Document Type: Original Article
Babol University of Technology
In this paper, rotational components of ground motion acceleration have been obtained using improved method from the corresponding available translational components based transversely isotropic elastic wave propagation in the soil. With this improvement, it becomes possible to consider frequency dependent wave velocities on rotational components of ground motion. For this purpose, three translational components of El Centro earthquake (24 January 1951) have been adopted to generate their relative rotational components based on SV and SH wave incidence by using the Fast Fourier transform with 4096 discrete frequencies. The translational and computed rotational motions were then applied to the concrete elevated water storage tanks with different structural characteristics and water elevations. The Finite element method is used for the linear and nonlinear analysis of water storage tanks considering the fluid-structure interaction using Lagrangian-Lagrangian approach and the concrete material nonlinearities have been taken into account through William-Warnke model. The linear and nonlinear responses of these structures considering the six components of ground motion show that the rotational components of ground motion can increase or decrease the maximum displacement and reaction force of the structure. These variations are depending on the frequency of structure and predominant frequencies of translational and rotational components of ground motion.