矮墩大跨连续梁体系桥纵向减隔震设计

以上海大治河桥为实例,分析了矮墩、大跨连续梁体系桥的结构动力特性与地震易损性一般规律。重点探讨了矮墩、大跨连续梁体系桥的纵向地震响应规律与合理抗震设计,并指出了该类桥梁不适宜按延性抗震进行设计。按结构纵向约束要求,提出了采用E型软钢阻尼器组的减隔震设计方案,并给出了具体的设计参数。从非减隔震设计与减隔震设计方案的结构抗震性能对比分析结果可以看出,减隔震设计体系可以有效缓解纵向固定墩支座、墩身以及基础地震惯性力大、构件能力匹配关系难以满足能力保护设计的特点,是矮墩、大跨连续梁体系桥纵向抗震体系的理想解决方案。

On Longitudinal Seismic Isolation & Reduction Design of Large-span Continuous Girder Bridge with Low Piers

Taking Shanghai Dazhi River Bridge for example,structural dynamic characteristics of large-span continuous girder bridge with low piers and general rules of seismic fragility are analyzed in this paper.And longitudinal seismic response of this type bridge and reasonable seismic design are discussed and stressed.It shows that ductility seismic theory is not suitable for this type bridge.According to structure longitudinal constraint requirements,a seismic isolation & reduction plan with E-typed mild steel damper is proposed,and moreover,detailed design parameters are given.Based on the structure seismic performance comparison analysis on seismic non-isolation & reduction design plan and seismic isolation & reduction one,the seismic isolation & reduction design system can reduce greatly the inertia forces transferred to the longitudinal fixed bearings,the pier columns and the pile foundations(matching relationship of members’ capability cannot protect the design).In a word,this seismic isolation & reduction plan discussed hereby is regarded as the ideal anti-seismic solution one for largespan continuous girder bridge with low piers in longitudinal direction.