Passive control systems for the blast enhancement of glazing curtain walls under explosive loads

Glass curtain walls are used in modern buildings as envelopes for wide surfaces due to a multitude of aspects. In glass curtain walls, tensile brittle panels are connected - through mechanical or adhesive joints - with steel frameworks or aluminum bracing systems, and due to the interaction of several structural components, the behaviour of the so assembled system is complex to predict, especially under exceptional loading conditions such as explosive events. In the paper, glazing curtain walls are investigated by means of Finite-Element (FE) numerical simulations, under the effect of air blast pressures of variable intensity. Their typical dynamic behaviour and criticalities under high-strain impact loads are first analyzed. By means of extended nonlinear dynamic FE parametric studies, innovative devices are applied to traditional curtain walls, at their support points, in order to improve their expected dynamic response. Two possible solutions, namely consisting of viscoelastic (VE) or elasto-plastic (PL) dampers, are proposed as passive control systems for the mitigation of maximum effects in the façade components deriving from the incoming blast pressures. As shown, although characterized by specific intrinsic mechanical behaviours, either VE or PL dampers can offer beneficial structural effects. In the first case, major advantages for the façade components derive from the additional flexibility and damping capacities of VE devices. In the latter case, PL dampers introduce additional plastic energy dissipation in the traditional curtain wall assembly, hence allowing preventing severe damage in the glazing components. It is thus expected that the current outcomes could represent a valid background for further experimental validation as well as detailed assessment and optimization of the proposed design concept.