非规则铁路连续梁桥抗震体系优化

从非规则铁路连续梁桥各桥墩协同抗震的角度,引入墩底摇摆隔震及支座减隔震,以1座(60+100+60)m连续梁桥为例,建立全桥动力分析模型进行地震反应分析,研究具有中等高度(20~30m)实心桥墩的非规则铁路连续梁桥采用摇摆隔震的适用性,以及全桥采用支座减隔震时的桥墩优化配筋准则。结果表明:采用摇摆隔震时,摇摆墩墩底恒载轴力大,提离位移敏感性高,地震作用下墩顶位移可控制在较小的范围且提离后墩底弯矩变化稳定,易随其余各墩协同抗震,经抗震性能验算确定摇摆墩配筋率为0.6%;采用支座减隔震时,桥墩本身地震反应贡献率最高可达71%,桥墩惯性力主控墩底内力,以地震作用下各墩同步保持弹性为原则,优化后各墩配筋率依次为0.7%,0.3%,0.5%和0.7%。以上2种优化均可使非规则铁路连续梁桥达到"大震不坏"的设防水平。

Optimization of Aseismic System for Irregular Railway Continuous Beam Bridge

From the view of the cooperative earthquake resistance of all piers for irregular railway continuous beam bridge,the rocking isolation at the bottom of pier and the bearing seismic isolation were introduced.Taking a(60+100+60)m continuous beam bridge as an example,the dynamic analysis model of the whole bridge was established for seismic response analysis.The applicability of the rocking isolation for irregular railway continuous beam bridge with medium height(20~30 m)solid piers was studied.The optimal reinforcement criterion for piers with bearing seismic isolation for the whole bridge was investigated.Results show that when the rocking isolation is adopted,the dead load axial force at the bottom of the rocking pier is large and the sensitivity of the lift-off displacement is high.The displacement at the top of the pier can be controlled in a small range under earthquake action,and the bending moment at the bottom of the pier changes steadily after lifting-off.It is easy to cooperate with other piers to resist earthquake,and the reinforcement ratio of the rocking pier is determined to be 0.6% by checking the seismic performance.When bearing seismic isolation is adopted,the seismic response contribution rate of the pier itself can be up to 71%,and the internal force of the pier bottom is mainly controlled by the inertial force of the pier.After the optimization of the pier based on the principle of keeping the elasticity of each pier synchronously under the earthquake,the reinforcement ratio of each pier is 0.7%,0.3%,0.5% and0.7% respectively.The above two kinds of optimization methods can make the irregular railway continuous beam bridge reach the level of"no collapse under large earthquake".