Experimental Study on the Shear Transfer of Composite Beams with Top Layer Using Different Shear Dowels Distribution

The interfacial shear behavior of composite concrete beams is a critical factor influencing their over-all structural performance and load-carrying capacity. When an additional concrete layer is added to an existing beam for strengthening purposes, the bond and shear transfer between the two layers play a crucial role in ensuring effective composite action. The interfacial shear capacity depends on fac-tors such as surface preparation, material properties, and the presence of shear connectors. Shear connectors, including dowels, studs, or roughened surfaces, help enhance load transfer and prevent premature failure due to delamination. The distribution and spacing of these connectors significantly affect the beam’s strength and ductility. Two primary methods are commonly used to evaluate inter-facial shear strength: one based on the maximum compressive forces at mid-span and the other on peak shear flow at the beam supports. Research has shown that concentrating shear connectors near the supports can improve ductility and prevent slip at the interface. Experimental studies have been conducted to better understand the shear transfer mechanisms and optimize design approaches. These studies have led to simplified analytical models for predicting interfacial shear capacity, validated through experimental results. Proper assessment and design of interfacial shear behavior are essential to ensure the ductility and efficiency of strengthened composite concrete beams.