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研究了变宽度连续箱梁桥在成桥状态下的动力特性.以某五跨变宽度连续箱梁桥为背景,建立整桥三维空间有限元模型,对大桥的模态进行分析,并选用50年超越概率分别为3%(E1)和10%(E2)两个水准的反应谱进行成桥阶段的地震响应分析.结果表明:E1,E2概率下,变宽度连续箱梁桥制动墩上的内力较大,且顺桥向地震荷载作用对制动墩的内力影响比横桥向地震荷载作用大,竖向地震荷载作用对桥墩轴力影响较大,而对桥梁上部结构位移影响不大,变宽度连续箱梁桥地震反应随桥墩高度增加而增强.建议桥梁设计时,重点考虑固定墩及固定支座的设计,并对固定墩底部进行加固处理,抗震分析时,慎重考虑地震荷载竖向分量取值.通过地震反应谱分析,在规范要求的地震荷载作用下,变宽度连续箱梁桥整体抗震性能良好,满足抗震设计要求.
The dynamic characteristics of a widened continuous box girder bridge under the condition of completed bridge are studied.The three-dimensional finite element model of the whole bridge is established on the basis of a five-span continuous box girder bridge, the modal of the bridge is analyzed, and 50 The seismic response analysis of the bridge stage with the response rates of 3% (E1) and 10% (E2) respectively is presented in this paper. The results show that under the E1 and E2 probabilities, The internal forces of the brake piers are larger than that of the transverse bridge, and the vertical seismic loads have a great influence on the axial force of the piers, but have little effect on the displacement of the superstructure of the bridge , The seismic response of widened continuous box girder bridge is enhanced with the increase of pier height.When the design of bridge is proposed, the design of fixed pier and fixed support should be emphatically considered, and the bottom of fixed pier should be reinforced to deal with it. In seismic analysis, The seismic response spectrum analysis shows that the seismic performance of the widened continuous box girder bridge is good under the seismic load required by the code and meets the seismic design requirements.