3D Analysis for Conical Tanks under Seismic Loads

摘要

In this study, conical ground and elevated tanks' seismic response has been investigated. This study has been motivated with the deficiency of data in design codes concerning conical tanks seismic analysis. Seismic analysis by American Water Works Association for welded steel tanks for water storage (AWWA D-100) or Egyptian code for loads (ECP201-2012) is based on an approximate method by using the mechanical analog of cylinder tanks by substituting the conical tank with an equivalent cylinder tank. 3D Finite element models have been modeled using added mass approach in order to represent the fluid-structure interaction. A previously established mechanical analog for conical tanks under horizontal seismic force has been used in the finite element model. The 3D finite element model is verified with El Damatty and Sweedan (2006) work and with Maheri et al. (1988) experimental work. A wide range of conical tanks has been studied to investigate the seismic response of conical tanks through evaluating maximum base shear, maximum overturning moment and maximummoment at the bottom of wall using response spectrum method. Those obtained values using finite element model, AWWA-D100 and ECP201-2012 have been compared to each other. This study reveals that approximate methods underestimate the seismic response of conical tanks, hence some correction factors have been suggested to be used if AWWA-D100 or ECP201-2012 procedures to be used. It also has been concluded that for the same tank volume and the same liquid height to radius at vessel base ratio (hw/Rb), a vertical inclination angle of tank's walls (θv) of 15° gives the minimum moment at the bottom of wall.