RESEARCH ON THE CONSTITUTIVE MODEL OF STEEL BAR CONSIDERING SLIPPAGE EFFECT IN CONCRETE STRUCTURE

To study the rebar slippage effects in reinforced concrete (RC) structures, the steel stress-slip relationship is derived by simplifying the distribution of the bond stress. Based on the existing pull-out test results, the derived steel stress-slip relationship is verified. The model of the plastic hinge length is introduced, and the slippage effects considering steel stress-strain theoretical relationship is established. The influence of the concrete strength, diameter of steel bar, and plastic hinge length on this relationship is analyzed and a simplified constitutive model of steel bar considering slippage effect is proposed. Based on the finite element platform OpenSEES, the fiber beam-column model implemented by the proposed model proved to be accurate and reliable by comparison with the existing experimental results, the fiber model without considering rebar slippage deformation, and the zero-length fiber model. The application scope of the proposed model is further discussed. The results show that the lateral load-displacement response of the RC column can be exactly calculated by the fiber model based on the proposed model; while the column additional lateral displacement caused by rebar slippage deformation can be well predicted.