Static structures (e.g. – buildings) – Sheetlike element assembled parallel to existing wall,...
Reexamination Certificate
1999-10-20
2001-04-10
Hansen, James O. (Department: 3636)
Static structures (e.g., buildings)
Sheetlike element assembled parallel to existing wall,...
C160S327000
Reexamination Certificate
active
06212840
ABSTRACT:
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to the protection of the contents of an enclosed space, especially people, against damage caused by flying debris when the walls of the enclosed space are destroyed and the window frames which are no longer secured thereby are ejected inwardly into the interior of the enclosed space.
Bomb blasts are unfortunately a relatively common occurrence, whether in the context of actual warfare or otherwise. Little can be done to prevent damage to persons and objects who suffer a direct hit from the blast.
However, a significant fraction of the persons and property which are hurt or damaged during a bomb blast do not suffer a direct hit and rather are separated from the detonation by a structure. Typically, the persons or objects are inside a house or building while the blast takes place outside the house or building.
It is known that in the case where a blast occurs outside of a structure, some of the damage caused to persons and objects inside the structure are brought about by flying pieces of the walls of the structure as they are broken up and thrust inward by the force of the explosion.
In many cases, a substantial portion of the damage is caused by window frames which are no longer secured by the disintegrating walls of the structure and are forced inwardly by the blast, hurting people and inflicting damage to property. For example, more than 90% of those killed and wounded in the recent blast of the American embassy building in Nairobi were hurt by window frames that were forcibly ejected from the walls and thrown into the rooms of the building, although the window glass in the American embassy in Nairobi were re-enforced with Mylar film coating.
An obvious solution to the problem is to build structures which have strong walls and window frame installations which are capable of withstanding the forces of any expected blast without breaking up. Such walls can be made to be sufficiently strong by increasing the thickness of the wall, reinforcing the wall, or making the wall from a stronger material, carrying blast proof window frames.
Such a solution is not always practicable. Use of blast-proof walls and window frames is expensive and, while certain blast-prone structures may feature such walls and frames, it is not feasible to equip every structure which is the potential target of a bomb blast with such walls and frames.
Retrofit attempts to reinforce existing walls with a reinforcing and protection structure have employed thermosetting adhesive between the reinforcing structure and the wall. Thermosetting adhesives by nature become rigid when cured, thus precluding the very properties of stretch and hold required for the reinforcing structure to perform effectively as a protective shield.
There is thus a widely recognized need for, and it would be highly advantageous to have, a means for protecting the contents of a structure, especially human beings, from harm which may be caused when a blast outside the structure breaks up the walls of the structure and forcibly sends pieces of the walls and the window frames into the structure.
SUMMARY OF THE INVENTION
According to the present invention there is provided a retrofit method for protecting the contents of a structure having walls and window frames in the walls in the event of a blast outside the structure. Further according to the present invention there is provided a structure rendered blast protected by the method of the present invention.
The method according to the present invention comprising the steps of (a) providing a flexible and stretchable woven sheet including strands of ballistic thread; (b) attaching a first portion of the flexible and stretchable woven sheet via a flexible adhesive to an inward-facing surface of at least one wall of the structure; and (c) attaching a second portion of the flexible and stretchable woven sheet to at least one window frame in the at least one wall; the flexible and stretchable woven sheet and the flexible adhesive being capable of stretching under impact of the blast, thereby reducing disintegration of the at least one wall and securing the at least one window frame in the wall upon the blast, preventing fragments from the at least one wall and preventing the at least one window frame from being thrown into an interior of the structure by the blast.
Accordingly, the present invention provides a blast protected structure comprising a wall having a window frame therein, an inward facing surface of the wall being covered by a first portion of a flexible and stretchable woven sheet, being attached thereto and including strands of ballistic thread, the window frame being covered by a second portion of the flexible and stretchable woven sheet being attached thereto, such that, in the event of a blast outside the structure, the flexible and stretchable woven sheet being capable of stretching under impact of the blast, thereby reducing disintegration of the wall and securing the window frame in the wall, preventing fragments from the wall and preventing the window frame from being thrown into an interior of the structure by the blast.
According to further features in preferred embodiments of the invention described below, the flexible and stretchable woven sheet has two surfaces, one of the surfaces serves for direct permanent attachment with the flexible adhesive to the inward-facing surface of the at least one wall while the other of the surfaces directly faces the contents of the structure.
According to still further features in the described preferred embodiments the strands of ballistic thread are surrounded by a sheath for facilitating attachment to the inward-facing surface of the at least one wall.
According to still further features in the described preferred embodiments the flexible adhesive comprises a thermoplastic and elastic material.
According to still further features in the described preferred embodiments the ballistic thread is a para aramid.
According to still further features in the described preferred embodiments the ballistic thread is Kevlar® (made by DuPont).
According to still further features in the described preferred embodiments the ballistic thread is Spectra® (made by Allied Chemical).
According to still further features in the described preferred embodiments the ballistic thread is Dyneema®.
According to still further features in the described preferred embodiments the sheath includes a natural fiber.
According to still further features in the described preferred embodiments the sheath includes cotton.
According to still further features in the described preferred embodiments the strands include a retaining thread.
According to still further features in the described preferred embodiments the retaining thread is coiled around the sheath.
According to still further features in the described preferred embodiments the step of attaching a second portion of the flexible and stretchable woven sheet to at least one window frame in the at least one wall is effected by (i) turning over at least one peripheral portion of the flexible and stretchable woven sheet so as to form at least one folded edge; (ii) positioning a thickening device in the at least one folded edge; (iii) attaching the at least one folded edge to the at least one window frame via a mechanical attachment, such that the thickening device prevents disengagement of the flexible and stretchable woven sheet from the mechanical attachment.
According to still further features in the described preferred embodiments the mechanical attachment includes a bar securable to the window frame.
The present invention is of a means for preventing blast damage inside structures when the blast occurs outside the structure. This result is accomplished by attaching, as by use of adhesives and mechanical means, to inward-facing walls of the structure and to the window frames thereof woven sheets of material which contains ballistic thread. The ballistic thread may be wrapped or surrounded by a second material which can be readily attached to the wall.
In th
Friedman Mark M.
Hansen James O.
LandOfFree
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