Parametric study on the behavior of short span composite bridge girders strengthened with carbon fiber reinforced polymer plates

In the last few years, extensive research has been done on the strengthening of concrete structures using fiber reinforced polymers (FRP) as externally bonded sheets or plates. A limited number of studies have also been performed on the strengthening of steel and steel–concrete composite structures. Constructing and testing steel–concrete composite beams is not only time consuming but also expensive. Following a successful experimental study by the authors on strengthening steel–concrete composite girders using carbon fiber reinforced polymer (CFRP) plates, it was desired to investigate the effect of various parameters on the behavior of strengthened composite sections. This paper presents an analytical parametric study on the behavior of steel–concrete composite beam that has been strengthened with CFRP plates. The parametric study investigated the influence of some of the important parameters on the behavior of the section through the moment–curvature relationship. Included were the effect of the concrete compressive strength, the yield strength of the steel, the stiffness of the CFRP plate, the thickness of the CFRP plate, the ultimate strain of the CFRP plate, and the steel beam bottom flange area. In addition, the effect of girder damage on the overall load distribution of a typical short span composite bridge is investigated for various load cases using the grillage method of analysis.