连续梁桥固定墩减震设计方法研究
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摘要
强震作用下,连续梁桥在固定墩发生屈服后,由于桥墩屈后刚度较小,整桥系统在纵桥向缺乏足够的恢复力机制,近似处于一种随遇平衡状态,震后固定墩可能发生较大的残余塑性变形。对连续梁桥固定墩减震设计方法进行探讨,介绍双曲面球型减隔震支座的构造特点、工作机理及安装方法,在此基础上提出一种新的减震方法,即将活动墩上的普通活动支座改为双曲面球型减隔震支座,利用该支座能提供可靠稳定的摩擦耗能以及能帮助上部结构回到平衡位置的特点,对固定墩进行减震设计。结合高烈度区某三跨连续梁桥,分别研究工程中经常采用的设置阻尼器方法以及本减震方法的减震效果,分析两种减震方法的不同参数设置对减震效果的影响。将阻尼器减震方法和本减震方法的减震效果进行比较。结果表明:本减震方法能有效地减小固定墩塑性变形、控制活动墩墩梁相对位移、提高结构抗震性能;明显优于传统阻尼器方法,可供工程实践参考。
The fixed pier for continuous bridges usually may become plastic when subjected to a major earthquake.As a consequence of the small value of post-yield stiffness of the fixed pier,there is a lack of restoring force in the longitudinal direction of the bridge system,which is almost at a condition for unstable equilibrium.As a result,the fixed pier may suffer major residual plastic deformation after earthquake.Earthquake-reduction design methods for the fixed pier of continuous bridges are discussed in this paper.Based on the construction features,the working mechanism and installation method for dual-spherical seismic bearings,a new damping method is proposed,in which ordinary sliding bearings in non-fixed piers are replaced by dual-spherical seismic bearings.The new damping method takes advantage of the features of dual-spherical seismic bearings for providing ability of dissipating energy and a restoring force to help the superstructure return to the equilibrium position,thus reducing the seismic effect of the fixed pier.For a three-span continuous bridge in a high earthquake-intensity area,the damping effect of the widely-used viscous damper method and that of the proposed damping method are studied,and the influences of different parameters of the two methods on the damping effect analyzed.Comparison of the damping effect between viscous damper methods and the proposed damping method is carried out.The results show that the proposed damping method could reduce the plastic deformation of the fixed pier,control the relative displacement between superstructures and piers,improve seismic performance of bridge structure,and that the proposed damping method is much more effective than the traditional viscous damper method.
The fixed pier for continuous bridges usually may become plastic when subjected to a major earthquake.As a consequence of the small value of post-yield stiffness of the fixed pier,there is a lack of restoring force in the longitudinal direction of the bridge system,which is almost at a condition for unstable equilibrium.As a result,the fixed pier may suffer major residual plastic deformation after earthquake.Earthquake-reduction design methods for the fixed pier of continuous bridges are discussed in this paper.Based on the construction features,the working mechanism and installation method for dual-spherical seismic bearings,a new damping method is proposed,in which ordinary sliding bearings in non-fixed piers are replaced by dual-spherical seismic bearings.The new damping method takes advantage of the features of dual-spherical seismic bearings for providing ability of dissipating energy and a restoring force to help the superstructure return to the equilibrium position,thus reducing the seismic effect of the fixed pier.For a three-span continuous bridge in a high earthquake-intensity area,the damping effect of the widely-used viscous damper method and that of the proposed damping method are studied,and the influences of different parameters of the two methods on the damping effect analyzed.Comparison of the damping effect between viscous damper methods and the proposed damping method is carried out.The results show that the proposed damping method could reduce the plastic deformation of the fixed pier,control the relative displacement between superstructures and piers,improve seismic performance of bridge structure,and that the proposed damping method is much more effective than the traditional viscous damper method.
引文
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[9]方海,李升玉,王曙光,等.高烈度区连续梁桥的减震设计方法研究[J].地震工程与工程振动,2005,25(6):178-182(Fang Hai,Li Shengyu,Wang Shuguang,et al.Research on earthquake-reduction design method of continuous girder bridges in a high-intensity earthquake area[J].Earthquake Engineering and Engineering Vibration,2005,25(6):178-182(in Chinese))
[2]蒋建军,李建中.隔震连续梁桥上粘滞阻尼器的减震效果研究[C]//第二届全国土木工程研究生学术论坛论文集.上海,2004
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[4]彭天波,李建中,范立础.双曲面球型减隔震支座的竖向位移分析[J].同济大学学报:自然科学版,2007,35(9):1181-1185(Peng Tianbo,Li Jianzhong,Fan Lichu.Analysis of vertical displacement of double spherical aseismic bearing[J].Journal of Tongji University:Natural Science Edition,2007,35(9):1181-1185(in Chinese))
[5]朱万彦.一种新型铁路桥梁双曲面球型减隔震支座安装技术[J].铁道建筑技术,2009(2):74-76(Zhu Wanyan.Installation technology for hyperboloid spheroidal antivibration supports in railway bridge[J].Railway Construction Technology,2009(2):74-76(in Chinese))
[6]Pekcan G,Mander J B,Chen S S.Fundamental considerations for the design of non-linear viscous dampers[J].Earthquake Engineering&Structural Dynamics,1999,28(11):1405-1425
[7]殷海军,王志强,胡世德.连续梁桥设置阻尼器参数分析[J].同济大学学报:自然科学版,2004,32(11):1437-1441(Yin Haijun,Wang Zhiqiang,Hu Shide.Analysis of continuous bridge adopted dampers[J].Journal of Tongji University:Natural Science Edition,2004,32(11):1437-1441(in Chinese))
[8]郭磊,李建中,范立础.大跨度连续梁桥减隔震设计研究[J].土木工程学报,2006,39(3):81-85(Guo Lei,Li Jianzhong,Fan Lichu.Research on seismic isolation design for long-span continuous bridges[J].China Civil Engineering Journal,2006,39(3):81-85(in Chinese))
[9]方海,李升玉,王曙光,等.高烈度区连续梁桥的减震设计方法研究[J].地震工程与工程振动,2005,25(6):178-182(Fang Hai,Li Shengyu,Wang Shuguang,et al.Research on earthquake-reduction design method of continuous girder bridges in a high-intensity earthquake area[J].Earthquake Engineering and Engineering Vibration,2005,25(6):178-182(in Chinese))
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