Axially loaded RC columns strengthened by steel caging. Finite element modelling

Reinforced concrete (RC) columns in buildings often need strengthening either due to defects in the columns themselves, having to support higher loads than those foreseen in the initial design of the structure, or as the result of ageing or accidental damage. The use of steel caging for this purpose is now a common practice in many countries throughout the world. Based on the results of an experimental study, this paper presents a parametric study using finite element models carried out with the aim of analysing the behaviour of RC columns strengthened by steel caging. The results of the study are used to analyse the influence that various parameters have on the behaviour of the strengthened column (size of the angles, the yield stress of the steel of the cage, the compressive strength of the concrete in the column, the size of the strips, the addition of an extra strip at the ends of the cage, the friction coefficient between the layer of mortar and the steel of the cage). The results obtained from the parametric study allow a series of guidelines to be established.