Behavior of RC columns strengthened by combined (CFRP and steel jacket)

Abstract

This paper presents a new technique of strengthening for RC columns. The columns were strengthened with both CFRP wrapping and steel jacket consisting of angles and strips. The experimental work included testing eight column specimens with two variable parameters that are; concrete compressive strength and the reinforcement ratio. The aim of using CFRP wraps is to increase the capacity of concrete to resist the lateral deformation resulting from axial applied loads. On the other hand, the steel jacket works together with concrete in composite action. The steel angles enhanced the column in the axial direction to withstand more loads while the steel strips provide lateral confinement to the column. Inversely, the CFRP wrapping, which has transverse unidirectional effect on the column provides confinement only, increasing the column capacity by enhancing the concrete compressive strength. The results of the tests showed an increase in loading capacity when compared with the reference columns. It increased between 90% and 128%. On the other hand, the ductility was also improved by using strengthening techniques by 3% to 24.3%. It was noticeable that the strengthening was more affected by columns of low concrete compressive strengths.