采用MIDAS/Civil软件建立了云南湃街渡大桥的桥梁结构力学模型.对模型的自振特性和动力时程分析进行了研究,分析了不同墩高下桥梁结构振型特征和弹性时程分析,获得了刚构桥下不同桥墩高度的抗震性作用.研究结果表明:墩高越高,则桥梁刚度下降,整体结构越柔软.在前十阶振型中,3个模型均以横弯为主,桥墩较高时易形成平面外弯曲变形;桥墩较低时更多的是表现出横弯和竖弯墩高的整体性改变,且y方向最易出现失稳;顺桥向和竖向激励下,主梁弯矩随墩高的变化影响较小,而横向激励对主梁弯矩造成很大影响,墩高相同时,由于桥梁横向刚度小于纵向和竖向,因而受横向地震响应较大,是重点考虑区,而竖向地震激励作用更易增加结构的竖向位移和主梁的内力作用;桥梁地震内力最大值通常出现在墩底处,主梁内力最大值出现在中跨跨中或主梁根部.%This paper adopts MIDAS/Civil software to establish the mechanical model of bridge structure of pai street bridge in yunnan province.The natural vibration characteristics of the model and dynamic time history analysis are studied,analyzed the different type bridge pier compete structure vibration characteristics and elastic time history analysis,obtained the rigid frame bridge under the different height of piers earthquake resistance.The results show that the higher the pier,the lower the bridge stiffness and the softer the overall structure.In the first ten modes,the three models are dominated by transverse bending,and the lateral bending deformation is easy to form when the pier is higher.When the pier is lower,it is more of the overall change of the transverse bending and the high Angle pier,and the Y direction is most unstable.Along the bridge and the vertical excitation,main girder bending moment along with the change of high pier is affected,and lateral incentive for the main girder bending moment caused great influence,high pier phase at the same time,because of bridge lateral rigidity is smaller than the longitudinal and vertical,and the transverse seismic response is bigger,is given priority area,and vertical earthquake excitation is easier to increase vertical displacement and internal force of main girder structure;The maximum internal force of the bridge is usually located at the bottom of the pier.The maximum internal force of the main beam appears in the middle span or the root of the main beam.
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