Cold formed rectangular steel hollow sections are widely used in load-carrying structures due to their good load transfer behavior and aesthetic form. In order to find the fatigue strength of cold formed members it is important first to investigate the factors which severely affect it. Notches in cold formed corners are the stress raisers and require special attention as their presence reduces the resistance to fatigue failure. Corner radii along with notches in cold formed rectangular hollow sections are the areas of higher stress concentrations. Small corner radii also cause high residual stresses in the corners and increase fatigue susceptibility due to large stress concentration factors. Therefore, this book presents the extensive investigation of factors affecting fatigue strength of cold formed steel members with the help of Finite Element Analysis (FEA). These factors include notches, residual stresses, radius and thickness at corners of cold formed members. This study is very helpful for the research teams and industries involved in computing fatigue strength of cold formed members made up of high strength steels.