Full-range Experimental Analysis of Flexural Performance of an Existing PC Hollow Slab

Abstract

Prestressed concrete (PC) hollow slab bridges are the most common type of short and medium span highway bridges in China. With the increasing load and environmental degradation factor, the flexural capacity of hollow slab bridges in service for many years can no longer meet the new safety regulations. Further research on the flexural capacity of these hollow slabs is necessary to ensure their safety. Experiments on the flexural bearing capacity of a full-scale damaged PC hollow slab are conducted. Elastic, cracking, re-cracking, and destruction tests are conducted to determine the deflection, strain, crack width, bearing capacity, stiffness, failure mechanisms, and dynamic characteristics of the slab. The strain measurements of the steel bar and prestressing tendons in the four-stage bending test indicate new failure characteristics of the PC hollow slab. After the steel bar yields, the concrete stress is redistributed, and the concrete on the top of the hollow slab exhibits tension, compression, and shear, providing science-based information to improve the ultimate bearing capacity of the slab. The cracking load (ultimate load) obtained from the full-scale bending test is 23% (72%) higher than the design value of the main slab’s internal force in normal service limit state (loading capacity limit state). The ultimate displacement in the midspan of the slab is 1/47 of the calculated span length, and the slab exhibits ductile failure characteristics, indicating very good ductility and sufficient strength of the slab after a 23-year service life. This study can provide a reference for the safety assessment and maintenance of numerous hollow slab bridges that have been in service for many years in China.