Seismic Performance Evaluations And Seismic Retrofits Of Municipal Bridges

The codes for seismic designs of highway bridges have been applied for threegenerations at present in China. As the seismic design methods have been developed andupdated, there are seismic safety hazards of varying degrees for the bridges which weredesigned by the former methods or which had no seismic designs. Therefore, the maincontents are as follows:The three-generation seismic codes applied in1997,1989, and2008are researched.Especially, the1989Specifications and the2008Guidelines are analyzed and compared inaspects of seismic fortifications, design methods, comprehensive influence coefficient,ductility seismic design, seismic isolation design, seismic measures, and so on. It is concludedthe major advances of ideas and methods of current codes, and the defects of previous codesare illustrated.The approaches about bridge seismic performance evaluations at home and abroad areanalyzed. Mainly, there are four-category approaches: the emergency seismic performanceevaluation approach based on field inspections, the speedy seismic performance evaluationapproach based on pre-existing information systems, the seismic performance evaluationapproach based on deterministic calculations, and the seismic performance evaluationapproach based on probability theory. By comparison, the suited bridge seismic performanceevaluation approach for pre-seismic detailed evaluation is obtained.We investigate the characteristics of177Beijing city bridges and9representativebridges are extracted on the basis of bridge characteristics. Then, the calculation procedure ofthe seismic performance evaluation approach based on deterministic calculations isestablished. And, it is concluded that the seismic defections of representative bridgesaccording to the capacity-demand ratios.The seismic retrofit technologies at home and abroad are researched. The concreteseismic retrofit strategies for municipal bridges are presented. And, superstructure seismicretrofit measures, substructure seismic retrofit measures, isolation seismic retrofit measures,and comprehensive seismic retrofit measures, which are suited for municipal bridges, arepresented.