Session: SE-01-01 Earthquake Resistance and Seismic Margin

Paper Number: 61343

Start Time: Tuesday, July 13, 2021, 09:00 AM

61343 - Study on the Predictive Evaluation Method for Loads Acting on Roof and Sidewall of Cylindrical Tank in Nonlinear Sloshing Based on Simplified Equations 

　When cylindrical tanks installed in the ground, such as oil tanks and liquid storage tanks, receive strong seismic waves, including the long-period component, motion of the free liquid surface inside the tank called sloshing may occur. If the high-amplitude sloshing occurs and the waves collide with the tank roof, it may lead to accidents such as damage of the tank roof or outflow of internal liquid of the tank. Also, there is a possibility that the sidewall of the tank may be damaged due to the fluid force generated by the high liquid surface level of the sloshing.
　In order to evaluate the load acting on the tank roof, an evaluation method of the load due to the collision of the nonlinear sloshing liquid surface is required. And, in order to evaluate the load acting on the tank sidewall, an evaluation method of the load due to the high nonlinear sloshing liquid surface level is required. If the sloshing wave height is small, liquid surface level and velocity can be calculated based on the linear theory. However, when the sloshing wave height increases, the sloshing becomes nonlinear, and the difference between the actual value and the calculated value based on the linear theory increases. Therefore, these loads should be evaluated in consideration of the nonlinearity of sloshing. In the past study, simplified equations of nonlinear liquid surface level and velocity were proposed, as input parameters needed in these load evaluations.
　In this study, an evaluation method of loads acting on the roof and the sidewall is proposed, for the nonlinear sloshing condition of cylindrical tanks. In this method, the impact pressure acting on the roof is evaluated based on a modification of the existing method of two-dimensional water entry problem developed by Wagner and the proposed simplified equations of nonlinear liquid surface level and velocity. And, in this method, the pressure acting on the sidewall is evaluated based on a modification of the linear theory method and the proposed simplified equations of nonlinear liquid surface level and velocity. The validity of this method was confirmed by comparing them with CFD and experiments. And future issues on the improvement of the method were clarified from the result.

Presenting Author: Shunichi Ikesue Mitsubishi Heavy Industries, Ltd.

Authors:

Shunichi Ikesue Mitsubishi Heavy Industries, Ltd.
Hideyuki Morita Mitsubishi Heavy Industries, Ltd.
Hidekazu Ishii Mitsubishi Heavy Industries, Ltd.
Hiromi Sago Mitsubishi Heavy Industries, Ltd.
Shinobu Yokoi Mitsubishi FBR Systems, Inc.
Tomohiko Yamamoto Japan Atomic Energy Agency