Progressive collapse prevention in high-rise precast wall buildings with prestressed voided floor elements assembled with mechanical connections

New technologies employing dry-assembled precast concrete elements avoiding any cast-in-situ concrete pouring in the superstructure are currently providing alternatives to more traditional emulative or partially precast structural systems for high-rise buildings. These systems typically struggle to get the horizontal tie systems required by current standards against the phenomenon of progressive collapse in medium- and high-rise buildings following a blast or impact load or an unpredicted event leading to the failure of one or multiple primary load-bearing elements. As a matter of fact, these systems may although exploit alternative sources of robustness to stop collapse progression. This paper describes a numerical investigation focused on the structural behaviour of a dry-assembled precast deck system based on prestressed voided slab elements connected to bearing walls through spaced dowel connections following the loss of one or multiple primary load-bearing vertical elements. The results of nonlinear analyses encompassing losses at different storey, from ground to roof, show the crucial contribution of the torsional strength/stiffness of the slab elements and their connections to the global structural robustness.