Sensitivity to Constitutive Modeling in Fiber-Based Discretization of Reinforced Concrete Members for Performance-Based Seismic Evaluation

Accurate constitutive models of the constituent materials in a reinforced concrete (RC) section, namely, unconfined concrete, confined concrete and reinforcing steel are necessary in fiber-based discretization of RC components for use in nonlinear analysis of RC structures. This paper examines the sensitivity to different constitutive models in predicting the inelastic seismic behavior of RC frame structures. In particular, the importance of incorporating confinement effects in modeling concrete behavior and including degrading effects in modeling the behavior of reinforcing steel bars so as to predict the monotonic, cyclic and seismic response of RC columns and frames is investigated. At the component level, it is shown that the inelastic response is controlled predominantly by the behavior of reinforcing steel. At the system level, the response of non-ductile structures is less sensitive to confined concrete models while the modeling of reinforcing steel is shown to influence the inelastic response of both non-ductile and ductile structures.