Proposed Equations for Calculating Dynamic Hydraulic Pressure in a Rectangular Structure

Abstract

When damaged by an earthquake, a general structure suffers only primary damage such as in the structure’s collapse, whereas a fluid storage structure can cause secondary damage such as environmental contamination or personal injury due to leakage of its internal fluid. In this study, the flow characteristics of fluid inside a fluid storage structure during an earthquake were analyzed, and an equation to calculate the dynamic hydraulic pressure of the fluid acting on the structure during an earthquake was proposed. The seismic load applied to the fluid storage structure was modified to satisfy the design response spectrum in 300 frequencies so that sufficient earthquake energy was obtained in any natural frequency of the fluid storage structure. In addition, the flow characteristics of the fluid inside the fluid storage structure were examined according to the shape change of the seismic wave and the ratio of the height of the fluid to the width of the fluid storage structure. A resulting equation for calculating the hydraulic pressure reflecting the fluctuation characteristics of the fluid was derived, and structural analysis was performed based on this equation and equations proposed by prior research to compare the member force and the hydraulic pressure in a dangerous section. As a result, it was confirmed that the equation proposed in this study showed similar values to previously proposed equations and could obtain fairly reliable results. Therefore, based on the proposed equation in this study, it is possible to calculate hydraulic pressure by reflecting the free-water surface fluctuation characteristics of fluid inside a fluid storage structure during an earthquake.