Abstract:
A temporary bridge for supporting heavy loads includes elongate hollow cylinders. A first rigid flat plate is horizontally disposed in overlying relation to each hollow cylinder and a second rigid flat plate is horizontally disposed in underlying relation to each hollow cylinder. Stress-distributing strengthening members formed by a pair of legs that are angularly disposed with respect to one another are circumferentially positioned about each hollow cylinder and the respective free ends of the legs are secured to their associated rigid flat plates. A key extends from a first end of each hollow cylinder and a mating socket is formed in a second end of each hollow cylinder to facilitate end-to-end interconnection of a plurality of hollow cylinders. Further embodiments include longitudinally-disposed timber mats, pedestrian walkways and curvature-creating members so that the bridge may follow a non-linear path of travel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of U.S. patent application Ser. No. 14/095,298, entitled Elongate Pipe-Base Structure For Supporting Heavy Loads, and filed Dec. 3, 2013 by the same inventors. That application is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates, generally, to temporary structures for supporting heavy loads over bodies of water or wetlands. More particularly, it relates to a modular heavy load-supporting structure having cylindrical sections that are laid end to end quickly to save time and materials. 
     2. Description of the Prior Art 
     It was a common practice before wetlands conservation was a concern to dredge out large sections of wetlands as needed when building roadways or bridges over such wetlands. Such dredging enabled barges to carry heavy equipment to the jobsite as the job site progressed across the landscape. 
     Over time, it became apparent that dredged wetlands were not recovering as expected, and laws now ban such dredging. 
     Stone causeways built in wetlands areas avoid such dredging, but they too are environmentally unacceptable. 
     The industry has adopted the practice of building a temporary bridge into the wetlands for the purpose of enabling heavy equipment to reach the job site. Although such bridges require pile driving, the small footprint of a pile causes no permanent damage to the wetlands, i.e., the wetlands recover quickly when the temporary piles are removed. 
     The primary drawback to the temporary bridge solution to the wetlands conservation problem is that such temporary bridges, since they must carry very heavy loads, can be quite expensive and time-consuming to build even though they are temporary structures that are removed when the main roadway or bridge is completed. 
     Thus there is a need for a temporary bridge structure that is assembled quickly from low cost materials but which can support extremely heavy loads. 
     There is also a need for a temporary bridge structure that is quickly disassembled as well when no longer needed. 
     However, in view of the art considered as a whole at the time of making the present invention, it was not obvious to those of ordinary skill in the art how the needed structure could be provided. 
     SUMMARY OF THE INVENTION 
     The long-standing but heretofore unfulfilled need for an improved structure for a temporary structure that supports heavy loads is met by a new, useful, and non-obvious invention. 
     The inventive structure includes at least one hollow cylinder having a longitudinal axis of symmetry and an elongate extent. In a preferred embodiment, a hollow cylinder has a thirty six inch outside diameter and a wall thickness of three-eighths of an inch. Such dimensions are preferred but are not critical because pipes of many different outside diameter and wall thicknesses can be used when building temporary bridges as disclosed herein. 
     A plurality of stress-distributing strengthening members is circumferentially positioned about and secured to the hollow cylinder in parallel relation to the longitudinal axis of symmetry. 
     The strengthening members have an extent substantially equal to the elongate extent of the elongate hollow cylinder and in the preferred embodiment each strengthening member has a generally “L” shape where the legs of the “L” are disposed in angular relation to one another. Another embodiment saves materials by providing one leg per strengthening member. 
     A first flat plate of rigid construction is disposed in a horizontal plane in overlying and secured relation to the hollow cylinder. A second flat plate of rigid construction is disposed in a horizontal plane in underlying and secured relation to the hollow cylinder in parallel and diametrically opposed relation to the first flat plate. The width of each flat plate may exceed but is substantially equal to the diameter of the hollow cylinder to which it is secured and the length of each flat plate is substantially equal to the length of its hollow cylinder. 
     In the preferred embodiment, a first pair of two-leg strengthening members is secured to a hollow cylinder on opposite sides of a vertical plane that bisects the hollow cylinder and above a horizontal plane that bisects the hollow cylinder. A second pair of two-leg strengthening members is secured to the hollow cylinder on opposite sides of the vertical plane and below the horizontal plane. 
     Each leg of each strengthening member of the first pair has a free end disposed in abutting and secured relation to the first rigid flat plate along the elongate extent of the first rigid flat plate. Each leg of each strengthening member of the second pair has a free end disposed in abutting and secured relation to the second rigid flat plate along the elongate extent of the second rigid flat plate. 
     As in the parent disclosure, an imperforate circular disc is positioned within the lumen of the hollow cylinder in perpendicular relation to the longitudinal axis of symmetry of the hollow cylinder and in longitudinally spaced relation to a preselected end of the hollow cylinder. 
     A first circular disc has a central opening formed therein is secured to a first end of the hollow cylinder. A second circular disc having a central opening formed therein is secured to a second, opposite end of the hollow cylinder. The central opening of the second circular disc having said central opening forms a socket that mates with a key when first and second hollow cylinder members are disposed in end-to-end abutting relation to one another along a common longitudinal axis of symmetry. 
     A first end of a truncate cylindrical member is secured to the imperforate cylindrical disc in concentric relation thereto and a second end protrudes through the central opening formed in the first circular disc having a central opening. The protrusion forms the key. 
     In a second embodiment of the invention, longitudinally disposed timbers form a timber mat. 
     At least one pedestrian walkway is provided in a third embodiment. 
     A fourth embodiment enables a non-linear connection between elongate hollow cylinders so that a temporary bridge may include at least two straight sections that are disposed at a predetermined angle relative to one another. 
     A fifth embodiment discloses strengthening members having only one leg. 
     An important object of the invention is to provide a temporary bridge structure capable of supporting extremely heavy equipment. 
     Another important object is to provide such a structure that can be made of any length. 
     Another object is to provide a structure that assembles quickly, without tight tolerances, and which is made from readily available materials. 
     Still further objects are to disclose a better method for building timber mats, pedestrian walkways, paths of travel having at least one angular turn, and strengthening members that save materials. 
     These and other important objects, advantages, and features of the invention will become clear as this disclosure proceeds. 
     The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts exemplified in the disclosure set forth hereinafter and the claims indicate the scope of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a fuller understanding of the nature and objects of the invention, reference should be made to the following detailed disclosure, taken in connection with the accompanying drawings, in which: 
         FIG. 1  is an end view of a hollow cylinder, strengthening members, and rigid flat plates used in the novel structure; 
         FIG. 2  is a top plan view depicting two hollow cylinders in transversely disposed relation to one another; 
         FIG. 3  is a top plan view of the  FIG. 2  embodiment after longitudinally and transversely disposed timbers have been added thereto; 
         FIG. 4A  is an end view of a first variation of a third embodiment; 
         FIG. 4B  is an end view of a second variation of the third embodiment; 
         FIG. 5  is a top plan view of a fourth embodiment including a predetermined angle between two straight sections of a bridge; 
         FIG. 6A  is a top plan view of a truncate hollow cylinder that creates a predetermined angle between end-to-end elongate hollow cylinders; 
         FIG. 6B  is a first side elevation view of said truncate hollow cylinder, taken along line  6 B- 6 B in  FIG. 6A ; 
         FIG. 6C  is a second side elevation view of said truncate hollow cylinder, taken along line  6 C- 6 C in  FIG. 6A ; 
         FIG. 6D  is an end elevation view of said truncate hollow cylinder, taken along line  6 D- 6 D in  FIG. 6A ; and 
         FIG. 7  is an end elevation view of a fifth embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  depicts an illustrative embodiment of a novel structural flexural element which is denoted as a whole by the reference numeral  10 . 
     Novel structure  10  includes elongate hollow pipe or cylinder  12  having a longitudinal axis of symmetry. Four (4) elongate, generally L-shaped stress-distributing strengthening members, denoted  14   a ,  14   a ,  14   b , and  14   b  are circumferentially positioned about elongate hollow cylinder  12  in parallel relation to said longitudinal axis of symmetry and are secured to said elongate hollow cylinder by suitable means such as welding. The legs of each L-shaped strengthening member are disposed in angular relation to one another. 
     A first flat plate  16  of rectangular configuration and rigid construction overlies cylinder member  12  and the first or upper pair  14   a ,  14   a  of the strengthening members is positioned to orient said first flat plate  16  in a horizontal plane. More particularly, the free end of each leg of strengthening members  14   a ,  14   a  is welded or otherwise secured to an underside of said first flat plate. Strengthening members  14   a ,  14   a  are secured to said hollow cylinder on opposite sides of a vertical plane that longitudinally bisects hollow cylinder  12 . 
     A second flat plate  18  of rectangular configuration and rigid construction underlies cylinder member  12  and the second or lower pair  14   b ,  14   b  of stress-distributing strengthening members  14   b ,  14   b  is positioned to orient said second flat plate  18  in a horizontal plane. More particularly, the free end of each leg of strengthening members  14   b ,  14   b  is welded or otherwise secured to a top side of said second flat plate. Strengthening members  14   b ,  14   b  are secured to hollow cylinder  12  on opposite sides of the vertical plane. Upper strengthening members  14   a ,  14   a  and lower strengthening members  14   b ,  14   b  are positioned on opposite sides of a horizontal plane that bisects hollow cylinder  12 . 
     First and second flat plates  16  and  18  are parallel to one another in their respective horizontal planes. 
     Defining the end view of hollow cylinder  12  as the face of an analog clock where twelve o&#39;clock is the highest point of said hollow cylinder as drawn in  FIG. 1 , upper strengthening members  14   a ,  14   a  are positioned roughly at the one and eleven o&#39;clock positions and lower strengthening members  14   b ,  14   b  are positioned roughly at the five and seven o&#39;clock positions. 
       FIG. 2  depicts a pair of said hollow cylinders  12  disposed in transversely spaced apart, parallel relation to one another. Said cylinders are interconnected to one another along their respective extents by a plurality of transversely disposed, longitudinally spaced apart diaphragm members, collectively denoted  19 . 
     As in the parent application, an imperforate circular disc  20  is positioned within the lumen of each hollow cylinder  12  in perpendicular relation to the longitudinal axis of symmetry of said hollow cylinder. A first circular disc  22  having a central opening  23  formed therein is secured to a first end of hollow cylinder  12 . A second circular disc  22   a  having a central opening  23   a  that forms a key-receiving socket is secured to a second, opposite end of hollow cylinder  12  in closing relation thereto. No reference numeral is provided for central openings  23  and  23   a  in  FIG. 2  to avoid cluttering of the drawings. 
     Truncate hollow cylinder member  24  has a first end  24   a  secured to imperforate circular disc  20  in concentric relation thereto, i.e., truncate cylindrical member  24  has the same longitudinal axis of symmetry as does elongate hollow cylinder  12 . Second end  24   b  of truncate cylindrical member  24  extends through the central opening formed in first circular disc  22 . The protrusion of second end  24   b  forms a key or pin that mates with the key-receiving socket formed in second cylindrical disc  22   a  when two (2) cylindrical members  12  are disposed in end-to-end abutting relation to one another along a common longitudinal axis of symmetry. 
     Thus a first or leading end of each elongate hollow cylinder  12  is provided with key or pin  24   b  as depicted in  FIG. 2  and the second or trailing end of each elongate hollow cylinder is provided with a key-receiving socket in the form of said central opening formed in second circular disc  22   a . The first and second centrally apertured circular discs  22  and  22   a , respectively, have the same structure. The difference in reference numerals merely points out their difference in positions at opposite ends of each elongate hollow cylinder. 
       FIG. 3  depicts a plurality of longitudinally-disposed timbers, collectively denoted  26 , supported by said transversely disposed diaphragms  19 . Timbers  26  collectively form a timber mat that provides a roadway for heavy equipment. As mentioned above, all prior art timber mats are formed by a plurality of transversely disposed timbers which are supported by longitudinally disposed diaphragms which are in turn supported by transversely disposed diaphragms. The novel arrangement of  FIG. 3  thus eliminates the longitudinally disposed diaphragms of the prior art. 
     As best understood in connection with  FIGS. 4A and 4B , each diaphragm  19  is connected at its opposite ends to a flat brace  21  that is welded to its associated hollow cylinder  12  in a vertical plane. The cylinder-abutting side of each brace  21  is arcuate to conform to the surface of its associated hollow cylinder. A plurality of openings, collectively denoted  28 , is formed in each brace  21  along its outboard edges and each diaphragm  19  has a plurality of openings formed in each of its ends which can be aligned with preselected openings  28 . Suitable nuts and bolts are used to secure the opposite ends of each diaphragm  19  to its associated brace  21 . 
     Such structure allows height adjustment of each diaphragm  19  along the vertical extent of its associated brace  21  and thus height adjustment of the timber mat supported by said diaphragms. The timber mat in  FIG. 4B  is elevated with respect to the timber mat depicted in  FIG. 4A . The  FIG. 4B  timber mat is a prior art timber mat having transversely disposed timbers. 
     In the embodiment of  FIGS. 3 and 4A , a pedestrian walkway is supported by a plurality of transversely disposed, longitudinally spaced apart boards, collectively denoted  30 , that are mounted atop and secured to rigid flat top plate  16  in cantilever relation thereto and which extend in an outboard direction relative to each hollow cylinder  12 . Elongate strips of plywood  32  or other suitable material overlie boards  30  and provide support for a pedestrian. As depicted in said  FIGS. 3 and 4A , such a pedestrian walkway is provided on the outboard side of each hollow cylinder. An upstanding safety hand rail  34  is provided on the outboard side of each walkway and a longitudinally disposed timber  26   a  that is smaller than a timber mat timber  26  may be used to provide a guiding curb for the equipment as depicted in said  FIG. 4A . Still smaller timbers  26   b  are used to support plywood  32 . 
       FIGS. 3 and 4A  also disclose transversely disposed shorter boards  30   a  directly overlying upper rigid flat plate  16  of their associated hollow cylinder  12  and filling in the spaces between the longer, cantilevered boards  30 . 
     As indicated in  FIG. 4A , the transverse spacing of piles  13  that support hollow cylinders  12  may be selected to directly support treads  11  of a crane  15  or other item of heavy equipment. 
     A pedestrian walkway may also be provided as disclosed in  FIG. 4B . In this embodiment, transversely disposed, cantilevered boards  30  and the shorter boards  30   a  therebetween are not used. A plurality of transversely disposed, longitudinally spaced apart elongate timber mats  27 , only one of which is depicted in the end view of  FIG. 4B , is mounted and secured to the rigid flat mounting plate  16  that surmounts each hollow cylinder  12 . Each of said timber mats  27  has a transverse extent that exceeds the distance between the transversely spaced apart hollow cylinders  12 . The distance by which each transverse timber mat  27  extends outboard of the hollow cylinders defines the width of each pedestrian walkway. Although not depicted in  FIG. 4B , a longitudinally extending strip of plywood  32  fills in the gap between timbers  27  to provide a pedestrian walkway and a suitable safety handrail may be provided as well. 
     The structure that enables the novel temporary bridge to turn relative to a straight line is depicted in  FIGS. 5  and  FIGS. 6A-D . 
       FIG. 5  depicts novel turn-creating member  40  and its position between two end-to-end elongate hollow cylinders  12 . Note that no such turn or curve-creating member  40  is provided between the transversely spaced associated elongate hollow cylinders  12  that are disposed end-to-end because such elongate hollow cylinders follow the interior curvature of the turn or curve and thus are not as widely spaced apart as are the elongate hollow cylinders on the outboard side of the curve. 
     Turn-creating member  40  is hereinafter referred to as the first or outer truncate hollow cylinder. It has a diameter equal to the diameter of each elongate hollow cylinder  12  and a structure that is much the same as the structure as each elongate hollow cylinder. 
       FIGS. 6A-D  respectively provide top plan, first side, second side, and end views of turn or curve-creating outer truncate hollow cylinder  40 . 
       FIG. 5  may be interpreted as depicting a turn to the left in the novel temporary bridge structure. Accordingly, the upwardly inclined (as drawn) second or inner truncate hollow cylinder  24  depicted in the top plan view of  FIG. 5  and in enlarged view in  FIG. 6A  indicates such left turn. Similarly, first centrally-apertured circular disc  22  is disposed at an obtuse angle in  FIG. 6A  relative to a horizontal plane, and the left side  40   a  of member  40  has a shorter extent than right side  40   b  thereof. Moreover, said left and right sides  40   a ,  40   b  are inclined upwardly from a horizontal plane as depicted in said  FIG. 6A . A member  40  for creating a right turn would include a downwardly tilted inner truncate hollow cylinder  24  in  FIG. 6A  and the respective lengths and inclinations of sides  40   a  and  40   b  would be reversed. 
     The rate of curvature is increased by employing more than one member  40  at the desired turn location. This cumulative structure is possible because each member  40  has a socket opening  23   a  formed in each centrally-apertured circular disc  22  and  22   a  and a key  24   b  that protrudes through the central opening formed in each first centrally-apertured circular disc  22 . 
     More particularly, first or outer truncate hollow cylinder  40  is truncate relative to said elongate hollow cylinders  12 , and said first truncate hollow cylinder  40  has a diameter substantially equal to a diameter of each elongate hollow cylinder  12 . 
     A second or inner truncate hollow cylinder  24  is disposed concentrically within said first truncate hollow cylinder  40  and has a longitudinal axis of symmetry disposed at a predetermined angle relative to a longitudinal axis of symmetry of said first truncate hollow cylinder  40 . Said second truncate hollow cylinder  24  therefore has a leading end disposed in oblique relation to a trailing end of said second truncate hollow cylinder. 
     First truncate hollow cylinder  40  is positioned between two elongate hollow cylinders  12  disposed in end-to-end relation to one another, one of which is a leading elongate hollow cylinder and one of which is a trailing elongate hollow cylinder. 
     As best understood in connection with  FIG. 5 , the trailing elongate hollow cylinder is in axial alignment with a trailing end of said first or outer truncate hollow cylinder  40  and said leading elongate hollow cylinder is in axial alignment with a leading end of said second or inner truncate hollow cylinder  24 . 
     The predetermined angle of said second truncate hollow cylinder  24  enables construction of a temporary bridge having at least two straight sections that form an angle with one another equal to the predetermined angle of said second truncate hollow cylinder  24  with respect to the longitudinal axis of symmetry of said first truncate hollow cylinder  40 . 
     In all other respects the structure of first or outer truncate hollow cylinder  40  is the same as each elongate hollow cylinder  12 . An imperforate circular disc  20  is positioned within a lumen of first truncate hollow cylinder  40  in parallel relation to a trailing end of said first truncate hollow cylinder and in spaced apart relation to the leading end of said first truncate hollow cylinder. 
     A first circular disc  22  having a central opening formed therein is secured to the leading end of first truncate hollow cylinder  40  and a second circular disc  22   a  having a central opening that forms a key-receiving socket is secured to the trailing end of said first truncate hollow cylinder  40  in closing relation thereto. 
     Second or inner truncate hollow cylinder member  24  has a trailing end secured to said imperforate circular disc  20  in concentric relation thereto and a leading end protruding through the central opening formed in first centrally-apertured circular disc  22 . The leading forms a key that engages said key-receiving socket. 
       FIG. 7  depicts an elongate hollow cylinder  12  having flat top plate  16  secured thereto in a horizontal plane and flat bottom plate  18  secured thereto in a horizontal plane. Top flat plate  16  makes tangential contact as at  16   a  with hollow cylinder  12  at the twelve o&#39;clock position of the circle defined by said hollow cylinder  12  in end view and bottom flat plate  18  makes tangential contact as at  18   a  with hollow cylinder  12  at the six o&#39;clock position of the circle. 
     Upper strengthening members  14   a ,  14   a  are formed integrally with or welded to flat top plate  16  and depend therefrom in normal relation thereto. Lower strengthening members  14   b ,  14   b  are formed integrally with or welded to flat bottom plate  18  and project upwardly therefrom in normal relation thereto. 
     Upper strengthening members  14   a ,  14   a  are positioned on opposite sides of the twelve o&#39;clock point of tangential contact  16   a  in equidistantly spaced relation to said twelve o&#39;clock point of tangential contact. Lower strengthening members  14   b ,  14   b  are positioned on opposite sides of the sic o&#39;clock point of tangential contact  18   a  in equidistantly spaced relation to said six o&#39;clock point of tangential contact. 
     This embodiment has the advantage of providing substantially as much strengthening as the above-disclosed embodiments with less materials in that each strengthening member has one leg instead of two. It has the disadvantage of requiring a more precise placement of legs  14   a ,  14   a ,  14   b ,  14   b  relative to the placement of the two leg embodiments because there are only four points of strengthening contact instead of eight. 
     It will thus be seen that the objects set forth above, and those made apparent from the foregoing disclosure, are efficiently attained and since certain changes may be made in the above construction without departing from the scope of the invention, it is intended that all matters contained in the foregoing disclosure or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense. 
     It is also understood that the following claims are intended to cover all of the generic and specific features of the invention herein described, and all statements of the scope of the invention that, as a matter of language, might be said to fall therebetween.