TRIPOD LEG

Abstract

An overhead door frame assembly has a horizontal header connected to tripod legs with splice assemblies. Each tripod leg has two upright columns connected to an upright I-bar. One of the splice assemblies is fastened to each upright column. Hinges pivotally mount an overhead door to the header to allow hydraulic cylinders to move the overhead door to an open position and a closed position.

Description

FIELD OF INVENTION

The invention is in the art relating to doors operable to close and open openings and doorways of buildings. More particularly, the doors are large one-piece overhead doors supported on frame assemblies and movable with hydraulic cylinders between closed positions and open positions relative to doorways of buildings.

BACKGROUND OF THE INVENTION

Commercial and industrial buildings, aircraft hangers, farm equipment shop and storage structures, marine and vehicle holding structures, and warehouses have large openings or doorways that are opened and closed with large and heavy doors. Overhead doors are used to maximize useable space of the doorways. Frame assemblies are employed to support the overhead doors independently of the building structure. Examples of overhead doors supported on frame assemblies and selectively moveable with hydraulic cylinders to open positions and closed positions are identified in the following U.S. patents.

K O. Jonsson in U.S. Pat. No. 3,464,161 discloses a garage having a swingable door mounted in a building frame comprising two vertical posts. Horizontals support arms secured to the posts are pivotally connected to moveable arms attached to the door. Piston and cylinder units pivotally connected to the support arms and the moveable arms balance the door so that the net force required to open and close the door is small. The entire weight of the door is subjected to the two vertical posts. D. J. Kerkvliet in U.S. Pat. No. 6,883,273 discloses an overhead door pivotally connected to a framework that is separate from a building structure. The framework has a horizontal member secured to vertical members. The vertical members are steel tubes secured with welds to opposite ends of the horizontal member. Hinges pivotally support the overhead door on the horizontal member. Hydraulic cylinders connected to the vertical members and overhead door are operable to move the overhead door between an upright closed position and a horizontal open position. The weight of the overhead door, the wind forces and the hydraulic cylinder forces subjected to the overhead door are transferred to the upright members. D. Crown in U.S. Pat. No. 7,814,952 discloses two hydraulic cylinders mounted on opposite sides of a building door frame operable to open and close an overhead door. Hinges pivotally mount the door to the horizontal member of the door frame. Each hydraulic cylinder is pivotally mounted on the door frame below the axis of rotation of the overhead door and attached to a side edge of the overhead door. The overhead door and the two hydraulic cylinders pivotally connected to the building door frame subject the building door frame to the overhead door weight and the forces of the hydraulic cylinders that move the overhead door between the closed position and the open position. R. W. Betker in U.S. Pat. No. 8,245,446 discloses a tilt-up door support on U-shaped channel members for movement by hydraulic cylinders to a closed position and an open position. The hydraulic cylinders located upright within the U-shaped channel members are anchored to the U-shaped channel members and pivotally connected to the door. The hydraulic cylinders are operable to tilt the door between an upright closed position and a horizontal open position. Upright I-beams are disclosed as supports for a track supporting the tilt-up door. The track controls the tilting movements of the tilt-up door. R. Peterson in U.S. Patent Application Publication No. US2011/0225895 discloses an overhead door pivotally connected with hinges to a horizontal header of a frame assembly. The frame assembly includes upright posts attached to opposite ends of the header that are located adjacent opposite sides of a doorway. The posts are tube stock material. U-shaped channel members secured to the header telescope into the tube posts to connect the header to the posts. Hinges at opposite ends of the header pivotally connect the overhead door to the header. Hydraulic cylinders connected to the posts and overhead door are operable to pivot the overhead door between an upright closed position and a horizontal open position. All the weight of the overhead door and the forces of the hydraulic cylinders that open and close the overhead door are subjected to the upright posts. M. L. Schweiss in U.S. Pat. Nos. 10,316,576, 10,358,860 and 10,604,991 discloses the combination of an overhead door and a frame assembly for supporting the overhead door for movement between an upright closed position and a horizontal open position relative to a doorway of a building. The frame assembly has a horizontal header attached with splice assemblies to two upright columns. Each column is a single upright tubular member. Hinges pivotally connect the overhead door to the header to allow hydraulic cylinders to move the overhead door between the upright closed position and the horizontal open position and allow the overhead door to move from the horizontal open position to the upright closed position. The weight of the over door, wind forces and forces of the hydraulic cylinders on the overhead door are subjected to the two upright columns.

SUMMARY OF THE INVENTION

The frame assembly of the invention supports an overhead door operable to be moved with linear actuators between a generally upright closed position and a generally horizontal open position. The frame assembly has a horizontal header supported by upright tripod legs. Each tripod leg has first and second upright columns connected to an upright I-bar. Connectors attach the tripod legs to opposite ends of the header. The connectors comprise splice assemblies having a first splice assembly fastened to a first upright column and a second splice assembly fastened to a second upright column. Cooperating retainers and fasteners align the tripod legs with the header and maintain the columns straight, flush and in the same upright plane of the header. A plurality of hinge assemblies pivotally connect upright members of the door frame to the header. Linear actuators, such as hydraulic cylinders or motor driven screws, connected to the door and tripod legs operate to swing the door between an upright closed position and a generally horizontal open position and allow the door to move from the generally horizontal open position to the upright closed position. The frame assembly supports the weight of the door and absorbs wind forces and the forces subjected to the door by the linear actuators during the opening and closing of the door thereby eliminating most if not all weight and forces on the adjacent building structure. Each splice assembly has an upright body having a wall and opposite end edges. A plurality of upright ribs attached to the body are retained in a flat surface engagement with a column by adjustable fasteners connecting the column to the body. The fasteners include nuts secured to the body and bolts mounted on the column engageable with the nuts. In use, the bolts are turned to move the columns into alignment with the header and secure the columns to the splice assemblies. A plurality of second adjustable fasteners comprise cooperating nuts and bolts. The bolts engage an edge of the body to hold the opposite edge of the body in engagement with the columns concurrently with the engagement of the ribs with the columns. The first and second adjustable fasteners retain the splice assemblies in engagement with the perpendicular walls of the columns. The hinge assemblies have sleeves rotatably mounted on non-rotatable pins. The sleeves are connected with arms to the upright members of the door frame. Header members or supports adjacent the sleeves are secured to the header whereby the hinge assemblies support the door on the header of the frame assembly for movement of the door between open and closed positions and absorb the forces of the linear actuators that move the door between the closed position and the open position. The tripod legs provide the frame assembly with lateral and vertical strength and stability required for large and heavy metal overhead doors.

DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a building equipped with an open overhead door pivotally attached to a frame assembly operable to open and close a doorway of the building;

FIG. 2 is an enlarged perspective view of a closed overhead door and frame assembly of FIG. 1;

FIG. 3 is a left side elevational view of FIG. 2;

FIG. 4 is a right side elevational view of FIG. 2;

FIG. 5 is a perspective view of the hinge assembly pivotally connecting the door frame to the header of the frame assembly;

FIG. 6 is an enlarged sectional view taken along line 6-6 of FIG. 2;

FIG. 7 is a foreshortened front elevational view of the frame assembly of FIG. 2;

FIG. 8 is a perspective view of the double splice assemblies of the frame assembly;

FIG. 9 is a front elevational view, partly sectioned, of the double splice assemblies secured to the upright columns of a tripod leg;

FIG. 10 is a sectional view taken along line 10-10 of FIG. 9;

FIG. 11 is an enlarged sectional view of a splice assembly connected to an upright column of a tripod leg;

FIG. 12 is a front elevational view of a tripod leg of the frame assembly of FIG. 7;

FIG. 13 is a top plan view of FIG. 12;

FIG. 14 is a sectional view taken along line 14-14 of FIG. 12;

FIG. 15 is a left side elevational view of the tripod leg of FIG. 12;

FIG. 16 is a right side elevational view of the tripod leg of FIG. 15;

FIG. 17 is a rear elevational view of the tripod leg of FIG. 15;

FIG. 18 is a sectional view taken along line 18-18 of FIG. 12;

FIG. 19 is a sectional view taken along line 19-19 of FIG. 12;

FIG. 20 is a sectional view taken along line 20-20 of FIG. 12;

FIG. 21 is a sectional view taken along line 21-21 of FIG. 12;

FIG. 22 is an enlarged elevational view of a lower corner section of the door frame; and

FIG. 23 is an enlarged sectional view taken along line 23-23 of FIG. 22.

DETAILED DESCRIPTION OF THE OVERHEAD DOOR

A building 9, shown in FIG. 1, includes a doorway or an upright opening to allow vehicles and equipment to move into and out the interior of the building. Examples of building 9 include aviation hangers, automotive shops, farm and ranch shops, commercial retail and marine buildings, warehouses and manufacturing plants. An overhead door 10 pivotally mounted on a frame assembly 11 is movable in an arcuate path between a horizontal open position, shown in FIG. 1, to an upright closed position, shown in FIG. 2. Linear actuators 16 and 17, shown as hydraulic piston and cylinder mechanisms, are operable to move overhead door 10 between the open and closed positions and hold the door in these positions. A hydraulic fluid pump unit 18 connected with fluid accommodating lines 19 to the dead ends of the piston and cylinder mechanisms 16 and 17 function to supply hydraulic fluid under pressure to control the operation of the piston and cylinder mechanisms 16 and 17 whereby overhead door 10 is selectively moved between the open and closed positions. A control 20 coupled to pump unit 18 is manually operable to regulate the operation of pump unit 18. A remote actuator 21 can also be used to regulate control 20. An example of a hydraulic fluid system for an overhead door associated with hydraulic cylinders is disclosed in U.S. Pat. No. 6,883,273. A linear actuator having a motor operating a screw is disclosed in U.S. Pat. No. 6,742,303.

As shown in FIG. 2, door 10 has a rectangular door frame 22 supporting sheathing and trim 23. Door frame 22 comprises tubular metal top and bottom horizontal members 24 and 25. A horizontal middle member 26 is located between members 24 and 25. Left side upright members 27, 28 and 29 are secured with welds to horizontal members 24, 25 and 26. Right side upright members 31, 32 and 33 are secured with welds to the horizontal members 24, 25 and 26. Upright members 34, 35 and 36 located between the end members 29 and 33 reinforce door 10. Door frame 22 is tubular steel bars welded together. The door frame members can be aluminum or composite materials. Large metal doors have a large amount of weight which require large forces to move the doors between open and closed positions. The frame assemblies for supporting the doors must have adequate strength to accommodate heavy overhead doors and wind forces directed to the doors.

Frame assembly 11, shown in FIG. 7, has a horizontal header 11 extended between and attached to upright tripod legs 13 and 14. Header 11 is a linear tubular steel beam having opposite end sections mounted on tripod legs 13 and 14. As shown in FIG. 2, a first hinge assembly 37 mounted on header 12 in alignment with tripod leg 13 is connected to upright door frame members 27, 28 and 29. A second hinge assembly 38 is also mounted on header 27 in alignment with tripod leg 14. Hinges 39, 40 and 41 are mounted on header 27 between the first and second hinge assemblies 13 and 14. Hinge assemblies 37 and 38 and hinges 39, 40 and 41 have a common horizontal axis allowing door 10 to be moved by linear actuators 16 and 17 between the upright closed position and the horizontal open position.

Tripod leg 13, shown in FIGS. 12 to 21, comprises a base 43 adapted to be secured to a support or floor 48 of building 9. Base 43 is a flat rectangular metal plate having a top wall 44 and a plurality of holes 46. Anchors 47, shown in FIGS. 3 and 4, extend through holes 46 to secure base 43 to floor 48. Tripod leg 13 has a first upright tubular column 49 and a second upright tubular column 51. Columns 49 and 51 are laterally spaced from each other and secured with welds to the front corners of the front section of base 43. An upright I-bar 52 is secured with welds to the middle of the rear section of base 43. Columns 49 and 51 and I-bar 52 have the same upright dimensions and are in parallel triangular orientation. I-bar 51 is an upright I-beam having lateral flanges 53 and 54 jointed with a flat cross member 55. A number of horizontal plates 56, 57, 58, 59, 60, 61, 62 and 63 are vertically spaced between columns 49 and 51 and I-bar 52. Welds secure each plate 56 to 63 to columns 49 and 51 and I-bar 52. A support assembly 64 for linear actuator 16 is located between upright columns 49 and 51 and I-bar 52. Support assembly 64 has flat transverse members 66 and 67 secured together in a right angle shape with the space between members 66 and 67 open to columns 49 and 51. As shown in FIGS. 17 and 18, members 66 and 67 engage columns 49 and 51. Welds secure members 66 and 67 to columns 47 and 51. A rib 68 secured to the inside center of members 66 and 67 has a hole 69 to accommodate a pin 104 connecting the dead end of linear actuator 16 to rib 68. Second and third ribs or right angle flanges 71 and 72 secured to the rear surfaces of members 66 and 67 reinforce members reinforce members 66 and 67. As shown in FIGS. 17 and 18, ribs 71 and 72 are also secured to flange 54 of I-bar 52.

The second tripod leg 14, shown in FIGS. 2, 4 and 7, has the same structure as tripod leg 13. Tripod leg 14 has a base 73 supporting first and second upright tubular columns 74 and 76 and an I-bar 77. Plates 78, 79, 80, 81, 82, 83, 84 and 85 secure columns 74 and 76 to I-bar 77. Columns 74 and 76 and I-bar 77 hold a support assembly 86 for retaining linear actuator 17. A rib 87 on the front center of support assembly 86 accommodates a pin that connects linear actuator 17 to rib 87. An anchor 88 secures base 78 to floor 48.

Proceeding to FIGS. 22 and 23, linear actuator 16 extended between support assembly 64 and a mount 89 is operable to pivot door 22, shown by arrow 90, between an upright door closed position and a horizontal door open position. Mount 89 comprises a flat first plate 91 located between upright door frame members 27 and 28. Welds secure plate 91 to door frame members 27 and 28 whereby the forces of linear actuator 16 are imparted to both door frame members 27 and 28. Plate 91 has three vertically spaced horizontal openings or slots 92, 93 and 94. A bar 96 is located in surface contact with the front of plate 91. A second plate 101 engages the back surface of plate 91. An arm 102 secured to plate 101 accommodates a pin 103 operable to pivotally connect linear actuator 16 to arm 102. A plurality of fasteners 97, 98 and 99, shown as nut and bolt assemblies, extended through slots 92, 93 and 94 clamp bar 96 and plate 101 to plate 91. The second plate 101 and arm 102 are laterally adjustable relative to the first plate 91 to align linear actuator 16 relative to support assembly 64. A second mount 106 secured to door upright members 31 and 32, shown in FIG. 2, has the same structure and functions including the horizontal adjustment as mount 89. Mount 106 is also pivotally connected to linear actuator 17 connected to second tripod leg 14.

Frame assembly 11 has first splice assemblies 107 and 108, shown in FIGS. 8 to 11, that secures tripod leg 14 to header 12. Second splice assemblies secure tripod leg 13 to header 12. The splice assemblies have the same structures and functions.

Splice assembly 107 has a body 109 comprising a flat upright member supporting a pair of upright ribs 111 and 112. Ribs 111 and 112 have flat end surfaces located in surface engagement with a first inside wall 119 of column 74 of tripod leg 14. Body 109 has a first end 113 located in engagement with a second inside wall 123 of column 74. A fastener 116, shown as a threaded bolt, cooperates with a nut 117 retained on body 109 to hold ribs 111 and 112 in upright surface engagement with inside wall 119 of column 74. A second fastener 121, shown as a threaded bolt, extends through a nut 122 secured to column 74. The distal end of fastener 121 engages second end 114 of body 109 and forces first end 113 of body 109 into engagement with second inside wall 123 of column 74. A fastener 124 cooperates with a nut 126 on body 109 and a third fastener 127 cooperating with a nut 128 on body 109 operates in concert with fastener 116 to retain ribs 111 and 112 in surface engagement with inside wall 119 of column 74. A plat 129 secured to body 109 and ribs 111 and 112 is fixed by welds to header 12.

Splice assembly 108 has an upright body 131 supporting a pair of upright ribs 132 and 133. Fasteners 134, 139 and 141 retained on column 76 cooperate with nuts 136, 142, 143 concurrently hold ribs 132 and 133 in upright surface engagement with a first inside wall of column 76. An additional fastener 139 threaded through a nut 138 secured to column 76 has a distal end that contacts body 131 and holds body 131 in engagement with a second inside wall of column 76. Body 131 and ribs 132 and 133 are secured to a plate 144. Welds secure plate 144 to header 12. Splice assemblies 107 and 108 are laterally spaced apart and telescope into the upper ends of tubular columns 74 and 76 of tripod leg 14. Fasteners 116, 124 and 127 secure splice assembly to column 74. Fasteners 134, 139 and 141 secure splice assembly 108 to column 76.

Hinge assembly 38, shown in FIG. 5, comprises a frame assembly unit 146 pivotally connected with a horizontal pin 147 to a door frame unit 148. Frame assembly unit 146 has a horizontal plate 149 secured with welds to the top surface of header 12. A plurality of vertical supports 151, 152, 153, 154, 155 and 156 are secured with welds to the bottom of plate 149. Adjacent supports are laterally spaced apart. First vertical members 157 and 158 located between supports 151 and 152 extend downward on opposite sides of door frame member 33. Second vertical members 159 and 161 located between supports 153 and 154 extend downward on opposite side of door frame member 32. Third vertical members 161 and 162 extend downward adjacent door frame member 31. Welds secure members 157, 158, 159, 160, 161 and 162 to door frame members 33, 32 and 31. Horizontal plates 163 secured to vertical members 157, 158, 159, 160, 161 and 162 retain vertical members 157, 158, 159, 160, 161 and 162 in lateral spaced relationship. Plates 163 also support arms 167, 168, 169 and 170 located between the upper sections of vertical members 158, 159, 160 and 161. Arms 167, 168, 169 and 170 have openings that accommodate cylindrical members or sleeves 171, 172, 173, 174 and 175. Pin 147 extended through supports 151 to 156, the upper sections of vertical members 157 to 162, and sleeves 171 to 175 pivotally connects frame assembly unit 146 to door frame unit 148 and supports an end of overhead door 10. A block 176 secured to support 151 functions to prevent pin 147 from rotating during the opening and closing of overhead door 10. A retainer 177, shown as a cotter key, on the end of pin 147 opposite block 176 limits axial movements of pin 147 relative to supports 151 to 156.

Hinge assembly 37 mounted on the end of header 12 opposite hinge assembly 38 has the same structure and function as hinge assembly 38. Hinge assemblies 37 and 38 are concurrently operative to support overhead door 10 on frame assembly 11 and allow overhead door 10 to be moved with linear actuators 16 and 17 from a door closed position and a door open position. Hinge assemblies 37 and 38 also support overhead door 10 in the open position on frame assembly 11.

Proceeding to FIG. 6, hinge 40 along with hinges 39 and 41 support door frame 22 between end hinge assemblies 37 and 38. Hinges 39, 40 and 41 have the same structure and functions. Hinge 40 is herein described as having a frame unit 178 connected with a horizontal pin 179 to a door frame unit 181. Frame assembly unit 178 comprises a horizontal plate 194 secured with welds to the top surface of header 12 of frame assembly 11. A pair of supports 183 and 184 extended vertically below plate 182 are secured to the bottom of plate 182. Door frame unit 181 has a plate 194 secured with a weld to top member 24 of door frame 22. Upright arms 196 and 197 secured to plate 194 are located adjacent the inside walls of supports 183 and 184. A cylindrical member or sleeve 201 extends through openings 198 and 199 in arms 196 and 197. Pin 179 extended through sleeve 201 and supports 183 and 184 pivotally connects door frame unit 181 to frame assembly unit 178 and supports overhead door 10 on header 12 of frame assembly 11. Pin 179 does not rotate during the pivoting of overhead door 10 between the open position and the closed position. Sleeve 201 has a large inside cylindrical surface that engages pin 179 and distributes forces along the length of pin 179 to reduce wear and shearing of pin 179. A block 191 secured to a first end of pin 179 engages a stop 172 secured to support 184 to prevent rotation of pin 179 relative to frame assembly unit 178. The second end of pin 179 accommodates a retainer 193, shown as a cotter key, to limit axial movement of pin 179 relative to supports 196 and 197.

The foregoing drawing and description of the overhead door frame assembly with tripod legs and splice assemblies is one embodiment of the invention. Persons skilled in the art of overhead doors can make changes and modifications of the structures and materials to the door, frame assembly and hinges without departing from the frame assembly and tripod leg defined in the claims.

Claims

1. A tripod leg comprising: a base,an upright first column secured to the base,an upright second column secured to the base, said upright second column being laterally spaced from the upright first column,an upright I-bar secured to the base, andmembers secured to the upright first column, the upright second column and the upright I-bar to connect the upright first column and the upright second column to the upright I-bar.

2. The tripod leg of claim 1 wherein: the base has a top wall having a front section and a rear section,said upright first column and the upright second column being secured to the front section of the top wall of the base,said upright I-bar being secured to the rear section of the top wall of the base.

3. The tripod leg of claim 1 wherein: the members connected to the upright first column, the upright second column and the upright I-bar comprise horizontal plates secured to the upright first column, the upright second column and the upright I-bar.

4. The tripod leg of claim 1 including: a support assembly secured to the upright first column, the upright second column and the upright I-bar.

5. The tripod leg of claim 4 wherein: the support assembly comprises transverse members secured to the first upright column and the second upright column, andupright ribs secured to the transverse members and the upright I-bar.

6. The tripod leg of claim 5 wherein: the transverse members comprise a first transverse member and a second transverse member, the first transverse member and the second transverse member being secured together in a generally right angle relation, andan upright member located between the first transverse member and the second transverse member and secured to the first transverse member and the second transverse member.

7. The tripod leg of claim 5 wherein: the upright ribs comprise a first upright rib secured to the transverse members and the upright I-bar and a second upright rib laterally spaced form the first upright rib secured to the transverse members and the upright I-bar.

8. The tripod leg of claim 1 wherein: the upright I-bar includes a first lateral flange, a second lateral flange spaced from the first lateral flange and a cross member extended between and joined to the first lateral flange and the second lateral flange, anda support assembly secured to the upright first column, the upright second column and the first lateral flange of the I-bar.

9. The tripod leg of claim 8 wherein: the support assembly comprisesa first transverse member,a second transverse member secured to the first transverse member,a first rib secured to the first lateral flange of the I-bar, the first transverse member and the second transverse member, anda second rib secured to the first lateral flange of the I-bar, the first transverse member and the second transverse member.

10. The tripod of claim 9 wherein: the first transverse member and the second transverse member have adjacent edges secured together to locate the first transverse member and the second transverse member in a generally right angle relation.

11. The tripod leg of claim 10 including: a third rib secured to the first transverse member and the second transverse member.

12. A tripod leg comprising: a base having a first front corner section, a second front corner section laterally spaced from the first front corner section, and a middle rear section,an upright first column secured to the first front corner section of the base,an upright second column secured to the second front corner section of the base,said upright second column being laterally spaced from and parallel to the upright first column,an I-bar secured to the middle rear section of the base,said I-bar located parallel to the upright first column and the upright second column,said I-bar comprising a first lateral flange, a second lateral flanged spaced from and parallel to the first lateral flange and a cross member extended between and joined to the first lateral flange and the second lateral flange,a plurality of horizontal plates secured to the upright first column, the upright second column and the I-bar to connect the upright first column and the upright second column to the I-bar, anda support assembly secured to the upright first column, the upright second column and the first lateral flange of the I-bar.

13. The tripod leg of claim 12 wherein: the support assembly comprisesa first transverse member,a second transverse member secured to the first transverse member,a first rib secured to the first lateral flange of the I-bar, the first transverse member and the second transverse member, anda second rib secured to the first lateral flange of the I-bar, the first transverse member and the second transverse member.

14. The tripod of claim 13 wherein: the first transverse member and the second transverse member have adjacent edges secured together to locate the first transverse member and the second transverse member in a generally right angle relation.

15. The tripod leg of claim 14 including: a third rib secured to the first transverse member and the second transverse member.

16. A tripod leg comprising: an upright first column,an upright second column laterally spaced from the upright first column,an upright I-bar spaced from the upright first column and the upright second column,a plurality of members secured to the upright first column, the upright second column and the upright I-bar for connecting the upright first column to the upright second column and connecting the upright first column and the upright second column to the upright I-bar,a support assembly secured to the upright first column and the upright second column,said support assembly comprisesa first transverse member secured to the first upright column and the second upright column,a second transverse member secured to the first upright column and the second upright column,a first upright rib secured to the first transverse member and the I-bar, anda second upright rib secured to the second transverse member the I-bar.

17. The tripod leg of claim 16 wherein: the first transverse member and the second transverse member have adjacent edges secured together.

18. The tripod leg of claim 16 wherein: the first transverse member is inclined in an upward direction and the second transverse member is inclined in a downward direction.

19. The tripod leg of claim 16 including: an upright third rib secured to the first transverse member and the second transverse member.

20. The tripod leg of claim 16 wherein: said I-bar comprises a first lateral flange, a second lateral flange spaced from and parallel to the first lateral flange and a cross member extended between and joined to the first lateral flange and the second lateral flange,said first rib being secured to the first lateral flange, andsaid second rib being secured to the first lateral flange.