圆管渡槽抗震计算流体等效简化模型

Simplified equivalent fluid model for seismic response calculation of pipeline bridge

提出了一个圆管渡槽内流体晃动分析的等效简化模型。将圆管渡槽内的水体假定为无黏性、无旋、可压缩及小幅晃动的流体,横向晃动的流体可等效为一个固定质量M0与一个质量-弹簧系统(M1,K1),根据等效原则,即实际的流体系统(采用有限元模拟)与等效模型具有相同的一阶自然晃动(振动)频率,以及对槽身具有相同的作用效应。采用最小二乘算法,通过数值拟合可得到等效模型中固定质量M0、弹簧振子(M1,K1)及其位置的近似计算公式。应用流体等效简化模型和有限元模型分别对某一管线桥流体-结构耦合系统的自振频率与地震反应进行了计算分析,数值算例表明两个模型的计算结果非常吻合,验证了流体等效模型的有效性与适用性,为圆管渡槽支撑结构地震反应分析提供一个简化的流体计算模型,可为渡槽抗震研究者与结构工程师提供参考。

In this paper,a simplified equivalent model was proposed to analyze the sloshing fluid in the pipeline bridge.The water motion in a pipeline bridge is assumed to be inviscid,irrotational,compressible,and linear(small displacement).The transverse sloshing fluid in a pipeline bridge can be simplified as a fixed rigid mass M0 and a mass-spring system(M1,K1).According to the equivalence rule,the actual fluid(computed by the finite element model)and its equivalent model have the same the first sloshing frequency and the same effects on the pipe.The approximate analytical formulae of the fixed mass M0,mass-spring oscillator(M1,K1),and its locations in the pipe were acquired by the least-squares and curve fitting algorithms.The simplified equivalent fluid model and fininte element model were used to calculate the first natural frequency and seismic response of a pipeline bridege(fluid-structure coupling system).The numerical results calculated by the two fluid models agreed well,which confirmed the validity and accuracy of the equivalent model.Therefore,the simplified model of sloshing fluid can analyze the seismic response of the support structure of pipeline bridge,which can provide reference of seismic resistance for the researchers and structural engineers.