GB2296020A - Blast-resistant mounting for, e.g. a window - Google Patents

Abstract

A blast resistant mounting for a window or the like which may be retro-fitted to a conventional window frame to retain blast proof glazing therein includes retaining members 5 positioned around the frame by engaging tongue 5a into outwardly facing groove 6. A resilient bead 8 of structural silicone material is bonded between the shoulder 7 of the each retaining member and the edges of the window 1. In the event of a shock wave impinging on the window the glazing unit will bow inwardly and /or outwardly causing the edges to rotate. A resilient shear force is exerted by the resilient head which cushions the shock and resists the flexing of the glazing and provides a higher resistance to blast damage. The retaining members are enclosed by conventional glazing beads 3. <IMAGE>

Description

Blast Resisting Mounting Device This Invention relates to a blast resisting device for mounting a building component such as a window or a panel or other element or assembly which.

in use, may be exposed to the shock wave caused by an explosion of some kind, the mounting device having incorporated therein a resilient component to resist the resultant shock loading and which can also accommodate normal structural movements and ioads, to which the component may be subjected In this specification, the term 'building component' includes. without limitation, windows and doors, frames, panels and claddings. for buildings and other structures of any sort which may be exposed to, or which may be vulnerable to any kind of explosive event and the term 'building Is to be understood and construed accordingly Intense suddenly applied dynamic loads of short duration and of appreciable magnitude as are produced by an explosion may result In an actual stress In excess of the original design specification for the building.Under these conditions, when a building component Is held by an unyielding mounting, which has been the practice hitherto, plastic strain deformation of the component may occur resulting In the premature failure of the building component In a conventional blast-resistant window system, for example, a suitable glass or composite glazing panel Is mounted, using an extruded glazing bead of the usual kind, Into relatively deep rebates provided around the retaining edge of a glazing frame, the rebates typically being about 30 to 35 mm In depth This glazing rebate depth Is generally considered necessary In order to provide protection from a magnitude of blast pressure as may be expected to occur without there being an unacceptable risk of the glass or glazing panel being bodily blown out of the retaining glazing frame In consequence of the blast twisting the frame and causing the violent ejection of the glass or glazing panel therefrom Accordingly glazing frames for conventional blast resistant windows must be specially fabricated to provide the degree of protection which Is normally required Conventional blast resistant glazing systems suffer from higher manufacturing costs since the glazing frames are larger and heavier than ordinary glazing frames.They are also generally identifiable, by external Inspection, as being security glazing, which may be undesirable for security or for aesthetic reasons A further disadvantage of conventional blast resistant glazing systems Is that in the event that an existing building or other structure is required to fitted with such glazing It Is necessary to replace the existing normal glazing, Including the conventional frames with conventional blast resistant glazing which also significantly adds to costs These disadvantages may be mitigated by means of the present Invention In one aspect, this Invention consists In a blast resistant mounting for a building component comprising a frame member for supporting a building component around a marginal edge portion thereof. retaining means being engageable with the frame member and arranged to extend along at least a portion of the frame member adjacent to a marginal edge portion of the building component which In use Is supported thereby a resilient member being disposed between the retaining means and the adjacent marginal edge portion of the building component whereby.In the event of a blast causing the building component to bow Inwardly or outwardly causing the edges thereof to correspondingly rotate the resilient member Is subjected to a shear displacement which resiliently resists the rotation of the said edge of the building component Advantageously, the retaining means Is adapted to be engaged in a channel formed along one side of the frame member Where It Is Intended to retro-fit existing glazing, for example with blast proof glazing mounted In accordance with this Invention, the existing glazing bead channel may be used to provide a suitable mounting for the retaining means This has the advantage that retaining means may be concealed by re-fitting a glazing bead so that the reglazed unit has the appearance of an ordinary window To facilitate installation In a pre existing frame the base portion of the retaining means may be provided with a tongue member which projects towards the Interior of the frame, the tongue being insertable Into an outwardly directed groove provided along the length of the frame member The retaining means is preferably formed with an outwardly Inclined shoulder portion facing towards the interior of the frame the shoulder being spaced apart from and located adjacent to the margiinal edge of the building component the said shoulder providing a seating surface for the resilient member This arrangement ensures that under blast conditions when the resilient member Is caused to shear by the rotation of a panel edge a minimum thickness of the resilient material will be preserved Irrespective of the flexing motion of the panel edge under such conditions To provide adequate mechanical strength and weather resistance the retaining means Is preferably In the form of an extruded profiled bar of corrosion resistant alloy such as brass The retaining means may be advantageously surface treated to Improve the bonding of the resilient member thereto The retaining means Is preferably adapted to be enclosed within a conventional glazing bead attached to one side of the frame In order to prevent sliding movement the resilient member Is preferably bonded to the retaining means and to the adjacent edge portion of the building component In a further aspect this Invention consists In a blast resistant assembly comprising a building component mounted In a frame In which each side of the building component Is provided with at least one blast resistant mounting as herein described and claimed.

We have found that when a building component such as a blast resistant glazing panel for example, is mounted In a glazing frame using an arrangement of blast resisting devices In accordance with this Invention the capacity of the resulting glazed unit to withstand blast Is so enhanced that special purpose blast resistant frames are no longer needed Substantially, the same degree of protection can now be obtained using conventional glazing frames. that Is. frames which provide a glazing rebate depth In the order of 20-22 mm, instead of the conventionally accepted 30 to 35 mm glazing rebate depth.A blast resistant glazing system utilising regular aluminium alloy glazing frame elements has numerous advantages Including lower production costs. the possibility of re-glazing existing Installed window systems with a blast resistant glazing system and the advantage that such systems are visually indistinguishable from conventional glazing systems The Invention will now be more particularly described by way of example only with reference to the accompanying drawings in which Figure 1 Is a cross sectional drawing of a glazing frame assembly incorporating a blast resistant mounting device In accordance with this invention and Figure 2 Is perspective view of the assembly Illustrated In Figure 1 Referring to the drawings, a building component In the form of a glazing panel, only a portion of which is shown as Indicated by numeral 1 Is a sealed double glazed unit having an Inner pane 1a of blast resistant laminated glass and an outer pane ib of annealed or toughened glass. The panel 1 Is glazed Into a rectangular glazing frame fabricated from conventional extruded thermally broken, aluminium alloy section shown generally as 2 The panel 1 is glazed into a rebate having a rebate depth d of 22 mm by means of a glazing bead 3 which retains a gasket 4 in contact with the Inner pane 1 a A retaining element 5 which may be of extruded brass has a tongue 5a which enters the groove 6 provided on frame element 2 whereby the retaining element 5 Is secured against counter clockwise rotation. as seen In Figure 1 The retaining means are secured to the mid point of each of the four frame elements forming the rectangular frame (not shown) by suitable fixings if necessary (also not illustrated) so as to provide a panel having four centrally positioned blast resistant mountings as more particularly described herein For panels of larger dimensions, more than one blast resistant mounting may be provided along each side or along the longer sides of the panel and In such cases, the mountings may be uniformly spaced apart for best effect As may be seen from Figure 1, the retaining element 5 has a sloping shoulder 7 which extends adjacent to the edge portion 1c of the panel 1 Before the glazing bead 3 Is fitted into place to cover the elements 5 a bead 8 of single -part structural silicone as supplied by Dow Corning Limited Is applied between the shoulder 7 and the adjacent edge 1c of the panel 1 bonding the two surfaces together and preventing slip occurring between the silicone bead and either the shoulder 7 or the edge of the panel When a shock wave Impinges on the external surface of the panel In the direction Indicated by the arrow A the outer annealed or toughened pane 1 b can be expected to shatter and absorb some of the blast whereas the Inner laminated pane la will bow inwardly at first and then outwardly and perhaps will thereafter oscillate, causing the marginal edges such as 1c to rotate | I e to follow an arcuate path. as Indicated by the exaggerated arc a shown in Figure 1 It can be seen that If the path of the arc described by the panel edge Is approximately parallel to shoulder 7 then the rotation of the edge will cause shear displacement of the bead 8 and there will generally be at least a component of shear displacement under all foreseeable conditions of operation. The profile of the shoulder 7 ensures that there Is no undue thinning of the bead 8 as the edge of the panel oscillates under blast conditions It has been found that the use of blast resistant devices as described permits the use of conventional aluminium alloy double glazing frame components having normal glazing rebate depths to be used for the first time in blast resistant glazing systems having the advantages mentioned above.

Claims (1)

1. Claims

   1 A blast resistant mounting for a building component comprising a frame member for supporting a building component around a marginal edge portion thereof, retaining means being engageable with the frame member and arranged to extend along at least a portion of the frame member adjacent to a marginal edge portion of the building component which, In use. Is supported thereby, a resilient member being disposed between the retaining means and the adjacent marginal edge portion of the building component whereby.In the event of a blast causing the building component to bow Inwardly or outwardly causing the edges thereof to correspondingly rotate the resilient member Is subjected to a shear displacement which resiliently resists the rotation of the said edge of the building component 2 A mounting as claimed In Claim 1 in which the retaining means Is adapted to be engaged In a channel formed along one side of the frame member 3 A mounting as claimed In Claim 1 or 2 In which the base portion of the retaining means Is provided with a tongue member which projects towards the Interior of the frame the tongue being Insertable Into an outwardly directed groove provided along the length of the frame member 4 A mounting as claimed In Claim 1 2 or 3 In which the retaining means Is formed with an outwardly Inclined shoulder portion facing towards the Interior of the frame the shoulder being spaced apart from and located adjacent to the margiinal edge of the building component the said shoulder providing a seating surface for the resilient member 5 A mounting as claimed In any preceding Claim In which the retaining means Is In the form of an extruded profiled bar of corrosion resistant alloy 6. A mounting as claimed In Claim 6 In which the retaining means is surface treated to improve the bonding of the resilient member thereto 7 A mounting as claimed In any preceding claim In which the retaining means is adapted to be enclosed within a conventional glazing bead attached to one side of the frame 8. A mounting as claimed in any preceding Claim In which the resilient member is bonded to the retaining means andtor to an edge portion of the building component 9 A mounting as claimed In Claim 8 In which the resilient member Is formed In situ from a one part structural silicone material 10. A blast resistant assembly comprising a building component mounted in a frame In which each side of the building component Is provided with at least one blast resistant mounting in accordance with any preceding Claim 11 A blast resistant mounting substantially as described with reference to Figures 1 and 2 of the accompanying drawings