Fiber model for reinforced concrete walls

Abstract

Due to the taller reinforced concrete (RC) buildings that have been constructed in recent years, shear walls at lower levels are subjected to higher axial loads and bending moments. Although complex finite element inelastic models for shear walls can effectively couple several effects at the stress-strain level, they are computationally demanding, and hence robust and computationally efficient models are necessary to quickly assess the earthquake performance of these buildings. Herein, a pure two-node fiber element model that takes into account axial and bending components only, was modified to produce objective results under common loading conditions of the walls identified in Chilean buildings, i.e., high axial loads with linear bending moment variation between floors. A regularization is required to predict results independent of the element size and a shear model based on the modified compression field theory was added into this element to simulate the behavior of shear walls adequately. This investigation focuses in the formulation of the proposed model, its validation with experimental tests reported in the literature, and its application to actual RC walls of buildings. It was found that the steel stress-strain constitutive behavior, the inclusion of shear deformation, and the strain penetration effects played an important role in reproducing the experimental behavior of walls. Additionally, the proposed model is able to predict the observed collapse mechanisms of walls in buildings damaged during the 2010 earthquake. Since the element is capable of reproducing experimental tests and earthquake response, and since it is numerically more efficient than other approaches, its use for complete 3D inelastic dynamic analysis of buildings is promising.