Finite element modeling of reinforced concrete beams externally strengthened in flexure with side-bonded FRP laminates

Abstract

Reinforced concrete (RC) beams are often strengthened through externally bonded (EB) fiber-reinforced polymer (FRP) systems. In such applications, improving the bending capacity of RC beams is of main interest and which is achieved via bonding EB-FRP systems to the soffit of beams. Access to soffit of beams can be restricted by existing structural members or limited (in case a RC beam span over neighboring compartments). In those scenarios, RC beams can still potentially be strengthened in flexure through longitudinal bonding of EB-FRP systems to the sides of beam's web. This paper examines critical parameters that influence the effectiveness of side bonded EB-FRP systems through a newly developed finite element (FE) model. This model utilizes state-of-art simulation techniques and is capable to trace the flexural behavior of RC beams externally strengthened with side-boned FRP laminates throughout all loading stages till failure. The model was validated by comparing with experimental data and the predicted and measured results were in good agreement. The validated model was then utilized to study the effect of concrete compressive strength, FRP material type, FRP size, and steel reinforcement ratio on the behavior of strengthened RC beams. Outcomes of this numerical investigation show the effectiveness of side-bonding FRP systems as an alternative to conventional soffit strengthening systems to improve the flexural capacity of RC beams.