An experimental study on steel-caged RC columns subjected to axial force and bending moment

Among the different methods of strengthening RC columns, steel caging is one of the most extensively used, for square or rectangular cross-section columns. Few studies have been carried out on steel caging and most of these have focused on axially loaded strengthened columns, without taking the effects of bending moments into account. This paper presents the results of a series of experimental tests on full-scale specimens strengthened with steel caging including simulation of the beam-column joint under combined bending and axial loads. Capitals were applied to all the specimens to connect the caging with the beam-column joint either by chemical anchors or steel bars to improve the transmission of forces. In all the specimens tested it was observed that steel caging increases both the ultimate load and ductility of the strengthened columns. The specimens fitted with steel bars reach higher ductility and strength than those with chemical anchors. The laboratory results were compared with three design proposals and the degree of fit with each one was analysed.