Assessing Seismic Sliding Behavior in Storage Tanks Employing Time-History Analysis

Abstract Extensive research on the seismic response of storage tanks has generated valuable design data, covering aspects like freeboard for sloshing, base shear, and overturning moments. However, a critical aspect, resistance to sliding, remains underexplored. Due to limited experimental data, standards like API 620 adopt a conservative approach by relying primarily on friction between the tank base and subgrade for sliding resistance. This approach can lead to overly conservative and impractical designs, particularly for large tanks where friction alone may be insufficient to prevent sliding. Building on prior research presented in PVP2024-123380 [1], which employed a conservative pseudo-dynamic method to demonstrate the effectiveness of anchor straps in providing sliding resistance, this study advances the analysis by implementing a dynamic time-history approach. The sliding behavior of a large-capacity storage tank is examined using time-history records from past earthquakes, which are matched and scaled to a target response spectrum. This response spectrum corresponds to a peak ground acceleration (PGA) that exceeds the tank’s design PGA, allowing for an assessment of sliding behavior under seismic forces that surpass the frictional resistance provided by the normal forces from the liquid’s weight and the tank’s dead weight. The study evaluates sliding displacement, the role of anchor straps in resisting sliding forces, and the frictional stresses in the bottom plate.