Rebar Anchorage Slip Macromodel Considering Bond Stress Distribution: Monotonic Loading and Model Application

Abstract

This study presents a modified macromodel for calculating the anchorage slip of rebar under monotonic loading and its application to the fiber beam–column element model. The proposed macromodel reflects bond stress distribution along rebar and hence captures slip responses over the entire rebar stress range. The anchorage slip problem is formulated using three governing equations among four bond fields, namely, bond stress, rebar stress and strain, and slip. The general framework for macromodels with a given bond stress distribution and micromodels with a given bond–slip relationship is established. Then, the proposed macromodel is developed using a refined bond stress distribution function, which is established by solving a validated micromodel. Available experimental results are used to calibrate the bond stress parameter and to investigate the validity of the proposed model. Comparisons indicate considerably improved accuracy of the proposed macromodel over the conventional macromodel for capturing stress-slip relationships and bond field distributions. Finally, the proposed macromodel is implemented into a conventional fiber beam–column model. The modified fiber model is applied to simulate a bridge column shake-table test, and shows success in capturing anchorage slip contributions. Therefore, the model is validated for both slip responses and model applications.