Seismic response analysis of an unanchored vertical vaulted-type tank

摘要

Oil storage tanks are vital life-line structures, suffered significant damages during past earthquakes. In this study, a numerical model for an unanchored vertical vaulted-type tank was established by ANSYS software, including the tank-liquid coupling, nonlinear uplift and slip effect between the tank bottom and foundation. Four actual earthquakes recorded at different soil sites were selected as input to study the dynamic characteristics of the tank by nonlinear time-history dynamic analysis, including the elephant-foot buckling, the liquid sloshing, the uplift and slip at he bottom. The results demonstrate that, obvious elephand-foot deformation and buckling failure occurred near the bottem of the tank wall under the seismic input of Class-I and Class-IV sites. The local buckling failure appeared at the location close to the elephant-foot beauses the axial compressive stress exceeded the allowable critical stress. Under the seismic input of class-IV site, significant nonlinear uplift and slip occurred at the tank bottom. Large amplitube vertical sloshing with a long period occurred on the fee surface of the liquid under the seismic wave record at Class-III site. The seismic properties of the storage tank were affecteed by site class and should be consifered in the seismic design of large tanks. Effective measures should be taken to reduce the seismic of storage tanks, and ensure the safety of tanks.