9 Design of glazing

Cormie, David; Mays, Geoff; Smith, Peter

doi:10.1680/beob2e.35218.0009

Cited by 6 publications

(12 citation statements)

References 2 publications

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“…This is observed in multiple, high strain-rate experimental tests performed by Nie et al (2009Nie et al ( , 2010, Peroni et al (2011), Zhang et al (2012 and Meyland et al (2018). For the blast design of glazing, recommended dynamic fracture strength values are presented by Smith and Cormie (2009) that were derived by extrapolating to the high strain-rates associated with blast loading the inherent, static strength value of annealed glass presented in prEN 13474-3using Brown's integral (risk integral) for stress fatigue (also known as sub-critical crack growth), and superimposing the relevant surface pre-stress from the thermal processing of heat-strengthened and toughened glaz-ing products. Lower strain-rates were considered in the above extrapolation for monolithic glazing, compared to the mean values recorded experimentally by Morison (2007) and Hooper (2011) for fractured laminated glass, as strain-rates depend on the maximum deflection of the panel.…”

Section: Glass Layersmentioning

confidence: 90%

“…It has become common practice for such tests to characterise the panel structural response by the (centre of panel) peak-displacement. Much research has therefore focussed on reproducing the experimentally recorded, peak-displacement time-histories of laminated glass panels, whether this is by finite-element analysis (FEA) (Hooper 2011;Larcher et al 2012;Hidallana-Gamage 2015;Pelfrene et al 2016), analytical solutions (Yuan et al 2017;Del Linz et al 2018) or equivalent single-degree-of-freedom (ESDOF) methods (Special Services Group, Explosion Protection 1997;Applied Research Associates 2010;Morison 2007;Smith and Cormie 2009). This approach, of developing models based on experimentally observed, peak displacements, enables the structural assessment of laminated glass panels under blast loading without having to perform additional, expensive blast testing.…”

Section: Introductionmentioning

confidence: 99%

“…Recommended design values for glass fracture strength of low (prEN 13474-3) and high(Smith and Cormie 2009;Morison 2007) strain-ratesGlass typeFracture strength, σ g,t (MPa) Low strain-rates (∼ 10 −5 s −1 ) High strain-rates (0.4−0.6 s −1 )…”

mentioning

confidence: 99%

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The effects of high strain-rate and in-plane restraint on quasi-statically loaded laminated glass: a theoretical study with applications to blast enhancement

2019

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Laminated glass panels are increasingly used to improve the blast resilience of glazed facades, as part of efforts to mitigate the threat posed to buildings and their occupants by terrorist attacks. The blast response of these ductile panels is still only partially understood, with an evident knowledge gap between fundamental behaviour at the material level and observations from full-scale blast tests. To enhance our understanding, and help bridge this gap, this paper adopts a 'first principles' approach to investigate the effects of high strain-rate, associated with blast loading, and the in-plane restraint offered by blast-resistant frames. These are studied by developing simplified analytical beam models, for all stages of deformation, that account for the enhanced properties of both the glass and the interlayer at high strain-rates. The increased shear modulus of the interlayer results in a composite bending response of the un-fractured laminated glass. This also enhances the residual post-fracture bending moment capacity, arising from the combined action of the glass fragments in compression and the interlayer in tension, which is considered negligible under low strain-rates. The post-fracture resistance is significantly improved by the introduction of in-plane restraint, due to the membrane action associated with panel stretching under large deflections. This is demonstrated by developing a yield condition that accounts for the rela-tive contributions of bending and membrane action, and applying the upper bound theorem of plasticity, assuming a tearing failure of the interlayer. Future work aims to complete the theoretical framework by including the assessment of plate-action and inertia effects.

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Section: Glass Layersmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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The effects of high strain-rate and in-plane restraint on quasi-statically loaded laminated glass: a theoretical study with applications to blast enhancement

2019

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“…Glass exhibits sudden breakage due to its extreme brittleness and does not show permanent yield or deformation; however, the strength of glass is dependent on the duration of the load (e.g. Larcher et al, 2010Larcher et al, , 2012Lin et al, 2004;Netherton and Stewart, 2009;Smith and Cormie, 2009). To model this effect is extremely difficult, so in the present study it is assumed that the window breaks immediately once the P-I (pressureimpulse) damage failure curve is reached.…”

Section: Scenario Descriptionmentioning

confidence: 99%

“…The P-I curves of interest are (1) low hazard and (2) high hazard (Figure 2). When rupture of the PVB interlayer begins to occur, and ‘before pieces have begun to be torn off’, the glazing still provides partial protection, and this is deemed a low hazard (Smith, 1991; Smith and Cormie, 2009). The window is damaged but still intact.…”

Section: Scenario Descriptionmentioning

confidence: 99%

Probabilistic assessment of airblast variability and fatality risk estimation for explosive blasts in confined building spaces

Alterman

Stewart

Netherton

2019

International Journal of Protective Structures

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Explosive blasts in confined building spaces, such as lobbies or foyers, can amplify blast loads. This article uses the computational fluid dynamics model ProsAir to estimate blast loads in a typical ground floor lobby of a commercial or government building. Monte-Carlo simulation is used to probabilistically model the effect that variability and uncertainty of charge mass and location, net equivalent quantity factor, temperature, atmospheric pressure and model errors have on airblast variability. The analysis then calculates the probability of casualties due to the effects of pressure and impulse, where human vulnerability due to the effects of pressure and impulse is a function of lung rupture, whole-body displacement or skull fracture (or the combination of the three). The terrorist threats considered are improvised explosive devices ranging in mass from 5 kg (backpack bomb) to 23 kg (suitcase bomb) detonated in various locations inside the building. As expected, blast pressure and fatality risks are dependent on the type of facade glazing (e.g. vulnerable glazing allows venting of the blast), improvised explosive device size and location. It was found that the mean fatality risk for a 23 kg terrorist improvised explosive device is 8.6%, but there is a 5% chance that fatality risks can exceed 20%. It was also found that a probabilistic analysis yielded lower mean fatality risks than a deterministic analysis. The effect of venting was also significant. Mean fatality risks increased by up to 10-fold if there was no venting (i.e. a bunker-like structure without windows), but reduced by about 30% for a fully vented structure (i.e. no windows). This probabilistic analysis allows decision-makers to be more aware of terrorism risks to building occupants, and how improved building design and security measures may ameliorate these risks.

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