US2605680A - Load transfer device - Google Patents

Description

Aug 5, 1,952 R. c..YEoMAN 2,605,680A

Patented Aug. 5, 1952 PATQENJ .orties a 2,605,680 ;LGAmTRANsFER-DEWGE tionen-Texas Application February zag-19,45; sesame, 519,333

l 11 C*This invention' Irelates -to`--loadtransfer L74devices 1 andfmore particularlyto devices"Tor-transferring *like '-In layingvconcretefpavings. aircraftvlanding"strips`,` factory-doors and-the like'of concr`ete,- l'"lit is'fdesir'able -to `break the-concrete structure up into slabs to prevent cracking or splitting'fthereof VV'fffdue'toexpansion andA contraction.""-1t has long fbeenfthe practice-to :utilizev vdowel structures of irvarious.fkin'fslsA imbedded;v in f the slabs: and#l spanninglif-the jointftherebetweento Ytran'sfer loads 'ffrom .onef'slabtoythe other. It is highly desirable :th'at j oints' off thischaracter be-.f so constructed ias :to -epermita' relativer horizontal :movementbefftweenthe slabs- Wh ile rnaintainingsthe` loadrtrans- :imi'ssiontz characteristics of :the -joints 2in1-order .jthatthe.:slabsrmayzseparatef and .move .relatively :,'togethergiund'er l temperatureschanges sor-that: they smvllnot buckleorzcrack.

. vItlismnes-zof the-:"lobjectszoftzthe. present invenf .,yrtionftofprovide axloadr'transfer-device whichzfwill effectively-.transfer vertical loadsrnbetween-.adjacent:slabsT and by..-which utherelativelyfrhori- A. .,.device .formed with .an .elongated `-duwel portion tol transmit vertical loads between the! slabsand with a laterally extending anchor portion coveredwith yielding material tcr'providefor a limited horizontal movement ini-the slabs.

A- still `further .obj ect .isgto :provide a'loadrtransfferjdevice .in Which..an..elongated strip for rod Lsinuously formedtoprovide al plurality 'of dowel 1.-. parts; extending .acrossthejoint betweenadjacent i slabs to'rtransfer .loads therebetween.

The above. :and other objects and; yadvantages bf the.invention...will .be more readily .apparent i."#from .the following.description when 4=read in 'connection-awiththeaccompanying drawing, in 'ifWhChZ Figure 1 is a sectional view through a joint between adjacent slabs showing a load transfer device embodying the invention;

Figure 2 is a View similar to Figure 1 illustrating a diierent position of the parts;

Figure 3 is a horizontal sectional View of an alternative vconstruction on the line 3-3 of Figure 4; and

(ClsQi-e-S) Y`."Figurel 4'- is a'section; ongthe line 4-J-4fof1igure 3. g c As 'shownminigures 1 and" 2, adjacent conmcretejslabs Il] andl II meet at ajoint which is 5*;lledrwith-"an expansive ller, I2 abutting against the adjacent faces ofthe slabs. The filler I2 #maybe vany-desiredtype ,ofmaterial which will Myield under' pressure and which will expand @slightly when lthe pressure` is relieved iny order mel-to maintain 'a tight iii; against the adjacentslab '-'faces-as the" yslabsY expand andcontract. I'One VAtypeofinaterial whichis suitable for this-pur- -pose is=compressed wood although anyv desired "ty-pe 'off filler might -bev employed. -In order tol-connect the slabs together Vtottransl fer v'loads ytherebetween as,l foreexample; when a load passed from one slab across the-joint to the other-slab, a plurality of load transfer de- 'f vices are employed extending acrossthe joint and Zo'fimbeddedin-theslabs. As shown', the load trans- "'-ferfdevices comprise elongated rods' or dowels I3 preferably formed of -steel orlike material-'which .1extend-intothe-slabs adjacent the joint. r'I'he #rodsfor-Ldowels AI3 are formedv at their ends with headed portions I4 forming .laterally extending wanchorfpar-ts. `"1`he anchor-partsvl are coveredr Witlr yielding-:material II 5 f such as Yrubber-or other ,asimilar-non-hardening plastics.

' installing, the. vload transfer devices;`-the rod offorffzdowelf1311s. preferably coated with' grease or :theglike asfindicatedA atl IG- tof'preventrther conicrete :frommadhering to;1.it. #The :load Vtransfer .3 deyices mayfbe' vassembledwiththe joint-material .5 J Zezbeforenthe: .plastic concrete.. is poured' so -that iithey will? :beimbeddedf-fin the.l concrete during pouring or they may be inserted-:in -thenplastic concreteby. vibrationl or similar meansA after it r' has-.beenrpoured and; beforey it has .'set. In either -caseggthe-rdevices fwhen r'installedy occupyf av posi- 4o: tion-.adjacentftheicentral part offthe joint, preffferably in theneutral plane of -thepslab ends, and may be spaced asfcloselyfxas necessary..,to.,carry the load to be transmitted between.; the,` slabs.

vWhen .ftherdevicesy areyinstalled any vertical :load on the 'end' ofkeither'slab will be transmitted '.from-onegfslab tothe otherthroughtherod or dowelzportions ,I3 sothat the slabs: will"` beheld in proper alignment to provide a smooth surface and so that the edge portions thereof will not easily be cracked or broken away. The slabs are shown in Figure 1 in their normal positions with the yielding covering m-aterial I5 substantially uniformly distributed around the heads I4. If the slabs should expand as, for example, under 56 an increase in temperature, the joint material I2 will be compressed as indicated in Figure 2 and the heads I4 of the load transfer devices will tend to move further into the slabs. This compresses the elastic material I5 at the outer ends of the head portions I4. If a owable material such as rubber is used, it will flow around the head portions to produce the condition illustrated in Figure 2. Similarly, on contraction of the slabs causing the joint to separate, the material will compress at the inner side of the head portions or will flow around the heads I4 to the outer surfaces thereof. During this motion, the dowel portions i3 of the devices will slide freely in the slabs due to the coating or covering thereon which prevents the concrete from adhering thereto.

With this construction, a limited horizontal movement between the slabs is permitted which is yieldingly opposed by the covering material over the heads of the devices. By properly proportioning the thickness of the covering material any desired amount of movement can be provided for to permit the slabs to expand and contract to the maximum expected extent without breaking at the joints. At the same time, this construction prevents excessive movement at onel or more joints which might cause the joints to separate completely such as might occur in a highway or the vlike where certain of the joints tend to accommodate the entire expansion and contraction in a relatively long stretch of road. With the present construction, the expansion and contraction is distributed more or less evenly throughout the several joints so that the center of each slab remains substantially xed and no substantial bodily movement of any one slab is produced.

In the alternative construction illustrated in Figures '3 and 4, an elongated rod or strip I'I of steel or the like is sinuously bent to form a series of substantially straight dowel portions I8 connected by loop portions I9. The loop portions I9 provide anchor parts extending transversely of the dowel portions so that the device is firmly anchored in the slabs. 1

In order1 to provide for limited movement between the slabs, the loop portions on one or, both sides of the device are covered with a yielding covering 2| of rubber or the like and the dowel portions adjacent the covered loop portions are greased a-s indicated at 22 to prevent adherence of the concretethereto. This construction functions in substantially the same manner as that of Figures 1 and 2 during expansion and contraction of the slabs to provide limited yielding movement between the slabs.

While two embodiments of the invention have been shown and described in detail, it will be understood that these are illustrative only and are not intended as a denition of the scope of the invention, reference being had for this purpose to the appended claims.

What is claimed is:

l. A load transfer device adapted to be imbedded in adjoining concrete slabs for transfering loads therebetween and for limiting separation thereof comp-rising an elongated dowel 4 member of uniform section throughout its length adapted to extend across the joint between the adjacent slabs and into the adjacent slabs, laterally projecting heads on the ends of the dowel member adapted to anchor the dowel member in the adjacent slabs, and a covering of yielding material ofv appreciable thickness enclosing at least'one ofthe laterally projecting heads and providing limited longitudinal lmovements of the head within the space occupied by the covering for controlling relative longitudinal movement of the slabs.

2. In combination with a pair of adjoining concrete slabs, a load transfer device imbedded in the adjoining slabs and comprising an elongated member of uniform section throughout its length extending across the joint between the adjacent slabs and into the adjacent slabs, the member being provided with parts projecting laterally from the ends thereof to anchor the member in the adjacent slabs, and a yieldable material disposed in a substantially thick layer all about the laterally projecting parts to permit limited movement of the part within vthe space occupied by the yieldable material for controlling relative longitudinal movement between slabs.

3. A load transfer device adapted to'be imbedded in aligned concrete slabs for limiting separation thereof and for load transfer, comprising an elongate member dimensioned to span the space between the slabs and to extend a substantial distance into the end portions of adjacent slabs in unbonded relation with the set concrete, the surface of the elongate member being treated to prevent a bonding relation with the set concrete, a projection extending laterally from the ends of the elongate member for anchoring engagement with the'cement, and a'thickness of Ayieldable material all about the laterally extending projection permitting limited longitudinal movement of the projection within the space occupied by the yieldable material thereby limiting relative longitudinal movement between the slabs.

4. A load transfer device as 'claimed in claim 3 in which a lubricant is provided on the surfaces of the elongate rod to prevent bonding relation with the set concrete.

' RAY CYRUS YEOMAN.

REFERENCES CITED' The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,039,775 Burgess May 5, 1936 2,094,853 Shaw Oct. 5, 1937 2,167,423 Nigro July 25, 1939 2,205,810 Carter June 25, 1940 2,244,337 Isett June 3, 1941 2,305,979vr Mitchell Dec. 22, 1942 2,308,677 Dailey Jan. 19, 1943 2,330,214 HeltZel n Sept. 28, 1943 2,358,323 Heltzel Sept. 19, 1944 2,419,022 Heltzel Apr. 15, 1947

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