考虑地震动空间效应的深水桥梁减震性能

Seismic Isolation Performance of Bridges in Deep Water Considering the Spatial Variability of Ground Motions

摘要:

以大跨深水连续梁桥为研究对象，提出了拉索减震体系。对考虑地震动空间效应的不同激励地震动输入的实现方法做了阐述，对比常规体系和弱固定体系，研究考虑地震动空间效应时深水桥梁拉索减震体系的减震效果，并进一步探讨了考虑地震动空间效应时动水压力对深水桥梁地震响应的影响。研究结果表明，拉索减震支座具有良好的减震性能，且其对地震动空间效应非常敏感；考虑地震动空间效应时动水压力对拉索减震体系、常规体系动力响应的影响较一致激励有所差异，且该差异随视波速、失相干系数及局部场地条件的不同而变化。因此，可为大跨度深水桥梁抗震设计提供一定的参考。

Abstract:

A cable seismic isolation system was proposed for long span continuous girder bridges in deep water. A method was presented for obataining the ground motion acceleration of different excitation points which based on the recorded ground motion arrays itself considering the spatial variability at the same time. Compared with the conventional system and the feeble fixed system, the seismic isolation effectivity of cable seisimc isolation system was studied when the spatial variability of ground motions was considered, and the effect of earthquake induced hydrodynamic pressure on the seismic response of deep-water bridges was discussed. The results indicate that the deep-water continuous girder bridges with cable-sliding friction aseismic bearing have remarkable isolation performance, and this bearing is sensitive to the spatially varying earthquake ground motions including wave-passage, incoherence and site-response effect. The effect of hydrodynamic pressure on the seismic response of bridges in deep water is different, considering the spatial variability of ground motions relative to a uniform excitation, which is also changed with apparent wave velocity, incoherence coefficient, local site condition when wave-passage, incoherence and site-reponse effect are considered. Therefore, this can provide a certain criterion of reference for seismic design of long-span deep-water bridges.