R/C columns strengthened by means of steel angles and battens: testing, modeling and design

An experimental investigation on the compressive behavior of eight short, confined, reinforced-concrete columns, externally strengthened by means of steel angles and battens with different spacing, is presented in this paper, together with an analytical model, which considers the strengthened column as a composite member. The model describes the favorable confining effect exerted by both the battens and the angles on concrete core, and takes care of the contribution of the angles to the load-carrying capacity of the column. (The angles are primarily subjected to an axial force, but some bending occurs because of the lateral angle-concrete pressure). The two cases of directly- and indirectly-loaded angles are addressed. The numerical results are compared with the experimental results available in the literature and with those provided by other analytical models. The fitting of the experimental results and the agreement with those obtained by using other models is satisfactory, for both directly- and indirectly-loaded angles. The proposed model allows to check and comment the available code provisions concerning structural strengthening via angles and battens.