Effect of Supporting Soil on the Seismic Response of Elevated Water Tanks under Different Excitations

Elevated water tanks are generally used to provide a high fluid pressure before distribution through pipe network. This may be the most economic mean to control the water distribution to different locations with the needed pressure. During earthquakes, the elevated water tanks have a very important role because the contained water can be used to resist fires which generally occur after earthquakes. Small numbers of researches have been done on the seismic behavior of this type of structures compared to the importance of the problem. The important factors that influence the seismic behavior of such structures are the dynamic properties of the tank itself, the structure-soil system and the excitation time history. Soil type and different excitations time histories are the governing factors in this study. A three dimensional model is constructed to analyze the problem. Time History analysis has been performed using the method of finite elements. In the analysis, the tank material is assumed to be reinforced concrete. The Mohr-Coulomb model has been used to describe the behavior of the soil model. Kobe, Northridge and El-Centro Earthquake records are used in this study as the bedrock Excitation. The study focuses on the horizontal and vertical displacements of the tank. The results show the effect of different types of supporting soil and different excitations on the seismic response of the tank.