Flexural Strengthening of RC Continuous T-Beams Using CFRP

Abstract

In this paper, experimental investigations for strengthening reinforced concrete (RC) continuous beams were performed. Eighteen T-beams were cast, twelve of which were inverted T-beams where the flange portion of the T-beam was subjected to positive flexure to represent the support region of a continuous beam. Six of the T-beams were non-inverted where the web is subjected to positive flexure. Carbon fiber reinforced polymer (CFRP) sheets with different widths were considered, and different strengthening configurations with the same area of CFRP were investigated. The use of one-layer, multiple layers, or multiple strips of CFRP were evaluated to investigate the effect of these configurations on the ultimate capacity and ductility of the strengthened beams. From the experimental observation of the non-inverted beams, it was found that the ultimate load capacities of the CFRP-strengthened beams were enhanced by 4% to 90% compared to the control beam. Using multiple layers of CFRP sheets enhanced the stiffness of the beams by 4% to 46%, depending on the CFRP area and configurations. The debonding of CFRP before the ultimate failure provided additional ductility to the tested beams. For the strengthening of the inverted beams, it was found that the addition of CFRP strips did not increase the strength of the beams when the width of CFRP to beam width ratio was less than 0.25, but the ductility of the beam was enhanced slightly. The use of multiple strips was found to be a more effective way for the strengthening of the negative moment region than using multiple layers. This can also provide more desirable modes of failure than when applying CFRP in multiple layers. Ductility was found to be lower if multiple layers were used compared to other configurations. Moreover, it was observed that as the compressive strength of concrete increased the addition of the CFRP improved the beams ductility.

Investigation of CFRP Reinforcement Ratio on the Flexural Capacity and Failure Mode of Plain Concrete Prisms

“…The strengthening of structural members to enhance their capacity and service life using FRP has been proven to be an effective technique. There are many different types of FRP and strengthening methods available, but strengthening structures via the use of externally bonded FRP has become very popular worldwide [ 26 , 27 , 28 , 29 , 30 ].…”

Repairing of reinforced concrete continuous beams by CFRP sheets

“…As well as, the dominant failure mode in the strengthened beam with nonprestressed FRP materials was debonding interfacial, but in the beam that was strengthened by prestressed FRP materials was tensile rupture of the CFRP sheet. Al-Khafaji and Salim [11] proved that as the ratio of the width of CFRP to the width of concrete increased, the ultimate load and stiffness for continuous Tbeams strengthened with CFRP enhanced. Strengthening by CFRP for preloading 100% and 90% beams can be enhanced the load capacity by 51.5% and 68.5% respectively [12].…”

Experiments on shear behavior of reinforced concrete continuous beams strengthened by C‐FRCM

“…[2][3][4][5][6][7][8] A typical FRP material used for retrofitting is carbon fiber-reinforced polymer (CFRP). Some existing experimental studies [9][10][11][12][13] have indicated that CFRP offered great performance in the improvement of the mechanical behavior of RC structures.…”