Probabilistic evaluation of earthquake-induced sloshing wave height in above-ground liquid storage tanks

Abstract

Past earthquakes have repeatedly demonstrated the need to properly design above-ground liquid storage tanks to mitigate their potential for damage due to seismic actions. One important damage mechanism in these plant items is the height of the sloshing wave exceeding the freeboard height provided to the tank. This paper proposes and presents a probabilistic framework to evaluate risk-oriented safety factors that can aid in the design of the freeboard height. The procedure is based on a series of dynamic analyses performed over a tank portfolio. The process accounts for record-to-record variability by using a set of 50 historical ground motion records, while it accounts for the variability in the geometric properties of tank prototypes by generating a random population of 100 cylindrical tanks through Monte Carlo simulation. The randomly generated tank properties are used to develop a simple mechanics-based model for each simulated tank, which is then subjected to the 50 ground motion records scaled to three seismic intensities by using two record scaling strategies. The trends in the resulting sloshing wave height values in relation to the randomly generated tank geometric properties are thoroughly analyzed and discussed, indicating that large and squat tank archetypes are particularly sensitive to sloshing. Finally, two sets of risk-oriented safety factors are developed by comparing the results of the set of dynamic simulations with those computed by using the prescriptions given by American standards.