Joel K. Linde’s research while affiliated with McMaster University and other places

Fiber-reinforced polymer (FRP)-confined concrete-steel composite columns have been recently introduced as a retrofit technique for structural steel columns. This technique involves placing a two-part FRP tube around an existing steel column and subsequently filling the void between the steel section and the FRP tube with concrete to create a composite column. The composite action occurs due to the concrete encasing the steel section and the FRP confining the concrete. Within this focus, an experimental investigation has been undertaken with the objectives of evaluating the effect of adding confined concrete to encase a steel W section, the effect of using a split-tube system as a practical encasement technique, and the effect of adding shrinkage-reducing admixtures (SRA) to the confined concrete. A total of 18 stub columns comprising six different column types were tested to achieve these objectives. The test results showed that the load-displacement response of the composite columns was similar to that of confined concrete combined with the elastic-perfectly plastic steel contribution. The experimental findings also demonstrated the enhanced composite column performance, including a significant increase in the ultimate capacity using the proposed split-tube retrofit technique. The results also indicated that the use of a SRA in confined concrete has an indistinguishable effect on the confined concrete strength.

Fiber reinforced polymer (FRP)-confined concrete-steel composite columns have been investigated as a retrofit technique for structural steel columns. However, the application techniques required to utilize this type of composite column in a retrofit scenario have not yet been fully developed. This paper investigates the use of a split tube that can be placed around an existing steel column to act as stay in place formwork. The split tubes used in this study are manufactured from glass fiber reinforced polymer (GFRP) sheets. The split tube elements surrounding the steel column are then wrapped with carbon fiber reinforced polymer (CFRP) sheets. The void between the steel section and the FRP tube is subsequently filled with concrete to create a composite column. The uniaxial CFRP sheets are applied in the hoop direction to provide confinement to the concrete. An experimental investigation has been completed to evaluate the relative performance of this composite system. A total of twelve stub columns, consisting of four different column types have been tested. Experimental findings demonstrate the improved performance of the proposed retrofit technique.