Performance evaluation of a 20m-T Section bridge beam strengthened by HB-FRP

ABSTRACT The multi T-beam finite element model with an initial crack was generated based on the element and direct methods. The element method was used to evaluate the bonding performance of the fibre reinforced plastic (FRP)-to a concrete interface. On the other hand, the direct method introduced the basic theory of elastic fracture mechanics and calculated the crack tip energy release rate of the initial crack. In addition, the crack propagation risk before and after hybrid bonding FRP (HB-FRP) reinforcement was discussed. The simulation results showed that under traffic load, the bonding stress of FRP-concrete interface is very small in the absence of an initial crack, but the intermediate crack (IC) debonding is easier occurred at the flexural crack of the beam mid-span. With the function of the mechanical fastener, the interface debonding was suppressed with regard to overloading less than 4 times the design traffic load. Furthermore, it was shown that the higher the crack was, the greater the G I value was at the crack tip, which means a more unstable the crack was, and the easier it was to propagate. Also, the higher the initial crack was, the weaker the effect of HB-FRP reinforcement was in suppressing crack propagation.