大跨连续梁桥减隔震方案对比分析

以1座(90+170+90)m城市大跨度连续梁桥为研究对象,提出并比较分析两种减隔震设计方案。采用弹性反应谱法及非线性时程反应分析方法研究E1及E2地震作用下结构的地震反应,针对两种方案比较摩擦摆支座的力学参数取值及结构地震反应的差异。结果表明:(1)对于大跨连续梁桥,由于纵桥向一联内仅设置一个制动墩,地震内力分布极不均匀;但横桥向结构内力分布较均匀,各墩联合共同受力;(2)采用摩擦摆支座,E2作用下各墩墩底截面纵、横向内力减震效果显著且各墩的内力分布趋于均匀,分布更加合理;(3)采用摩擦摆支座,E2作用下减隔震后的墩底内力通常小于E1作用下弹性反应分析结果。E1作用下摩擦摆支座是否允许滑动,对结构的地震反应影响显著。在实际设计中应认真加以分析对比。

Comparative Analysis of Isolation Schemes for Long-span Continuous Girder Bridge

Taking a long-span urban continuous girder bridge with spans of( 90 + 170 + 90) m as the research objective,this paper proposes two isolation schemes for comparison and analysis. Structural seismic response under earthquake action of E1 and E2 is studied with elastic response spectrum method and nonlinear time history response analysis method. The differences in structural seismic response and in the selection of mechanical parameters for the friction pendulum bearing( FPB) related to the two schemes are compared. The results show that:( 1) because only one braking pier is set up at one continuous unit in the longitudinal direction for the long-span continuous girder bridge,the structural internal force distribution is extremely uneven in the longitudinal direction,but the structural internal force distribution is comparatively more uniform in transverse direction,and each individual pier shares the stress;( 2) FPB has obvious damping effect on the internal forces of the bridge substructure both in longitudinal and transverse directions and internal force distribution for individual pier tends to be more even and reasonable.( 3) the internal force at pier bottom obtained by use of FPB under E2 is usually less than that obtained from seismic elastic response under E1. Whether FPB is allowed to slide or not under E1 will have a significant effect on structural seismic response,which needs to be carefully analyzed and compared in the design.