Development of seismic fragility curves of cylindrical concrete tanks using nonlinear analysis

Fluid storage tanks are one of the most important components of vital arteries that play a key role in various water and industry networks, including oil, petrochemical, and water transmission systems. A study of seismic damage reports of tanks in previous earthquakes shows that one of the major damages in reinforcement concrete tanks that are commonly used to store water is cracking and liquid leakage. Therefore, in the present paper, the analysis and evaluation of ground concrete tanks are investigated to develop the fragility curve for these tanks. For this purpose, nonlinear numerical analyzes have been performed for three types of concrete cylindrical tanks with variable height to diameter ratio, taking into account the cracking of concrete. Then, the fragility curves of the tanks for the critical crack width are extracted according to the recommendation of Journal 123. These curves are compared with the results of previous research conducted in a linear manner without considering the cracks in the reservoir body, and the effects of applying crack widths in the analyses are discussed. The results indicate the need to apply tank cracking conditions in increasing dynamic analysis and extraction of fragility curves.