Overweight trucks are common on the highways in China, which presents fatigue damage problem for the reinforced concrete (RC) bridges. Externally bonding CFRP sheets is increasingly being used to repair the damaged bridges. The degradation of adhesive bonding in a wet-dry environment, however, may have a significant adverse effect on the long term durability of the repaired bridges. This paper presents an experimental study on the flexural capacity of damaged RC T-beams strengthened with CFRP sheets subjected to the wet-dry cycles. A total of 19 specimens in 8 series were tested. The specimens were damaged by constant fatigue loading which were equivalent to the repetitive loadings caused by the overweight trucks across a bridge in one year. The specimens subjected to wet-dry environment were exposed to a period of 3 months or 6 months. A wet-dry cycle was 24 h including a wet cycle (salt water) of 10 h and a dry cycle (hot air at 40 ℃) of 14 h. The experimental results showed that a slight reduction in stiffness was observed for the strengthened beams due to overloading damage or wet-dry exposure. The residual deflection and cracks caused by overloading damage reduced the effect of CFRP strengthening. The wet-dry cycles induced degradation to bond at the concrete/FRP interface. Only in the first 3 months, however, the wet-dry environmental exposure can obvious reduce the strength of the retrofitted beams.
展开▼
