Studies on Aboveground Storage Tanks Subjected to Seismic Excitation and Foundation Settlement
Abstract
The author aims to investigate the current design provision for seismic and foundation settlement design of aboveground open-top storage tanks using finite element analysis. The thesis is divided into two independent but closely related studies: (1) seismic analysis of open-top storage tanks with flexible foundation and (2) fitness-for-service of open-top storage tanks subjected to differential settlement. The present seismic design provisions in American Petroleum Institute’s storage tank standard API 650 (2013) assumes the tank foundation is rigid and therefore, ignores the effect of uplift during a seismic excitation. In the first study, the objective was to quantitatively critique rigid foundation assumption and conclude if the assumption is acceptable or not for a given tank geometry. Tanks with three different height to diameter ratio (H/D), i.e aspect ratios, of 0.67, 1.0 and 3.0 representing broad, nominal and slender geometry, respectively, were modelled having both rigid and flexible foundations. The flexible foundation was modelled with series of non-linear compression only springs. Additionally, for each tank model two different hydrodynamic pressure distribution suggested by (1) Housner and (2) Jacobsen-Veletsos were applied which are used by API 650 and Eurocode 8, respectively. Geometric non-linear analysis with non-linear material properties was conducted (GMNA) using Riks algorithm in Abaqus finite element analysis (FEA) program. The hoop stresses, longitudinal stresses, uplift and buckling capacity of each rigid foundation tank model were compared with its respective flexible foundation tank model and corresponding API 650 rule based provisions. It was observed that the assumption of rigid foundation from design point of view is acceptable for the broad tank, however, for the nominal and slender tanks this assumption is not acceptable. The buckling capacity of nominal and slender tanks having flexible foundation are significantly lower compared to rigid foundation. Therefore, the effect of uplift should not be neglected for design purposes for nominal and slender tank geometries.
Degree
M.Sc.
Advisors
Guzey, Purdue University.
Subject Area
Design|Fluid mechanics|Geophysics|Geophysical engineering|Marketing|Mathematics|Mechanics
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.