Cold-formed thin-walled steel structures as vertical addition and energetic retrofitting systems of existing masonry buildings

According to the current trend for sustainable constructions in urban areas, the present paper deals with the analysis of vertical addition systems for energetic retrofitting of existing masonry buildings. Starting from the current European (EN 1998-3:2005) and Italian (NTC 08) technical codes for the seismic assessment of existing structures, first a FEM model has been implemented to investigate the structural performances of masonry units with variable storeys (1, 2 and 3) and material strength (fk = 1, 3 and 6 MPa). Later on, traditional (reinforced concrete, masonry and steel) and innovative (glued laminated timber and cold-formed thin-walled steel) technologies have been proposed as a solution for vertical addition of the studied buildings. Therefore, a numerical campaign of linear dynamic analyses has been undertaken on the examined structures aiming at selecting the best vertical addition solution. The achieved numerical analysis results have provided cold-formed steel systems as the dominant solution for improving the energetic behaviour of the inspected existing masonry buildings. Finally, the achieved numerical results have been confirmed by a consistent and reliable multicriteria decision-making (MCDM) TOPSIS method, where the proposed vertical addition systems have been compared with each other in terms of structural, environmental and economic performance parameters.