the elastic distribution and plastic redistribution of the system,and the redundancy evaluation method of time-varying system was established considering the time-varying variability of load mechanism.The management program of time-varying evolution parameter set of element fibers was written based on MATLAB/OpenSEES,and the influence of material deterioration on the rebalancing and internal force redistribution of the system was studied.The overall elastoplastic process analysis of the structure under asymmetric load was carried out based on the numerical increment algorithm.The accuracy of the numerical model was verified by comparing it with the failure tests at the component-system level,and then a nonlinear redundant numerical simulation method of time-varying system based on fiber macro-element was established.Results showed that material deterioration caused the transformation of the system from multi-girder cooperative bearing mechanism to single beam bearing mechanism,and resulted in varying degrees of degradation of member ductility,system redundancy,and reliability.Fewer beams or fewer transverse connections,while better suited for on-site rapid assembly,were prone to insufficient component safety and system redundancy in the service life.The failure of main beam,middle transverse joint,and end transverse joint had a great impact on the bearing performance of the system,which were key members of steel plate composite beam bridge,whereas the sensitivity of other transverse connections was low,which were non-key components.