深水桥梁动水效应规范算法的近断层地震动检验

Check of code calculation methods of hydrodynamic effect for deep-water bridge excited by near-fault earthquakes

以典型深水桥梁的等效单墩模型为对象,以代表性近断层地震动为输入,采用考虑桥墩水体动力相互作用的流固耦合全数值计算方法,检验了我国、日本以及欧洲相关规范动水效应计算方法的准确性.结果表明:水环境的存在会导致结构自振周期的延长,各规范方法的误差率随水深增加而变大,欧洲规范偏大,日本规范偏小,我国铁路规范最接近流固耦合法计算值.在分布动水压力方面,我国铁路规范存在一定偏差,日本规范明显偏大,在墩底处约为流固耦合法计算值的5倍.在总动水压力方面,日本规范偏于保守,不同水深下的误差率在90%~153%;我国公路细则误差率在-50%^-61%;我国铁路规范最接近流固耦合法计算值,其误差率在-46%~30%.在总动水压力的作用位置方面,我国公路细则较为合理,而我国铁路规范给出的作用位置偏高,日本规范则偏低.在动水压力下的结构地震响应方面,欧洲规范计算结果偏大,日本规范结果偏小,我国铁路规范结果吻合度最高.总体来看,我国铁路规范精度较高,但在分布动水压力及总动水压力的计算上还存在改进空间.

The equivalent pier model of a typical deep-water bridge excited by a group of near-fault ground motions was studied. The accuracy of different code methods for hydrodynamic effect calcula- tion was checked based on complete fluid-structure interaction numerical method. The result shows that the existence of surrounded water will longer the natural vibration period of the structure. The er- ror rates of different codes get greater with the increase of water depth. The period calculated through Eurocode 8 is larger and that of Japanese Code is smaller, while the result of Chinese Railway Code is close to the calculation value by fluid-structure interaction method. For distributed hydrodynamic pres- sure, there is some deviation for Chinese Railway Code, and the result from Japanese Code is more conservative, which reaches 5 times at the bottom. For total hydrodynamic pressure, Japanese Code tends to be conservative and the error rate covers from 90 % to 153 % under different water depth, and that for Chinese Highway Code is - 50 % to - 60 %, while the calculated value from Chinese Railway Code is most close to the calculation result by fluid-structure interaction method and the error rate is about - 46 % to 30 %. For the application location of total hydrodynamic pressure, Chinese Highway Code is reasonable. The application location from Chinese Railway Code tends to be higher and that of Japanese Code is lower. For the seismic response of the pier, the dynamic response of Eurocode 8 is greater, the result of Japanese Code is smaller and that of Chinese Railway Code is closer to the calcula- tion value by fluid-structure interaction method. In general, Chinese Railway Code has higher accura- cy, but the method for calculating distributed and total hydrodynamic pressure should be improved.