US1822331A - Expanded metal joist - Google Patents

Description

P 3, 1931- A. J. BATES, JR 1,822,331

EXPANDED METAL JOIST Filed May 7, 1928 Patented Sept. 8, 1931 UNITED STATES PATENT OFFICE ALBERT J. BATES, JR., OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, '10 BATES EXPANDED STEEL CORPORATION, OF EAST CHICAGO, INDIANA, A CORPORA- TION OF DELAWARE EXPANDED ME'IAL JOIS'I Application filed Kay 7, 1928. Serial No. 276,563.

The invention relates generally to joists or girders for use in building construction and the like. More particularly the mvention relates to that type of joist which como prises a pair of longitudinal members and a separately formed zigzag lacing or lattice unit extending between the members and forming diagonal trussing.

Heretofore, in the fabrication of j oists of 19 this type, it has been the practice to use separate or independent metallic bars in forming the longitudinal members at the sides of the lacing and to construct the ends of the joist by bending the ends of the lower bar :w wardly and then outwardly to form bearing members which are secured to the ends of the upper bar by a welding operation or the use of separate reinforcing plates. Because of the diflicult and numerous steps in the manufacturing operation, these joists are costly and therefore cannot be used economically in actual practice.

The primary object of the present invention is to provide a joist or supporting beam which is an improvement upon and may be fabricated at a much lower cost than joists manufactured in accordance with the aforementioned method or process in that the upper and lower longitudinal members are integral and are formed by slitting and ex anding a metallic structural element, suc for example, as an I-beam.

Another object of the invention is to provide a joist which is generally of new and improved construction and in which the lacing is so formed and positioned with respect to the ends of the joist that the joist is efiectively reinforced at the points or places where most needed.

A further object of the invention is to provide a joist of the aforementioned type in whichthe metal forming the upper and lovger members and ends of the joist is distributed to effect the maximum resistance to deflection in proportion to the amount of 1 metal used.

Other objects of the invention and the various characteristics and advantages of the present joist construction will be manifest from a consideration of the following detailed description.

The invention consists in the several novel features hereinafter set forth and more particularly defined by claims at theconclusion hereof.

In the drawing which accompanies and forms a part of this description or specification and in which like characters of reference denote corresponding parts throughout the several views:

Figure 1 is a side elevation of an I-beam from which the frame or major part of the joist or supporting girder is formed, showing the manner in which the beam is slitted pr sheared prior to the expanding opera- Figure 2 is a side elevational view showing the beam after it has been expanded to form the upper and lower longitudinal members of the joist;

Figure 3 is an elevational view of the zigzag lacing or lattice unit which, when secured in its operative position, forms the diagonal trussing;

Figure 4 is a side elevation of the finished joist;

Figure 5 is an end View;

Figure 6 is a transverse section taken on the line 6-6 of Figure 4;

Figure 7 is a section taken on the line 77 of Figure 4; and

Figure 8 is a fragmentary side elevation of a joist which embodies two zigzag lacing units.

The joist or beam which forms the subject matter of the invention is adapted for use in connection with buildings and the like comprises an upper longitudinal member which consists of a vertical web a and a horizontal flange a rojecting laterally from both sides thereof and forming the top of the joist; a bottom longitudinal member which consists of a vertical weba and a horizontal flange a projecting laterally from both sides thereof and forming the bottom of the joist; and a zigzag lacing or lattice unit which extends between the upper and lower members and is secured thereto as hereinafter described to form diagonal trussing con- 100 sisting of tension and compression members a, a. The upper and lower members which form the frame or skeleton form for the lacing are integral and are formed of a rolled metallic structural element, such, for example, as an I-bealn or bar A (Figure 1). The upper and lower flanges of this bar correspond to the flanges a? and a of the oist.

In the mamlfacture of the joist, the web of the I-beam is first sheared to form a single continuous slit (1 The latter is straight and extends longitudinally throughout the central or intermediate portion of the beam, the ends thereof terminating inwardly of the beam-ends so as to form supporting portions 11:. These portions are left uncut and as a result are of a height equal to the entire width of the beam, that is, the aggregate height of the web and the side flanges. The portions of the flange a which underlie the portions a form integral bearing plates a at the ends of the joist whereby the joist may be supported in its operative position upon a suitable supporting structure B which may consist of cross-girders or I-beams as shown in Figure 4. In operation the plates a serve to hold the joist against transverse rocking movement and prevent the joist from cutting into the structure B which sometimes is formed of brickwork. A characteristic of forming the joist-ends in this manner is that said ends are of maximum strength due to the fact that they are uncut and consequently no additional or non-integral reinforcing is necessary. Furthermore, the portions a serve to connect integrally the separated web portions, that is, the parts of the beam which form the upper and lower members of the joist. In addition the bearing plates a are formed as integral parts of the upper member with the result that no separate or independent operation is necessary in their formation.

The ends of the longitudinal slit 0, terminate inwardly of the end edges of the beam a sufficient distance to give the supporting portions at the necessary or desired length. The slit is spaced from the top of the beam a greater distance than it is spaced from the bottom so that the web a of the upper member will embody more metal than the web a of the lower member. By positioning the slit and distributing the metal in this manner the joist operates to exert the maximum resistance to transverse deflection in proportion to the total amount of metal in the beam.

After the beam A has been slitted as described, it is heated and then subjected to the action of a parallel expanding machine, such, for example, as the one shown and described in Letters Patent of the United States No. 1,260,857. In arranging the beam in this machine the lower flange ais gripped a considerable distance inwardly of the terminating points of the slit a so that the end portions a of the lower member are free. T has as the upper and lower members are. expanded or separated in parallelism these end portions a which are connected to the supporting portions a are stretched and deflected into the angular position shown in Figures 2 and 4 and in such position serve as end tension members. A characteristic of slitting and expanding the beam A in the manner set forth is that the completed frame is formed in but two operations. members a embody both a web-portion and a laterally projecting flange they are efficiently reinforced and the joist is strengthened at its ends at which places reinforcement is most needed. The completed frame or skeleton form consists of the upper and lower longitudinal members which are parallel, the end portions at including the plates a", and the upwardly and outwardly extending truss forming members a which are joined to the ends of the lower longitudinal member and said end portions (1 All of these parts are integral and therefore the use of separate pieces or plates is avoided.

The joist shown in Figure 4 embodies a onepiece lacing or lattice construction. This lacing which forms the diagonal compression and tension members a and a is made in any suitable manner by bending or rolling a bar or rod into the zigzag form shown in Figure 3. The diagonal elements which comprise the lacing are preferably made to extend at a substantially angle and are connected together at their ends by integral arcuate or curved apex members a. The width of the lacing is such that it fits between the upper and lower members and the bends or curved apex members a abut against the inner edges of the webs a and (L The lacing is secured in place so that the diagonal members form the compression and tension members a and a, by welding the apex members a to the contiguous portions of the adjoining webs. This welding is designated by the reference character a. In applying the lacing it is positioned or arranged so that there are two members a adjacent the intersections or junctures of the truss members a and the ends of the lower longitudinal member (Figure 4), and the two outermost diagonals extend upwardly and outwardly from said members to form tension members at the ends of the lacing. These end tension members act as supplements to the flanged truss members a and are arranged so that their upper ends terminate in the outermost members a which are welded midway between the inner ends of the supporting portions (1 and the second members a A characteristic and a result of forming or positioning the lacing in the manner set forth is that the ends of the joist are efiicientlv reinforced and operate to resist eflectivelytransverse deflection. The rod or bar from which Since the end truss the lacing is formed is made of steel and is preferably of greater width than the web of the beam so that the diagonal truss members will be rigid and capable of withstanding great longitudinal forces.

In the manufacture of the extremely long joists it is impractical to make the zigzag lacing from a single rod and therefore two or more lacing units of the character shown in Figure 3 are utilized. These units are serially arranged and welded in place in the manner shown in Figure 8. In this form of the invention, the end, lacing units are positioned so that the outer ends thereof are positioned similarly to the single or one-piece unit shown in Figure 4.

The joist or structural supporting element disclosed herein may be fabricated in a comparatively simple manner and is of maximum rigidity or strength relatively to the amount of metal used. It embodies no welded or auxiliary reinforcing plates with the exception of the zigzag lacing and may be economically used for building and other purposes.

In the manufacture of the joists any suitable'machine may be utilized to shear the longitudinal slit in the beams.

. The invention is not to be understood as restricted to the details set forth, since these may be'modified within the scope of the appended claims, without departing from the spirit and scope of the invention.

Having thus described the invention, what I claim as new and desire to secure by Letters Patent, is:

1. As a new article of manufacture, a joist comprising a frame made of an I-beam slit and expanded to form an elongated flanged upper member having a longitudinally extending web portion with a straight lower edge, and an elongated flanged lower member having the intermediate part thereof arranged parallel with the upper member and embodying a longitudinally extending web portion with a straight upper edge and its ends extending upwardly and outwardly and formed integrally with the ends of the upper member to form truss-members at the ends of the joist, and a separately formed one-piece of the lower member to form supplementary end truss-members.

Signed at East Chicago, Indiana, this th day of April, 1928.

ALBERT J. BATES. JR.

zigzag lacing extending betweenthe members and having the apex parts thereof abutting against and welded to the straight edges of the aforesaid web portions.

2. As a new article ofmanufacture, a joist comprising a frame made of an I-beam slit and expanded to form an elongated flanged upper member having a longitudinally extending web portion with a straight lower edge, and an elongated flanged lower member having the intermediate part thereof arranged parallel with the upper member and embodying a longitudinally extending web portion with a straight upper edge and its ends extending upwardly and outwardly and formed integrally with the ends of the upper

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