Withdrawn: Interface dependency of reinforced concrete jacketing for column strengthening

Abstract

The structural capacity enhancement of concrete columns due to reinforced concrete (RC) jacketing was investigated. To assess the structural capacity and integrity of jacketed columns, 12 retrofitted column specimens with different jacket thicknesses were experimentally tested. The specimens were prepared with different types of interfaces, including no surface treatment, the addition of a bonding chemical, roughening of the old surface, application of welded ties and changes in clear cover, to investigate the influence of interface bonding between new and old concrete. Analytical equations for jacketed columns were formulated as per the elastic principle maintaining strain compatibility at the interface along with concrete modelling. Column interaction diagrams derived from analytical equations were compared and verified with existing Japanese code specifications and available finite-element (FE) software packages. The experimental investigation showed that failures occurred earlier at the column interface than at the core of the retrofitted column. The comparative study in terms of interaction diagrams revealed that the experimental results agreed well with the computed analytical results but deviated from the FE analysis. An interface bonding reduction coefficient in the range of 0·65–0·88 is proposed for RC jacketed columns subjected to different types of interfaces.