钢管混凝土组合桁梁桥近、远场抗震性能

基于对传统预应力混凝土连续刚构桥的优化，提出了钢管混凝土组合桁梁桥结构形式，即上部结构采用矩形钢管混凝土组合桁梁，下部结构采用圆形钢管混凝土格构式桥墩。采用数值分析手段对比研究了传统预应力混凝土连续刚构桥、连续刚构优化桥型及新型钢管混凝土组合桁梁桥在近、远场地震作用下的抗震性能。结果表明:钢管混凝土组合桁梁桥、连续刚构优化桥型抗震性能要明显优于传统混凝土连续刚构桥，且钢管混凝土组合桁梁桥抗震性能更佳，近场地震作用下桥墩弯矩下降达41.9%，剪力下降达66.1%，远场地震作用下桥墩弯矩下降达37.5%，剪力下降达76.4%；相较远场地震，近场地震作用致使结构输入的地震能量大幅增加，相同桥型桥墩位移最大增幅达5.7倍，桥墩弯矩最大增幅达3.5倍；钢管混凝土组合桁梁桥是一种抗震性能优越的桥梁结构形式，可为西部地区装配式钢混组合桥梁的设计选型提供参考。

Anti-seismic Performance of CFST Composite Trussed Bridge Caused by Near-field and Far-field Earthquake

Based on optimization toward the continuous prestressed concrete rigid bridge，a new type of bridge, whose superstructure adopted rectangular concrete filled steel tubular(RCFST) composite truss girder and superstructure adopted circular concrete filled steel tubular (CFST) lattice pier, was proposed. The comparative study of seismic performance of traditional continuous prestressed concrete rigid bridge, continuous prestressed concrete rigid optimization bridge and CFST composite trussed bridge caused by near field and far field earthquake were analyzed by numerical analysis method. The results show that anti seismic performance of CFST composite truss bridge and continuous prestressed concrete rigid optimization bridge are superior to traditional continuous prestressed concrete rigid bridge. Comparing to the traditional continuous prestressed concrete rigid bridge, the anti seismic performance of CFST composite truss bridge is excellent, bending moment and shear force of the pier decrease by 41.9%, 66.1% in the near field earthquake, and decrease by 37.5%,76.4% in the farfield earthquake. Compared to far field earthquake，near field earthquake enables the initial earthquake energy of structure to increase greatly, displacement and bending moment of the pier jump as much as 570%, 350% respectively. Therefore, CFST composite trussed bridge is a type of bridge which has excellent anti-seismic performance, can provide a good reference for the design selection of prefabricated steel and concrete bridge in the western regions.
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