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TECHNICAL FIELD 
       [0001]    The invention generally relates to structures to protect building occupants from earthquake effects. 
         [0002]    More particularly the invention relates to protective structures fitting under an office desk or similar furniture and allowing an office occupant to enter the protective structure which is resistant to overhead impact. 
       BACKGROUND ART 
       [0003]    Articles such as earthquake or tornado protection pods or protection structures are known. 
         [0004]    Such a structure is known, for instance, from U.S. Pat. No. 5,662,132 entitled “Structural Protective Shelter” and granted on Sep. 2, 1997 which describes a tubular steel structure designed to be used around a bed, chair or desk. The structure is comparatively large and not easily assembled or moved. 
         [0005]    U.S. Pat. No. 6,349,508 describes a high strength case with openings to allow a person to enter and remain within for some time, however the case is comparatively large and an integral whole and again is not easily moved. 
         [0006]    Such structures fail to solve all the known problems of earthquake protection pods since they do not readily allow placement where an office worker can seek shelter and are not amenable to assembly on site. 
         [0007]    Therefore a need exists for a solution to the problem of ease of access, ease of placement and ease of construction. 
         [0008]    The present invention provides a solution to this and other problems which offers advantages over the prior art or which will at least provide the public with a useful choice. 
         [0009]    All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. 
       SUMMARY OF THE INVENTION 
       [0010]    The invention consists in a protection pod having at least three compression resistant elongate legs capable of resting substantially vertically on a floor, each leg having at the upmost end a socket capable of receiving laterally within itself at least one portion of a bracing frame extending between the upmost ends of all the legs, each socket and received portion of bracing frame being retainable together by a fastening means such that the bracing frame is retained substantially at right angles to the legs and has a spacing between socket and bracing frame which will crush under loading on the upmost end of the socket. 
         [0011]    Wherein the protection pod has at least one brace extending between the lower portion of a first leg and a second leg. 
         [0012]    Wherein the braces are lateral. 
         [0013]    Wherein the braces are at an angle and in the plane between the first leg and the second leg. 
         [0014]    Wherein the pod has a floor plate, the floor plate being affixed to the lowermost end of each leg of the protection pod. 
         [0015]    wherein the floor plate has a stub fitting within each leg of the pod. 
         [0016]    Wherein the socket at the upmost end of a leg has a lower crush resistance to vertical forces than the remainder of the substantially vertical leg of which it forms a part. 
         [0017]    Wherein the pod is dismantleable and relocatable. 
         [0018]    These and other features of as well as advantages which characterise the present invention will be apparent upon reading of the following detailed description and review of the associated drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  is a rear perspective view of a protection pod. 
           [0020]      FIG. 2  is a front perspective view of a similar protection pod. 
           [0021]      FIG. 3  is a detail view of the joint at the top of each pod leg. 
           [0022]      FIG. 4  is a view of a pod with a grid top and a base floor. 
           [0023]      FIG. 5  is a view of the top leg joint after impact by a heavy vertical load. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0024]    Referring now to  FIG. 1  a protection pod  101  is shown. The pod is intended to fit under an item of office furniture such as a desk and includes leg posts  102  resting on a floor with frame sockets  103  at the top of the legs, and a top frame  104  which locates into the sockets  103 . The top frame is intended to clear the bottom of a desktop so that a pod may be slid under a desk, but differing dimensions may be used for differing furniture. The space within the pod is sufficient to easily accommodate a seated hunched person, and someone within the pod would be substantially protected from impacts from above. 
         [0025]    Legs  102  may be stabilised at set distances by linking bars  106 ,  107  which may be secured to the legs by internal nuts, by devises, by pins, or by any other fixing method holding legs  102  a fixed distance apart at floor level. There is no linking bar along one edge to allow unimpeded access for a potential occupant. As shown there are four leg posts  102  but the pod may have three legs or more than four, provided that it provides a stable enclosure not collapsing under the unusual loads placed on it by loose furniture and parts of a building falling on it during an earthquake or tornado. 
         [0026]      FIG. 2  shows the same enclosure of legs  102  and top frame  104  with a floor plate  202  in place. Preferably the floor plate  202  has stubs  203  as seen in  FIG. 4  locating the legs in place with the aid of linking bars  107  passing within the stubs to hold the legs to the stubs. The floor plate  202  prevents the legs  102  being driven down through a wooden floor during a heavy impact from above. The floor plate may have a lip along the edges which do not face in the direction of entry to provide additional rigidity. Additionally where an earthquake involves significant lateral forces a pod with a floor plate will retain any occupant, rather than moving about independently of the occupant. 
         [0027]      FIG. 3  shows the detail of the connection of frame sockets  103  at the top of legs  102  with the ends  301  of frame  104 . Clearance holes in the frame sockets  103  and frame ends  301  receive bolts  105  and locking nuts  302 . Note that there is clearance between the frame sockets  103  and the frame ends  301 . This intentional clearance provides a crush space which is intended to allow the initial crushing down under overload of the top of frame socket  103  onto the frame ends  301 , and after this space is taken up to allow the collapse of the side walls of both frame sockets  103  and frame ends  301  inwards where weakened by the holes receiving bolt  105 . If the top loading is sufficient the socket  103  and bracing frame end  301  will collapse by a significant amount, reducing the impact loading on the leg  102  itself. 
         [0028]      FIG. 4  shows a bottom perspective view of the pod with a top intrusion guard  401  fitted to prevent intrusion of stray items from above and to add transverse rigidity. The intrusion guard  401  may be of perforated sheet metal secured to frame  104  by tack welding or may be a steel bar grid. The figure also shows the stubs  203  typically welded to the floor plate  202  which may have a leg mounted over them to be secured by passing a linking bar  107  through leg  102  and stub  203 . 
         [0029]      FIG. 5  shows the profile of a frame socket  103  and frame end  301  which has been subjected to a 2 ton weight falling 10 feet. As can be seen the frame socket  103  has been significantly compressed, as has the frame end  301 , however neither has been compressed to the extent that the side walls have caved inwards, so there is still significant resistance to compression remaining before the post beneath the frame socket is subjected to an impact rapid enough to cause failure and compression of the space within the pod. 
         [0030]    The crushing inwards of the walls of the frame sockets  103  and frame ends  301  may be aided if packing washers (not shown) are inserted to take up the side gap between the side walls of the two tubes, and if bolt  105  and nut  302  are initially tensioned to stress the side wall of frame sockets  103  inwards. 
         [0031]    The entire protection pod is of parts which can be assembled on site, allowing the parts to be easily carried to the desired location. 
         [0032]    While the drawings show horizontal linking bars these may be replaced by linking bars at 45 degrees to the vertical to provide more resistance to shearing forces, or by transverse welded beams. Any linking bars may be secured by devises, by locking pins, by nuts or by some locking configuration which receives the bars during assembly to retain them once assembled. 
         [0033]    While the pod displayed has four supporting legs a viable pod may have three or more, depending on the number of persons to be sheltered and the space available. 
         [0034]    It is to be understood that even though numerous characteristics and advantages of the various embodiments of the present invention have been set forth in the foregoing description, together with details of the structure and functioning of various embodiments of the invention, this disclosure is illustrative only, and changes may be made in detail so long as the functioning of the invention is not adversely affected. For example the particular elements of the protection pod may vary dependent on the particular application for which it is used without variation in the spirit and scope of the present invention. 
         [0035]    In addition, although the preferred embodiments described herein are directed to protection pods for use in an earthquake situation, it will be appreciated by those skilled in the art that variations and modifications are possible within the scope of the appended claims, for instance the pod could be used in a tornado area if grid walls are provided on the version shown in  FIG. 4 . 
         [0036]    The protection pod may also be stored and transported in the form of a flatpack, the flackpack comprising all of the components ready to be assembled into the end product. 
       INDUSTRIAL APPLICABILITY 
       [0037]    The protection pod of the invention is usable in the protection of life in locations in which objects damaging to a person may fall, such as buildings likely to be involved in earthquakes or tornados, mines or quarries. The present invention is therefore industrially applicable.

Summary:
An earthquake protection pod for providing a safe space primarily for office personnel has a structure which may be sized to fit beneath a desk, which can support considerable weight and which provides a small crush zone in its structure to take the initial surge of a massive overload. Legs support a frame by sockets which have a crush zone for vertical impact loads. The pod is assembled on site.