Structural behaviour of pre-damaged reinforced concrete beams strengthened with natural fibre reinforced polymer composites

This paper examines the use of natural jute fabric reinforced polymer (JFRP) composite sheets as external strengthening material of reinforced concrete (RC) beams. Pre-damaged RC beam specimens are prepared to represent seismic damage. The shear behaviour of pre-damaged deep RC beams strengthened with JFRP sheets are investigated subjected to non-reversed cyclic three-point bending load test. The JFRP strengthening ratio and the pre-damaged level of RC beam are considered in this study. The test results revealed that JFRP can significantly improve the shear strength capacity of beams. All strengthened beams show a similar failure mode which is a rupture on JFRP sheets. The shear enhancement of JFRP strengthened pre-damaged beams are comparable to that of non-damaged beams strengthened with conventional FRPs, proving the applicability of JFRP strengthening in pre-damaged shear-deficient beams. In addition, the experimental results are compared with the predicted values by the Japanese design codes.