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

Abstract– Deficiencies of RC structures can be overcome by strengthening/retrofitting using different strengthening methodologies. This paper emphasises the effectiveness of externally applied U-shaped CFRP anchorages/strips on the performance of RC beams of relatively low compressive strengths (approximately 21 MPa). Three types of the beams were cast based on the shear reinforcement detailed as containing “no shear reinforcement”, “minimum shear reinforcement” and “adequate shear reinforcements” as suggested in ACI 318-08. All beams were provided adequate flexural reinforcement as recommended by ACI 318 to fail the beams in flexure. U-shaped CFRP anchorages and strips were bonded to the beams in the predominant shear and 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 anchorage alone and in combination with CFRP strips) as well as the effect of U-shaped CFRP anchorages applied over full and partial applied beam depth was also the parameter of investigation in the current study. Results showed that externally bonded U-shaped anchorages applied along the beam span and at the ends together with CFRP strips improved the deformability, strength and performance of RC beams by transforming failure manner from brittle to ductile. Moreover, use of partial depth anchorage is beneficial to attain higher load in comparison to the full depth anchorages, particularly anchorage height equal to 3/4 of the beam depth is found to be most suitable. Keywords–