Seismic response of reinforced concrete elevated water towers.

Modern composite elevated storage tanks were developed in late 1970's in response to increasing demand for a reliable, economical and low-maintenance water storage system in Canada and the U.S. The popularity of composite elevated water towers rose tremendously in the last 30 years, as the new type of construction offered many advantages over traditional elevated water storage tanks. Despite the increasing rate of construction, the performance of this type of structure under ground motions is not fully understood. During the recent earthquake of Bhuj 2001, many shaft staging elevated water towers experienced severe damages, signifying the lack of considerable ductility, redundancy and energy dissipation in the system. This thesis investigates the current approach to the design of shaft staging elevated towers, and also summarizes a comprehensive literature review of structural theories, latest research and studies. The response of a selected concrete shaft staging elevated tower, designed according to the currant [sic] practice and subjected to gradually increasing lateral load was investigated through a non-linear static finite element analysis. Additionally, the seismic performance of the structure during four different ground motions with various peak ground accelerations was studied through several time-history non-linear finite element analyses. The results of static and dynamic finite element analyses were used to evaluate and establish the response modification factor used for design of these types of structures.