US3683580A

US3683580A - Composite end connection for steel joists

Info

Publication number: US3683580A
Application number: US79022A
Authority: US
Inventors: Ira J Mcmanus
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-10-08
Filing date: 1970-10-08
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15

Abstract

A joist end connection providing composite action between a supporting beam and a concrete slab when the bearing end of the joist is encased in the concrete slab whereby the encased joist end is employed as a shear connector. This is accomplished by employing metal formwork and anchoring means for keying the supporting beam to the concrete at the bearing end of the joist.

Description

[ 51 Aug. 15, 1972 United States Patent McManus [54] COMPOSITE END CONNECTION FOR 10/1931 Sealey.........................52/421 3,147,571 9/1964 Welch........................

STEEL JOISTS [72] Inventor:

Ira J. McManus, 39 Lincoln Ave., 2/ 35 Fl h p k NJ. 0794 3,392,499 McManus....................52/333 Oct. 8, 1970 Primary Examiner-Henry C. Sutherland Attorney-James J Cannon [22] Filed:

[21] Appl. No.: 79,022

[57] ABSTRACT A joist end connection providing composite action between a supporting beam and a concrete slab when the bearing end of the joist is encased in the concrete [52] US. 52/336 [51] Int. 1/16, 1504b 5/29 [58]. Field of Search........................52/334-336, 340,

slab whereby the encased joist end is employed as a [56] References C'ted shear connector. This is accomplished by employing UNlTED STATES PATENTS I metal formwork and anchoring means for heying the supporting beam to the concrete at the bearing end of 1,863,258 6/1932 Tash lan..............;.......52/336 the joist 1,734,358 11/1929 Yeager........ ....52/334 910,757 1/ 1909 Wilson 52/336 8 Claims, 8 Drawing Figures PATENTEDaus 1 5 I972 SHEET 2 BF 3 WI" "I'm CONNECTION FOR STEEL JOISTS CROSS-REFERENCE TO RELATED APPLICATIONS In my U.S. Pat. No. 3,392,499, issued July I6, 1968,

COMPOSITE END and co-pending US. Pat. applications, Ser. No.

751,930, filed Aug. 12, 1968, now US. Pat. No.

3,527,007 and Ser. No. 10,399, filed Feb. 11, 1970,

now US. Pat. No. 3,624,980 there are disclosed various novel improvements relating to end connections between open-web steel joists and steel beams or girders supporting them such that there is obtained composite action between the supporting beam or girder and a concrete slab poured over the joists so as to completely encase the bearing ends of the joists. The present invention is directed toward improvements 'over the steel joist end connections disclosed therein.

SUMMARY OF THE INVENTION The present invention relates to a novel and improved end connection for steel joists where at the bearing ends of the joists there there is provided in one embodiment a unitary metal pan including a flat bottom surface and outwardly sloping sides extending upward above the top chord of the joist to provide support at the bearing ends of the joist for the concrete to DESCRIPTION OF THE PREFERRED EMBODIMENTS Having reference to the accompanying drawings wherein like reference numerals designate similar parts, there is shown in-FIGS. 1 through 4 a first embodiment of the invention comprising standard openweb steel joists 10, each of which comprises top pairs of opposed angle irons l2 and 14 secured by conventional means such welding along their 'apice's at upper extremity of a zig-zag shaped bar web 16 to form the top chord of each of the joists, and a bottom pan of opposed angle irons l8 and 20 (only one pair being partially shown) similarly secured at the bottom extremity of the bar web 16 to form the bottom chord of each joist 10. At the bearing end of the top chord of each be poured thereover, and anchoring means secured at one end to the joists and extending upward into keying relationship with the main body of the concrete. Accordingly, it is a primary object of the present invention to provide a novel and improved end bearing connection for steel joists whereby there is obtained composite action between the supporting steel beam or girder and the concrete encasing the joist end.

Another object of the present invention is to provide a novel and improved end connection for open-ended steel joists wherein at the bearing end of the joists there is provided smooth-surfaced metal pan meansfor receiving concrete to be poured into encasing relationship with the joists.

'A further object of the present invention is to provide a novel and improved end bearing connection for steel joists wherein the desired composite action between the supporting member and encasing concrete is effected by means of a unitary metal form or separate opposed metal .forms disposed at the bearing ends and anchoring means operably keying the supporting member to the concrete through the steel joists.

Various other objects, features and advantages of the present invention will become apparent from the following detailed description of the invention when read in connection with accompanying drawings wherein:

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a perspective view of a joist end connection constructed and arranged according to the tion encased in a concrete slab;

FIG. 4 is a cross-sectional view taken substantially along the line 4-4 in FIG. 3; v

joist there is provided a pair of

opposed seat angles

22 and 24, which either may be separate from or integrally formed with the top chord of the joist. These

seat angles

22, 24 extend below the top chord for a predetermined distance whereupon the angles are formed with laterally outward extending

flanges

26, 28, respectively, to form a substantially U-shaped member or channel. These seat angles,which are encased in a concrete v slab 30 (see FIG. 3), as hereinafter described in detail,

seat upon a supporting composite beam or girder 32 and are secured thereto by suitable means, such as welding, to provide the necessary shearing strength in the direction of the longitudinal axis of the supporting beam 32 (which axis is perpendicular to that of the joists) by rigidly connecting the concrete slab 30 to the beam or girder 32 The U-shaped construction of the joist end seat angles enhance encasement of the concrete to the support beam through the joist end connection.

At each joist bearing end there is provided anchoring means 34, which may take the form of a headed stud or bolt 34' or a hooked rod 34", and which is snugly fitted between and secured to the

opposed angle irons

12, 14

and the

seat angles

22, 24 as by welding designated 58 or the like as shown in FIG. 4. The anchors 34, as best shown in FIG. 3, extend upward above the top chord of each joist into keying relation with the main portion of the concrete slab 30 poured over, such that the anchor is solidly embedded therein whereby the slab securely is interconnected with the supporting beam or girder 32 through the joist end connection.

Corrugated sheet metal fonn plates 36, as shown in FIGS. 1, 2 and 3, are placed along the top chords of adjacent parallel joists between the ends thereof to form a bottom support for the concrete slab 30 to be poured over. These forms 36 extend between the

seat angles

22, 24 provided at each joist end (see FIG. 3). To prevent any leakage of the concrete when poured along 1 the sides of the joist ends there is provided over each joist end a substantially U-shaped notched metal closure plate 38. Each plate 38 comprises a top surface or bright portion 40 and a pair of similar notched vertical sides or legs 42, the notches being formed as at 44 so that a forward portion 46 of each side 42 may be bent inwardly toward the corresponding vertical side of the joist end to prevent any leakage of the concrete beyond the desired area at the joist end, which could detract from the desired connection between the beam or girder 32 and the concrete 30.

On top at each joist end there is provided a continuous support rod 48, which rod extends continuously between adjacent parallel joists and is securely connected thereto by means of welding. These rods in the preferred embodiment of FIGS. 1 to 4 support the ends of a unitary or single metal pan 50 situated at each joist end connection. The pan 50 comprises a flat bottom 52, upwardly outward sloping sides 54 and marginal downward sloping sides 56, and is of sufiicient width to fit snugly between adjacent parallel closure plates to prevent leakage of concrete. The metal pan 50 is supported at its ends by the support rod 48 disposed directly below the bend formed between 54 and 56. The bottom 52 is supported by the top flange of the supporting beam. The extremities of the corrugated metal formwork 36 are supported by the marginal ends 56 of the pan 50.

As described heretofore, in order to obtain the desired composite action between the concrete slab 30 and supporting beam 32 there is provided an anchor 34 in the form of a headed stud or bolt 34 or hooked rod 34" secured between the back-to-back

top chord angles

12, 14 and the

seat angles

22, 24, respectively, forming the joist bearing end and secured thereto by welding shown as 58 to obtain the necessary keying of the concrete to the joist end. Other alternates for obtaining the desired keying action are shown in FIGS. and 6, where there is illustrated a continuous rod 60 including top keying members 62 (see FIG. 6) and bottom support members 64 interconnected by sloping sides 66. The rods 60 are welded as at 68 in the field, preferably to the top chords of the joists. The keying members 62 of each rod 60 are sufficiently spaced vertically above the top chords within the main body of the concrete 30, that is, above the center line of the concrete slab 30, to effect the desired composite action.

As illustrated in FIGS. 7 and 8, in lieu of the previously described metal pan 50 and metal closure plates 38, there is provided pan of separate notched metal plates 64 which are designed to fit snugly between the vertical sides of the joist bearing ends to prevent any concrete leakage. These notched plates 64 each comprise a flat bottom surface 66 secured by welding to the top flange of the supporting beam or girder 32, a side wall 68 which slopes upward away from the longitudinal center line of the supporting beam 32 and a central bent marginal member 70 having a terminal downward sloping side 72. The continuous rod 48 supports the end of the plates 64 by engaging the sides 70 and 72 at their bend. A pair of notched downwardly bent comer members 74 are disposed on either side of the central member 70 so as to be located below the horizontal laterally extending flanges 76 of the top chord angles 12 and 14 (only 14 being shown in FIG.

7). To place these metal plates 64 properly in position the plate is slid horizontally toward the supporting beam or girder between the lateral flanges 76 of the joist top chords past the support rod 48. The central bent member then is raised into its supported position by the rod 48 (see FIG. 8) with the notched corners 74 being disposed below the flanges 76 of the top chord (see FIG. 7). However, for convenience these comers may be removed completely before installation of the plates 64.

While there have been disclosed herein various forms of the present invention, it is to be understood that such forms are preferred only and should not be construed as limited of this invention in any sense. Thus, while there has been disclosed steel joists comprising angle members, the novel features of this invention may be employed with other types and-configurations of joist ends. Accordingly, reference should be made to the following appended claims to determine the full extent of the scope of protection afforded by the present invention.

Having thus set forth the nature of the invention, what is claimed herein is:

1. In a steel joist construction and end connection therefor, the combination comprising, first and second pairs of parallel steel joists, anchor means extending upwardly from the ends of each pair of steel joists, each of said joists having a top chord, a bottom chord and means for securing said top and bottom chords in vertically spaced relation, said top chord having a seating angle provided at its ends extending below said top chord and being supported by a beam running in a direction substantially perpendicular to the direction of said steel joists, closure form means of inverted U- shape seated on the top chords of each joist adjacent the ends thereof, each closure form means having a bight portion seated on the top of each top chord and pairs of legs extending from the bight portion to the upper surface of said beam between said joist seat angles, a sealing plate form means disposed between the parallel joists of each pair, each sealing plate form means including flat bottom means supported by said beam and oppositely outward sloping sides supported at its ends by rods extending between parallel ones of said steel joists, said sealing plate having its edges in contact with the legs of said closure form means, whereby when a concrete slab is poured over said concrete form means in the vicinity of said steel joist end connection into encasing relation with said end connection there is obtained composite action therebetween.

2. A steel joist end connection according to claim 1 wherein said anchor means extends upwardly from the end of said steel joists above said top chords to enhance the interlocking action between the concrete slab and the joist end connection.

3. A steel joist end connection according to claim 2 wherein said anchor means comprises a continuous member extending between parallel ones of said steel joists and having lower portions secured to the top of said steel joists and upper portions adapted to be embedded within said concrete slab.

4. A steel joist end connection according to claim 3 wherein the legs of said closure means have a portion thereof nearest said steel joist end bent inwardly into contact with the vertical sides of said steel joists.

5. A steel joist end connection according to claim 1 wherein said plate form means comprises a unitary pan comprising a continuous bottom and sides for providing a receptacle for the concrete slab in the vicinity of said end connection.

6. A steel joist end connection according to claim 5 wherein said sides each slope outwardly and have bent outer portions to facilitate supporting said second concrete form means by said supporting rods.

7. A steel joist end connection according to claim 1

Claims

1. In a steel joist construction and end connection therefor, the combination comprising, first and second pairs of parallel steel joists, anchor means extending upwardly from the ends of each pair of steel joists, each of said joists having a top chord, a bottom chord and means for securiNg said top and bottom chords in vertically spaced relation, said top chord having a seating angle provided at its ends extending below said top chord and being supported by a beam running in a direction substantially perpendicular to the direction of said steel joists, closure form means of inverted U-shape seated on the top chords of each joist adjacent the ends thereof, each closure form means having a bight portion seated on the top of each top chord and pairs of legs extending from the bight portion to the upper surface of said beam between said joist seat angles, a sealing plate form means disposed between the parallel joists of each pair, each sealing plate form means including flat bottom means supported by said beam and oppositely outward sloping sides supported at its ends by rods extending between parallel ones of said steel joists, said sealing plate having its edges in contact with the legs of said closure form means, whereby when a concrete slab is poured over said concrete form means in the vicinity of said steel joist end connection into encasing relation with said end connection there is obtained composite action therebetween.

7. A steel joist end connection according to claim 1 wherein said sealing plate form means comprises a pair of opposed separate metal members extending between adjacent one of said parallel pairs of steel joists.

8. A steel joist end connection according to claim 7 wherein said metal members each have notched marginal corner portions underlying the supporting rod and a centrally disposed bent member which overlies and is supported by said supporting rod.