Prediction of IC debonding failure of precracked FRP strengthened RC beams using global energy balance

Abstract

Reinforced concrete (RC) beams strengthened with fiber reinforced polymer (FRP) have been extensively investigated, but the failure load of precracked beams strengthened with FRP has not been fully studied yet. When structurally deficient RC beams are repaired or strengthened using FRP, flexural cracks due to service load usually appear on the beams. Strengthened beams with precracking have been rarely examined, and most existing methods for predicting premature failures ignore the precracking effect. This research proposes a method for predicting debonding failure induced by intermediate crack (IC) for FRP-strengthened beams with precracking. The method consists of a numerical study on structurally damaged RC beams retrofitted with FRP laminate in the tension side of the beam. The method also applies the global energy balance approach in combination with fracture mechanics criteria to predict failure load for complicated IC-induced failure. The simulated results are validated against published experimental data and show good correlation.