Development of sustainable concrete bridge deck slab systems using corrosion-resistant GRFP bars
thesisposted on 08.06.2021, 09:28 by Imad E. Khalafalla
This research investigates the use of glass fiber reinforced polymer (GFRP) bars to reinforce the bridge deck slabs as well as jointed precast bridge deck slab in prefabricated bulb-tee pre-tensioned bridge girders. The experimental program included two phases. In phase (I), six precast slab joint details between flanges of precast bulb-tee girders were developed incorporating GFRP bars with straight ends, L-shaped ends and headed ends, embedded in a closure strip filled with non-shrink cement grout or ultra-high-performance concrete (UHPC). A total of 11 actual-size specimens representing the one-way slab system with the proposed joint details, in addition to 5 cast-in-place control specimens, were built and tested to failure to examine the structural adequacy of the proposed joint details. Based on the results from Phase (I), the best joint was selected for further tests in Phase (II) to examine its fatigue life and ultimate load carrying capacity under vehicular wheel loading. A total of 8 actual-size, GFRP-reinforced, 3500 X 2500 X 200 mm concrete deck slabs were designed for this purpose according to CHBDC specifications. Ultimate strength, fatigue behavior and fatigue life of the GFRP-reinforced deck slabs were investigated using different schemes of fatigue loading, namely: accelerated variable amplitude fatigue loading and constant amplitude fatigue loading. Overall, the experimental results indicated that GFRP-reinforced deck slabs showed high fatigue performance. A new prediction model for fatigue life of the GRFP-reinforced deck slabs was developed. The failure mode of the tested composite slabs was punching shear. Correlation between the experimental findings and the prediction models for punching shear resistance available in the literature showed that the prediction models by CSA S806-12 (2012) and El-Gamal et al. (2005) can accurately predict the punching shear capacity of the cast-in-place and precast jointed bridge deck slabs reinforced with GFRP bars. In addition, the average observed mid-depth punching shear perimeter for the cast-in-place deck slabs and the precast jointed deck slabs were measured to be 1.25 d and 1.33d away from the sides of the loaded area, respectively, which are more than twice the corresponding distance specified in ACI 440.1R-06 and CSA S806-12 for calculating the critical punching shear perimeter.