Effect of strand debonding on the shear strength of existing pretensioned PC hollow slab

•The debonding mechanism and failure mode of the pretensioned PC hollow slabs were analyzed.•Effects of strand slipping and pavement layer on the shear failure of pretensioned PC hollow slabs.•Crack width distribution along the height direction of the pretensioned PC hollow slabs.•The shear failure controlled by strand yielding and strand debonding was compared.•A refined model to predict the shear strength subjected to pretensioned PC hollow slabs was built.