Experimental study on the bond capacity of RC beams incorporating concrete strength, corrosion and loading rate

In this study, 26 beam specimens were subjected to flexural loading to discuss the effects of cylinder concrete compressive strength (28 MPa, 37 MPa and 43 MPa), tensile reinforcement corrosion (mass loss rates of 2.1% to 10.3%), stirrups corrosion (mass loss rates of 11.2% to 26.3%), and loading rate (0.5 – 300 mm/min) on bond capacities. The following results are shown: (1) the increase of concrete strength could increase the bond strength, but results in the bond stress decreasing more rapidly after bond failure; (2) the existence of stirrups could not significantly improve the bond strength in a corrosive environment, since a wide transverse crack width (e.g., greater than 1.0 mm) on concrete would be induced by their severe corrosion; (3) the increases of loading rate lead to about 34.8% increases in the bond strength while decrease the peak slip; (4) a simplified model for the bond stress-slip curve, incorporating the concrete strength, tensile reinforcement corrosion, stirrups corrosion and loading rate, is proposed and validated.