Proposal of simplified design methods to evaluate second-order effects in tall reinforced masonry walls

A previous experimental campaign has demonstrated the good behavior of tall rein-forced masonry (RM) walls, with vertically perforated clay units, when subjected to lateral actions. The samples tested represent typical construction systems of commercial and industrial single-story RM buildings provided with deformable roofs. However, to date, EN1996 does not have a consistent approach to check the second-order effects due to out-of-plane loads in such structures, providing requirements for RM walls which are too restrictive. This paper firstly discusses some of the major results of a recent numerical parametric study which implements fiber FE models calibrated from the above tests, as the actual slenderness limits for RM walls, also on the basis of experimental evidences. Then, more rational simplified approaches than that provided in EN1996 for evaluating second-order effects in tall RM walls are proposed, starting from the design methods of the Model Column (MC) and the Nominal Curvature (NC) generally used for RC structures; details on how these general methods were adapted to be used for RM tall walls are given in the paper. Finally, their reliability is assessed with respect to the numerical results of the previous parametric study, as well as that of the Moment Magnifier (MM) method proposed by the American (TMS 402) and Canadian (CSA S304) standards.