摘要
为保证在罕遇地震下桥梁结构满足规范要求,以主跨120m的高墩大跨连续刚构桥——云南万拉木特大桥为例,运用MIDAS Civil建立连续刚构桥空间有限元模型,对其进行动力特性及罕遇地震作用下的非线性时程分析,并优化延性抗震设计。分析结果表明:桥梁振型以梁墩的横向振动为主,第1阶横向侧弯的自振周期为1.697s,全桥最大振幅出现在桥墩墩顶位置。在罕遇地震(50年超越概率为2%)作用下,中跨墩顶、底受力较大,均已进入屈服,但其弯矩均小于钢筋极限弯矩,桥梁满足"大震不倒"抗震性能目标。对塑性铰区进行优化,将墩底以上3m空心与实体分界位置处截面外层部分主筋弯折,形成最不利塑性铰区域;加强墩顶、底塑性铰区域横向约束钢筋布置,提高墩柱延性。
To ensure that the bridge structure could meet the code requirements under the action of a rare earthquake,the Wanlamu Bridge,a long-span continuous rigid-fame bridge with a main span of 120 mand with high-rise piers in Yunnan province,was cited as an example for the study.The MIDAS Civil software was used to set up the finite element model of the continuous rigid-frame bridge,to examine the dynamic performance of the bridge,carry out non-linear time history analysis and optimize the ductile anti-seismic design.The results of the analysis indicate that the transverse vibration of the piers is the dominant vibration mode of the bridge,the natural vibration period of the 1st order transverse lateral bending is 1.697 s,and the maximum vibration amplitude of the whole bridge was found at pier tops.Under the action of rare earthquakes（the exceedance probability in 50 years is 2%）,the top and base of middle span piers bear heavier loads,which has been identified in yielding period;however,the bending moment of the middle span piers is less than the ultimate bending moment of the steel reinforcement,and the bridge satisfies the anti-seismic performance target of＂collapse-proof in big earthquake＂.The plastic hinge areas were optimized,by draping some reinforcement in outer layer of the cross section of the interface between the void and solid sections that is 3mabove the pier base so as to form a most unfavorable plastic hinge area.The arrangement of reinforcement providing transverse restriction in the plastic areas of the pier top and base were strengthened to improve the ductility of the pier columns.
出处
《世界桥梁》
北大核心
2015年第2期51-54,共4页
World Bridges
关键词
连续刚构桥
动力特性
罕遇地震
抗震设计
时程分析
continuous rigid-frame bridge
dynamic performance
rare earthquake
anti-seismic design
time history analysis
