The effect of FRP stiffness vriation on FRP debonding from concrete

In wet lay-up fiber reinforced polymer (FRP) bonded concrete members, fiber sheets are applied by hand and the cured FRPs do not have constant properties. Therefore, the behaviour of FRP bonded concrete specimens varies among specimens even the same materials are used. In this research, a mathematical method is used to predict the variation of load versus deflection responses of FRP bonded concrete specimens subjected to Mode I and Mode II loading due to the variation of FRP properties. In an effort to effectively model the variation of FRP properties, a random white noise using a one-dimensional standard Brownian motion is added to the governing equations of FRP debonding from concrete subjected to Mode I and Mode II loading, yielding a stochastic differential equation. The bounds of load vs. deflection responses with 95% probability are found for different experimental tests. The variations of FRP stiffness for these tests are also determined by a systematic method.