Shear strengthening of high-strength reinforced concrete beams using fibrous composites

Abstract

A series of seven rectangular high-strength concrete beams were tested under third-point loading to study the effectiveness of using externally applied high-strength steel fibre-reinforced concrete jackets (SFRC) as a method of strengthening shear deficient high-strength reinforced concrete beams. The overall response of the beams loaded up to failure, the onset of cracking, and crack development with increased load and ductility were described. Two types of steel fibres were used, brass-coated and hooked end with fibre content ranging from 1 to 4% and an aspect ratio of 40 and 60 respectively. The test results indicate that all beams strengthened with SFRC jackets displayed excellent shear behaviour. The ultimate shear strength of the strengthened beams was much higher (about 60%) than that of the reference beams, depending on the energy absorbed in debonding and stretching the fibres. The use of SFRC jackets transformed the mode of failure into a more ductile flexural one. A design procedure is suggested for a more accurate prediction of the shear capacity of the strengthened beams.