Critical comparison between two strengthening techniques of reinforced concrete columns

In last years, in order to better understand the behavior of confined reinforced concrete, a lot of studies have been made. In addition, also a lot of experimental test have been conducted. In particular the attention has been devoted to the columns strengthened with FRP, while other old techniques have been completely forgotten. Herein a comparison between different methodologies for the strengthening of concrete columns is presented. In addition to columns confined with FRP the concrete confined with angles and battens is considered. The comparing between these two methodologies shows that some advantages arise when battens and angles are used. In fact, they can be effectively used, also when the ratio between the two sides of the column section is greater than 2, by means of steel bar passing through the section. In such a case the confining action due to FRP is negligible. In addition, angles can provide strengthening both in tension and in compression, depending on the structural detail adopted at the concrete floor slab.