Study On The Seismic Collapse Capacity Of High Pier Bridges

In recent years, earthquakes all over the world caused great destroy in structures and loss in facilities. Destroy of bridge structures not only cause direct pecuniary loss, but also brings great inconvenience in rescue work after earthquake. So the research on the seismic performance of bridge structures, especially how to guarantee less destroy in bridges or greatly destroyed but not collapse, is necessary. This paper focus on the simulation of accumulative damage in structures and its influence on the seismic demand of high pier bridges, based on which seismic collapse capacity of high pier bridges is investigated.The main contents are as follows:(1) The seismic analysis methods of bridges, seismic collapse analysis methods of structures, destroy and collapse rules, research methods and status quo on the seismic collapse capacity are reviewed and summarized.(2) Using stiffness-based element and two flexibility-based elements(GL element and GR element), under two circumstances: hardening and softening, three kinds of load modes are adopted: nonlinear static load, nonlinear dynamic load and incremental dynamic load, then the computational effectiveness of three elements are compared.(3) SDOF (Single Degree of Freedom) system was modeled, using IDA (Incremental Dynamic Analysis) method, it was studied how various accumulative damage effects (stiffness deterioration, softening, pinching effects and damage based on deformation) influence the seismic demand of SDOF system.(4) MDOF (Multi Degree of Freedom) system was modeled, based on the elastic-plastic response peculiarity analysis of high piers when it lies within elastic, post-yielding and post-ultimate range, using IDA (Incremental Dynamic Analysis) method, it was studied how various accumulative damage effects (stiffness deterioration, softening, pinching effects and damage based on deformation) influence the seismic demand of MDOF system. (5) High pier bridge structure was modeled, based on the elastic-plastic response analysis of high piers within longitudinal and transverse directions, combined the analysis of SDOF and MDOF system, the response peculiarity of high pier bridges was summarized , and the assessment index of collapse capacity and its influence factor was discussed.