THE FORMULATIONS OF SHEAR FORCE AND OVERTURNING MOMENT OF THE LARGE-UPRIGHT-UNANCHORED INDUSTRIAL LIQUID STORAGE TANKS SUBJECTED TO HORIZONTAL GROUND EXCITATIONS

摘要

The dynamic response analysis is performed for the formulations of shear force and overturning moment of the large-upright-unanchored industrial liquid storage tanks subjected to horizontal ground acceleration. As the tank is accelerated in the horizontal direction, it tends to uplift from its foundation, and hydrodynamic pressures on the tank wall vary with height in non-linear fashion. In this study, the distribution of hydrodynamic pressures and its center are directly correlated to formulate shear force and overturning moment. Initially, the equations of shear force and overturning moment derived by assuming hydrodynamic pressures exerted on tank wall vary in parabolic trend. Then derived equations are multiplied by dynamic coefficients, which are basically the function of peak ground acceleration, excitation frequency and the ratio of liquid's height to radius of tanks. Dynamic coefficients are formulated through the shake table experiment of the model tanks excited by computer generated ground motion. The equations proposed in this paper for base shear and overturning moment are only the function of total weight of tank, the ratio of liquid's height to radius, specific weight of liquid and dynamic coefficients for shear force and overturning moment. Therefore, proposed equations are very simple, efficient and easy to perform in calculating of shear forces and overturning moments of the large-upright industrial liquid storage tanks subjected to lateral earthquake loads. The results are verified with different codes (e.g. Eurocode8, API and AWWA-100…).