US1649577A

US1649577A - Fabricated joist

Info

Publication number: US1649577A
Application number: US5146A
Authority: US
Inventors: William C Coryell
Original assignee: Truscon Steel Co
Current assignee: Truscon Steel Co
Priority date: 1925-01-27
Filing date: 1925-01-27
Publication date: 1927-11-15
Anticipated expiration: 1944-11-15

Description

' Nov. 15, 1927. 1,649,577

W. C. CORYELL FABRICATED JOIST Filed Jan. 27. 1925 4 Sheets-Sheet l Nov. 15, 1927.

1,649,577 W. C. CORYELL FABRICATED JOIST Filed Jan. 27. 1925 4 Sheets-Sheet 2 ITHIIIIII /I'm! LL ((4 1 3 3 V Nov. 15, 1927. 1,649,577

W. C. CORYELL FABRICATED JOIST Filed Jan. 27.- 1925 4 Sheets-Sheet 3 Nov, 15, 1927.

W. C. CORYELL FABRICATED JOIST Filed Jan. 27, 1925 4 Sheets Sheet 4 Patented Nov. 15,1927.

UNITED STATES WILLIAM C. OORYELL, OF'YOUNGSTOWN, OHIO, ASSIGNOB, BY ME SNE ASSIGNMENTS,

vTO TBUSOON STEEL COMPANY, OF YOUNGSTOWN, OHIO, A. CORPORATION OF MICHI- GAN.

rnnmcarnn .rorsr.

Application filed January This invention relates to fabricated joists orgirders, and more particularly to a joist.

A primary object of the invention is to; provide a joist that may be fabricated from standardized materials and is designed in such a way that the assembling operation requires only ordinary tools and workmen with ordinary skill, theparts being so related that the danger of the girder being weakened due to carelessness and oversight of the workmen and eliminated.

A' further object of the invention is to provide a fabricated joist or girder that may be readily, handled either by cranes or by hand, and when placed in position on the job can be readily tiedtogether by bridging Wires, and if left accessible to painting can be readily painted on'both sides of the web members. Furthermore, by reason of the fact that the ,construction of the girder is free from pockets or dust and dirt collecting crevices, it is thereby possible to keep the girder comparatively dust free.

A further and impdrtant object of the invention is to provide a fabricated girder consisting of top and bottom chord members which are connected by strut or shear members in the form of novel web plates which may be easily and readil arranged between the chord members an thereby facilitating the building of a girder from stock materials accordin to the speciinspectors is practically fications required for a particu ar job.

With the above and other objects in view which Will more readily appear as the nature of the invention is better understood, the same consists in the novel construction, combination and arrangement of parts hereinafter more fully described, illustrated and claimed.

A preferred and practical embodiment of the invention is shown in the accompanying drawings, in which Figure 1 's a, view illustrating a girder constructed in accordance with the present invention. I

Figure 2 is an enlar ed detail view of one end of the girder a I. pair of the strut members.

quickly adjusted- 27, 1925. Serial N0. 5,146.

- Figure 3 is a detail horizontal sectional view taken on the line 3-3 of Figure '2.

Figure 4 is a vertical sectional view taken on the line 4-4 of Figure 2.

Figure 5 is a detail elevation of a modified form of construction.

Figure 6 is a vertical sectional view take on the line 6-6 of Figure 5.

Figure 7 is a detail view of one end of a girder constructed in accordance with a modified arrangement of parts.

Figure 8 'is a horizontal sectional view taken on the line 8-8 of Figure 7.

Figure 9 isa vertical sectionalview taken on the line 99 of Figure '7.

Figure 10 is a detail perspective view of one ofthe strut plates employed in the construction of Figures 7, Sand 9. l

Figure 11 is an elevation of a girder ems ploying a continuous novel Web construction.

Figure 12 is a detail horizontal sectional view taken'on the line 12-12 of Figure 11.

Figure 13 is aside elevation of a portion of the joist illustrating a modification of the invention'wherein rolled struts areused to form the web of the joist.

Figure 14 is a horizontal taken on the line 14-14 of Figure 13.

Figure 15 is a vertical sectionafview taken on the line 15-15 of Figure'13.

1,649,577 PATENT OFFICE.

sectional view 7 Figure 16 is a detail side elevation illustratin a modification of the invention wherein the rolled struts are attached at their ends directly to the inner edges of the' chord members.

Figure 17 is an enlarged transverse sectional view of the type of strut shown in Figure 16.

Similar reference characters designate corresponding parts throughout the several figures of thedrawings. i

In carrying the resent inventioninto effect, it is propose to provide a girder construction consisting of compression and tension chord members adapted to be connected by a series of web forming units which may be employed in any desired number and spaced between the chord members in ac- -ordance with any desired specification, or on i the other hand it may be so arranged as to provide in effect a continuous web portion, or as shown in one of the modifications of the present construction the web itself may be continuous, but even in that case the same embodies novel features of construction which permit of the facile assembly of the girder in accordance with one of the primary objects of the invention. I

In constructing the present type of girder it is proposed to utilize a web or plate member having a body which is Warped, deflected or troughed at right angles to the plane of the sheet of which it is formed thereby to provide a strut member of inherent stiffness and load carrying capacity, while at the same time having the added advantage of providing means for embracing or engaging the sides of the top and bottom chord members in such a way that the attachment of the web units to the chord members reduces itself to a simple, practical and effective securing operation, such for example as may be accomplished by the use of a welding are or electrical welding apparatus or its equivalent.

Referring more particularly to the forms of the invention shown in the accompanying drawings, and which illustrate applications of the principles of the invention, it will be observed that the present joist or girder includes the upper compression chord member A and the lower tension chord member B,

having therebetween a novel Web element designated generally as V, the said tension chord member preferably having oblique end portions C which terminate in the end portions D parallel'with the ends of the top chord A, thereby to facilitate the connection of the top and bottom chord members by the plates E or their equivalent. As shown in the drawings, the ends of the joist or girder thus formed may rest upon the supports S which may be abutments of a building, main girders or other members adapted for carrying joints or girders of the type disclosed herein.

The top and bottom chords A and B are preferably rectangular or oblong in cross section, although as shown in the drawings, other forms of chord members may be used such as channels or T-shapedsections. As-

suming that the girder is of the type shown in Fi ures 1 and 2, the designer will make use of standardized tables and standardized diagrams which indicate in a conventional manner the size, length, depth and other details of the girder parts, and then the material suited to the girder will be taken from stock and the lower chord bent into the shape shown. The web element or elements WV may then be positioned between the top and bottom chord members and the cheek plates E may then be secured to the ends of the chords A and B to hold the same in the desired position.

The web construction of the girder as previously indicated may consist of one or more web units according to the length of the units or web plates W, it will be observed that the same are preferably made from relatively thin sheet metal, and comprise a body portion which is troughed or deflected thereby to produce the end wings 1-1 lying in the normal plane of the sheet and the oil'- set intermediate wing 2 connected to said and wings by the oblique wall portions 3, the said oblique wall portions 3 imparting great stillness to the sheet and reinforcing the same in such a way that they have relatively great edgewise load carrying capacity. The end wings 1-1 as well as the intermediate wing or wall 2 are provided with the chord engaging lugs 1 and 2 which are adapted to engage opposite sides of the chord members thereby embracing the chord members .in such a way as to be frictionally interlocked therewith. With the web units W thus interlocked with the chord members, it will be apparent that when the said chord members are connected by the cheek plates E or their equivalent or otherwise held from spreading, the said web members may be readily shifted or moved along between the chords to be located in accordance with the specification of the designer. The lugs 1 and 2 may then be welded to the sides of the chord bars either by are or acetylene welders in the hands of operators or automatic machinery may be used for doing this work.

The feature of providing a web unit TV that may be interlocked between the chord members by the mere connecting of the latter is of particular importance because it facilitates the assembly of the girder b making it possible to place all of the web units in position between the chord members and then locate them in accordance with the distribution of the load to be carried by the girder. When the units W are used in multiple as shown in Figure 1, the spacing thereof readily permits of the attachment of expanded metal or the like to the lower chord bar by conventional supporting devices, or when the web unit 7' is used the bottom edge thereof may be provided with a series of tie-receiving openings 4 as shown in Figure 11. Referring more especially to the type of web member W shown in the figure just mentioned. it will be observed that the web member in this embodiment includes the alternating wall or wing members l and 2 connected by the oblique wall portions 3". The manner of assembling the web W between the chord members, however, is the same as the manner of assembling the shorter web members W, and greatly facilitates the handling of the girder during further fabrication.

From the" foregoing, it will be apparent that one of the primary features of the web unit W is to provide a web unit made from relatively thin material which has not only the advantage of economizing material, but substantially lightening the girder while at the same time obtaining maxlmum facility and. convenience in assembling both from the standpoint of the manufacturer and the architect or designer in charge of the building operation. With the web units formed as proposed herein it will be apparent that through the use of .a suitable tool or press the relative thickness of the web unit may be varied thereby to make the web unit accommodate chord bars of greater .or less width according to the joist being fabricated. In other words,by exertinga pressure on'opposite faces of the web. unit or upon opposite ends of the web unit the relative spacing between the members 1 and 2 can be changed to suit different size chord members.

Figures. Sand 6 of the drawings illustra-te the embodiment of the invention in connection with a top chord member A of T-shaped cross section. In this arrangement the web units W perform the same functions and are assembled-inthe same way heretofore explained, and the only difference in these members and units is that the walls 3 thereof must be notched as indicated at w to receive the shank portion of the T- shaped girder.

Also as shown in Figures 5 and 6, an end panel W may be used at the end of the joist between the oblique portion ofthe bottom chord member and the topchord. This panel W has its lower end formed on an oblique angle corresponding to that of the oblique portion C of the bottom chord, and like the web. units W is provided with the chord engaging and embraclng lugs 5. This arrangement is desirable when heavy loads are to be carried by the joist, thereby enabling the joist to better withstand the greater load whichis carried to the ends of the joist adjacent the supports therefor.

Figures 7 to 10, inclusive illustrate a further embodiment of the invention wherein the web units W may be provided at the ends thereof with the inturned flanges 6 which are cut square at the top and bottom edges, thus offering a greater seating area for the .chord members. One of the features in connection with this type of web unit is that a suitable clamping device may be applied to the flanges 6-6 to exert a compressive force toward the center of the unit thereby causingthe lugs 1*" and 2 to separate and loosely slide along the chord members to facilitate the location of the unit at the proper place.

Also in the form of the invention shown in the drawings above referred to the top chord A may be in the form of a channel member while the bottom chord B is of relatively flat cross section.

In channel members the least radius of gyration is measured in a direction directly vertical to the web. This least radius of gyration is used in. relation to the length of top chords between adjacent web members. It is necessary to guard against the buckling of the top chord due to compression, over longer lengths than merely from one web member to another web member. The top chord member therefore is next considered with reference to lateral deflection from one point of bridging attachment to the next point of bridging attachment. The top chord if not still enough may deflect laterally from one point of bridging to the next point ofbridging, if the length between bridging should exceed the distance of 120 times the greater radius of gyration. The greater radius of gyration is measured in the direction of the, web, or what is called the depth of the channel. If bridging is not used, or the joist is not attached to the floor,

then of course the to chord in totallength must not exceed 120 times the greater radius of gyration. In other words, no portion of the top chord from point to point must exceed the radius of gyration by'the value120, when theradius of gyration is taken in the same direction as the deflection being guarded against. It will thus be seen that a channel member as disclosed in Figure 9 is an ideal section for fulfilling the conditions of topchord stillness.

Another feature of the joist herein disclosed consists in the novel method of fabricating the same. It is well known that the top chord of a joist usually carries a floor load This floor load is transmitted directly through the chord member by a compressive stress into the web member and to the point of attachment to the bottom chordQ It is there resolved into a dia-gonal stress within the web member and a tensional stress in the bottom chord. It therefore follows, that if the combination of the top and bottom chord members and the web member are subjected to a compressive stress before and the joists have been made in this manner,

the localized stresses occurring within and immediately about the welded joist will have been reduced to a minimum, when "they are in a building and carrying normal loading. Usually, indeterminate stresses will be present in the joints when the joists are stacked in storage or otherwise in a free position. This method of manufacturing the joists has a marked effect in directing the strength of the joint material into useful stresses for carrying a load, and therefore tends to produce a joist of maximum strength.

Figure 13 shows a form of joist wherein the strut or web members W are made of rolled Z-bars. These Z-bars have a greater thickness .than the web members IV. and need not be soiwide. However, the ends of the web members are cut away to straddle the chord bars A and B, thereby providing the lug portions 2 In this form of the invention it will be observed that the rolled Z-bar includes the transverse body portion 10 which is positioned directly between the chord members while the

wing portions

11 and 12 are located outside of the plane of the sides of the chord members whereby the lug portions may embrace oppo site sides of the said chord members thereby providing points of attachment at opposite sides of the chords.

Figures 16 and 17 of the drawings show a further modified form of strut I. In this type of strut it is proposed to utilize a rolled Z-bar section, the same lying entirely within the plane of the chord members A and B. That is to say, the wings 11- and 12 as well as the web 10 lie entirely within the plane of the chord members as shown in Figure 17, thereby permitting of the attachment of the strut members with the chord members by the. welds 13 and 14 located at opposite sides of the chord members. Thus, in this form of the invention, the feature of providing a web member with ofl'set attaching portions is also adhered to since the same can be-connected at opposite sides of the chord members as shown by the

welds

13 and 14.

Another advantage of the type of joist shown in the present drawings is that its relatively open characteristic makes it possible to readily pass piping or wiring therethrough, while at the same time'beln also adapted to receive the ends of lateral joists.

As previously indicated, one of theimportant features of the invention is the ease of fabrication. That is,"by first assembling the top and bottom chord members in the desired relation, the web or strut members may then be fitted between the chords and adjusted to the final location or position prior to securing them in place as a permanent part of the beam. Also another important feature of the invention resides in subjecting the top and bottom chord members to compressive stress after they are assembled, and then welding the chord members and web members together while under such stress.

From the foregoing, it will be apparent that the present invention provides a fabricated joist or girder construction wherein the chord members are connected by one or more web units having chord embracing and attaching lugs adapted to unite the chord members in such a way as to constitute a light but stiff load carrying strut. Also the invention has particularly in view, a pressed sheet metal strut which may be readily made and manipulated prior to assembling into a girder while at the same time enabling the designer and the workmen to readily adjust the web or strut members at any desired point between the chord members.

I claim 1. A fabricated joist comprising top and bottom chord members and a connecting sheet metal web member, said sheet metal web member being provided with opposite wall portions connected by oblique wall portions adapted to bear respectively against the underside of the top chord and against the upper side of the bottom chord, and the ends of said wall members projecting over the sides of the top and bottom chord members.

2.-A fabricated 'oist including top and bottom chord mem ers and a plurality of spaced sheet metal web members for connecting the same, said members each being pro vided with offset wall portions connected by intervening oblique wall portions, and said first named wall portions being provided with lugs adapted to embrace opposite sides of the chord members. and means for securing said lugs to the chord members.

3. A fabricated joist consisting of a straight compression member, a straight ten- -sioned member with upturned ends and standardized strut elements connecting said compression and tension members and consisting of sheets dished throughout their length and terminating in lugs which embrace the opposite sides of the top and bottom chord members.

4. A fabricated joist consisting of top andsignature. 1

WILLIAM C. CORYELL.