Assessment of Seismic Response Reduction Factor for RC Shaft Supported Tank
- Vol.102(1), March
- New York Springer 2021
- 75-90p.
The force-based design method as suggested by the major international seismic codes considers the nonlinear behavior through response reduction factor, R, in an indirect way. To obtain the design base shear, the elastic base shear demand is divided by the R factor, assuming adequate ductility and good post-yield behavior of the structural elements. This study aims at the evaluation of values of R factor of elevated water tanks supported on reinforced concrete shaft. A total of 21 shaft supported elevated RC tanks of different heights and sizes are analyzed using pushover analysis to obtain the R values. These water tanks were designed using relevant Indian standards. The computed values of R factor are compared with those suggested by the Indian design code. The influence of various important parameters like time period, staging height, and height to diameter ratio on the strength factor, ductility factor, and response reduction factors is also investigated. The results of the study show that the tank height, tank size, and height to diameter ratio of shaft have a considerable effect on the values of R factor of shaft supported elevated tanks. Therefore, it is suggested not to use the similar value of the R factor for all shaft supported tanks irrespective of their height and size.