城市高架桥合理抗震体系选择与经济性对比

Structural performance and cost comparison of different seismic resisting systems for urban expressway viaducts

探讨了基于两水准设防的城市高架桥的合理抗震设防标准与相应的结构性能目标。选取两座典型的城市高架桥结构,包括一座正线桥和一座匝道桥,分别采用延性抗震体系和减、隔震体系进行结构抗震设计。对比了不同结构抗震体系所对应的结构在各水准地震作用下具体抗震性能表现,结果表明减、隔震体系具有更优的抗震性能。在此基础上,进一步从经济性的角度上对两种抗震体系进行了比较,结果表明减、隔震体系能有效地减小桥梁下部结构尤其是基础部分的地震反应,进而控制该部分的工程用量,在抵消减、隔震装置的成本增幅后,对总的工程造价还可以实现可观的节约。

The rational multilevel seismic fortification criterion and the corresponding performance objectives were discussed for urban expressway viaducts.Two typical continuous girder viaducts,a mainline bridge and a ramp bridge,were analyzed in this study.For each bridge,a traditional ductile earthquake resisting system and an isolation earthquake resisting system were considered.The detail structural seismic performances corresponding to the two different earthquake resisting systems were compared at each design level of earthquake actions for the two typical bridges.It showed that although both the earthquake resisting systems can satisfy the requirements of the performance objectives,the isolation earthquake resisting system exhibited more perfect seismic performance for both the typical bridges.Furthermore,the added costs corresponding to the two different earthquake resisting systems were also compared for the two typical bridges.It indicated that the isolation system would also achieve a considerable saving in construction cost.This may be attributed to the avoidance of a volume increase in foundations due to seismic actions since they were effectively controlled by the isolation system.