Experimental study of torsional strengthening on thin walled tubular reinforced concrete structures using NSM-CFRP laminates

Abstract

Although the use of near surface mounted (NSM) reinforcement for shear and flexural strengthening of reinforced concrete (RC) structures has been examined extensively in the past twenty years, its performance as torsional strengthening solution has never been assessed. This paper presents an experimental program on the use of NSM carbon fibre reinforced polymer (CFRP) laminates to enhance the torsional behaviour of RC thin walled tubular elements. Six specimens were tested as part of this work, including two reference specimens and the remaining four strengthened with different configurations of longitudinal and transverse CFRP laminates. The research shows that the addition of NSM CFRP laminates is very effective in increasing the torsional moment carrying capacity, stiffness and torsional deformability, and arresting the crack propagation, with imperceptible alteration of the geometry of the strengthened element.