Abstract:
A mobile aboveground safety shelter to provide protection from dangerous events such as storms, tornadoes and similar occurrences is provided. The shelter includes a pallet and a room connected to the pallet. The pallet has a generally planer base and a wall extending upward from the base. The wall and base form a cavity suitable for containing a weighting material.

Description:
FIELD OF THE INVENTION 
     The present invention relates to safety shelters used to provide protection from dangerous events such as storms, tornadoes and similar occurrences. More specifically, the present invention relates to aboveground safety shelters. 
     BACKGROUND OF THE INVENTION 
     There are many parts of the world that are periodically exposed to storms, tornadoes and other severe wind conditions. Conventional aboveground safety shelters are either built belowground or depend almost completely upon attachment to a concrete foundation or ground anchors to resist movement. To resist wind induced overturning, uplift and sliding, such concrete foundations are generally comprised of expensive subterranean concrete footings. Some conventional metal shelters can be unbolted from their heavy concrete foundations for movement to a new location; however, each new location requires the preparation of another heavy concrete foundation to which the shelter can be bolted. In most instances the cost and inconvenience of pouring of a new foundation (and the attendant environmental impact of their subsequent demolition and removal) renders impracticable the redeployment of a metal protective shelter for temporary use. 
     SUMMARY OF THE INVENTION 
     In accordance with one embodiment of the invention there is provided an aboveground safety shelter comprising a pallet and a room. The pallet has a generally planer base and a wall extending upward from the base wherein the base and the wall form a cavity suitable for containing a weighting material. The room is connected to the pallet. The pallet and room are configured such that, when the weighting material is added to the cavity, the shelter resists movement in storms without additional anchoring means or belowground components. 
     In accordance with another embodiment of the invention there is provided a method of deploying an aboveground safety shelter. The method comprising:
         (a) transporting, to an installation site having a ground surface, the shelter including:
           a pallet having a generally planer base and a wall extending upward from the base wherein the base and the wall form a cavity suitable for containing a weighting material; and   a room connected to the pallet wherein the pallet and cylindrical room are configured such that, when the weighting material is added to the cavity, the shelter resists movement in storms without additional anchoring means or belowground components;   
           (b) placing the shelter on the ground surface; and   (c) introducing the weighting material into the cavity.       

    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a safety shelter in accordance with one embodiment of the present invention which is shown without the presence of a weighting material. 
         FIG. 2  is a perspective view of the safety shelter of  FIG. 1  shown with the weighting material added. 
         FIG. 3  is a side view of the safety shelter of  FIG. 1 . 
         FIG. 4  is a side view of the safety shelter of  FIG. 1  shown on a roll-off container transport trailer. 
     
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     With reference now to  FIGS. 1-3 , there is illustrated an aboveground safety shelter  10  in accordance with one embodiment of the current invention. Safety shelter  10  generally includes a room  12  and a skid or pallet  30 . Safety shelter  10  relies on a weighting material  60  contained in pallet  30 , along with the weight of the material of construction for safety shelter  10 , to provide the majority of resistance, and preferably the primary resistance, to overturning, uplifting and sliding caused by storms having severe wind conditions such as tornadoes and hurricanes. While weighting material  60 , along with the weight of the material of construction for the safety shelter, provides the primary resistance, secondary resistance can be provided by the shape of the storm shelter, as further described below; however safety shelter  10  does not rely on anchoring means or belowground components, such as poured ground foundations, in ground anchors or stabilizing arms. By “primary resistance” it is meant that the design of safety shelter  10  is such that weighting material  60 , along with weight of the material of construction of the safety shelter, can provide all the resistance necessary to meet or exceed limits established by the National Storm Shelter Association (NSSA) standard, the Federal Emergency Management Agency (FEMA) standards, the American Society of Civil Engineers (ASCE) standards and/or the ICC/NSSA 500 standard to prevent overturn, uplifts and sliding caused by severe wind conditions without reliance on the secondary resistance provided by the shape of the storm shelter and without reliance upon additional anchoring means or belowground components. Additionally, it is preferred that the weight of the storm shelter be concentrated below the top of the pallet to increase resistance to overturning, uplifting and sliding by creating a lower center of gravity for the storm shelter. Accordingly, at least 60% of the weight of the storm shelter can be in the pallet after addition of the weighting material. Generally, at least 70% of the weight of the storm shelter can be in the pallet after addition of the weighting material. For some embodiments, at least 80% or even at least 90% of the weight of the storm shelter can be in the pallet after addition of the weighting material. 
     Returning now to  FIGS. 1-3 , room  12  has a generally cylindrical shape. The cylindrical shape helps facilitate air flow around room  12  so that torque and movement of room  12  caused by high wind conditions are reduced. Room  12  can have other shapes but ones that facilitate air flow around room  12  are preferred, such as room shapes that have simple curved shapes; for example ones that are circular or oval in cross-section. Additionally, such curved shapes help deflect impact from air borne debris and, thus, reduces the chance of penetration. 
     Room  12  comprises a wall  14 , a roof  20 , a floor  24  and door  26 . Wall  14  has upper end  16  and lower end  18 . Wall  14  is shown as being a cylindrical wall but wall  14  can have other shapes. Generally, wall  14  can have a simple curved cross-sectional shape, as described above for room  12 , and preferably can have a cylindrical shape; that is, a circular cross-section. As can best be seen by  FIG. 3 , roof  20  is connected along edge  22  to upper end  16  of wall  14 . Roof  20  can be attached by welding or other means to secure it to or make it integral with pallet wall  14 . Roof  20  has a curved contour such that it is higher near the center of the room than at the walls. A curved contour, while not required, is believed to provide secondary resistance against overturns and sliding because of its aerodynamic structure. Additionally, a curved contour helps deflect impact from air borne debris and thus, reduces the chance of penetration. Generally, where wall  14  is cylindrical, roof  20  can be in the form of spherical cap. Floor  24  is connected to lower end  18  of wall  14 . Floor  24  can be formed from part of base  32  of pallet  30 . 
     As best seen in  FIGS. 1 and 2 , room  12  has door  26  for accessing the interior of room  12 ; that is, for allowing ingress into and egress out of room  12 . It is preferred that door  26  be configured so that debris that falls outside door  26  cannot block it from functioning. Accordingly, it is preferred that door  26  mounted inside room  12  or so that it opens inward into room  12 . Thus, in one embodiment door  26  can be a sliding door mounted on the interior of wall  14 . In another embodiment door  26  is hinged mounted and opens into the interior of room  12 , as illustrated in  FIG. 2 . Also, latch  27  is provided for securing door  26  during severe weather conditions. Additionally, room  12  can have a turbine vent  28  connected by vent duct  29  in order to provide ventilation for room  12 . 
     Pallet  30  is shown as having a generally rectangular shape. The rectangular shape facilitates loading on a trailer and moving of safety shelter  10 ; however, other shapes can be used if desired, such as square, oval or oblong. Pallet  30  comprises base  32 , side walls  34  and  38 , and end walls  36  and  40 . Base  32  comprises a bottom planer surface  31  and a top planer surface  33 . Typically, bottom planer surface  31  is designed to fit flush on the ground surface of the installation site without any gaps, holes or other voids that would allow wind to get underneath base  32 . 
     Walls  34 ,  36 ,  38  and  40  extend upward from base  32  to form one or more cavities  42 , as further described below. Room  12  is attached to pallet  30  and a portion of base  32  can serve as the floor  24  of room  12 . Room  12  can be attached by welding or other means to secure it to or make it integral with pallet  30 . Additionally, room  12  can extend across pallet  30  so as to extend into and/or form a portion of side walls  34  and  38 , as illustrated in the figures. Accordingly, side walls  34  and  38  and end wall  36  form three sides of first cavity  44  with wall  14  of room  12  serving as the fourth side of first cavity  44 . Similarly, walls  14 ,  34 ,  38  and  40  form second cavity  46 . Second cavity  46  is further divided into an entry way  52 , and a first portion  48  and a second portion  50  located on each side of entry way  52 . Entry way  52  is defined by a first wall  54  and second wall  56  and has stair  58 . Entry way  52  allows for door  26  to extend downward adjacent to base  32  by defining a cavity portion where there is no weighting material, best seen in  FIG. 2 . Thus, entry way  52  allows for a taller door, without adding height to room  12 , than would be allowed if entry way  52  were filled with weighting material. 
     As shown in  FIG. 2 , first cavity  44 , and first portion  48  and second portion  50  of second cavity  46  are filled with a weighting material  60  when the safety shelter  10  is configured for use as a storm shelter. Weighting material  60  can be any material that has suitable weight so that safety shelter  10  resists uplifts, overturns and sliding. Generally, the type and amount of weighting material  60  should be sufficient to provide safety shelter  60  with enough resistance to overturn, uplifts and sliding to meet NSSA, FEMA, ASCE and/or ICA/NSSA standards. Typically, concrete can be used as the weighting material because it can be readily added to cavities  42  either before or after the safety shelter&#39;s initial placement and, once hardened, is not subject to being blown-out under severe wind conditions. Optionally, other weighting materials can be used. If a substance susceptible to being blown-out, such as sand is selected, then it can necessitate a top being attached to pallet  30  over cavities  42  to ensure that a suitable amount of weighting material is retained in the cavities during servere wind conditions in order to resist uplifts, overturns and sliding. While the amount of weighting material will be dependent upon the particular dimensions of the safety shelter, generally cavities  42  can contain a total weighting material of at least 14,000 pounds and can contain a total weighting material of at least 20,000 lbs or even at least 25,000 pounds. As mentioned above, most of the weight of the safety shelter will be in the pallet, thus once cavities  42  are filled, the pallet can weigh over 24,000 pounds, can be over 30,000 pounds, and can be over 40,000 pounds. 
     Pallet  30  can have other features such as tow bars  62 , which aid in the loading and unloading of safety shelter  10  from a trailer, such as a roll-off container transport. Additionally, walls  34  and  38  can have inclined outer surfaces  64 , which are at an acute angle to base  32  and, thus, form a side edge  66  that can dig into the ground if lateral sliding occurs and, hence, aid in resisting such lateral motion. 
     Where applicable, the components for safety shelter  10  are formed from a material suitable to resist breakage and penetration during severe wind conditions from stresses both caused by the wind and by flying debris. For example, room  12  should be composed of a material suitable to prevent penetration from flying debris. In the past, such rooms have been constructed of layers of metal and concrete. It is an advantage of the current design that the primary weighting of the safety room is in the pallet; thus, room  12  can be more economically made from metal alone. Additionally, this construction provides for a lower center of gravity to provide better resistance to overturns, uplifts and sliding and aids in the portability of safety shelter  10 . Generally, safety shelter  10  will be primarily constructed of metal formed and/or welded together and of sufficient strength to protect occupants and contents of safety shelter  10  from severe winds (typically, winds exceeding about 50 mph and which can exceed 150 mph or even 250 mph) and impact from associated wind borne debris. By “primarily constructed” it is meant that at least the pallet base  32  and walls  34 ,  36 ,  38  and  40  and room wall  14 , roof  20 , floor  24  and door  26  are constructed of metal. Typically, they will be formed from structural steel. Suitable structural steels are grades A36, A572 Grade 50 and similar. Generally, the steel will have a thickness from 1 inch to 1.5 inches; however, the steel should be of sufficient size and grade to meet or exceed deflection and penetration limits established by the National Storm Shelter Association (NSSA) standard, the Federal Emergency Management Agency (FEMA) standards, the American Society of Civil Engineers (ASCE) standards and/or the ICC/NSSA 500 standard. Lesser or greater material thickness, types and strengths can alternatively be used. 
     When cavities  42  are filled with weighting material, pallet  30  is low and flat; that is, generally planer so as to be close to the ground and to thus, minimize wind forces on pallet  30 . Safety shelter  10  is sized so as to facilitate relocation and yet still ensure adequate resistance to severe wind. Accordingly, a typical safety shelter can have a pallet  30  with a width of about 7 feet to about 12 feet and a length of from about 16 feet to about 24 feet, and can have a width of about 10 feet and a length of about 20 feet. The width of room  12 , which for cylindrical rooms will be the diameter, can be equal to or less than the width of the pallet. Typically, the width of room  12  is about the same as the width of pallet  30 ; hence, can be about 7 feet to about 12 feet, and can be about 10 feet. More generally, in order to provide suitable size cavities  42  for weighting material  60 , the length of pallet  30  can be more than 150% the width of pallet  30  or the width of room  12 , and can be more than 175% of the width of pallet  30  or the width of room  12  and often can be about 200% or more of the width of pallet  30  or the width of room  12 . 
     Safety shelter  10  can have a height from the bottom of base  32  to the top of roof  20  of less than 8 feet, can be from about 6 feet to less than 8 feet and can be from about 6.5 feet to about 7.5 feet. Typically, room  12  will extend substantially the entire height of the safety shelter but can be less. A pallet meeting the above described dimensions can have a height of from about 15% to about 35% of the height of safety shelter  10 , can have height from 20% to 30% of the height of safety shelter  10 , and typically, can have a height of about 25% of the height of safety shelter  10 . 
     In accordance with the above, an exemplary safety shelter could be 20 feet long and 10 feet wide having safety shelter height of 7 feet 2 inches and a pallet height of about 1 foot 7 inches. When the weighting material is added the exemplary safety shelter would be about 44,000 pounds with about 40,000 pounds being attributed to the pallet (including weighting material). 
     Turning now to  FIG. 4 , there is depicted a side view of safety shelter  10  shown on a transport trailer  70 . Safety shelter  10  is ready for transport to an installation site for use. Safety shelter  10  can be loaded on to the trailer  70  by conventional means such as using a winch to drag the safety shelter up a ramp onto the trailer. Preferably, transport trailer  70  is a roll-off container transport trailer and can be angled by hydraulic or similar adjustment means to form a ramp so that safety shelter  10  can be loaded and unloaded without use of a separate ramp. In accordance with one embodiment of the method of the invention, after it has been loaded onto the transport trailer  70 , safety shelter  10  is transported to an initial installation site having a ground surface. 
     The ground surface of the installation site can be prepared for safety shelter  10  prior to installation. Generally, the only preparation that is needed is leveling off the ground surface so that safety shelter  10  will sit level on the ground. For soft ground, which might be prone to settling, additional ground preparation may be needed such as excavating the top soil so as to reduce settling. 
     After arrival at the initial installation site safety shelter  10  is unloaded from the trailer  70  and placed on the ground surface. For the initial use of safety shelter  10 , weighting material  60  can be added prior to loading on the trailer for transport to the initial installation site. Thus, upon unloading from trailer  70 , the safety shelter is ready for use. Alternatively, safety shelter  10  can be transported without the weighting material and weighting material  60  can be introduced into cavities  42  after safety shelter  10  is placed on the ground surface. Thus, safety shelter  10  would be ready for use after an appropriate curing time. 
     Once safety shelter  10  is no longer needed at the initial installation site, it can be loaded onto a transportation trailer  70  and can be transported to a second or subsequent installation sight having a ground surface. After arrival at the second installation sight, safety shelter  10  is placed on the ground surface of the second installation site and is ready for use. 
     As has been described, the safety shelter  10  is an aboveground safety or protective shelter, which is capable of redeployment. Safety shelter  10  resists movement in storms without additional anchoring means or belowground components, such as poured ground foundations, in-ground anchors, or stabilizing arms. The above described safety shelter is capable of protecting people from severe winds up to and even exceeding 250 mph and withstanding uplifting, overturns and sliding forces generated by such winds. 
     Although the disclosed invention has been shown and described in detail with respect to a preferred embodiment, it will be understood by those skilled in the art that various changes in the form and detailed area may be made without departing from the spirit and scope of this invention as claimed. Thus, while the present invention is well adapted to carry out the object and advantages mentioned as well as those inherent therein, numerous changes may be made by those skilled in the art and such changes are encompassed within the spirit of this invention as defined by the appended claims.