Developing a hybrid FRP-concrete composite beam.

Current materials engineering trends put forward the development of efficient structural solutions. The steel replacement with fiber-reinforced polymers (FRP) exemplifies the key to the corrosion problem. However, the relatively low deformation modulus of typical FRP materials raises the deformations of the structural components. Together with the self-weight reduction increasing the kinematic displacements, the latter issue makes developing hybrid structures comprising compression-resistant concrete and high-performance in tension FRP profiles important. Although such hybrid systems are applicable for bridge engineering, the uncertainty of the inter-component bonding properties complicates developing these innovative structures, including the design models. The typical solution focuses on the local bond improvement, e.g., employing FRP profile perforation and mechanical anchorage systems. However, this study introduces an alternative solution, using the stress-ribbon bridge structural system for creating the hybrid beam prototype, which combines the synthetic fiber-reinforced concrete slab and pultruded FRP profile fixed on the supports. This work exemplifies the structural development concept when the finite element (FE) modeling outcome defines the target reference of the design procedure. Thus, on the one hand, this innovative structure simplifies the corresponding numerical (FE) model, which assumes the perfect bond between the components of the hybrid beam system. On the other hand, the solution to the support problem (resulting from a low resistance of pultruded FRP profiles to transverse loads) improves the structural performance of the bridge prototype, doubling the structure's flexural stiffness and load-bearing capacity regarding the weak concrete supports' system. The bending tests proved the adequacy of this solution in describing the design reference for further development of the proposed structural concept.