On the Shear Behaviour of Concrete Beams Reinforced by Carbon Fibre-Reinforced Polymer Bars: An Experimental Investigation by Means of Acoustic Emission Technique

摘要

This paper reports test results of 20 concrete beams reinforced by carbon fibre-reinforced polymer (CFRP) bars, without any shear reinforcement, subjected to three-point bending tests. The tests were conducted at the Official Laboratory of the Department of Structural Engineering of the University of Calabria with the aim of both analysing and improving the knowledge of the mechanical behaviour of these new structural elements and to validate, from an experimental point of view, some theoretical relationships suggested in the recent Italian Guidelines CNR-DT 203/2006. All tested specimens were classified into four groups according to the different concrete compressive strength and to CFRP-bar reinforcement. Mid-span deflection, moment-curvature and bar strains were investigated by means of linear inductive displacement transducers, centesimal dial gauges and strain gauges directly applied onto CFRP bars. In almost all cases, shear failure mode was observed. A major diagonal crack within the beam shear span extended horizontally at the level of the CFRP bars indicating bond failure. During the experimental study, the acoustic emission technique was used to find out the beams cracking moment and to investigate the damage phenomena occurred inside the beams during the experimental tests, by means of a monitoring system set up.