IL167287A - Roof protection device and method - Google Patents

Description

167287 i?'Ti I 453353 mx ROOF PROTECTION DEVICE AND METHOD ROOF PROTECTION DEVICE AND METHOD Field of the Invention The present invention is generally in the field of ballistic shielding for the protection of the roofs of static structures, such as buildings, factories, houses and the like (hereinafter all the aforesaid kinds of buildings will be called simply "buildings"), from ballistic explosive devices, such as mortar shells, explosive artillery shells of up to 122 mm diameter, so-called "Kassam" and "Katyusha" missiles (hereinafter all the aforesaid kinds of shells, explosive devices and missiles will be called simply "ballistic explosive devices of missiles"). More specifically, the present invention concerns a novel, modular, light-weight ballistic protection device placed at a distance from the upper exposed surface of a roof, which absorbs the explosion of the aforesaid ballistic explosive devices, preventing same from contacting and damaging directly the roof. Likewise, the present invention also concerns a method for1 protecting the roofs of buildings, from ballistic explosive devices, which comprises constructing the aforesaid protection device above the roofs, or as an integral part of newly constructed roofs.

In addition, the present invention relates to the protection of roofs from kinetic impact of explosive devices - including circumstances where the explosive device does not explode and is thus essentially a kinetic impact device.

Background of the Invention Recently with the increase of terrorist activity, a number of buildings, both residential, including houses, and commercial, including factories, schools and other public buildings, have been seriously damaged, with the loss of lives in many cases, as a result of direct hits from ballistic explosive devices, launched from remote sites, landing and exploding directly on the roofs of such buildings or penetrating them, resulting in serious damage to the roof and causing fixtures, such as lights, ceilings, etc., being dislodged from the lower inner surface of the roof and falling together with shrapnel and explosion shock waves into the rooms below the site of the explosion, resulting in injury to those unfortunate to be there at the same time and also damage to the property.

Generally it is very difficult to protect civilian buildings of the type mentioned above from such ballistic explosive devices and likewise to prevent them from being launched against civilian targets, because these are usually launched from remote sites hidden from view. Accordingly, there has been a long-felt need to provide a roof protection device and a method for protecting a roof from such explosive devices, which would primarily prevent any direct explosion on and/or penetration of the roof of such a civilian building.

A number of proposals have been made for protecting the roofs from such ballistic explosive devices, usually of the kind launched from mortars, such as mortar shells, homemade so-called "Kassam" rockets, "Katyusha" rockets and artillery shells of up to 122 mm diameter. Most, if not all, of these proposals have been found to be impractical, either because they are too expensive to produce and implement on a large scale, or because they exceed the accepted free weight permissible on the roofs of the buildings for which they are intended. For example, there have been proposals to increase the thickness and strength of the upper, generally cement, layer of the roof to withstand ballistic explosive devices of the above mentioned type. Such a solution is not practical, because it would greatly increase the cost of the building by requiring all of the internal structures to be reinforced to withstand the additional weight of such a thickened roof, and also when such a roof does withstand the impact of such a missile, there will be at least superficial damage to the roof on its exposed surface, which in time may result in cracks opening up in the roof and subsequently such a roof would not be able to withstand an additional missile explosion and/or penetration, nor would it be impermeable to rain, with the consequences that the residents or workers would be exposed to additional missile attacks and/or natural elements, which is undesirable. In addition, such a damaged roof would require essentially complete replacement for purposes of repair, which is time-consuming, very impractical for the residents or workers in the building and expensive. Moreover, the above solution is not really practical for implementation on existing roofs, which in most instances are the primary roofs iryieed of protection as people already live or work under such roofs.

Another example of a possible solution is to add various layers of steel, steel and concrete, and the like¾ directly on to an existing roof to protect it from ballistic missiles. This is also impractical, because besides the limitation of the weight of the additional structure onto the existing roof, the roof would still be in direct contact with the explosion and/or penetration, this being dynamically transmitted from the protective . layers on to the upper exposed layer of the roof, so that either at the first or subsequent explosion and/or penetration, damage will be incurred directly on to the roof with the above noted consequences, leading to significant expense and time input for the purposes of repair of the roof.

Accordingly, it is an object of the present invention to provide a light-weight protective device which is modular, namely, it may be constructed from a number of identical or similar modules which may be readily replaced following a missile explosion, and which device may be placed sufficiently above the exposed upper surface of the roof, so as to prevent any direct impact of the explosive device or of any of the components of the protective device after their absorption of the initial explosion.

It is another object of the present invention to provide the above protective device for protecting a roof from the kinetic impact of explosive devices, even in circumstances where the explosive device does not explode and is thus essentially a kinetic impact device.

It is a further object of the present invention to provide the above protective device in a form which may be constructed above the exposed upper surface of the roof without bearing any weight on the roof itself, but rather to be placed on pre-existing supports on the roof, for example the outer structural walls which are higher than the roof surface and serve as a protective barrier, preventing people or objects from falling from the roof, or any other kinds of protective barriers normally placed on the roof to prevent people or objects falling there from. In this way, the weight of the protective device will be transferred to the ground via the outer building supports and will not be transferred to the roof itself, leaving the roof with the maximum required free weight.

It is yet another object of the present invention to provide a protective device as above which may be readily mass-produced in large quantities and flexible in construction, so as to be ready for direct implementation on any kind of roof, for example flat roofs, slanted roofs of the type in industrial buildings or private houses, which roofs are tiled, and the like. As such, it is an object of the present invention to provide a protective device which may be readily implemented by large-scale building constructors or even private citizens.

It is another object of the present invention to provide a method for protecting roofs of the above mentioned kinds of buildings from ballistic missiles, which comprises providing and constructing over such roofs the above mentioned protective device.

These and other objects of the present invention will be described in further detail in the following detailed description of the present invention.

Summary of the Invention In accordance with the present invention, a number of protective devices were constructed an tested in field testing with real ballistic missiles, as well as in computerized ballistic simulations, the surprising results of which determined that the protective device in accordance with the present invention may be a simple and inexpensive construction of modular design which is highly replicable, may be readily mass-produced and may be implemented by large-scale building constructors or even by private consumers. It may be placed over any kind of existing roof or it may be incorporated into the roofs of new buildings under construction.

The testing conducted included tests wherein the ballistic missile exploded and also wherein the missile used was designed not to explode in order to simulate the situation where an unexploded missile impacts a roof - as may be the case when a missile fails to explode for any number of reasons, for example, a fuze failure.

Accordingly, the present invention provides a protective device for the protection of a roof from ballistic missiles, which comprises: an upper plate; a lower plate; and a mid-layer comprising elongate ribs connected to both the upper and lower plates, each rib having essentially the same length as the upper and lower plates and the ribs being spaced from each other along the upper and lower plates.

In a particular embodiment of the present invention, the upper plate is made of 3-10 mm thick steel; the lower plate is made of 5-20 mm thick steel; and the ribs are made of 2-5 mm thick steel.

The ribs may be disposed orthogonal to the plates, but also at angles to each other along the length between the upper and lower plates.

According to another particular embodiment of the present invention, the protective device comprises: an upper steel plate of thickness in the range of 3 mm - 10 mm; a lower steel plate of thickness in the range of 7 mm - 15 mm; and a mid-layer comprising steel ribs of thickness in the range of 2 mm - 4 mm, which are connected to both the upper and lower steel plates, each rib having the same length as the upper and lower steel plates and the ribs being spaced from each other along the width of said upper and lower plates and connected to the upper and lower plates, and wherein the height of the ribs is in the range of about 250 mm -500 mm, and wherein the ribs may be parallel to each other or may be at angles to each other along the length between the upper and lower plates.

In a further embodiment of the invention, the protective device is placed on pre-existing support structures on a roof, said support structures having a height between about 100 mm and 400 mm, to provide a total height between the surface of the roof and the upper plate of said protective device in the range between at least 350 mm and about 900 mm.

In another embodiment of the invention, the protective device is constructed on the roof of a new building, said new building being built with support structures surrounding the roof of height between about 100 - 400 mm upon which said device is placed to provide a total height between the surface of the roof and in upper plate in said protective device in the range of at least 350 mm and about 900 mm.

In yet another embodiment of the invention, the protective device has said upper and lower plates of a flat planar shape.

In a further embodiment of the invention, the protective device has said lower plate of a flat planar shape and said upper plate and said ribs of the mid-layer of an angular shape.

In another embodiment of the invention, the protective device has said upper and lower plates with an angular shape.

In another embodiment of the invention, the protective device is used to cover an entire roof surface.

In yet another embodiment of the invention, the protective device for the purpose of covering the entire roof said device is of modular design, a number of identical or similar devices being connected to each other to cover the entire roof surface, with the outer modules being placed on the support structures on the outer walls of the roof and the inner modules being connected to and carried by the outer modules.

The present invention also provides a method for protecting a roof from ballistic missiles comprising - 167287/1 providing a protective device as described above; and attaching said protective device to support structures pre-existing on the roof or newly constructed on a new roof, to cover the entire roof surface.

Embodiments of the method of the invention include those wherein the protective device is according to any of the above embodiments.

The present invention will now be described in greater detail in the following non-limiting embodiments of the invention.

G83435-V001 6a Brief Description of the Drawings Figs, la - lc show schematically different views of the roof protection device of the invention, where Fig. la is a perspective schematic view, Fig. lb is a front or back schematic view and Fig. 1 c is a side schematic view; Fig. 2 is a schematic depiction of the component parts of the protection device of the invention; Figs. 3a and 3b show schematically the results of field testing (also determined by ballistic simulation tests using computers) of the protection device of the invention to protect against a typical warhead, wherein Fig. 3a shows the protective device before the explosion and Fig. 3b shows the protective device following the explosion; Figs. 4a - 4c are actual photographs the field test of the protection device of the invention, wherein in Fig. 4a there is shown a photograph before the explosion, in Fig. 4b there is shown a photograph following the explosion and in Fig. 4c there is a photograph of the concrete slab (simulated roof) following the explosion after removal of the protective device; Figs. 5a - 5d are additional photographs from field tests of the protection device of the invention, where in Figs. 5a and 5c there are shown the device before the explosion, Fig. 5a being a view from the front/back of the device and Fig. 5c being a view from the side of the device, and wherein Figs. 5b and 5d there is shown the result of the explosion of an explosive device directly above the upper plate of the protection device, Fig. 5b being a head on view and Fig. 5d being a close up view, of the protective device following the explosion; Fig. 6 is a schematic representation of a number of modules, each being a protective device of the invention placed above the roof of a flat roof building; Fig. 7 is a schematic depiction of an industrial building with a flat or angular roof upon which are arranged in an angular fashion protective modules of the invention; Fig. 8 is a schematic view of a large building with a long and wide roof span upon which is placed an angularly shaped protective device of the invention; Fig. 9 is a schematic representation of a private house with a triangular roof usually of the kind covered by roof tiles upon which has been placed an angularly shaped protective device of the invention; and Fig. 10 is an exploded perspective view of an embodiment of the protective rood device of the present invention.

Detailed Description of the Invention The following is a non-limiting detailed description of the preferred embodiments of the present invention as depicted in the accompanying drawings: In Figs, la-lc is a schematic depiction of the roof protection device of the present invention, wherein Fig. la is a perspective schematic view showing the three-layered protection device 1, comprising an upper steel plate 2, a lower steel plate 3 and the mid-layer comprising a number of ribs 4 running the length between the upper and lower steel plates and connected thereto. Preferably the connection between the upper plate 2 and the top edges of the ribs 4 and between the lower plate 3 and the lower edges of the ribs 4 is by way of welding. The protection device for illustration is placed on supports 5, which in turn are placed on a concrete slab 6, which is typical of the type incorporated into most roofs, and which concrete slab is placed on support blocks 7, which essentially simulates the walls over which the simulated roof (concrete slab 6) is placed.

Fig. lb shows a front or back view of the protection device of Fig. la, in which the aforesaid layers of the device and supports, concrete slab and support blocks as in Fig. la are depicted with the same reference numerals. In this depiction, only the first (or last) of the mid-layer ribs 4 connecting between the upper and lower steel plates 2 and 3 is apparent.

Fig. lc is a side view of the depictions in Figs, la and lb, from which the spacing of the mid-layer ribs 4 is apparent along the length of the upper and lower steel plates 2 and 3, the remaining supports 5, concrete slab 6 and support blocks 7 being as in Figs, la and lb.

It is apparent from the depictions in Figs la-lc that there is a substantial space between the top of the protection device, i.e. the upper steel plate 2, and the concrete slab (a roof), which is the total height of the protection device 1 and the height from the lower support to the concrete slab, which is the height of the supports 5, so that upon explosion of a ballistic missile in the proximity of the upper steel plate, the energy of explosion and the various, pieces of shrapnel are absorbed first in the upper steel plate 2, the air between the ribs 4, the ribs 4 themselves, and finally on the lower steel plate 3, without causing any significant deformation of lower plate 3 and without directly contacting in any way the concrete slab 6, thereby preventing any direct damage to the roof.

The protection device depicted schematically in Figs, la-lc is representative, and is but one example of a module of dimensions between 3 m - 4 m in length, 2 m - 3 m in width and of height between 250 mm - 500 mm, this being essentially the height of the ribs of the mid-layer 4. To cover a complete roof, a number of these modules may be placed lengthwise and/or widthwise and screwed or otherwise connected together on existing support structures surrounding the roof, such as a protective wall or barrier, as will be detailed below with respect to Figs. 6-9. Such existing structures (referred to as 5 in Figs, la-lc), themselves have a height between 100 mm - 400 mm, so that the total height between the roof (concrete slab 6 in Figs la-lc) and the upper steel plate 2 of the protection device 1 is between about at least 350 mm - about 900 mm, which provides for absorption of essentially all of the energy and shrapnel from the blast to occur well above the actual roof surface, thereby protecting same from any damage.

The upper plate 2 by virtue of its having a minimum thickness of about 4 mm and the fact that it is directly connected to the mid-layer ribs 4 which are connected directly to the lower plate 3, has a direct influence on the explosion of the explosive device and its placement at at least 350 mm and up to about 900 mm above the roof surface also determines the place of the explosion. More specifically, many explosive devices explode on impact so that the aforesaid minimum thickness of the upper steel plate 2, will not permit the explosive device to penetrate this plate before it explodes i.e. contact with this plate will result in an explosion of such explosive devices and by virtue of the fact that this has been caused at the upper plate 2 the explosion will therefore be at least 350 mm and up to about 900 mm from the roof surface. Other explosive devices which do not have to impact any structure before exploding but rather have proximity fuses, will also be caused to explode when coming into proximity with the upper plate 2 having such a minimum thickness so that again the upper plate 2 and its position of at least 350 mm and up to about 900 mm, determines where the explosion will be. Accordingly, placement of the protective device 1 on the support structures surrounding the roof and the construction of protective device 1 as described above both determines the distance from the roof at which the explosion will occur and it also ensures that the explosion will be in the proximity of the upper plate 2 and not within the protective device nor. in any close proximity to the roof surface itself. - Furthermore, in those instances where it will be necessary to make a protective device of substantial length and breadth, to cover large roof areas, for example a roof area of 20 m by 10 m, or even larger, without the need for placing any structures on the roof surface itself, the upper plate 2 may be angularly (for example, triangular) shaped for additional strength both as regards resistance to the explosive device and with regards to the protective device 1 as a whole. In such instances it may still be possible to retain the lower plate 3 as a flat planar structure without the fear of it buckling under its own weight, this because the lower plate 3 is connected to the ribs 4 of the mid-layer which are connected to the upper plate 2. In this way, the upper plate 2 also serves to "carry" the mid-layer and lower plate 3 and prevents buckling of lower plate 3 when same is necessarily of large dimension.

The size of the protective device to be placed on a roof is determined by the existing support structures on the roof as it is on these structures that the protective device will be placed without adding any additional weight to the roof surface itself. Accordingly," a number of identical or similarly sized modules may be connected together with the outer modules being directly placed on the existing roof support structures and the inner modules being connected to the outer modules and essentially being carried by them so that the complete roof covering by the protective device modules will be above the roof itself at a distance of between about 100 - 400 mm, depending on the height of the existing support structures on the roof. For new buildings support structures surrounding the roof surface may be constructed specifically to provide an optimum support for the protective device modules so that the entire covering of the roof by these modules will be carried entirely by the support structures and transferred to the ground and not to the roof surface itself.

The steel plates themselves of all of the layers are any commercially available steel plates, for example steel plates designated ST37 by various manufacturers.

In Fig. 2 is a schematic depiction of the construction of the protection device 1 of the invention, from which it is apparent that the ribs connecting between the upper steel plate 2 and lower steel plate 3 may be placed at angles to each other, or parallel to each other, angular design providing for extra strength. When the ribs are to be placed angularly, then the length of each, to provide for the desired height of between at least 250 mm to 500 mm between upper plate 2 and lower plate 3, will be slightly more than at least 250 mm or slightly more than the maximum 500 mm to achieve the aforesaid desired height.

Figs. 3a and 3b show schematically (as also determined by ballistic simulation tests using computers) the results of field testing of the protection device of the invention against a missile of the kind for which this device is intended to provide protection. In this test, before the explosion depicted in Fig. 3a, the protection device 1 of the invention is shown, having an upper steel plate 2 is of 4 mm thickness, the height of the ribs 4 between the upper and lower steel plates 2 and 3 is approximately 400 mm, and the height of the supports 5 is also approximately 300 mm to provide a distance of approximately 700 mm between the upper steel plate 2 and upper exposed surface of concrete slab 6 (simulated roof). Following the explosion, as depicted in Fig. 3b, it is clearly apparent that essentially only the upper steel plate 2 was damaged, shown by the deformity 10 where the missile hit, and some slight bending of some of the mid-layer ribs 4, without essentially any deformation of the lower steel plate 3 and no damage at all to the concrete slab 6, providing proof that the protection device 1 provided complete protection to the roof. As mentioned above, because of the modular construction of the protection device when' covering an entire roof, following an explosion, the module that is damaged (as shown in Fig. 3b) may be simply removed and replaced with an identical new module which is both quick and inexpensive for the owners of the building on which was placed he protection device.

Figs. 4a, 4b and 4c show actual photographs of the field test described with reference to Figs. 3a and 3b above, in which a ballistic missile was exploded above the protection device 1. In Fig. 4a, before the explosion, there is a schematic showing of the point of impact and explosion 11 above the upper steel plate 2 of the protection device 1, the rest of the components being numbered as in Figs. 1-3 above. In Fig. 4b there is shown the protection device, after the explosion, from which it may be discerned that there is a deformity 12 in the lower steel plate 3 (as the photographs are from the side, it is not possible to see the damage on upper steel plate 2, as in Fig. 3b, nor the deformation of some of the mid-layer ribs 4, as in Fig. 3b), which clearly is still some distance, approximately 300 mm, from the concrete slab 6, clearly demonstrative of the fact that the protection device 1 indeed protected the concrete slab 6 (simulated roof) from the explosion.

Fig. 4c shows the concrete slab 6 following removal of the protection device 1 from above it following the explosion, from which it is clearly apparent that no damage at all occurred to this concrete slab, this being proof that the protection device 1 is fully capable of protecting a roof.

Figs. 5a-5d show additional photographs from additional field tests of the protection device 1 of the invention. In Figs. 5a and 5c there is shown the construction from the front/back (Fig. 5 a) or from the sides (Fig. 5 c), before explosion. In Fig. 5c, the angular spacing of mid-layer ribs 4 is apparent between the upper steel plate 2 and lower steel plate 3.

In Figs. 5b and 5d there is shown the result of the explosion of a device directly above upper plate 2, from which it is apparent that this explosion caused a deformation of lower plate 3 (the damage to the upper plate 2 and some of the ribs 4 is not apparent, because of the head-on view of Fig. 5 b or the close-up view of the space between the concrete slab 6 and lower surface of lower plate 3, but it is essentially as schematically depicted in Fig. 3b above.

Again, these experiments demonstrate beyond doubt that no damage occurred to the concrete slab 6 (simulated roof) following the explosion, all of the energy and shrapnel of the explosion being absorbed in the various layers of the protection device 1.

A number of field tests using different constructions of the protective device 1 of the invention were carried out, each protective device having a different weight but within the above mentioned dimensions for each of the upper steel plate 2, lower steel plate 3 and ribs 4. In all of these tests the different protective device all performed well, preventing any damage to the simulated roof surface (concrete slab 6 of Figs. 1, 3, 4, and 5). From all of the field tests it was apparent that immediately upon impact or proximal explosion of the explosive device in the immediate vicinity of the upper steel plate 2, this upper steel plate took most of the brunt of the explosion, is damaged at the site of the explosion and there was observed deformation of some of the mid-layer ribs 4 but no apparent deformation of lower plate 3 and no damage at all to the concrete slab 6 (simulated roof), indicative of the fact that the protective device by virtue of its steel plates, inner ribs and air between the ribs and in the spaces between the upper and lower plates 2 and 3 are able to absorb essentially all of the shock waves of the explosion and the shrapnel without any thereof passing the lower plate 3 and hence not reaching the surface of the roof.

Fig. 6 is a schematic depiction of a side view of a building 13, representative of for example, a school, having a flat roof with existing roof supports upon which has been placed a number of protective devices 1 of the invention. In Fig. 6 it is seen that there are five protective devices 1 placed along the length of the roof 6 upon existing roof supports 5, each protective device having the aforementioned 3 layers: the upper steel plate 2 of thickness in the range of 3 - 10 mm, a lower steel plate 3 of thickness in the range of 7 - 15 mm and a mid-layer 4 comprising steel ribs each of thickness in the range of 2-4 mm. Each separate module is closely connected to its neighboring modules to provide a complete covering for the roof. In the event that the building 13 did not have pre-existing supports 5 extending above the surface of the roof 6, such supports may be placed at the alter edges of the roof and in the intervening portions of the roof above structural support walls 14, so that when modules of the protective device 1 are placed on the support structures 5 the weight of the modules will be transferred to the ground and not to the roof surface. As previously mentioned such support structures have a height of between 100 - 400 mm so that together with the height of the protective device 1, there will be a distance of at least 350 mm up to 900 mm or even more between the roof surface 6 and the upper plate 2 of the protective device 1 , to provide optimal protection for the building 13 depicted in Fig. 6.

Fig. 7 is a schematic depiction of a side view of an industrial building 15 which may have either a slanted roof structure as is often the case or it may have a flat roof structure, upon which have been placed modules of the protective device 1 in an angular construct for maximum protection and when necessary when the underlying roof of the building 15 is slanted as is often the case. In Fig. 7 there are shown above each portion 16 of the building 15 modules of the protective device 1, each having the three layer configuration, each layer within the range of dimensions as mentioned herein above placed at an angle to each other. The placement of each module of the device 1 is at the external support structure above the roof surface for the outer modules and on the internal support structures 14 for the internal modules. In Fig. 7 it is shown that one of the modules is of greater length than the other, with the longer module connected above the shorter module. The direction of the angular construction of the protective modules is such that the longer modules are facing and inclined towards the expected direction of entry of an explosive device as depicted by the arrow in Fig. 7, this configuration providing the optimal protection against the explosive device.

Fig. 8 is a schematic depiction of a side view of a large building 17, for example a hall, warehouse, school or the like covered by protective device modules 1 of the invention. In Fig. 8 it is apparent that the span of the roof 6 of building 17 is extremely large so that the protective module 1 is constructed with a flat planar lower plate 3, with the ribs 4 having a triangular shape of greatest height at their end above the mid portion of the roof and their lowest height at the external support wall 7 of building 17. The upper plate 2 is also of angular shape reaching its apex at the mid portion above the roof. At the apex an additional plate is placed along the width of the module and provides further internal strengthening for the protective module. The triangular construction shown in Fig. 8, and as discussed herein above, provides maximum strength for the module 1 while also preventing any buckling under its weight of the lower plate 3.

Fig. 9 is a schematic depiction of a side view of a private house 19 having a protective module 1 placed above its roof. The house 19 is of the kind having an angular roof, usually covered by tiles. The protective module 1 is therefore configured such an angular structure to closely follow the contours of the house's roof and so that its weight is transferred to the outer support walls 7 of the house and not on to the roof 6 of the house. As before, the protective device 1 has the 3 layers each layer within the dimensions mentioned herein above and indicated with the same numerals in Fig. 9. For aesthetic purposes, the roof tiles normally placed on the roofs of houses of a type shown in Fig. 9, may be placed directly above the protective device 1.

In accordance with the present invention as already mentioned, the protective device may be readily applied to existing buildings to protect roofs using the support walls or barriers already in place around the roof surface upon which will be placed the modules of the protective device and which will be connected each to each other providing a complete covering of the roof. Following any explosion on any of such modules, the damage that module may be readily removed and replaced with a new one.

In the event that the roof is not a flat roof but rather a slanted roof of the type present in industrial buildings or private houses (usually tiled roofs), the modules of the protective device may be also applied onto such slanted roofs, when necessary the upper and lower plates 2 and 3 of the device may be formed with an angle to get the closest and best fit of the device onto the underlying slanted roof structure while all the time ensuring that there is a distance of at least 350 mm and up to about 900 mm or more between the actual concrete slab of the roof and the outer surface of the upper plate 2 of the protective device. As described and also depicted herein above, depending on the size of the roof surface to be covered by the protective device of the invention, so will the dimensions and shape of the protective device be determined, i.e. it may be made as a planar 3 layered structure of varying lengths and widths, or it may be constructed in an angular or triangular shape, and in some cases (e.g. that depicted for industrial buildings as in Fig. 7), modules may be constructed one above the other for an angled construction for optimal protection. In situations where a very long protective device module is required there will be a danger of buckling of the lower plate 3 because of the weight of the steel plate itself which could result in the lower plate impacting the roof at the trough of the buckling following an explosion at the upper plate 2 with damage to the roof. In such instances the construction (e.g. see Fig. 8) it would therefore be desirable to use a flat lower plate, and to have the upper plate in an angled shape pointing upwards and likewise to so construct the ribs of the mid layer to prevent any such buckling.

It should also be noted that ease of construction and implementation of the protective device of the present invention allows for its standardization so that any number of manufacturers may produce it and install it in accordance with the necessary regulatory specifications. In such instances where the protective device of invention is placed upon an existing roof and that roof already has various fixtures such as solar heaters, solar energy collection plates, antennas, ventilation outlets or devices, decorative items, or the like, all of these may be removed from the roof, the protective layer placed on the roof and then the aforesaid fixtures being replaced on top of the protective device so that the roof inclusive of the protective device will be as before with no inconvenience to the people using the building under the roof.

Likewise, in the construction of new buildings, the protective device may be directly constructed as part of the roof by the constructor who will ensure that there is a height of at least about between 350 mm - 900 mm or more between the actual concrete slab of the roof and the top of the protective device. In such new buildings, the upper part of the protective device may have applied to it all the necessary additional fixtures as noted above and even painted in a decorative way so as not to be aesthetically undesirable.

Fig. 10 illustrates an exemplary embodiment of a roof protection device la of the present invention, which has shown to be particularly useful for preventing the penetration of missiles that have not exploded (i.e. a kinetic type impact). The device la comprises an the upper plate 2a that may be made out of 10-20 mm thick steel; a lower plate 3a that may be made of 5-20 mm thick steel; and ribs 4a that may be made of 3-5 mm thick steel. The distance between the plates 2a and 3a may be 500-1500 mm and the distance between the lower plate and the roof (e.g. concrete slab 6 in Figs la-lc which is not seen in Fig. 10) may be 500-1500 mm.

For increased strength, the roof protection device la may further comprise supports 20 spaced at intervals between the ribs 4a. To help locate the supports 20, the ribs 4a may comprise slots 22, or any of a number of other arrangements.

Further shown is an example of module connector system 24 useful for connecting modules.

It should be understood that materials other than steel may be used in construction of the roof protection device of the present invention, including other metals, alloys, composites or any other suitable material, mutatis mutandis (including adjustments in the thicknesses of the plates 2 and 3 and the ribs 4; and spacing between those plates and between the ribs). 167287/5

Claims (19)

1. A roof structure providing protection of buildings against kinetic impact and explosion of ballistic missiles, comprising: an upper steel plate 3-10 mm thick; a lower steel plate 5-20 mm thick; a mid-layer comprising elongate 2-5 mm thick steel ribs connecting the upper and the lower plates, each rib having a length corresponding essentially to a length of the upper and lower plates and the ribs being spaced from each other along the upper and lower plates; and support structures for supporting the lower plate at a spacing from a pre-existing roof surface; said roof structure adapted to be deformed but not penetrated by impact of ballistic missiles.

2. A roof structure according to claim 1 , wherein the ribs are disposed at angles to each other.

3. A roof structure according to claim 1 , wherein: the mid-layer comprises steel ribs of a thickness in the range of 2-4 mm; the ribs being spaced from each other along a width of said upper and lower plates; a height of the ribs is in a range of 250 mm - 500 mm; and the ribs are one of parallel to each other or at angles to each other along the length between the upper and lower plates.

4. A roof structure according to claim 1 , wherein said support structures have a height between about 100 mm and 400 mm, to provide a total difference in height between the surface of the pre-existing roof and the upper steel plate of said roof structure of between 350 mm and 900 mm.

5. A roof structure according to claim 1 , wherein the upper and lower plates are of a flat planar shape.

6. A roof structure according to claim 1 , wherein the lower plate is of a flat planar G90863-V00I .Doc 19 167287/5 shape and the upper plate and ribs of the mid-layer are of an angular shape.

7. A roof structure according to claim 1 , wherein the upper and lower plates are of an angular shape.

8. A roof structure according to claim 1 , wherein said roof structure is used to cover an entire roof surface of a building.

9. A roof structure of claim 8, comprising a number of identical or similar roof structure modules connected to each other to cover the entire roof surface, with outer modules supported on support structures constructed on outer walls of the building and inner modules connected to and supported by the outer modules. -

10. A roof structure providing protection of buildings against kinetic impact and explosion of ballistic missiles, comprising: an upper steel plate 10-20 mm thick; a lower steel plate 5-20 mm thick; a mid-layer comprising elongate 3-5 mm thick steel ribs connecting the upper and lower plates, each rib having a length corresponding essentially to a length of the upper and lower plates and the ribs being spaced from each other along the upper and lower plates; and support structures for supporting the lower plate at a spacing from a pre-existing roof surface; said roof structure adapted to be deformed but not penetrated by impact of ballistic missiles.

11. A roof structure according to claim 10, wherein said support structures have a height between about 100 mm and 400 mm, to provide a total difference in height between the surface of the pre-existing roof and the upper steel plate of said roof structure of between 350 mm and 900 mm.

12. A roof structure according to claim 10, wherein the upper and lower plates are of a flat planar shape.

13. A roof structure according to claim 10, wherein the lower plate is of a flat planar G90863-V001.Doc 20 167287/4 shape and the upper plate and ribs of the mid-layer are of an angular shape.

14. A roof structure according to claim 10, wherein the upper and lower plates are of an angular shape.

15. A roof structure according to claim 10, wherein said roof structure is used to cover an entire roof surface of a building.

16. A roof structure of claim 15, comprising a number of identical or similar roof structure modules connected to each other to cover the entire roof surface, with outer modules supported on support structures constructed on outer walls of the building and inner modules connected to and supported by the outer modules.

17. A building designed for protection against kinetic impact and explosion of ballistic missiles, comprising: a roof having a roof structure comprising: an upper steel plate 10-20 mm thick; a lower steel plate 5-20 mm thick; and a mid-layer comprising elongate 3-5 mm thick steel ribs connecting the upper and the lower plates, each rib having a length corresponding essentially to a length of the upper and lower plates and the ribs being spaced from each other along the upper and lower plates, said roof structure adapted to be deformed but not penetrated by impact of ballistic missiles; and support structures for supporting said roof structure, said support structures extending above a height of the building between 100 - 400 mm to provide a total height between the height of the building and the upper plate of the roof structure of between 350 mm and 900 mm.

18. A method for protecting a building from kinetic impact and explosion of ballistic missiles, comprising: providing a roof structure comprising: an upper steel plate; G90863-V001.Doc 21 167287/2 a lower steel plate; and a mid-layer comprising elongate steel ribs connecting the upper and the lower plates, each rib having a length corresponding essentially to a length of the upper and lower plates and the ribs being spaced from each other along the upper and lower plates; and said roof structure adapted to be deformed but not penetrated by the impact of ballistic missiles; and providing support structures on a building roof; and attaching said roof structure to said support structures to cover an entire roof surface; wherein when contacted by a ballistic missile said roof structure is deformed but not penetrated.

19. A method in accordance with claim 18, wherein: the upper steel plate has a thickness in the range of 3 mm-10 mm; the lower steel plate has a thickness in the range of 7 mm-15 mm; the steel ribs have a thickness in the range of 2 mm-4 mm; the height of the ribs is in a range of 250 mm-500 mm; the ribs are one of parallel to each other or at angles to each other along the length between the upper and lower plates. For the Applicant Seligsohn Gabrieli & Co. G90863-V001.Doc 22