Direct Performance-Based Seismic Design for Liquid Storage Tanks

A performance-based design methodology has been developed for liquid storage tanks based on a surrogate, yet robust beam-element model. Following the identification of failure modes through Incremental Dynamic Analysis, appropriate performance levels are defined based on an existing seismic assessment methodology. The concept of Response Frequency Spectra (RFS) is proposed in view of offering a unique representation of the entire solution space for structural performance. RFS find an excellent application for the case of liquid storage tanks by adopting design parameters such as the tank wall thickness and the anchorage ratio. Although the wall thickness changes the strength capacity for the well-known Elephant’s Foot Buckling failure mode, the corresponding probabilities of exceedance are not significantly modified. On the contrary, anchorage seems to be very important as the associated probabilities may be reduced even by 50% in some cases.