Patent Application
20120125186
1. Field of the Invention
The present invention relates to architectural glass block panels and windows (“panels”) and methods of making such panels. More particularly, the invention relates to a glass block panel that is resistant to the shock wave effects of a blast event, for example, an explosion.
2. Background of the Invention
Glass blocks may be used instead of solid (i.e., non-transparent) materials, plate glass or other fenestration materials in the construction of walls and partitions. Aside from the aesthetic advantages that the glass blocks may provide over other solid or glass materials, the glass blocks may be preferable because they are transparent and allow light to filter through, thereby permitting viewing with desired levels of privacy through the wall, or creating a brighter room or office space.
With the increased threat and awareness of terrorist and criminal attacks from explosive ballistic devices, responsible government and commercial organizations are responding with more stringent building requirements along with better products and construction methods. In the past, the majority of injuries to building occupants have been caused by shattered glass fragments or shards sent flying through the air from the blast force.
An explosion will cause variations in air pressure, called shock waves, to radiate from the source of the blast. The actual effect of a blast is a function of its type, magnitude, duration and distance from where the blast took place. “Standoff distance” is a distance maintained between a building and the potential location of an explosive detonation, like a sidewalk or parking lot, by use of a fence and gated entry, where inspections for explosives are done. Standoff distances will be longer where there is potential to detonate a larger explosive device, like one driven in a car or truck, and shorter where the device could be carried. With a nearly infinite range of explosive devices and potential standoff distances, standards have been developed to simplify blast parameters for testing and application purposes. To that end, a blast pulse is often simplified to a triangular shape where the pressure rises from ambient pressure almost instantaneously and then declines linearly back to ambient.
The key parameters used to define a blast in standards and specifications for fenestration are:
The other key parameter for fenestration is how well it resists a blast in order to protect people inside of a building. The two commonly used standards defining that protection are the ASTM Hazard Rating (from ASTM International, previously American Society for Testing and Materials) and the GSA Performance Condition (from the General Services Administration).
ASTM has developed a document with designation F 1642-04 titled “Standard Test Method for Glazing and Glazing Systems Subject to Airblast Loadings.” It is used to define standard testing procedures and resulting “Hazard Rating.” GSA is a government agency that provides support to federal, state and local government agencies and to contractors and suppliers providing goods and services to them. Part of their function is to qualify suppliers and products. For blast resistant fenestration, they provide GSA Test Protocol GSA-TS01-2003 titled “US General Services Agency Test Method for Glazing and Window Systems Subject to Dynamic Overpressure Loadings.” GSA has prescribed the following Building Classifications:
Thus, there is a need for glass construction material that provides the aesthetic and visual benefits discussed above in conjunction with increased resistance to explosive blasts. Historically, most glass block installations were done with masonry, such that the glass blocks were connected to each other with mortar or mortar-like adhesives, akin to the construction of a brick wall. With the advent of improved sealants and adhesives, however, an increasing number of glass block installations have been done with silicone, either alone or in conjunction with plastic spacer systems. One advantage the better silicones can offer over traditional mortar is that the assembled glass block panel can flex, allowing it to absorb forces from powerful air pressures caused by nature or those that are man made. While natural air pressure, such as that found in hurricanes, may be on the order of 100 pounds per square foot, air pressures for blast events may be ten to twenty times larger, sometimes approaching or even exceeding 1800 pounds per square foot. The present invention seeks to provide a glass block panel that can withstand such high pressures without any glass cracking or any loss of material.
Flat glass fenestration has made good progress in blast resistance by utilizing glass lamination and framing techniques to allow a glass pane to flex, so that even when the glass cracks, the underlying laminate layer may help hold the pane together, thereby limiting the scattering of glass fragments. The invention described herein builds on the natural structure of glass block construction to allow the fenestration to flex elastically to blast pressures. The structure behaves like a flexible web of independent glass units. Whereas laminated flat glass panes often will crack and release fragments during a blast, there is no such cracking or loss of glass with the present invention. This is particularly important to people who are in the proximity of a building when a blast event occurs because they may be pushed up against the building and underneath windows where shattered glass might be raining down on them.
Accordingly, it is an object of the present invention to provide a glass block construction material that provides the aesthetic and visual benefits of an ordinary glass or glass block panel in conjunction with increased resistance to explosive blasts.
The nature of the glass block panel allows it to flex in response to the shock wave emanating from a blast event, thus absorbing much of the force. Conceptually, this is like a trampoline mesh made up of a grid of rigid elements (the glass blocks) held together by a network of flexible elements (the silicone spacer system). The grid assembly of rigid blocks held together by a silicone spacer system is placed into a frame unit that is attached to the substrate of an opening in a building wall. It is assumed that the substrate and containing structure are robust enough to withstand the force of a blast as captured by the glass block panel.
Some preferred characteristics of this invention are:
For the present invention to be clearly understood and readily practiced, the present invention will be described in conjunction with the following figures, wherein like reference characters designate the same or similar elements, which figures are incorporated into and constitute a part of the specification, wherein:
It is to be understood that the figures and descriptions of the present invention have been simplified to illustrate elements that are relevant for a clear understanding of the invention. The detailed description will be provided hereinbelow with reference to the attached drawings.
Referring to
The glass block panel 10 preferably is assembled using track spacers 8 running between the blocks both horizontally and vertically as shown in
A structural silicone 16 (for example, Pittsburgh Corning Glass Block Sealant) is used to bond the spacers 8 to the adjoining glass blocks 2. A rectangular glass block panel 10 is made by progressively assembling blocks 2 and spacers 8 with the structural silicone 16 until the desired dimensions are attained. Spacers 8 may run continuously in either the horizontal or vertical direction for structural strength.
A perimeter channel 18 may then be applied around the perimeter of the glass block panel also using a structural silicone 16, as shown in
The glass block assembly 10 may be framed by a metal or otherwise rigid frame 20 as illustrated in
For the preferred embodiment, the thickness and alloy of aluminum used in the channel 22 should meet minimum conditions as prescribed by blasting tests and engineering analysis. For example, the glass block panels 10 of the present design with sizes ranging between 4 feet by 4 feet to 8 feet by 8 feet preferably should perform to ASTM “Minimal Hazard” or GSA “Performance Condition 2” or better for:
Smaller windows would meet the same standards with a thicker aluminum frame, stronger aluminum alloys and specific anchoring requirements.
The entire glass block assembly is then attached or anchored into the desired opening, which may be steel, concrete, masonry, wood or another suitable material. For panels that are 4 feet or larger in both dimensions up to 12 feet in both dimensions, the aluminum frame is preferably 0.125-inch thick 6063 T6 alloy, and attaching the frame may be as follows:
For panels 32-inches by 32-inches to 4-feet by 4-feet, the aluminum frame is preferably 0.15-inch thick 6063-T6 aluminum, and attaching the frame may be as follows:
For smaller panels, the preferred requirements are as follows:
Although the invention has been described in terms of particular embodiments in an application, one of ordinary skill in the art, in light of the teachings herein, can generate additional embodiments and modifications without departing from the spirit of, or exceeding the scope of, the claimed invention. Accordingly, it is understood that the drawings and the descriptions herein are proffered by way of example only to facilitate comprehension of the invention and should not be construed to limit the scope thereof.
This application is a continuation and claims the benefit under 35 U.S.C. §120 of U.S. patent application Ser. No. 12/421,531, filed Apr. 9, 2009, the contents of which are hereby incorporated by reference, which itself claims the benefit under 35 U.S.C. §119(e) of the earlier filing date of U.S. Provisional Application No. 61/043,959, filed Apr. 10, 2008, entitled “Glass Block Blast Resistance System”.
| Number | Date | Country | |
|---|---|---|---|
| 61043959 | Apr 2008 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12421531 | Apr 2009 | US |
| Child | 13359474 | US |
