Exploratory numerical analysis of two-way straight cable-net façades subjected to air blast loads

Based on numerical and analytical results of previous literature contributions, the paper investigates the dynamic behaviour of a structural two-way straight cable-net façade subjected to medium-level blast loads. Numerical studies are dedicated, specifically, to a cable-net prototype already experimentally investigated under seismic loads. Several numerical finite-element (FE) models are developed in ABAQUS/Standard. A geometrically simplified, lumped-mass FE-model (M01), a detailed cable-glass model (M02) and a further simplified but computationally efficient cable-glass model (M03) are presented. The models are assessed and calibrated to test data of literature, as well as to simplified SDOF analytical formulations, in order to investigate the dynamic response of the façade under high-rate impulsive loads. Since axial forces in the cables and maximum stresses in the glass panels abruptly increase when the explosion occurs, specific viscoelastic and frictional devices are applied at the connection between glass and cables, as well as at the end of the cables. The main advantage of the presented technological solution is given by the partial dissipation of the incoming energy. In the first case, viscoelastic connectors add flexibility to the point-supported glass elements, hence reducing the amount of incoming blast energy. In the latter case, frictional devices dissipate through friction mechanisms the strain energy stored by the bearing cable-net. A proper combination of these multiple devices, in conclusion, can manifest a marked increase of structural efficiency for the examined structural typology.