Influence of columns' confinement on pre-code existing reinforced concrete buildings

The paper analyses the effect of columns' confinement on existing reinforced concrete moment-frame structures originally designed for gravity loads only. The design of strong-beam/weak-column buildings is simulated in compliance with pre-seismic Italian provisions. The geometrical and mechanical properties of the materials are parametrically varied according to typical ranges through an automatic procedure to obtain a representative sample of the built environment. Different levels of confinement interventions are subsequently designed, according to modern retrofitting methods based on fibre-reinforced materials, to improve the performance of columns under the combined action of axial and bending forces. Finally, the performance of such archetypical structures is analysed before and after the retrofitting intervention considering the gravity and seismic loads. The linear and non-linear analysis results are evaluated in terms of local and global engineering parameters, evaluating the degree of improvement that selected confinement actions can effectively confer on pre-code buildings. The overall objective of the work is to explore a range of appropriate retrofitting techniques that could be efficiently adopted to reduce the seismic vulnerability of many structures composing the postwar national built environment.