Experimental Work to Study the Strengthening Effect of SFR and CFRP on a Part or Whole of the Length of Slender RC Columns

This paper is focussed on the investigation of the strengthened column by steel-fibre-reinforced (SFR) and carbon fibre-reinforced polymer (CFRP) on a part or a whole of the length of the column under axial force, and to obtain the effective length, which is responsible for the increasing of the ability of the column to resist buckling. Seven samples were designed as slender reinforced columns with dimensions of 2000 mm length and cross-sections of 120 mm x 60 mm. It was shown that the strengthening of the middle half of the column length by SFR gave an ultimate load similar to the strengthening of the whole column with same material. Also, it was found that the column strengthened by SFR increased its ultimate load by 42.6 %, 42.1 % and 33.3 % for strengthened lengths of dimensions L, L/2 and L/3, respectively, compared to the non-strengthened column. The increase in ultimate load that could be borne by the column strengthened by CFRP were 53.0 % and 33.8 % for strengthened lengths of L and L/2, respectively, only. Interaction diagram had been depended as a theoretical analysis for slender concrete columns. The interaction diagram for the column strengthened by CFRP is greater than for the column strengthened by SFR, which in turn is greater than the non-strengthened column.