Experimental investigation of the role of reinforcement in tee strength of concrete deck slabs

In order to study systematically the role of different reinforcement in concrete deck slabs of girder bridges, a full-scale model was built of a 175 mm thick concrete deck slab on two steel girders. The 12 m long deck slab was conceptually divided into four 3 m long segments, identified as Segments A B, C and D. Segment A contained isotropic steel reinforcement in two layers, conforming to the requirements of the Ontario Highway Bridge Design Code. Segment B contained only the bottom layer of steel reinforcement. Segment C contained only bottom transverse steel bars. Segment D contained bottom transverse GFRP bars having the same axial stiffness, but 8.6 times the strength, as those of the steel bars in Segment C. Each segment of the deck slab was tested to failure under a central concentrated load All segments failed in a punching shear mode. The failure loads for the four segments were found to be 808, 792, 888 and 756 kN, respectively; these failure loads are similar in magnitude to that of a 175 mm thick steel-free deck slab with straps having nearly the same per metre length cross-sectional area as those of the bottom transverse bars in the first three segments. The tests on the four segments of the full-scale model have confirmed that (a) only the bottom transverse reinforcement influences the load carrying capacity of a reinforced concrete deck slab, and (b) the stiffness of the bottom transverse reinforcement, rather than its strength, is of paramount importance.