Experimental Study on Cracks of CFRP Reinforced Prestressed Concrete Beams

Abstract

Abstract Ten prestressed concrete beams were designed and manufactured, which were preloaded with 40% and 60% ultimate load to crack. Then the beams were reinforced by CFRP and immersed in chloride condition for 120 days. After that, a four-point bending test was performed. Based on the statistics and fractal theories, the cracking mechanism, distribution and shapes of cracks in mid span were researched, considering the initial cracks, CFRP reinforcement and chloride corrosion. The test results demonstrate that CFRP has a restraining effect on the cracks, and the effect decreases with the increases of heights. The crack widths conform to normal distribution, and the dispersion coefficient, average widths and characteristic widths decrease with the increase of the heights, and the three parameters of CFRP reinforced beams at the same heights are all smaller than those of unreinforced beams. The fractal dimensions of cracks in unreinforced beams and CFRP reinforced beams increase linearly and exponentially with load steps, respectively. CFRP reinforcement and Chloride corrosion makes the fractal dimension increase, respectively. The corrosion effect of chloride can be weakened by CFRP. Therefore, the fractal dimensions of beam cracks can be used to evaluate the damage caused by several coupled load conditions.