PERFORMANCE OF RC BEAMS STRENGTHENED FOR SHEAR AND FLEXURE USING DIFFERENT SCHEMES OF U-SHAPED CFRP ANCHORAGES AND/OR STRIPS

Abstract

Deficiencies of RC structures can be overcome by strengthening/retrofitting usingdifferent strengthening methodologies. This paper emphasises the effectiveness of externallyapplied U-shaped CFRP anchorages/strips on the performance of RC beams of relatively lowcompressive strengths (approximately 21 MPa). Three types of the beams were cast based on theshear reinforcement detailed as containing “no shear reinforcement", “minimum shearreinforcement" and “adequate shear reinforcements" as suggested in ACI 318-08. All beams wereprovided adequate flexural reinforcement as recommended by ACI 318 to fail the beams inflexure. U-shaped CFRP anchorages and strips were bonded to the beams in the predominant shearand flexural loading regions and tested under four-point bending condition by varying shear spanto-depth ratio (a/d) as 2.46 and 3.38. Different strengthening schemes (including CFRP anchoragealone and in combination with CFRP strips) as well as the effect of U-shaped CFRP anchoragesapplied over full and partial applied beam depth was also the parameter of investigation in thecurrent study. Results showed that externally bonded U-shaped anchorages applied along the beamspan and at the ends together with CFRP strips improved the deformability, strength andperformance of RC beams by transforming failure manner from brittle to ductile. Moreover, use ofpartial depth anchorage is beneficial to attain higher load in comparison to the full depthanchorages, particularly anchorage height equal to 3/4 of the beam depth is found to be mostsuitable.