为研究跨断层桥梁地震响应规律及合理跨越断层角度,以一座跨走滑断层的连续梁桥为研究对象,采用混合模拟法合成了该桥的地面运动时程曲线,基于多点激励位移输入模型,采用非线性时程法对其地震响应规律进行了分析,并以桥梁轴向与断层交角θ为研究参数分析了其对结构地震响应的影响,得到了θ对结构地震响应的影响规律和变化曲线。计算结果表明:跨断层桥梁桥墩扭矩设计值较大,桥墩横向弯矩随断层距的减小而增加;其位移响应以主梁纵横向大位移、面内扭转变形、支座和桥墩残余位移为主要特征,具有较大的落梁破坏风险;当桥梁垂直跨越断层时(θ=90°),桥墩受力合理性和经济性最优,断层错动产生的顺桥向位移分量最小,落梁风险相对较低。研究成果可为该类桥梁的抗震设计与桥位布置提供参考和依据。
Abstract
This paper presents a study on seismic response feature and the best crossing angle for the bridges crossing active fault. One bridge crossing strike-slip active fault was taken as an example. The seismic ground motions at the site of the bridge are generated following a hybrid simulation methodology. Multi-support excitations displacement input models and nonlinear time history analysis was used to calculate seismic response of structures. The influences of the crossing angle θ between bridge and fault on seismic response is also analyzed and the influence law and variation curve were acquired. The results showed that design pier torque values of bridge crossing fault was greater, and pier transverse bending moment increased with the decreased of the fault distance. The displacement response is with the main characteristics as large displacement and plane torsional deformation of main girder, residual displacement of bearings and piers, which pose significant unseating risk. When the bridge vertically across the fault(θ=90°), the optimal rationality and economy for piers internal force is presented, the bridge axial displacement component caused by fault dislocation is minimal, accordingly, the risk of unseating is relatively low. The results provide in this research can be used as a reference to the seismic design and bridge location.
关键词
桥梁工程 /
跨断层 /
地震响应 /
跨断层交角
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Key words
bridge engineering /
across faults /
seismic response /
crossing angle between bridge and fault
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