Nonlinear Beam-Based Modeling of RC Columns Including the Effect of Reinforcing-Bar Buckling and Rupture

This study presents a beam-based modeling approach for the analysis of reinforced concrete (RC) frame members under cyclic loads that can capture the effect of inelastic buckling and rupture of reinforcing steel bars. The approach uses force-based elements with a fiber-section model and a corotational formulation to account for the geometric nonlinearity effect on the response of columns. A recently proposed phenomenological uniaxial model for steel reinforcement, capable of simulating inelastic buckling and rupture due to low-cycle fatigue, is used for the reinforcing steel fibers. Numerical simulation models also account for strain penetration effects in the analyses. The modeling approach is validated with the results of experimental tests on RC columns under cyclic loads. A sensitivity study is also pursued to elucidate the impact of bar buckling and strain penetration on the analytical results.