Modelling of the behaviour of reinforced concrete columns retrofitted for flexure using concrete jackets

The present paper provides methods for analyzing reinforced concrete column sections strengthened with concrete jacket. First, the prediction of the axial load versus moment interaction curve is presented based on a lamellar analysis and a simplified method of analysis. The predicted results are compared with experimental results of jacketed columns. Second, the prediction of the moment versus curvature behaviour of a retrofitted column section under an axial load, is presented based on both the methods of analysis. Finally, the lateral load versus displacement behaviour of a beam-column-joint sub-assemblage with retrofitted columns, is predicted using an incremental non-linear analysis. The predicted behaviours are compared with experimental results. It is concluded that the lamellar analysis provides good prediction of the strength, as well as the moment versus curvature behaviour of a retrofitted column section. The simplified analysis gives a conservative value of the strength. It cannot predict the ductility in the behaviour reasonably well. The incremental non-linear analysis provides substantial better prediction of the behaviour of a retrofitted sub-assemblage specimen, as compared to a conventional pushover analysis.