Reinforced concrete jacketing -: Interface influence on monotonic loading response

Reinforced concrete (RC) jacketing is most frequently used to strengthen columns. The common practice to prepare the interface is empirically based and consists on increasing the surface roughness, applying a bonding agent and eventually steel connectors. An experimental study was performed to analyze the influence of the interface treatment on the structural behavior of columns strengthened by RC jacketing. Seven column-footing, full-scale models were built. Three months later the columns were strengthened by RC jacketing after their surface had been prepared considering different techniques. Later the models were tested under monotonic loading. It was concluded that, for current undamaged columns (that is, where a bending moment-shear force ratio is greater than 1.0 m), a monolithic behavior of the composite element can be achieved even without increasing their surface roughness, using bonding agents, or applying steel connectors before strengthening it by RC jacketing.