Cracking characteristics of RC beams strengthened with FRP system

The cracking characteristics of fiber-reinforced polymer (FRP) strengthened reinforced concrete (RC) beams in both the short- and long-term is addressed in this paper. First, an empirical equation based on regression analysis of test results obtained from 36 beams was derived for the evaluation of crack widths in FRP-strengthened RC beams under short-term loading. The equation accounts for the effective concrete area in tension, steel stress, proximity of tensile longitudinal reinforcement, and primary crack height. Next, the long-term crack widths of glass FRP-strengthened RC beams under sustained loads were studied. Beams strengthened with glass FRP laminates showed improved cracking characteristics with smaller crack widths compared to conventional RC beams. Based on the investigation, two empirical equations are presented to compute the long-term crack widths in FRP-strengthened beams.