Coupled effect of freeze-thaw and chloride immersion cycles on bond-slip behavior of steel and FRP rebars in concrete

초록

This experimental study investigates the bond-slip behavior of steel and FRP rebars in concrete under the coupled effect of freeze-thaw (FT) and chloride immersion (CI) cycles. While both FT and CI can individually diminish load-carrying capacity by reducing the bond strength, their combined effect on rebars with different material properties and surface conditions remains insufficiently explored. To address this, a thorough experimental investigation was conducted on the bond-slip behavior of steel, in-production helically wrapped glass fiber reinforced polymer (IHW-GFRP), and post-production helically wrapped carbon fiber reinforced polymer (PHW-CFRP) rebars embedded in concrete. A total of 36 cubic concrete specimens reinforced with these rebars were subjected to up to 300 FT cycles and 5 CI cycles, followed by pull-out testing to evaluate the combined effect of these cycles on bond-slip behavior. Additionally, 18 cylindrical concrete specimens underwent the same conditions and were tested under compression to assess changes in compressive strength. The experimental results revealed that the combined FT and CI cycles reduced the peak bond stress by 14.63 %, 16.46 %, and 43.51 % for steel, IHW-GFRP, and PHW-CFRP rebars, respectively. In addition, the CEB-FIP analytical model for FRP rebars was modified to enhance the accuracy in estimating bond-slip curves of specimens subjected to the combined FT and CI cycles. This modification provided an improvement compared to the estimated curves using the conventional CEB-FIP model.

키워드