Flexural–shear deformation theory (FSDT) for modeling of mechanical responses of RC beams strengthened in shear with ETS-FRP bars

Abstract

The flexural–shear deformation theory (FSDT) approach for simulating the shear behavior of reinforced concrete (RC) beams strengthened in shear with embedded-through section fiber-reinforced polymer (ETS-FRP) bars is developed in this study. The key feature of the FSDT approach is to mix both flexural and shear deformation parameters constituted in the beam into an algorithm, which is able to simplify the analysis and shorten the computation time. Most of the formulations adopted in the model are built on the basis of mechanics by applying a few common theories involved in stress and strain fields. Particularly, to couple the participation of the ETS-FRP strengthening system into the developed FSDT, the newly developed bonding-based mechanism between the ETS-FRP bar and concrete is used. The calculation outcome produces the vertical strain (εv), which is the main parameter used to determine the resistance of shear reinforcement. The shear contribution of concrete is derived via the concrete principal tensile strain (ε1). Then, the minimized discrepancy between shear forces induced by flexural (VT) and shear actions (Vtotal) is the condition for termination of the calculation. Through the broad corroboration of the developed model to the experimental data with respect to structural responses, excellent agreement and high accuracy are found. To offer prospects for the design practice of ETS-strengthened beams, a parametric study on the effects of important design variables is implemented against the results assessed by a guideline released by the American Concrete Institute (ACI). Consequently, the proposed FSDT approach provides more insight into the responses of ETS-strengthened beams than the ACI guideline, which is helpful for practitioners.