Modified Reinforced Concrete Plane Stress Element Formulation for the Nonlinear Response of Seismic Resisting Systems

Abstract

Design of economic seismic resisting structural systems with an acceptable safety margin requires continuous improvements for the available numerical models and analysis tools. In this work, an improved reinforced concrete membrane element based on the modified compression filed theory (MCFT) is presented. The developed element is implemented into a developed finite element program in order to study seismic response of different types of seismic resisting systems which are commonly used in the construction of concrete buildings in Egypt. Two types of floor systems, (beamed/beamless floors) and two types of seismic resisting systems, (frames/coupled frames with shear walls), are investigated. Reinforced concrete flexibility-based beam column and plane stress elements were used to model frames and shear walls, respectively. The static response of these systems subjected to triangular load pattern was investigated through nonlinear static analysis. It was concluded that, the predicted force reduction factor based on nonlinear static analysis of the examined systems is 50% to 75% less than those provided by Egyptian code; such variation could lead to uneconomic or inadequate design.