Experimental Study on the Compressive Load Carrying Capacity of FRP Wrapped Steel Cylinders

In the last decades, Fiber-reinforced polymer (FRP) jackets have been widely used to confine reinforced concrete (RC) columns for enhancement in both strength and ductility. The current paper investigates experimentally the ultimate load carrying capacity of steel cylindrical tubes as columns primarily in origin state and then wrapped by FRP layers. This study shows the beneficial application of FRP in increasing of ultimate compression strength and ductility of steel tube members. The results are depicted in load-axial end shortening curves for two major aspect ratios of intact and CFRP retrofitted steel cylinders. The mode of failure in the form of local buckling, non-linear post buckling and the influence of the externally wrapped FRP on the behavior of steel tubes are discussed in details for all tested specimens as well. In addition, the presented results show that using appropriate CFRP materials for over wrapping of thin cylindrical shells under axial compression is an effective strengthening method for such shells failing by elephant’s foot collapse near the base.