Parametric study of carbon fiber reinforced polymer laminates geometry on the mechanical behavior of strengthened reinforced concrete beams under standard four-point bending test

This article presents the results of an experimental parametric study on reinforced concrete (RC) beams strengthened by an external bonding of carbon fiber reinforced polymer (CFRP) laminates to their tensile faces. This experimental work investigates the effects of both CFRP laminate sizes and concrete compressive strength on the flexural behavior of strengthened RC beams. Accordingly, a total of 10 RC beams have been cast, eight of which were strengthened in flexure by external bonding of CFRP laminate by varying its sizes, such as length, width, and thickness, and two control beams. All prepared beams were tested under standard four-point bending until failure. The load-deflection response curves and failure modes were recorded and compared. Results show that failure modes of strengthened beams varied with the CFRP laminate characteristics from steel yielding, CFRP peeling off, and interfacial debonding laminate, Also, the load-deflection curves showed a considerable increase in the load capacity by up to 1% and 112%, compared to the unstrengthen beam, if the CFRP laminate length ratio passes from 0.40 to 0.94, respectively. In addition, the load capacity contribution increases from 56% to 112% when the CFRP laminate width increases from 50 to 100 mm. On the other hand, when laminate thickness increases from 1.2 to 2.4 mm, the load capacity contribution increases from 56% to 76%. Finally, it is concluded that the mechanical behavior of strengthened beam is strongly affected by the CFRP laminate sizes.