US1763943A - Metal joist and the manufacture thereof - Google Patents

Description

June 17, 1930.

A. J. BATES. JR

METAL JOIST AND THE MANUFACTURE THEREOF Filed 001;. 8, 1927 Patented June 17, 1930 UNITED STAES.

PATENT OFFICE ALBERT J". BATES, JR., OF CHICAGO, ILLINOIS, ASSIGNOR TO BATES EXPANDED STEEL TRUSS 00., OF EAST CHICAGO, INDIANA, A CORPORATION OF DELAWARE METAL JOIST AND THE MANUFACTURE THEREOF Application filed October 8, 1927.

The invention relates to metal joists or beams and the manufacture thereof.

The main objects of the invention are-to provide a joist or beam which is formed of an expanded integrally flanged beam and which has its end portions formed to bring the point of intersection of the stress lines as close to the supported portions of the ends to increase the resistance against bending moment in the zones adjacent and inwardly of the supports for the ends, and to provide a method of forming an expanded joist or beam of integral members, by which the beam will be slitted so that the integral end portions of the web will be formed to' give additional strength to the joist or beam against bending moment adjacent the supported end portions.

Other objects of the invention will appear from the description.

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

In the drawings: Fig. 1 is an elevation of an I-beam from which the joist is formed. Fig. 2 is a view showing the manner of slitting the beam before it is expanded, Fig. 3 is an elevation of the beam after it has been expanded. Fig. i is an elevation of a finished joist or beam. Fig. 5 is a section on line 55 of Fig. 4. Fig. 6 is a section on line 6-6 of Fig. 4. Fig. 7 is a section on line 7-7 of Fig. 4.

The invention is exemplified in a joist or beam consisting of a longitudinal upper member comprising a vertical web a and a horizontal flange a projecting laterally from one or both sides thereof and forming the top of the joist; a lower longitudinal member comprising a vertical web a and a horizontal flange 05 projecting laterally from both sides thereof and forming the bottom of the joist; a series of substantially parallel diagonal truss members a between the vertical web of the upper and lower members and oppositely extending series of diagonal or truss members a between the webs of the upper and lower members and medially united with the diagonal members Serial No. 224,802.

All of these members are integral and are formed of an I-beamor bar A shown in Fig. 1, with upper and lower flanges corresponding to the flanges a and a In the manufacture of the joist,- the web of the the ends of the slits a? and a and to form expansible strands a These slits are cut so that the end slits of the lower series will intersect the ends of the beam, and the metal of the web between said slits and tnetop and bottom flanges is otherwise left uncut to points some distance inwardly of the ends to form portions a which bear. on the structure, beam or wall supports, and these portions are of a height equal to the aggregate height of the web a and the strands between slits a and a and between a and at which form the diagonal,members. The upper slits 1, are omitted from the portions of the beam disposed inwardly of the portions a to provide only diagonal tension members adjacent the beam-ends and to additionally reinforce the upper member of the joist adjacent the suported ends thereof. By omitting these slits, portions @4 are provided, between the end portions a and the second diagonal or truss members of the joist, of an aggregate height corresponding to the web a and one of the truss-members w. As a result of this formation, the intersection of the stress lines in the upper member and the diagonal tension members a are projectedendwise closer to the ends of the joist so as to approximately reach or ex tend beyond the point of support, as indicated by dotted lines a in Fig. l. This exemplifies a method of slitting the joist preparatory to expansion, so that the upper member will be reinforced by an integral web portion adjacent the supported ends of the joist. A characteristic of'this method and result is that the metal of thediagonals n r u the beam and prevents sagging adjacent the supports and to bring the points of intersection of the stress-lines closer to the supportends 01 of the beam. In other words, the strips of metal which would otherwise form the outwardly and downwardly extending truss members at the ends of the beam are instead utiliZedin reinforcing the upper member of the beam in portion a ad acent the ends and in the portion a.

After the beam has been slitted as described, it is heated and the upper and lower flanges are spread'apart in parallelism by suitable expanding mechanism to the shape shown in Fig. 8. This expanding operation will stretch and deflect the strands of the web formed by the slits, into diagonal members a a", leaving their ends joined to the web and their medial portions joined together. This forms a central series of diamond shaped openingsin the-web and permits the extent of expansion necessary to form a joist of the desired height. The slits a arespaced from the top of the joist a greater distance than the slits m are placed from the bottom of the joist, to give, greater strength to the top portion of the joist. Sufficient portions of the vertical webadjacent the ends are left to reinforce the upper horizontal flange vertically where it is supported. By leaving the ends of the web between slits a and the top flange unslitted, the end portions of the upper member will be properly reinforced.

Struts a are placed and suitably secured, as by welding, between the upper and lower longitudinal members in the openings nearest the ends of the joist, to act as compression members between said longitudinal members. These compression members are disposed a suitable distance from the ends of the beam to directly transmit stresses between the upper and the lower longitudinal members.

In a trussed joist, it has been found advantageous to support the ends of the upper longitudinal member and leave the lower member in suspension, and for this purpose, the lower member is sheared off at a (Fig. after the beam has been expanded, so the upper members will project over a suitable support B, as shown in Fig. l. This shearing will remove suflicient metal from the ends of the lower longitudinal member so the latter will not bear on or connect with the support and will therefore act onlyas a suspension member. Either plates or pieces a,

sheared off the lower longitudinal members, are then welded on the bottom of the ends of the projecting end portions of the upper member to form bearing plates for the upper member. If desired, the web portion of the piece n may be cut away before attaching it to the projecting end of the upper member, according to the height desired in the web of the upper longitudinal member, to form I the space desired above the top of the sup port B. These bearing plates hold the joist against transverse rocking and prevent the lower edge of the portions a of the upper longitudinal membersfrom cutting into the supporting wall or beam.

The invention exemplifies, a joist which is formed of a slatted expanded bar or beam with diagonal truss members which serve as compression and tension members to increase the strength of the oist and in which provision. is made for strengthening the end portions of the upper member and in which the points of intersection of the stress lines in the upper-member and the tension members nearest the ends are brought as near as possible to the ends of the joist and the supports therefor, to prevent sagging or bend ing of the joist in the'zones disposed in wardly of the end portions; a joist in which this result is attained by utilizing the metal which would otherwise form a substantially non-stressed diagonal member; and also a method of attaining this result by the manner of slitting the beam prior to expansion, and without the necessity of add ing non-integral reinforcement to the portions of the joist near its ends.

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. The slitting may be advantageously done in a machine of the character set forth in an application filed by me Nov. 5, 1926, Serial" No. 141,702. The expanding may be done in a machine of the type set forth in Patent No. 1,260,857 dated March 26, 1918.

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

1. That improvement in the manufacture of expanded metal joists which consists in slitting the medial portion of a flanged beam to form a pair of longitudinal member-s and two intermediate and side-by-side series of expansible strands with bonds between themselves and said members, and slitting the ends of the web to form single expansible strand-s only; and then expanding the beam to space apart the longitudinal members and to form single diagonal truss mem bers adjacent the ends of the beam and op truss members in the medial portion of the beam.

2. That improvement in the manufacture of expanded metal joists which consists in slitting the medial portion of a flanged beam on three longitudinal lines to form a pair of longitudinal members and two intermediate and side-by-side series of expansible strands with bonds between themselves and said members, and slitting the ends of the beam on one of the lines to points located inwardly of the extreme ends of the beams so as to form single expansible strands only adjacent the beam-ends; and then expanding the beam to space apart the longitudinal members and to form single diagonal truss members adjacent the ends of the beam and oppositely extending centrally united diagonal truss members in the medial portion of said beam.

3. That improvement in the manufacture of expanded metal joists which consists in slitting the medial portion of a flanged beam on three longitudinal lines to form a pair of longitudinal members and two intermediate and side-by-side series of expansible strands with bonds between themselves and said members, and slitting the ends of the beam from the end slits of the intermediate line to points adjacent the extreme ends of the beam so as to form single expansible strands only adjacent the beam-ends; and then expanding the beam to space apart the longitudinal members and to form single diagonal truss members adjacent the ends of the beamand oppositely extending centrally united diagonal truss members in the medial portion of said beam.

4. That improvement in the manufacture of expanded metal joists which consists in slitting the medial portion of a flanged beam on three longitudinal lines to form an upper and a lower longitudinal member and two intermediate and side-by-side series of expansible strands with bonds between themselves and said members, and slitting the ends of the beam on the lower line to intersect the end edges and form end-portions for the lower longitudinal member that are disconnected with respect to the end portions of the upper member, and also slitting the ends of the beam on one of the other lines to form single expansible strands adjacent said end-portions and the ends of the beam; and then expanding the beam to space the lower member and its end-portions from the upper member and to form single diagonal truss members adjacent the ends of the beam and oppositely extending centrally united diagonal truss members in the medial portion of the beam.

5. That improvement in the manufacture of expanded metal joists which consists in slitting the medial portion of a flanged beam on three longitudinal lines to torm an upper and a lower longitudinal member and two intermediate and side-by-side series of expansible strands with bonds between themselves and said members, and slitting the ends of the beam onthe lower line so as to intersect the end edges and form end-portions for the lower longitudinal member that are disconnected with respect to the end portions of the upper member, and also slitting the ends of the beam on the intermediate line to form single expansible strands adjacent said end-portions; and then expanding the beam to space the lower longitudinal member and its end-portions from the upper member and to form single diag- Q onal truss members adjacent the ends of the beam and oppositely extending centrally united diagonal truss members in the medial portion of said beam.

6. An expanded metal joist formed of a flanged beam and comprising upper and lower longitudinal members, oppositely extending centrally united diagonal truss members acting as tension and compression members in the medial portion of the beam and formed integrally with the upper and lower longitudinal members, and diagonal tension members only adjacent the ends of the beam and also formed integrally with said upper and lower members, substantially the entire amount of metal embodied in the ends of the beam being utilized in said end tension members and the end-s of the longi tudinal members.

7. An expanded-metal joist formed of a beam having a web and flanges, said joist comprising upper and lower longitudinal members, oppositely extending centrally united diagonal truss members formed integrally with the upper and lower longitudinal members and diagonal tension members only adjacent the ends of the beam and also formed integrally with said members, the ends of the lower longitudinal member being extended to underlie the single diagonal

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