A versatile numerical model for the nonlinear analysis of squat-to-tall reinforced-concrete shear walls

Abstract

Reinforced concrete (RC) walls are extensively used to resist lateral forces in tall buildings as well as in the majority of medium to low-rise structures designed for protective purposes. In the framework of seismic performance-based design, where an adequate modeling of the lateral load versus lateral displacement relationship and a full understanding of the damage evolution are required, numerical models represent an effective tool to conduct nonlinear response analyses of such systems. For practical applications and for performing extensive nonlinear analyses, it would be desirable to have a robust yet simple numerical model that is capable of capturing the global and local characteristics of the response for different levels of damage. To this end, this paper presents a finite element-based model implemented in OpenSees [1] capable of simulating the in-plane nonlinear static and dynamic response of RC walls across a broad range of aspect ratios. The proposed model includes (i) the element technology, in which the state-of-the-art isoparametric elements are coupled with layered sections, and (ii) a novel plane-stress plastic-damage concrete material. A simple simulation-based method for determining the concrete material parameters is proposed. Model validation is conducted through a comprehensive comparison against experimental tests collected from the literature. Results show that the proposed numerical tool can be reliably used to simulate the nonlinear global and local response of RC walls spanning a broad range of aspect ratios (from 0.4 to 2.3). Moreover, model hysteresis damping is analytically analyzed to provide modelers with insight into the equivalent damping to employ when nonlinear and equivalent linear dynamic analyses are performed with the proposed model. Finally, an extensive parametric study comprising a total of 12,288 nonlinear simulations is developed to investigate the sensitivity of the numerically predicted response to changes in the concrete model parameters and gain insight into the factors that most affect the walls peak shear and dissipated energy.