FRP materials are now increasingly being used in the construction industry. Confinement of circular concrete members using FRP is a popular application. As such, studying the performance of concrete members confined by FRP jackets, under severe weather conditions is quite important for both rehabilitated and new structures in cold climatic conditions. However, no sufficient data on FRP wrapped cylinders subjected to the two conditions combined, as in actual structures, which may have a synergetic effect. Stress level and temperature are two factors that influence creep-strain in composites. Orientation of the fibres is another factor that needs to be considered when analyzing creep in FRPs.
This research is intended to examine the combined effects of freeze-thaw cycles and sustained loads, simultaneously applied on FRP-confined concrete cylinders, including cylinders with GFRP wraps and CFRP wraps. Test results of specimens subjected to the combined effects have been compared to those of other specimens subjected to sustained loading only at room temperature and to those of specimens subjected to freeze-thaw only without sustained loading. It should be noted that columns in actual structure are not free to expand axially as they are restrained by the floors above or below. As such, it is believed that the sustained loading setup used in this study has represented the end constraints and has provided boundary conditions similar to actual conditions. In general, the study showed that freeze-thaw cycling had minimal effect on FRP-wrapped concrete cylinders without sustained loads, and almost no effect on FRP-wrapped concrete cylinders with sustained loads. On the other hand, plain concrete cylinders under the same freeze-thaw conditions were completely disintegrated after only 100 cycles. It was also noticed that the sustained loading changes the stress-strain curve of FRP-confined concrete, where the transition in the bi-linear curve occurs at higher load.