US 3256671 A
Description (OCR text may contain errors)
June 21, 1966 H. E. HANDLEY ELONGATED RIGID STRUCTURE 4 Sheets-Sheet 1 Filed Sept. 13, 1962 INVENTOR HAROLD E. HANDLE? ATTORNEY June 21, 1966 H HH EY 3,256,671
INVENTOR HAROLD E. HANDLEY ATTORNEY June 21, 1966 H. E. HANDLEY 3,256,671
ELONGATED RIGID STRUCTURE Filed Sept. 13, 1962 4 Sheets-Sheet 3 I l 82 8o 2 80 INVENTOR XMROLD E HANDLE V c mw/ m ATTORNEY June 21, 1966 H. E. HANDLEY 3,256,671
ELONGATED RIGID STRUCTURE Filed Sept. 13, 1962 4 Sheets-Sheet 4 INVENTOR HAROLD E. HANDLE! @WMJ ATTORNEY 3,256,671 ELONGATED RIGID STRUCTURE Harold E. Handley, Jackson, Mich., assignor to McGraw- Edison Company, Elgin, 11]., a corporation of Delaware Filed Sept. 13, 1962, Ser. No. 223,391 3 Claims. (Cl. 52731) The present invention relates to improvements in structural members to be fabricated in Whole or in part from extrudable materials such as aluminum alloys.
It has long been recognized that the use of aluminum in structural members offered many advantages over steel-in such areas as weight, aesthetics, maintenance,
electrical conductivity, and resistance to corrosion. However, the relative cost between aluminum and steel, the difliculty of welding aluminum, lack of practical means and methods of field assembly of aluminum components, and the lower strength factor of aluminum has restricted aluminum structural members to uses in which the saving in weight over the use of steel dominated all other factors of consideration.
It is an object of the present invention to broaden the use of structural aluminum by making it economically feasible to utilize the numerous advantages of aluminum over steel and other metals which have heretofore been conventionally used in the fabrication of structural members.
While it is to be understood that the fields in which the principles of the present invention will find application are substantially unlimited, for the purposes of illustration, these principles will be disclosed as applied to structural members for use in the fabrication of substations of electrical distribution systems.
With the increased capacity of electrical distribution systems in urban areas, it has been necessary to locate substations in such areas. The principles of the present invention permit the economical erection of an aesthetic structure for such a purpose at the center of the electrical load area with a minimum of right-of-way and easement problems.
The construction of an economical, aesthetic substation structure has resulted, to a great extent, from the substitution of solid-appearing structural members for the complex-appearing laced box trusses which have heretofore been used. This has been possible by the present invention through the economical association, in a structural member, of aluminum extruded chord members and solid-surface sheet material, preferably aluminum sheet.
In substation construction, as in other fields, a solidappearing structural box truss, while of pleasing appearance, would be lacking in utility as a support structure if it necessitated the use of long bolts projecting through both faces of the truss in order to removably secure connecting plates and other accessory support and attachment means to the exterior surfaces of the truss. This difficulty has been overcome through the provision of extruded bolt tracks on the chord members. These tracks also avoid the necessity of bolt holes or handholds in the solid side plates, thus giving greater strength. I
By joining the side plates at their longitudinal edges to the chord members, in a manner to be hereinafter described, they can be analyzed as part of a section modulus of the truss and carry the shear forces in'the structure as well as in compressive and tensile loadings.
Thus, an object of the invention is to provide an improved structural member which may be economically fabricated from aluminum yet be competitive in cost with standard structural shapes fabricated from corrosionprotected steel.
1 ited States Patent Another object is to provide a structural member of improved aesthetic characteristics.
Another object is to provide a solid box truss having an exterior bolt track.
A further object of the invention is to provide an improved mechanical joint and method of making the same in structural members between chord members and the web lacing or plates spacing the chord members.
A still further object is to provide a structural member with a bolt track which will permit insertion of the bolt at any desired position longitudinally of the member.
A further object of the invention is to provide an improved bolt track, bolt, and load-transfer plate assembly which is characterized by the fact that the load-transfer plate functions to obviate spreading of the bolt track and remove shear from the bolt shank.
These and other objects and advantages residing in the combination, arrangement and construction of components of my improved structural member will appear from the following specification and appended claims.
The principles of the invention have been illustrated in the accompanying drawings as applied to a box section structural member used as a beam or column.
In the drawings:
FIG. 1 is a perspective view of the invention showing the chord member and side plates assembled by a mechanical joint,
FIG. 2 is a perspective view of a short length of the extruded chord member,
FIG. 3 is an enlarged fragmentary end view of one of the locking jaws of the chord member,
FIG. 4 is an enlarged fragmentary perspective view of an end of one of the serrated longitudinal edges of the side plate,
FIG. 5 is a view similar to FIG. 4 of the same end and edge of FIG. 4 being viewed from the opposite side,
FIG. 6 is a plan view of the serrated edge,
FIG. 7 is an end view of the bolt used in the bolt track of the chord member,
FIG. 8 is a side elevational view of FIG. 7,
FIG. 9 is a plan View of the construction and method of manufacture of the load-transfer plate,
FIG. 10 is a cross-sectional view taken on line XX of FIG. 9,
FIG. 11 is a cross-sectional view taken on line XI-XI of FIG. 9,
FIG. 12 is a side view of one of the finished transfer plates shown removed from the strip of FIG. 9,
FIG. 13 is an enlarged fragmentary perspective view showing a bolt and transfer plate mounted on one of the bolt tracks of the structural member, I
FIG. 14 is a view similar to FIG. 13 showing two bolts and a two-section transfer plate as well as the attachment plate to be secured to the bolt track, and
FIG. 15 is a diagrammatic view of the manner in which i bolt holes, yet capable of being used in the fabrication connected to the chord members 12. However, it is anticipated that the surface of the plates 14 may be shaped or formed to provide any desired appearance or strengthening, such as the provision of ribs, channels, embossments, open-work structure, and the like. Also it is anticipated that in lieu of the mechanical connection hereinafter described between the chord members 12 and the side plates 14 that the side plates 14 may be connected along their longitudinal edges to the chord members 14 by such conventional means as rivets, bolts or welding.
' CHORD MEMBERS As more clearly shown in FIGS. 2 and 3, each chord member 12 has a central hollow portion 16, the sides 18 of which define the webs of integral bolt track portions 20. The track portions 20 have inturned flanges 22 with the sides 24 and 26 of the hollow portion 16 spacing and stiffening the track portions 20. Disposed at one side of each track portion 20, and also acting to stiffen the same, are spaced flange portions 28 and 30 which constitute the locking jaws for the side plates 14.
The chord members 12 are most conveniently and economically fabricated by extrusions from suitable extrusionable materials and plastics such as aluminum polytetrafluoride and the like. It would be obvious to those skilled in the art that the structural sections of FIG. 2 could be rolled or otherwise formed sheet sections welded together, bolted or cast.
As an extruded section, the hollow portion 16 may be provided without any difliculty and it provides a convenient conduit running longitudinally of the chord members 12 to receive electrical conductors and other utility conduits such as gas and water lines. Such use of the portions 16 would be particularly important when the member of FIG. 1 is used as an aesthetic column or beam either alone or to mask poured concrete structure, with the member of FIG. 1 acting as a form. for the concrete. Obviously, when used as a concrete form suitable exterior bracingof the member 10 would be required during the pouring and setting of the concrete.
PLATE-CHORD MECHANICAL JOINT The preferred joint between the chord member 12 and side plates 14 is a mechanical joint which will permit assembly by unskilled labor at the factory as well as in the field. The advantages of being able to ship the components of the hollow light-weight structural member 10 of FIG. I knocked down with the fabrication of the mechanical joint being done at or adjacent the point of erection, are obvious.
As a truss, the member 10 of FIG. 1 is dependent for its structural strength upon the tightness of the joint be tween the longitudinal edges of the side plates 14 and the locking jaws defined by the flanges 28 and 30. The following described details of construction of the edges of the side plates 14 secured in the locking jaws, and the design and manufacture of the locking jaws, has produced in practice a satisfactory joint.
The flanges 28 and 30 of FIG. 3 are extruded with one or more longitudinally extending ribs or beads 32 which are preferably in opposed relation, as shown. In practice, with the chord member 12 extruded from an aluminum alloy and the flanges 28 and 30 being approximately .062" in thickness, the projection of the ribs or beads 32 will be in the order of .015" with the penetration of the ribs or beads 32 by the knurls or serrations on the plates 14 being in the order of .005".
As extruded in practice, the flange 28 is disposed at a 10 angle to the plane aa with the flange 30 being substantially parallel to the flange aa. At the-time the jaw, defined by the flanges 28 and 30, is closed upon the longitudinal edge of the plate 14, the flange 28 is first hinged about the area 34 and thereafter deformation takes place in the area 36. To facilitate the deformation in the area 36, the flange 28 has a slight stepped portion 38 and the flange 30 is provided with an opposed stepped portion 40.
Referring to FIG. 15, the manner in which the flanges 28 and 30 are closed upon an edge of the plate 14 is shown. The face of the lower die 42 conforms to that portion of the contour of the chord member 12 (as extruded) which defines the outer surface of the flange 32 and the hinged area 34, while the face of the upper die 44 conforms to the outer surface of the flange 28 after it has been hinged into a position parallel to the flange 30. As the upper die is lowered, it first engages the outer end of the flange 28 along the die face portion 46 to bring the flange 28 down parallel to the flange 30 and into juxtaposition with the side plate 14 located between the flanges 28 and 30. At this point in the travel of the upper die 44, the die face portion 48 engages the flange 22 of the bolt track portion 20 opposite the portion 40 backed up by the lower die face portion 50. This results in deformation of the area 36 at the same time the jaw defined by the flanges 28 and 30 is being closed upon the longitudinal edge of the side plate 14. By this sequence of deformation, spring back of the flanges 28 and 30 has been obviated with an attendant live clamping of the flanges 28 and 30 upon the edge of the side plate 14.
To keep the edge of the side plate 14 in shear relation with the locking jaw defined by the flanges 28 and 30, a series of ribs or serrations 58 and 60 have been provided along the longitudinal edge 62 of the side plate 14, as shown in FIGS. 4 and 5. It will be noted from a comparison of FIGS. 4 and 5 that the ribs 58, on one side of the plate 14 are inclined in one direction and that the ribs, on the opposite side, are inclined in the opposite direction. Thus, penetration of the ribs 58 and 60 of the side plate 14, for example, into the ribs or heads 32 of the flanges 28 and 30 will place the side plate 14 in shear relation with the locking jaws defined by the flanges 28 and 30, regardless of the attempted relative movement between the locking jaw and its associated side plate. The ribs 58 and 60 may be formed by being rolled, knurled or coined in any well known manner. It will be understood that penetration of the ribs or beads 32 by the ribs 58 and 60 will necessitate a degree of relative hardness of the respective materials from which the ribs are formed. In practice, with the side plate 14 of aluminum alloy similar to that used in the extrusion of chord member 12, the work-hardening to form the ribs 58 and 60 will result in sufficient relative hardness to cause ribs 58 and 60 to penetnate the ribs or beds 32 to provide the desired shear relationship with the resulting tight joint which enables the side plates 14 to carry the shear forces as well as to function in the section modulus of the truss.
LOAD TRANSFER PLATE The design of the load transfer plate 64 is preferably such that shear is removed from the bolt 66 and the plate 64 will function as a member reinforcing the bolt tracks 20. In practice, the load transfer plates 64 are fabricated from a noncorrosive metal, such as a suitable aluminum alloy or stainless steel, and preferably the latter, to provide the plates 64 with a greater hardness than that of the extruded aluminum chords 12.
The plates 64 are stamped from a strip of material in a progressive die in a well known manner. As shown in FIGS. 9 and 10, the plates 64 are connected with fragile bars scored at 70 to aid in and define the fracture line where the plates 64 are to be separated from the strip 72 of FIG. 9. It will be understood that the strip 72 of FIG. 9 shows the same in two stages of fabrication. The section 74 of the strip 72 shows the first operation which blanks out the form from the sheet metal with forming being confined to the locating tabs 76. Sections 78 of the strip 72 represent the' completely blanked and formed are formed into the twisted shapes of fingers 80 of the section 78.
To project the sharp upper and lower edges 82 of the fingers 80' beyond the upper and lower surfaces of the flat central portion 84, each finger 80' is twisted about a centrally located axis. As a result, when the transfer plate 64 is applied over the bolt 66 and disposed between the flange 22 and the accessory mounting member 86, tightening of the nut 88 on the bolt 66 will cause the edges 82 to become embedded in the opposed surface of the flange 22 and member 86. Thus, the fingers 80' so disposed in shear relation with such opposed surfaces and all shear is removed from the bolt 66. By having the edges 82 angularly and oppositely disposed to the longitudinal axis of the flanges 22, both longitudinal and transverse relative movement between the flanges 22 and member 86 is avoided and the transfer plate prevents the flanges 22 from spreading apart as the nuts 88 are tightened. This enables the plate 64 to reinforce the flanges 22 while the bolt 66 functions solely in tension.
To improve the load factor of the design, an epoxy or other suitable adhesive may be applied to that portion of the plate 14 disposed between the flanges 28 and 30 prior to the closing operation shown in FIG. 15.
To facilitate the insertion of the head 66' of the bolt 66 in the bolt track portion 20, a nylon insert 66" is provided in the threaded area of the shank of the bolt 66. As shown in FIG. 7, the shape of the head 66 of the bolt 66 is such as to enable the head 66 to pass between the flanges 22 and then to 'be partially rotated to position opposed corners of the head 66 beneath the flanges 22 into the position shown in FIGS. 13 and 14. As the nut 88 is rotated upon the shank of the bolt 66, it engages the insert 66" and the resistance offered by the insert 66" to being threaded by the nut 88 will be sufiicient to rotate the bolt 66 to bring the head 66 beneath the flanges 22. In a well known manner, the insert 66" will also have its usual function of resisting relation rotation between the bolt 66 and nut 88. At the exposed end of the bolt 66, an indicator slot 66" is shown to advise the operator of the nut 88 that the bolt 66 has taken its proper position in the bolt track 20. It Will be understood that the longest dimension of the bolt head 66' is greater than the width of the bolt track 20 measured beneath the flanges 22 whereby the bolt head 66' cannot be completely rotated.
Having thus described my invention, what I claim as new and desire to cover by Letters Patent is:
1. A structural member having a chord member and a web member attached by a mechanical joint, said chord member being of extruded section and having a pair of spaced locking jaws with inner faces in opposed relation to each other, said faces having ribs projecting the-reform, said web member having first and second sides and a longitudinal edge disposed between said jaws and clamped thereby, hardened serrations defined on said web first and second sides adjacent and obliquely related to said longitudinal edges, said serrations on said web member first side being obliquely related to said longitudinal edge in a direction opposite to that of said serrations defined on said web member second side.
2. In an extruded section structural member such as a beam, column or the like having as an integral part of its extruded section a track to receive a headed fastener, said track being defined by a channel having flanged edges, a headed fastener located in said track and engaging behind said flanged edges, a detachable mounting plate in bridging relation to said track, a load transfer plate disposed between said track and said plate and bridging said flanged edges of said track, said fastener having a shank portion extending through said plates, means on said shank portion for clamping said transfer plate between said mounting plate and said track flanged edges, and interference edges defined on said transfer plate adapted to embed into said flanged edges and mounting plate to reinforce the channels by restraining the same from spreading, a portion of the interference edges associated with each flanged edge being obliquely related in opposite directions relative to each other and the length of the associated flanged edge.
3. A hollow structural member, such as a beam, column, or the like, comprising a plurality of chord members of extruded section having longitudinal edges and each having, as an integral part of its extruded section, a track to receive a headed fastener capable of being tightened, said track being defined by flanged edges, a headed fastener within said track, load transfer means cooperating with said headed fastener received within said track bridging said track and overlapping said flanged edges, said load transfer means having an interference fit with said flanged edges upon tightening said headed fastener, deformable web-gripping means defined on said extruded section longitudinal edge, and webs having longitudinal edge-s received within and gripped by said deformable web-gripping means upon deforming said We. gripping means into engagement with said web longitudinal edges.
References Cited by the Examiner UNITED STATES PATENTS 2,200,227 5/ 1940 Olson 52-364 2,266,593 12/1941 Emmons 189 36 2,345,650 4/1944 Attwood 189-36 2,707,012 4/1955 Cox 151-35 2,828,931 4/1958 Harvey 52-143 X 2,853,195 9/1958 Malcolm.
2,928,512 3/1960 Slater et al. 189-36 2,936,051 5/ 1960 Martin 52-6'94 2,963,131 12/1960 Brockway 52122 3,032,089 5/1962 Gutshall 151-35 FOREIGN PATENTS 1,231,738 11/1960 France.
853,581 11/1960 Great Britain.
FRANK L. ABBOTT, Primary Examiner.
RICHARD W. COOK-E, CHARLES E. OCONNELL,
Examiners. R. S. VERMUT, Assistant Examiner.