An engineering approach for the basic design of glazed surfaces under blast waves

Nowadays the design of blast-resistant glazed façades is acquiring importance to comply with building safety standards. The high-pressure generated by the blast-wave air-front can lead to catastrophic failure of the glass panes and/or their load-bearing structure, with possible projection of fragments that constitutes a potential threat for human lives and properties. The time-dependent deformations-history is usually assessed via numerical analyses and/or experimental investigations, but it is difficult to recognize the role of each element in the dynamic response of the whole. Here, to guide structural design, we propose a simple analytical model that permits a synthetic view of the phenomenon. The dynamic interaction among the blast wave and the ensemble of glazed panels and load bearing structure is studied in few paradigmatic lumped element models, representing glass panels supported by beams or tensioned cables, using Rayleigh’s method to reduce the plate-behavior of each glass panels to a SDoF oscillator. With reasonable approximations of the Friedlander waveform, the dynamic equations are readily solved. This analytical treatment quantifies the importance of the load-bearing structure in absorbing the biggest part of blast wave energy, to preserve the integrity of glass. The goodness of the approach is confirmed by comparison with FEM models.

Gianni Royer Carfagni

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