Performance of Laminated Glass Units under Simulated Windborne Debris Impacts

Severe windstorm events such as Hurricane Andrew in 1992 have underscored the vulnerability of building envelopes to breaching under the combined effects of windborne debris impacts and wind pressures. Damage to building interiors and disruption of building functions are exacerbated greatly when building envelopes are breached. When the inner glass ply in a laminated glass window unit is unbroken, the integrity of that part of the building envelope is preserved—provided that the inner glass ply has sufficient resistance to subsequent positive and negative wind pressures. In an effort to develop glazing systems that are resistant to breaching due to windborne debris impacts, laboratory studies have been conducted to investigate the resistance of various laminated glass units to inner glass ply fracture when subjected to simulated windborne debris impacts. Laboratory data indicate that increased interlayer thickness (i.e., the thickness of the polymeric layer between the glass plies in a laminated glass unit) reduces significantly the observed probability of inner glass ply fracture resulting from small windborne debris impacts.