The need for strengthening structural members is well known and research is progressing in this field. In recent years the use of fiber reinforced polymers (FRP) for strengthening has shown to be a efficient method both regarding structural performance and economical aspects. However, most of the research in this field has been undertaken on concrete of old and damaged structures and for flexural and shear strengthening. So, this paper presents axially loaded steel columns strengthened for increased load capacity and improved stability. The topic is studied theoretically. The theory covers analytical method, and a numerical finite elements (FE) analysis. Different types of most common commercial FRP systems have been examined and used in this study