Seismic Behavior of Free-Standing Systems

A free-standing system/body is a common appearance in many of the industries and household. Due to various reasons, they are not fixed to the base which gives rise to an important question - What will happen to the system/body, in case of an earthquake? This book emanated from the above mentioned basic question and attempted to ascertain the stability of a free-standing system subjected to seismic excitations. Experimental and numerical studies highlighted novel findings. A new parameter known as base excitation frequency was observed to govern motion initiation of a system from the rest state in addition to the other three known parameters. Studies revealed that for the base excitation frequencies matching the system free rocking frequencies an uplift is possible at base excitation amplitudes much lower than the statically required minimum value. This highlighted a new phenomenon of frequency induced uplift/rocking in a flexible system. A clear distinction in the dynamic behaviour of the geometrically similar rigid and flexible system is presented. Various case studies on actual containment structures being used in nuclear facilities are presented in the book.