ABSTRACT of the Doctoral Thesis
Earthquake resistant design of liquid storage tanks has been an essential topic in the field of earthquake engineering. To prevent damage of grave consequence, it is necessary to have proper codes for engineers dealing with the construction of liquid storage tanks. For this reason an essential aim of this thesis has been the development of simple formulas and diagrams for earthquake resistant design of anchored and unanchored cylindrical liquid storage tanks. Analytical procedures are applied for approximating the dynamically activated fluid pressures caused by horizontal and vertical earthquake excitation.
Superposition rules are derived for unidirectinally horizontally excited tanks on a rigid foundation. Time integration is used to find a suitable rule to superpose the dynamic pressures caused by a two-dimensional horizontal and vertical excitation. The stability behaviour of the tank wall and its load carrying capacity are analyzed by the finite element method. Using the finite element method parametric studies were carried out to obtain a design chart for approximating the increase of the axial membrane force in the tank wall due to uplifting of unanchored tanks. A modified response spectrum method is adopted to investigate the amplitude dependent dynamic behaviour of uplifting tanks. Dynamic instabilities (parameter and parameter-combination-resonances) are discussed. In addition a dynamic non-linear finite element analysis of a horizontally excited model tank is carried out. RESULTS: A concept for calculating the dynamic loads acting on an earthquake excited anchored or unanchored tank is presented. A consistent design rule for earthquake loaded anchored or unanchored tanks is presented. A number of examples show the efficiency of the concept.