Modeling and Nonlinear Seismic Simulation of Shear Walls in Multistory Reinforced Concrete Buildings

The seismic behavior of reinforced concrete shear walls in Chile generally demonstrated adequate performance as seen from the response of most Chilean multistory shear-wall reinforced concrete buildings after the 1985 and 2010 earthquakes. While shear walls are widely used in building construction, models for simulating the nonlinear response of shear walls have seen limited advances. The need to accurately model shear wall behavior is becoming more important as increased confidence in the seismic behavior of RC walls has led to more relaxed requirements for reinforcement and confinement of typical wall configurations. For example, walls built prior to the 1985 earthquake in Chile were based more on traditional practice and were not necessarily enforced by seismic codes. The majority of post-1985 construction was based on ACI-318 guidelines with relaxed provisions for the confinement of the walls. The changes in the structural configurations and reinforcement details of post-1985 shear-walls in Chile resulted in different behavior and observed damage compared to the pre-1985 walls. In this study, typical Chilean walls are modeled and analyzed so to evaluate the effectiveness of a wall macro-model developed to reproduce the observed behavior of those walls during the 2010 Chilean earthquake. Due to its simplicity and lower computational cost, a multi spring macro-model is used for the simulation. Since the modeling of an entire building presents numerous modeling and computational challenges, a 2D section of the building is modeled using OpenSEES. The calibration of the 2D section model is performed through comparison of the dynamic properties with a 3D elastic model of the entire building developed in SAP2000. The macro-model development includes recommendations for modeling shear behavior of selected structural walls. The research also provides guidelines for calibrating the spring properties of the macro-element as a function of the slenderness ratio of the wall, and the wall web reinforcement ratio. Findings from the study will be useful in advancing nonlinear simulation models for analysis of shear wall structures.