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

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.