Experimental and Finite Element Study on the Shear Performance of Existing Super-Span Concrete T-Beams Retrofitted with Glass Fiber-Reinforced Plastic

Super-span, reinforced concrete, T-shaped cross-section beams (T-beams) with a service life of more than 30 years are widely used in highway bridges in China. Most of these beams have been retrofitted with glass fiber-reinforced plastic (GFRP) to prevent performance degradation. However, the actual shear performance, ultimate state, and failure mechanism of the existing retrofitted super-span concrete T-beams are currently unclear for many inextricable problems. To fill these gaps, in this study, one super-span concrete T-beam, in service for 31 years and retrofitted with GFRP, was extracted from a highway bridge to conduct shear experimentation in a structural laboratory. To assess the particularity of the specimen, finite element analysis was also conducted using ABAQUS software as a supplement to the shear tests. The failure procedure of the specimen was investigated, and the influence of the loading mode on the shear performance of a super-long and old T-beam was also studied. It is concluded that the failure of the super-span T-beam begins with small cracks at the bottom of the mid-span, rather than a loading point.