Developing an innovative approach for retrofitting the existing cylindrical liquid tanks

According to the past seismic records, ground level cylindrical liquid tanks are a part of vulnerable life lines in the earthquake events. Roof failures due to liquid sloshing are the most frequent damages in cylindrical liquid tanks after shell bucking failure modes. Dynamic investigations of several cylindrical liquid tanks as well as several internationally accepted publications have shown the negligible influence of the bottom anchor approach on the wave amplitude of liquid tanks. In this regard, high criteria for liquid freeboard in liquid tanks are established as a countermeasure. In this paper a method called "Cell Division" is developed for improving the liquid sloshing behavior in cylindrical liquid tanks. The computer program ANSYS was selected to develop a Finite Element Analysis (FEM) model of an existing ground-level, cylindrical steel shell and roof tank structure with contained fluid under seismic loading. The ANSYS program was selected for its ability to include shell and structural steel elements, contained fluid elements, fluid-structure interaction, geometrical nonlinearities and contact type elements. Using dynamic analysis of finite element models, the seismic behavior of the tanks is studied. The vulnerability of both original and retrofitted tanks is evaluated. Analysis results show a significant reduction in liquid sloshing amplitude, uplift and settlement of the tank. As well as avoiding expensive retrofitting countermeasures, this method increases the economical benefits of the existing tanks by optimum utilization of the tanks' capacity.

کلیدواژه ها:

Liquid tanks ، sloshing ، retrofitting ، freeboard ، Cell Division ، Curtain