Seismic response factors of reinforced concrete pedestal in elevated water tanks

Abstract

Reinforced concrete (RC) elevated water tanks are critical structures that are expected to remain functional after severe earthquakes in order to serve the water system networks. Despite this significant role, the number of research studies which investigated the nonlinear seismic response of RC pedestals in elevated water tanks is very limited. In the current codes and standards, the seismic response factors are mainly based on engineering judgement. In this paper, a systematic approach is employed to establish the seismic response factors for a wide range of elevate water tank sizes and RC pedestal dimensions commonly built in industry. In total, forty-eight model configurations (prototypes) are selected and designed based on current codes and standards. The finite element (FE) method is then used for nonlinear static (pushover) analysis of the prototypes. The pushover curve of each prototype is developed and the seismic response factors are determined accordingly. The effect of various parameters such as fundamental period, height to diameter ratio, seismic design category, and tank size on the seismic response factors of elevated water tanks is evaluated. Furthermore, the cracking propagation pattern in RC pedestal is studied. The result of the study shows that the tank size is a critical parameter affecting the seismic response of elevated water tanks. It is recommended not to use the same seismic response factors for all RC elevated water tanks regardless of the tank size. In addition, two different patterns of cracking depending on the height to diameter ratio of the pedestal are detected and discussed.