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近远场地震下RC大跨轻柔拱桥减隔震支座方案优化

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为探明不同地震动输入对某大跨轻柔拱桥减隔震的影响,通过非线性有限元模型分析近远场地震下桥梁结构的响应规律,得到大桥支座的优化布置方案.首先,基于模态分析,对比该桥与传统钢筋混凝土(RC)拱桥动力特性差异;其次,选取不同脉冲周期的近场地震动、近场无脉冲及远场长周期地震动记录;最后,研究近远场地震下拱桥的响应行为和损伤演化路径,得到优化桥梁的减隔震支座设计方案.研究结果表明:近场脉冲及远场长周期地震下的桥梁结构响应大于无脉冲地震响应;纵竖向地震下高墩柱剪力及弯矩包络曲线呈"S"形,墩身中部易形成塑性铰,高阶振型影响显著;桥梁纵桥向先于横向震损,损伤路径依次为矮柱、高墩柱及拱肋实心-空心截面段;摩擦摆支座减震效果最佳但位移较大,高阻尼支座方案在近场中长脉冲周期及远场长周期地震下仍会发生损伤,板式橡胶支座方案因无法保证支座同步滑移而不能形成准隔震体系;"高阻尼+摩擦摆"混合方案的支座位移小,拱肋及墩柱均处于弹性,是近断层大跨轻柔RC拱桥的优选减隔震方案.
Optimization of Seismic Isolation Bearing Scheme of RC Long-Span Soft Arch Bridge under Near-Field and Far-Field Ground Motions
In order to investigate the influence of different ground motion inputs on the seismic isolation of a long-span soft arch bridge,the response law of the bridge structure under near-field and far-field ground motions was analyzed by nonlinear finite element model,and the optimal arrangement scheme of the bridge bearings was obtained.Firstly,based on modal analysis,the difference in dynamic characteristics between the bridge and the traditional reinforced concrete(RC)arch bridge was compared.Secondly,the records of near-field ground motions with different pulse periods,near-field pulseless ground motions,and far-field long-period ground motions were selected.Finally,the response behavior and damage evolution path of the arch bridge under near-field and far-field ground motions were studied,and the design scheme of the bridge's seismic isolation bearing was optimized.The research results show that the structural responses of the bridge under near-field pulse and far-field long-period ground motions are larger than those under pulseless ground motions.The envelope curves of shear force and bending moment of high pier columns were distributed in an S shape under longitudinal and vertical ground motions.A plastic hinge is prone to form in the middle of the pier body,and the effect of high-order vibration mode is significant.The longitudinal direction of the bridge first encounters seismic damage,followed by the transverse direction,and the damage paths are successively low column,high pier column,and solid-hollow section of arch rib.The friction pendulum bearing embodies the most excellent seismic isolation performance with larger displacement.High damping bearing scheme fails to avoid damage under near-field middle and long pulse period ground motions and far-field long-period ground motions.The laminated-rubber bearing scheme can not form a quasi-seismic isolation system because it cannot guarantee the synchronous sliding of the bearing.The hybrid scheme consisting of high damping bearing and friction pendulum bearing leads to small bearing displacement,with arch rib and pier column in an elastic state,which is the optimal seismic isolation scheme for long-span soft RC arch bridge in the near-fault regions.

long-span soft arch bridgenear-field pulse ground motionsfar-field ground motionsdamage evolutionhybrid seismic isolation designhigher order vibration mode

邵长江、崔皓蒙、漆启明、韦旺、庄卫林、黄辉、袁得铮

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西南交通大学土木工程学院,四川成都 610031

西南交通大学陆地交通地质灾害防治技术国家工程研究中心,四川成都 610031

大跨轻柔拱桥 近场脉冲型地震 远场地震 损伤演化 混合减隔震设计 高阶振型

国家自然科学基金国家自然科学基金四川省科技计划

51978581511783952017JY0059

2024

10.3969/j.issn.0258-2724.20220122

西南交通大学学报
西南交通大学

西南交通大学学报

CSTPCD北大核心
影响因子：0.973
ISSN：0258-2724
年,卷(期)：2024.59(3)
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