EXPERIMENTAL RESEARCH ON FATIGUE PROPERTIES OF CONCRETE STRUCTURE STRENGTHENED WITH CFRP SHEETS

The method of the torsional low cycle fatigue experiment is first put forward in this paper, and the fatigue properties of the bonding at the interface of CFRP and concrete are studied using the proposed method. According to elasticity theory, it is found that the formula to calculate the bonding stress at flexion state is identical to that at shearing state. Therefore, the torsional low cycle fatigue experiment is more efficient and precise than the flexural fatigue experiment to study the fatigue properties of the bonding. Experiment results show that the fatigue bonding strength at the interface of CFRP and concrete is 64% of the static bonding strength in the condition of R=0.2. This reduction need to be paid more attention in the design of concrete structures strengthened with CFRP sheets. A safety factor of the fatigue strength at the interface of CFRP and concrete should be applied in design.