Pounding responses of a base-isolated liquid storage tank under bidirectional earthquakes

The probability of seismic pounding of sliding isolation liquid storage tank (LST) is high. Considering normal impact force and tangential friction force at the location of pounding under bidirectional earthquake, a 3D calculation model of sliding isolation LST is established based on a finite element method. Pounding dynamic responses under unidirectional and bidirectional earthquakes are comparatively investigated, and frequency domain analysis is also conducted. Finally, mitigation measure for adverse effect caused by the pounding is proposed. Results show that the influence of concrete nonlinearity on the pounding is very significant. Dynamic responses are significantly increased due to the pounding, and the maximum tensile stress of tank wall reaches 2.510 MPa under ChiChi earthquake, which exceeds the concrete tensile strength. Besides, pounding causes a high-frequency response. A reasonable rubber cushion design can ensure that the maximum displacement of the sliding isolation LST is limited by the moat wall, and the failure probability caused by the pounding is decreased.