Bond Stress–Slip Relationship between FRP Sheet and Concrete under Cyclic Load

Fifty-four bond specimens were subjected to cyclic bond tests to obtain the bond stress–slip relationships between the fiber reinforced polymer (FRP) sheets and concrete. The specimens were prepared in accordance with Japan Concrete Institute recommendations (in 1998). The tests were conducted using three experimental variables: (1) type of FRP (aramid, carbon, and polyacetal); (2) sheet layers (single layered and double layered); and (3) loading hysteresis. The bond stress–slip model was developed on a Popovics base envelope and consisted of seven empirical parameters: The maximum bond stress ${\tau }_{\max }$ , the corresponding slip $s_{\max }$ , the curve characteristic constant $a$ , the unloading stiffness $K$ , the ultimate slip $s_u$ , the friction stress ${\tau }_{\mathrm{fp}}$ , and negative friction stress ${\tau }_{\mathrm{fn}}$ . Numerical analyses using the model compared well overall to the experimental cyclic responses of the specimens.