Elastoplastic Seismic Response Of Bridge Structure Analysis And The Ductility Design Method

The article discuss mostly the analytic means of bridge structures' elastic-plastic earthquake response and the design method and procedure of ductile earthquake-resistance.Regular bridges' ductile earthquake-resistance design and checking calculation could be made by simplified analytic means of elastic-plastic earthquake response. The means solve first elastic seismic force by response spectrum, and then reduce elastic seismic force by reduced factor, at last make earthquake-resistance design and checking calculation by reduced seismic force.Complex bridges' ductile earthquake-resistance design and checking calculation could be made by the means of elastic-plastic temporal analysis. There are different elastic-plastic finite element in all-around structural finite element analysis software and exclusive seismic response analysis program, the former disposing of elastic-plasticity on material layer and thus needing large calculation capacity and time, the latter on cross-section layer. Every finite element has respective merits and demerits, considered problems and ignored problems. The writer make detailed analysis and appraisal of these finite elements, which could be refered to when selecting elastic-plastic earthquake response analysis' softwares and finite elements.On the base of these finite elements' analysis and research, the writer put forward with a new elastic-plastic element. The method disposes of elastic-plasticity on cross-section layer, thus needing little calculation capacity and time, and considers yielded cross-section stiffness' regression when it is unloaded and load inversely. The method could be applied to one-dimension horizontal earthquake response analysis conveniently, to two-dimension if were disposed properly, but not to three-dimension.Simplified analytic means needs ductility ratio, while the means of elastic-plastic temporal analysis needs cross-section's yielding point and ultimate point, which need to solve cross-section's M- φ curve. The article compile independently M- φ curve' solving program that has friendly interface and so could be used.