非一致激励对三塔自锚式悬索桥地震响应的影响

摘要

作为一种新型的桥梁结构形式，三塔自锚式悬索桥的静动力性能较传统双塔自锚式悬索桥更为复杂。由于其跨越能力较大，抗震分析中地震动空间效应通常不能忽略。以某三塔自锚式悬索桥为工程背景，根据实际场地条件拟合得到空间多点地震动时程，基于时程分析法研究了波传播效应、局部场地效应、失相干效应等地震动空间效应对三塔自锚式悬索桥地震响应的影响规律。研究结果表明：非一致激励会使得主塔内力增大、主塔索鞍抗滑安全系数下降、主塔纵向加速度和变形增大、主梁内力增大。因此，对于三塔自锚式悬索桥地震响应分析时应考虑多点非一致激励的影响。进一步研究表明，非一致激励对于各构件响应的影响程度不尽相同；即使对于同一构件，不同地震动空间效应的影响规律也相差较大。综上所述，非一致激励的影响规律十分复杂，需要后续更深入地探讨非一致激励对多塔悬索桥地震响应的影响机理。%Here,a real project of a three-tower self-anchored suspension bridge (TSSB ) was taken as a background.Spatially varying non-stationary ground motions were simulated according to real site condition.Based on the finite element model of TSSB,the time history method was used to discuss effects of ground motion spatial variations,such as,wave passage effect,coherency loss effect and local site effect.On seismic response of TSSB,respectively.Results showed that spatially non-uniform ground motions increase seismic response of towers and decreases safety factor against cable sliding;it is necessary to consider effects of ground motion spatial variations in seismic design of TSSB.Further studies showed that the levels of the impacts of spatially ground motion on each component are different and influence rules of different spatial effects are also quite different;the influence laws of spatially ground motion on seismic response of TSSB are very complicated,more in-depth study on this topic is needed.