Material model incorporating buckling for reinforcing bars in concrete structures subjected to seismic loads

An efficient material model was developed for reinforcing steel in reinforced concrete (RC) columns that implicitly incorporates the degrading effects of bar-buckling. Utilizing the beam-on-springs model developed by the writers to characterize a buckling bar in a RC column, a comprehensive parametric study was performed to identify the effects of several important column parameters on the buckling behavior of the longitudinal reinforcement in RC columns. Features of average stress-strain curves of compressively loaded reinforcing bars are summarized. Constitutive relations as functions of critical column parameters were developed for direct use in fiber-section model-based nonlinear analysis of RC structures. Comparison of the numerically simulated global response of experimentally tested RC columns confirm the validity and utility of the proposed material model as a simple and effective way to include bar-buckling effects in inelastic analysis of RC frame structures. © 2014 American Society of Civil Engineers.