This paper proposes a new system for constructing composite post-tensioned precast concrete girders with top slabs where the bottom part is precast, and the top part is cast in place. The experimental study consisted of testing six composite T-girders under two-point loading. The first specimen is post tensioned T-section cast monolithically and acts as a control specimen. In the other five specimens, the web and the girder flange were poured separately and then connected. The investigated variables are the shear connectors' distribution, extended girder stirrups acting as shear connectors, the top slab width, and the concrete strength of the top slabs. Available models from the literature and international code provisions are used for calculating shear transfer failure loads. Based on the obtained results, an analytical study was conducted based on the available model results. This was done to determine the most accurate correlation with the experimental results. The test results showed that using the shear connectors or full stirrups to connect the top slabs to the girders could achieve the total capacity of the monolithic girder. Using shear connectors of 10 mm diameter achieved 100% of the monolithic T-section girder, while using shear connectors of 12 mm diameter achieved 105%. Extending girder stirrups to connect the top slabs to the girders instead of using the shear connectors achieved 100% of the capacity. In addition, increasing the slab width by 50% improved the ductility of the composite T-girders and increased the capacity of the girder by 3%. Moreover, using lower concrete strength for slabs increases slippage between slabs and girders and decreases ultimate girder capacity by 15%. Comparisons between the theoretical results obtained by the available models, codes provisions, and experimental results
were made, and conclusions were drawn. The comparisons showed that the Loov’s equation is the least conservative value with the experimental results. |
