The aim of this study is to investigate the reinforcing effect of externally prestressed steel strands on precast prestressed concrete T-girders and the residual load-carrying capacity after vertical cracking.The study compares the flexural test results of one full-scale precast prestressed concrete T-girder without any measures taken and one T-girder reinforced with externally prestressed steel strands.Various aspects are analyzed including experimental phenomena,deflection,strain response,residual prestress,and cracks.The results demonstrate that the reinforced test girders showed a significant 70％improvement in stiffness during conventional load testing.Furthermore,there was no notable decrease in stiffness as the load continued to increase after cracking.The bearing capacity also exhibited a significant improvement.Both steel strains and concrete strains decreased significantly.After prestressing,the cracks in the T-girders were effectively closed.The stiffness and crack resistance of unreinforced beams are slightly poor,but they still have sufficient safety reserves.This method effectively enhances the stiffness,crack resistance,and load-carrying capacity of T-girders with vertical cracks.
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