Continuous Composite Beams Stiffened with CFRP Sheet at the Hogging Moment Region

Abstract

The improvement in the flexural response and cracking resistance of steel-concrete composite beams stiffened with Carbon Fiber Reinforced Polymers (CFRP) sheets at the hogging moment regions is investigated experimentally and numerically in this study. The experimental program consists of two composite beams tested in an inverted position to simulate a portion of a continuous composite beam at the hogging moment region. The concrete flanges of the beams are reinforced externally with corrugated steel deck which used also as a permanent formwork. The experimental findings are used to develop and validate a reliable finite element (FE) model which able to simulate the non-linear performance of the stiffened beams as well as plain beams. In addition, a FE analysis on full-scale continuous composite beams with reinforced concrete flange is carried out to confirm the influence of using CFRP strips as a strengthening technique at the hogging moment regions. The beam deformation, steel flange strain, concrete strain, and CFRP strain confirm good agreement between the FE analysis and the test data. The beam capacity is enhanced only by 11% due to a premature failure in the composite flange. Although the composite connection between the concrete flange and the steel beam is improved by enhancing the cracking resistance of the concrete, the ductility of the strengthened beams is reduced by 20% in comparison to the un-strengthened beam.