US1776467A - Structural-steel truss joist - Google Patents

Description

Sept. 23, 1930. R. M. FRANDSEN I STRUCTURAL STEEL TRUSS JOIST m 0 I Am 1b N a W e NMQNRN N T h N Nw I4" mm Q M w 1 I l l 1 l I l|k ||l||l||ll111V I I I I 1 I 1 I l l 1 1 1 l Q 1 I I I I lllll i lll 51-: I 5

Filed D80. 16, 1927 Sept. 23, 1930.

R. M. FRANDSEN STRUCTURAL STEEL TRUSS JOIST Filed Dec. 16, 1927 3 Sheets-Sheet 2 \N 1 QHQNK mm Sept. 23, 1930. R. M. FRANDSEN STRUCTURAL STEEL TRUSS JOIST s Sheets-Sheet 5 Filed Dec. 16, 192

llllllllllllll INVENTOR.

' HAS/105M. FRA NDSEN. BY

4 i /(ATTORNEY Patented Sept,- 23, i w I I 1 I I f ssnesnis mnsm, or eiin emae mom '7 istention-menswear TRUss orsrT -T i V v l I e Application filediJeceznber 16,112 327. Serial d v I 'lvhe present. invention relatesito improve- Figure 5 is a fragmenta yside elevation, i i ments'in structuralsteel truss-joist construcshowingajslightly modified form of joist;

i H tions, and has for its primary object the for supporting increased weights in heavier p provision'of a-structuralsteel joist consiststructures; I 5 in'g I-of several seriesofvarying lengths,- F'gure 6 isaplan detail of one of the 5 depths,,load capacities, 8136,2111 toibe fabri- T-shaped compression web members of the cated of commercially obtainableqstructural truss or joist; i 1

shapes,gangles, Ts and flats connected by Figure 7 is a side elevation thereof? PATENT oF'F- electric spot-welding processes and designed Figure 8 is antend View of the members i Q tofloarry" floors in'steel constructions, the shown in Figures '6 and 7; i r V [trusses being designed in accordance with i- F lglll'e 9is a plan view of one ,of the the latest specifications forstructurallsteel screed clips used'in connection withmy imbu'ildings a's formulated andrecommended proved truss or'joist; i i x by the Americanlnstitute of Steel Co'nstrutz- Figure 10 is I a sectional detail taken J ti t 1 Another, objectlot my invention is the joist, showing'ithe manner; in which the H i vprovision of a fabricated steel truss, or "joist "screed clips are vsecured in place betweem through the upper chord of the truss 0136:;

which is adaptedto be; placeduponspaced the'angle bars comprising the upper chord i supportingbeamsofsteel structures to span of thejoist;

2O 'theintervening space,withen d 1 1 11 up Figure 11 is an end view of the screed traction of the structure, i Figure 12 is atop planiview of a slightly Anfiadditional and most important object modified form of screed clip for use in rea of the invention is the provision of'a fabritaming transversely arranged stringers;

,portedasto allow for expansion and confclip shown in Figures 10 and 11;

2s atedt truss orjoist constituted of comp'ara- Figure 13 is an elevation of the clip shown i tively light-weight material spot-weldedtoin Figure 12; v I V i geth'er in such inanneras to cause theva Figure 14; isa sectional detail taken iribus elements thusjoined to be fused to through the upper chord of thetruss and 'g'ether substantially as t], rigid unit; a showing the clip supportedin place between so ,In-.,the accompanyingdrawings, forming a the angle bars of the upper chord of the jjipartiof "this specification,"and, in which, wtruss, as inFigure 10;. h i V, similarcharacters of referencereferto like a I ig r 15 is an elevation of a furring -part ,*thf hout5L1 i i staple'used in connection witlrmytruss or Y I .L-Figu re 1- ,1A "is a si'de elevation of a joist to hold the metal lath in position; 3 I truss or. joist constructedjin accordance with Figure 16 is an edge view thereof, and

the principles of my invention, showing one v Figure 17 is, a sectional detail of the clip end ther'eof resting 'upon' anTLbeam of a used in connection with the lower chord buildingstructure, a} fragmentary portion anglebars for holding the tuning channel o'ff which is shown; lstraps in position, the section being indi ri g '2 top joist 'shown'in Figure1'11A; In designing the trusses a uniform floor Figure, 3 is an end vView, showing the" load of 40 lbs. per square foot of live load relative arrangeinent of the various parts and 50 lbs. per quare foot of dead load is constitutingthe truss or joist; assumed, and a spacing of 2 feet center planwiew the cated by the line 17-17 in Figure 1. d

o 45 Figure Li's a'verticalsectional view taken to center of the trusses. Each truss is de- I throughtheupper and lower chord members signed for its maximum span and'its maxiof the truss or joist, showing the diagonals mum shears. As the shears are inversely andcompression'web members'thereof,the proportional to the spans, the shear loads section being taken on the line of are inversely proportional to the spacings. 1 ti) Figure 1 d The trusses are also designed to care for 1 Web shears" caused by applying live loads over only part offthe span. [Double di reversal of stress in the (liagonalsan o ecasional llve load-1s assumed at eachpanelagonals, or counter braces,- are introduced 'Where partly uniformly distributed "loads will change tensional stresses in diagonals to compression; In determining those panels which will requirecou'nter braces to prevent point equal to three times the dead: load.

above between each panel point. *The bot tom chord members are designed to take the tensional stresses plus-'tliebending moment dueto ceiling loads apphed' at' center points a between panel points i ranging commerciallyobtainable smallstrue- V tural shapes in such manner as W-lll most eco 'Z10111l0&ll} take c'areofthe ii nposed loads un 'der L -l'assumedconditions; andcon-ne'eting together these members by an electrical 7- ""sp ot- Welding, fusing of them through and through; prac'ti ces to my linewledgepnever before attempted, either in the assemblageoit material or in the joining of thesestog'ether'; i Electric Welding inthiseonstruction has been 'foundto be "perfectly feasible; only necessi- 1 I tating' thebuilding=ofspecially.' constructe' electric welding machines, and much-moi e economical?- than the Welding accomplished Withthe arc-Welding process. I p v It'is realized that there areother types of steel joists, but these-are either of I-loeam character or formed of roundbars,'tlie same as are usedinconcrete reinforcing: The: bar types are products of thearc welding "process and are possessed of but little lateral 7 stii'l nessivln. these the neutral 'a'xe sof thechord members are practically at thecenter econoinieal in requirement,offmetal to meet the stresses. 7 The long leg of the top chord anglesyalw-" s horizontal, gives f kio more lateral-stiffnessthan that of any other sys-" tem thus far introduced." Additionallyuny compressionWeb'me nbei's are all of T-sliape and vertical. arrangement; making for increased stillnessiand greatereconon y over those of bar type,;wliile the tensional web members are all of flats, meeting require ments, since these are not desl'gnedztocarry compression stresses and greatly reducing Weight ofmate '"i al.

Thevariation ofstresses in the 'end'meinbers resulting from the Variation. of span oi supports has alsoibeen taken eare of'in a novel manner by the combination or princi;

plesfor'angle and plate girdersthe canti'lever; beam; and the modified Pratt truss.

. v For thesake of practicability andsimple I all angles for all trusses;

liminary to shipping, :i v

L a Beferrr gw'ithgreat'erparti The invent on resides in the method of arother, providing interstices-v 25 and chord'inem into the inter ticesQfi'zind-QH the cho d? ine ofthese bars, Whilein my system the I neutral axes are nearer the extremities of the v V c f -6 fip ct vely, of successive com chord me1nb'ers,' this, tlieref-ore,[be1ng; more pression members, as'showni'n Ltliese 1111 tending toast as tensionlngmembers;asfher' f of fiat bars, as shownin cross [s ection in urea, and are variedln-crosssectrona a the upper chord memherifoi cl'is tia ncelan 1;

terminate flush withitheouter ends thereof. 1 v w The ends 30of the angle'fhar's' 235T24 a1id' 23 H p and '24 l'iaving interposedtherebetween' Web p and easy fabrication; the bottom chord an 7 'gles are allrbent, to the'same slope for all trusses,"'an 8? to 12 slope; i' llhus one 'spe- 7 cially set bulldozer can bemadeto deform 1 Y 4 r 1 insure-perfect spotweld ng results, it "is absolutely required that all fstee'l mist fbe' c'lea'nedof rust and' seale by ilie pieklin 7 process to insure p erfectcontact offinetal; e and that. the'ltrussinembers be assembled in iaClQCftfllGClarol'hr" I v I v itable clamped in placethereon, and moved to a stationary electrio w elding inachine for welding'. Afteip f Welding, they arefsub nitted to rigid tests,

painted by subjecting them to the clipping process; and hereafterf thoroughly dried :pr'e-- I drawings, the numeral desig aee v trussor' joist as-awlmle, which joist o c sts g of ancuppen hOrd-memberQI a lower chord member E22 betlrchofrc'l"members eon-f sisting; of longitudinally positioned palette; it

back to back-and in close proximity to' 'each: "9 01 5- .t'h'ere' between extending throughout gtheir engthas clearly shown i n Figures 2 3-antl" 1, A; pluralityof iferticall disposed cofrnpfres sion members 26 arearranged at equalinter-f Vale between the 5 chord 1members and have their ,extreinit esffi enter ing-theinterstices? f ai'icl-"25 iffor said compression n1e'mhers ;consi'sting of ed between, the; angle bars,

shaped bars havin notohed ls' pr'oy the members 27, as

hown -in Figures lull) Between each compress-ion member" more diagonals 28ers -m1gedand I from the upper chord '1 ember to tl' ejjlower e 'viththeir extreinltiesfitting members and abutting against theup per a1 inb'efore described-IE These diagonals cons j lower chord member are bent jupyyardlygto V iorm angularlyi 'disposed 'e'xtensions 29 ;Figyen" ure 1,.Which inturn are bent ,te'fJf rmthe V ehdsBO, which ends 30"extend'par allelfwith plates; 31; which plates extend fromltheouter f 1 ends of'biotl-i iupp'er and lower chords tjo the I first compression member 26'," as shown in;

Figure 1.

fine" V ends of the lower chord member of the joist are adapted to:rest upon the i I-beam Supports 32 of the structure, and the lower angle bars 23 or 24 are adapted for clamping to the I-be'ams by meansl of C- a shaped clamps 32, which clamps prevent vertical movement of the joist ends relative to i the supporting beams" butallow of longitudinalmovement dueto expansion and contraction of the parts constituting the'joist.

I Only one end of the truss or joist has been fshownba'nd one supporting beam but it is of "course to be understood that the opposite end of the truss (notshown) is an exact duplicate'ofthat illustrated in Figure 1 and rests I upon a like supportingbeam' of the building structure.

structures where it is desired to linish I: *the interior with a plaster or like finish the truss or joist isprovided with furring'chanhell-supports 33, which supports consist of L -shaped straps havingtheir upper ends bent to 'forin U-shaped; retaining members. 34,

Figuresl and 3, adapted to hook over the upperangle bars 23'and 24 of theupper chordmember and to depend therefrom with their right angle extensions 35 aligned with the lower chord member angle bar 24 and to which angle bar they are secured by means of clips 26, Figures 1 and 17.

j The upright members 37 of the supports 33 I are provided with furring channels 38 and 'theextensions 35 carry furring channels 39 I t'o'which themetal lath40 and plaster 41 are secured, asshown in Figure 1.

-Ashereinbefore described, the various elements constituting the truss or joist are as- .s'embled and the web members 31 aresecurely' welded and united to the angle bars 23 and 24 and 23 and 24' forming respectively, the

I upper'and lower chords,'at a series of electrically weldedpoints 42' and 43 and the upper andlower extremities of the compression members are electrically welded to said barsatthe points 44 as are also the diagonals v at the points 45. The fusing ofthe various -parts constitutingjthe truss or joist at the ,poin ts indicated causetheir securement together-as a rigid unit, as described, this vthese parts; In the use of a mere surface a weld, such asthat' obtained through the so welding process consists of a complete fusing of the various parts at the points indicated, which welding process tends to actually unite called spot weldingprocess, the parts would i not be sufficiently united to produce a rigid structure calculated'to withstand strains and stresses to which the joist may be subjected in actual practicel I (to In Figures 1A and 2A, I' have illustrated the preferred method of anchoring the reinforcing material to the joists, and, in this constructiomsuch reinforcing material consists of laying expanded metal 46, across the joists, which material is provided with ribs angles.

47' adapted to be embraced by special staples 4 8, Figures 1A, 2A' and 15', having shanks 49 adapted to fit into the interstices 25 of the joist-rand to be driven home to securely hold the reinforcing material iinplace. Special, screed clips 50 are also provided for use in connection with my improved truss or joist and comprise stringer; retaining members 51. i

and shanks 52 adaptedforwedging into the interstices 25 "ina similar manner to that of the staples 48. These screed. clips receive the stringers '52'and, the retaining members 51 thereof holdthe stringersin spaced relation above the reinforcing material, as shown in'either the wood floor, construction, the con- V crete floorconstruction, or the tile finish.

,It will be observed withreference to Figure 5 that I have shown a'slightlyimodified form of joist construction, such form being utillzedin large structures and comprising upper and lower chord members 53 and 54 compression bars 55, and diagonals 56. The

material usedin thisformis somewhat heavier than that used in the otherrforms shown,

the various elements being considerably heav-' ier and thelower chord 54 extendingjupward ly "and angularly and abuttin against an auxiliary chord member 57 wh ch is electrically welded to the web 58 at the points 59, with the lowerchord extension'GO, welded at the points 61 to said web plate 58'. f

In the present improved; truss and floor construction, special provisions are made for floor support, when constructed on expanded metal, through the employment of a special galvanized iron staple, such as is shown in Figures 15 and 16, this being of a thickness on i somewhat greater than the slightly spaced interstices between the backs of the top chord panel points is driven secure y home, thus servlng to secure the expanded metal in posi- The staple when placed over the expanded metal and as close as ossibleto the tion and prevent its movement either laterally or longitudinally.

I Obviously,my construction of trusses permits the use ofmuch lighter materials for the support of a given weight than would be required under present constructions, there be ing here no loss of material through punch bars arranged in close proximity and of opposite disposition, vertically disposed compression members extending between said chord members and having their extremities interposed between the angle bars comprising each pair, diagonals comprising flat tens memb'ei being inclined itipwardiowai'd the theicherd bars the inner end of the upper Y edge o'f sgxid ebj plate terminating short of I the point efconnectionefthe' upper end 0f '7 1 upper chord, el'ldtheilower edgeof said plate extending a s hortd isteuncedown the inelin'ed' 7 z portion 01" the IOWBf ChOrd and then inclined upwardlyend terminating near the'point'ef teq 'm e i n, Qfih e 2111 6 endj upp r e 'edgeofaid fieb teQtHejWeMed connection g H 6f thenpperig nd lower' edges of thew'eb b'eupper, chord bars and thenext ending: para 7 lel'therewith above the longitudlinal axis of the truss; providing a supporting -er lctitom", the I joist, and a Web plate lying bet-Weenthebacks' of the angle bars forming the end portions'of theen dlnest 'coxnpfession member with the ingfcbnfined' respectively to" the upper her-i z'pnta'l member, the lower' -horizontal member end a; p' rtion of; the upper end'of the inclined i eh'ordof thefsnpp orting ber,jl927.

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