FLEXURAL STRENGTHENING OF RC BEAMS USING ACI 440.2R-08: DESIGN AIDS

摘要

The aim of this research is to develop a non-iterative design aid for flexural strengthening of RC beams using FRP based on the current iterative ACI 440.2R-08 design procedure. The ACI 440 design procedure is iterative due to the existence of two major sectional tensile forces in the steel and FRP materials as well as the likelihood of different failure modes. Two unique straight line functions were determined to obtain the neutral axis depth and FRP ratio for all material and design parameters. These relationships are indirectly related to the strain in the concrete and FRP materials at failure as well as the thickness of the FRP. By using these two straight line relationships the FRP area needed can be directly calculated. The FRP area calculated using the design aid has been shown to correlate very accurately to the exact area determined iteratively according to the ACI 440 document. This is also shown to be a very quick and accurate initial estimate for the ACI 440 procedure. A design example is solved to illustrate the potential of this design aid in expediting the design process.