Evaluation of Response Modification Factor for R.C. Elevated Water Tanks Subjected to Seismic Loads

Abstract

Reinforced concrete elevated water tanks have been considered as a major element of the water distribution networks. The seismic design loads for this construction, like other structural systems, are based on the concept of permeating plastic deformations during earthquakes to minimize the design elastic force, which is determined by the structure's ability to dissipate induced seismic energy. The values of the R Factors adopted in the most national and international codes dose not distinguish between several factors like the seismic zones, the vertical and horizontal configuration of framed supporting elements, the response spectrum function type. Thus, the necessity of enhancing the seismic resistance capacity of the elevated tanks is put forward.

This work gives a thorough investigation into the estimation of the Response Modification Factor (R) for raised liquid and water tanks made of reinforced concrete. Developed in accordance with Egyptian load code ECP-201 (2012). Firstly. A verification application of the algorithm of nonlinear pushover analysis is made to compare the outcomes of the application with previously published case study. Then, a comprehensive parametric study is performed on two configurations of R.C. Elevated tanks, considering the variation of the tank height, the seismic zones, the tank capacity, the response spectrum function type comprise 108 case study. The obtained results which is higher than the adopted conservative values in the different codes enhance the understanding of the factors affecting the R factor.

KEYWORDS: Response Reduction Factor (R); Pushover analysis; Nonlinear static analysis;