减震榫在宝兰客专48 m简支梁桥中的设计应用

Design and Application of Shock Absorber for 48 m Simple Supported Box Girder Bridge of Baoji-Lanzhou Passenger Dedicated Line

研究目的:位于高烈度地震区的高速铁路大跨简支梁桥具有质量重、跨度大、抗震设防问题突出等显著特点。多遇地震下可通过加强墩身及基础配筋来满足抗震需要,而罕遇地震下如何合理确保结构的安全,成为亟待解决的关键问题。本文针对宝鸡至兰州客运专线上位于0.3g动峰值加速度区的48 m大跨简支梁桥开展设计研究,采用墩顶设置减震榫的方式进行减隔震设计。研究结论:(1)减震榫采用"支座功能分离"的构思,将传统支座的水平力传递和竖向支撑功能完全分离,梁体竖向反力及梁端转角仍由支座实现,水平力及水平位移由采用低屈服点钢阻尼器减震榫支撑和控制,结构构造简单,设计理念先进;(2)减震榫的减震效率在顺桥向随着墩高的变化而变化,当墩高≤12 m,多遇地震下减震率最大达54%,当墩高增大到20 m时,多遇地震下减震率最小为29%,横桥向的减震率基本维持在43%~55%;(3)罕遇地震下,采用减震榫后,可以将墩顶罕遇地震下的水平地震力减小到多遇地震未采用减震榫时墩顶水平地震力的程度,随着墩高的增加,设置减震榫后罕遇地震下的水平地震力将略大于多遇地震下未设置减震榫的墩顶水平地震力;(4)本研究成果可为今后高烈度地震区大跨桥梁的减隔震设计和施工提供参考。

dResearch purposes： High speed railway large span simple supported girder bridges in high seismic intensity area have remarkable characteristics with big mass, large span and difficult seismic design. Aniti -seismic needs could be satisfied by strengthening pier and pile concrete reinforcement under frequent occurred earthquake, but it is still a problem under rarely occurred earthquake to ensure the safety of the structure. The paper carries out research on 48 m simple supported box girder bridge in high seismic intensity area with 0.3g of Baoji - Lanzhou passenger dedicated line, and takes shock absorber as seismic isolation on the pier. Research conclusions： （l） Adopting idea of ＂bearing function separation＂, shock absorber is a simple and advanced device which separates the bearing transmitting horizontal forces from vertical supporting completely, vertical forces and rotation are still realized by bearing, and horizontal forces and displacement are realized by shock absorber. （2） The damping efficiency of shock absorber varies with different pier height along bridge direction, when pier height ≤ 12 m, the damping efficiency could be as high as 54% under frequent occurred earthquake, when pier height is 20 m, the damping efficiency is 29% , and the transverse damping efficiency is 43% -55%. （3） The earthquake forces applyingshock absorber under rarely occurred earthquake could be reduced to a level which is equal to frequent occurred earthquake level; with the increase of pier height, rarely occurred earthquake forces that using shock absorb will be a little bigger than frequent earthquake forces without shock absorber. （4） The research result can provide references on large span bridge seismic isolation design and construction in high seismic intensity area in the future.