Investigation of the flange splitting stresses in composite bridge beams

The existence of tensile splitting stresses in the compression flange of concrete T-beams is well established. Experimental tests have shown that these stresses can cause longitudinal cracking in the concrete slab at the intersection between the flange and the web which leads to premature failure of the beam. Consequently, design codes include requirements for transverse reinforcement in the compression flanges to prevent this failure mode. To date, experimental and analytical work has been performed on isolated T-beams with little research being performed on multi-girder systems. This paper presents the results of a finite element analysis investigation of tensile splitting stresses in a five girder bridge under several load cases. The Waterloo Creek Bridge, which is constructed with a steel-free concrete bridge deck, is used as a case study. The study shows that the splitting stresses reduce in magnitude from the exterior cantilever section of the slab to the interior panels of the bridge due to the confining effect of adjacent girders. The analysis also shows that the lateral restraint straps used in a steel-free bridge deck system reduce the magnitude of stresses in the concrete.