Experimental study on the flexural resistance of existing prestressed hollow-core slab beams

With increasing service life and highway loading, the load-carrying capacity of hollow-core slab bridges built more than a decade ago is barely sufficient to meet the requirements of safe use, making it necessary to conduct further studies on the flexural performance of old PC hollow-core slabs that have been in service for an extended period. This study presented the findings from testing two 14.2 m prestressed concrete hollow-core slab girders that have been in service on highway bridges for over 20 years. Testing involved using a large structural test loading system to evaluate its bending properties, damage modes, and ultimate load-bearing capacity. Additionally, the crack development diagrams, load-span displacement curves, and load-concrete span strain curves of the experimental girders were derived and analysed. The results indicated that the old PC hollow-core slab experienced shear brittle damage and compression shear damage, following flexural testing. Moreover, each cross-section of the beam approximately adhered to the assumption of a flat section. Throughout all stages of loading, the girders exhibited bending characteristics typical of concrete beams, and the utilization of a 3D digital scattering strain measurement and analysis system effectively compensated for the limitations associated with traditional displacement measurement devices.