钢管混凝土高墩连续梁桥弹塑性抗震性能研究

Research on elastic-plastic seismic behavior of continuous girder bridges with concrete-filled steel tubular high piers

以四川省干海子特大桥为工程依托,应用Midas Civil有限元软件构造三跨一联的钢管混凝土高墩连续梁桥计算模型。采用弹塑性时程方析法,对比分析E_(1)、E_(2)地震作用下全桥结构的内力响应分布规律、屈服机制与结构延性等抗震性能特性;同时,运用增量动力分析法(incremental dynamic analysis,IDA)进一步探究钢管混凝土格构墩的失效顺序和破环机理。结果表明:在E_(2)地震作用下,该类桥的内力分布规律特征与E_(1)相似,均为固定墩墩顶位移响应值最大,墩底为弯矩控制截面;结构的失效由柱肢混凝土开裂逐渐发展为纵向缀管部分屈服,随后柱肢钢管截面屈服破坏。该研究成果可为同类桥梁结构的抗震设计和工程应用提供理论支撑,也可为钢管混凝土组合结构桥梁的抗震设计规程提供参考和借鉴。

Continuous girder bridge with high piers of concrete filled steel tubular(CFST)laced column is a new type bridge,which is often used in high-intensity areas in western China due to its good ductility and high bearing capacity.Based on the Ganhaizi Bridge in Sichuan Province,the Midas Civil finite element software is used to build the calculation model of the three-span symmetrical continuous beam bridge with concrete-filled steel tubular high piers.The elastic-plastic time-history method is used to compare and analyze the internal force response distribution law of the whole bridge structure under E_(1) and E_(2) earthquakes,the yield mechanism of concrete-filled steel tube lattice pier and the seismic behavior of the structure such as ductility.Meanwhile,the incremental dynamic analysis(IDA)is used to analyze the failure sequence and failure mechanism of CFST lattice piers.The results show that under E_(2) earthquake,the internal force distribution characteristics of this kind of bridge are similar to those of E_(1) earthquake,with the maximum displacement response at the top of the fixed pier and the moment control section at the bottom of the pier.The failure sequence of the structure is as follows:first the concrete cracks at the column limbs;then,the longitudinal pipe fitting part yields gradually,and finally the steel tube section of the column limbs yields.The research results can provide theoretical guidance for the seismic design and engineering application of similar bridge structures,and also provide reference for the further improvement of seismic design codes of CFST composite structure bridge.