矩形柱体地震动水压力的附加质量简化模型∗

针对矩形柱体在水中的振动问题,提出一种代替水-结构动力相互作用的附加质量模型。基于矩形柱体动水压力的计算公式、自由振动方程、自振频率和振型的计算公式,建立了水中矩形柱体地震动力反应的计算公式;基于柔性结构的一阶频率降低率,建立了矩形柱体柔性运动引起动水力的附加质量简化公式,并给出了水中矩形柱体自振频率的简化计算公式;基于刚性运动引起的动水力,建立了矩形柱体刚性运动引起动水力的附加质量简化公式;建立了地震作用下水中柱体结构的简化分析模型,即分别采用柔性和刚性运动附加质量的简化公式代替相应的水-结构相互作用。

A Simplified Added Mass Model for Dynamic Water Pressure Calculation of Rectangle Cylinder under Earthquake

Aiming at the vibration problem of rectangle cylinder in water, an added mass model for fluid-structure dynamic interaction calculation is presented. On the basis of the formula for hydrodynamic pressure calculation, the free vibration equation, and the formula for natural frequencies and mode shape, the response equations of rectangular cylinders in water subjected to earthquake are derived. A simplified added mass formula for hydrodynamic pressure calculation of rectangular cylinders caused by flexible motion is established based on the first-order frequency reduction rate of flexible structures. A simplified formula for natural frequencies estimation of rectangular cylinders in water is also given. Considering the hydrodynamic pressure caused by rigid motion, a simplified added mass formula for hydrodynamic pressure on rectangular cylinders caused by rigid motion is established. A simplified model for computing the seismic responses of the cylinders surrounded by water is established, in which the hydrodynamic action is replaced by the simplified added mass formulas obtained by flexible and rigid motion.