Experimental and numerical study on wrapping concrete cylinders post heating and cooling under preload using CFRP fabrics

This paper reports test results and describes a numerical investigation of the effectiveness of using carbon fibre reinforced polymer (CFRP) fabrics for strengthening concrete cylinders that have been undamaged and damaged due to heating under preload. The purpose of this research was to investigate whether there is any difference in the performance of CFRP-wrapped cylinders if the wrapping is done under preload, and those for which neither heating, cooling nor wrapping was done under preload. The cylinders were exposed to 30% of maximum load at ambient temperature during heating and cooling before being wrapped under preload. Of 18 Ø 100 × 200 mm identical cylinders, 6 were left as control samples without heating, 12 were exposed to 600 °C of target heat exposure and maintained for 2-hours. The cylinders were subjected to subsequent cooling with or without applied stress of 0.3f′co and were treated with CFRP and tested to failure. Finite element analysis (FEA) was established using ATENA-GiD software to estimate the load-carrying capacity of the tested cylinders. The outcomes illustrate that CFRP considerably increases the load-bearing capacity of undamaged and post-heated samples. The outcomes also prove that the use of CFRP composites is an active technique to retain some of or the full capacity of concrete next damage through the addition of even a single layer of CFRP sheet. Whether the CFRP is added under preload or not does appear to have a significant effect on load enhancement and it was concluded that this subject requires further follow-up. The FEA provides a good prediction of experimental outcomes.