Behavior of Reinforced Concrete Beams Strengthened in Flexure using Externally Bonded Aluminum Alloy Plates

Abstract

The utilization of carbon, glass, aramid and basalt fiber reinforced polymers (FRP) in shear and flexural strengthening of reinforced concrete beams have been well established and proved its effectiveness. As externally bonded strengthening materials, FRP composites have many advantages and some disadvantages. The main disadvantage of FRP composites are that they brittle materials. Aluminum Alloy (AA) plates are ductile materials, which is a desirable characteristics for reinforced concrete (RC) beams. This study investigated the structural integrity of RC beams strengthened in flexure using externally bonded AA plates. Four beams were cast and three of them were strengthened in flexure using AA plates. The AA plate covered 90% of the beams’ span and two of the beams were anchored at both ends of the AA plates using one layer and two layers of carbon fiber reinforced polymer (CFRP) laminates. The control beam was not strengthened and was therefore used as bench mark for measuring the performance the strengthened beams with and without anchorages. The beams were tested until failure under four-point bending. Load-deflection curves and load-strain curves were plotted and the ductility indices of the tested beams were calculated. It was observed that the strengthened beams showed increase in strength up to 40.3% and in ductility up to 55% of that of the control beam. However, the failure ductility of the strengthened beams with two layers of U-wraps decreased slightly, by 5% of that of the control beam. It can be concluded that AA plates could be used as strengthening materials to enhance the flexural performance of RC beams. In addition, the use of U-wrap CFRP anchorages influenced the types of failure modes of the tested beams.