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According to the current trend for sustainable constructions in urban area, in this paper different constructive technologies for vertical addition of existing masonry buildings have been examined. Based on the analysis methodology of the new technical Italian code (M. D. 14/01/08) for assessing the behaviour of historical masonry buildings, a FEM model of a structural masonry unit has been implemented in order to allow for the comparison among different solutions for vertical addition, namely traditional technologies and innovative ones. A numerical campaign of linear dynamic analyses has been undertaken by changing both the number of floors (1, 2 and 3) and the strength (fk=1, 3 and 6 MPa) of the base masonry structure. The seismic performance of the analysed structures, expressed in terms of PGA, has shown that cold-formed steel systems represent the best solution for vertical addition of existing masonry buildings.

The paper describes a comparison of experimental results and theoretical predictions regarding the lateral force‐displacement response of built‐up steel columns with semi‐continuous (semi‐rigid and partial‐strength) base‐plate connections. Two specimens, representing samples from real columns of an existing industrial building, were fabricated and tested. The columns were both made of two I‐shaped profiles connected by means of battens, but with significant differences in the scheme of battening from one specimen to the other. The base plate connections were also significantly different in the two cases, in terms of local detailing. Preliminary tests were carried out in the elastic range of response, under varying levels of applied axial force. Such elastic tests were used to measure variations of the initial stiffness and corresponding yield displacements with the applied axial force. Subsequently, a cyclic loading test was carried out, per each specimen, to investigate the inelastic response. Initially, the paper describes and comments on the relative performance of the two tested specimens, in terms of stiffness, resistance and ductility, as resulting from the experimental tests. Subsequently, the paper provides theoretical predictions along with a comparison to the experimental results. Firstly, results from finite‐element (FE) models – developed using the Abaqus software – are described. Secondly, results from the application of simplified mechanical models are illustrated. The adopted mechanical models essentially followed the component‐method stipulated by Eurocode 3, but with some adaptations and modifications. The paper finally provides a comparison of experimental results with both numerical and analytical models.