Storage tanks are structures widely employed in various chemical and petroleum industries for the storage of liquids and gases. These structures, which store flammable and explosive substances, can lead to events such as fire and explosion in the event of any hazardous situation. Such accidents can have adverse effects on human life, facilities, the economy, and the environment. Earthquakes, as a natural threat affecting all structures, also trigger events like fire and explosion in storage tanks. Therefore, the assessment of seismic risks for storage tanks, the prediction of damage, is crucial for both existing and newly constructed tanks. In this study, the seismic behaviors of spherical and horizontal cylindrical storage tanks were investigated based on observational and finite element analysis data. Fragility analyses of tanks were conducted considering several commonly used statistical approaches, and fragility curves were derived. By using fragility curves, the probability of structural damage due to earthquakes is observed as a function of ground motion parameters. These curves express the likelihood of reaching or exceeding a pre-determined damage state under seismic effects for the considered type of structure. They are developed to predict potential damage during earthquakes and are outputs of seismic risk assessments. Fragility curves are utilized as indicators to determine physical damage during both the main shock and lowerintensity aftershocks. They can provide insights into whether the structure can be reused after earthquakes. Additionally, they are employed to reduce economic losses and casualties in the face of seismic events. For these reasons, fragility curves are essential statistical tools for decision-making both before and after earthquakes.
