Experimental and Theoretical Investigations on the Bond–Slip Behavior of Newly Poured Concrete and Reinforcement Bars Under Traffic-Induced Vibrations in Bridge Widening

This study investigates the bond–slip behavior of newly poured concrete and reinforcement bars under traffic-induced vibrations in bridge widening. Center pull-out tests were conducted on C60 concrete specimens with HTRB400 steel bars to examine the effects of bar diameter, vibration frequency, amplitude, and anchorage length. Based on the experimental data, the bond–slip constitutive model of newly poured concrete-reinforcement bars was developed. Test results indicated that larger bar diameters reduced ultimate bond stress and relative slip. Specimens with 8 d (d is the diameter of reinforcement bar) anchorage length exhibited lower bond strength than those with 5 d. Vibration amplitude had minimal influence on bond behavior, while higher frequencies decreased bond stress but increased slip. The constitutive model can provide a reliable prediction of bond behavior under dynamic disturbances. The findings offer practical insights for bridge widening projects, ensuring structural integrity under traffic loads.