US3307304A - Composite structural systems - Google Patents

Description

March 7, 1967 E. s. KLAUSNER COMPOSITE STRUCTURAL SYSTEMS 6 Sheets-Sheet 1 Filed June 2, 1964 INVENTOR fan/4E0 df/fiausA/se ATTORNEY March 7, 1967 E- s. KLAUSNER COMPOSITE STRUCTURAL SYSTEMS 5 Sheets-Sheet 2 Filed June 2, 1964 INVENTOR ATTORNEY March 7, 1967 E. s. KLAUSNER 3,

COMPOSITE STRUCTURAL SYSTEMS Filed June 2. 1964 3 Sheets$heet 3 v /2 INVENTOR fan/A20 i/flnuswme I ATTORNEY United States Patent 3,307,304 COMPOSITE STRUCTURAL SYSTEMS Edward S. Klausner, 101 Park Ave., New York, N-Y. 10017 Filed June 2, 1964, Ser. No. 372,069 12 Claims. (Cl. 52-99) This invention relates to a composite structural system and more particularly to a building construction of steel and concrete which utilizes most efiiciently the structural characteristics of both components.

It is the object of the present invention to provide a composite steel and concrete structural system which is particularly adapted for light-weight construction, exemplified by multiple story buildings or skyscrapers, wherein standardized structural units may be employed. These may be fabricated and shipped at comparatively low cost, with no possibility of damage in transit. These units are capable of assembly at the building site, with maximum safety and with the use of unskilled labor, to obtain a structure having a high ratio of loading capacity to deadweight of the steel and concrete in the building assembly.

It is another object of the present invention to integrate the flooring slabs in a building construction with the structural steel supporting network therefor to derive the maximum structural strength against both tensile and compressive stresses, while employing structural steel joists with supporting girders therefor which may be easily installed at the building site with the use of standard structural units of minimal height and comparatively light weight.

It is another object of the invention to provide sufficient bond strength between the contact surface of the structural steel network and the mass of cementitious material supported thereby. This bond strength is utilized in lieu of conventional shear connectors in transmitting horizontal shear in a composite construction. Thereby, the construction of the structural steel building shell may proceed with maximum speed and safety to the workmen in the course of erection of the building.

The invention proceeds upon the principle of forming the top chord of the joist in a wedge-shaped channel, into which metal chairs with forked legs are placed in close spacings. Continuous metal rods in the direction parallel to the channel are welded on the metal chairs. These metal rods, which are commonly used in the structural building industry as reinforcing bar supports, known as slab bolsters or continuous highchairs, also serve to support the reinforcing wire mesh forming a part of the floor slab. Upon the pouring of the concrete mass over the mold forms and tops of the structural joists, these metal chairs which :become embedded in the concrete mass serve as shear reinforcement for the portion of concrete poured into the channel of the top chord of the joist. Thereby, the concrete is securely bonded to the joists without reliance on the more costly forms of shear connectors which have been employed in the art heretofore in the form of spiral windings and luig reinforcements of all shapes and contours which have been welded to the top flanges of structural joists.

The top chord in accordance with the invention may also be provided with dimples or depressions for keying the concrete in contact therewith for the purpose of resisting horizontal shearing stresses imposed thereon.

The composite construction of the present invention, employing molding forms which may be installed easily preparatory to the pouring of the concrete and as easily stripped therefrom following the curing thereof, lends itself to the obtention of an effective composite T-beam assembly at the junction of the ends of the structural joists and the girder supports therefor, whereat the ends of the joists function as effective shear connectors for the girders. The end segments of the top chord are embedded securely into the deepened concrete haunch, thereby composite action is further enhanced. This results in marked economies because lighter structural members may be employed to carry the designed loads.

Other objects and purposes will appear from the detailed description of the invention following hereinafter, taken in conjunction with the accompanying drawings, wherein FIG. 1 is a perspective view of a supporting lgirder for the structural steel joists which are designed especially to have incorporated therewith the wedge-shaped channel, into which are inserted the metal chairs supporting the continuous bars, and which shows the molding forms supported by the joists and girder frame members before the laying of the reinforcing wire mesh and the pouring of the concrete thereover;

FIG. 2 is a vertical sectional view of the assembly shown in FIG. 1 following the pouring of the concrete flooring slab on each side of the girder;

FIG. 3 is a plan view of the framing composed of the girders and joists with the molding forms supported thereby, but with the metal chairs omitted, in the interest of clarity;

FIG. 4 is a vertical sectional view of the floor construction following the removal of the molding forms;

FIG. 5 is a vertical sectional view along line 55 of FIG. 2;

FIG. 6 is a vertical sectional view along line 66 of FIG. 1; and

FIG. 7 is a perspective view of the separate lengths of slab bolsters or continuous lengths of high chairs which are to be employed in strengthening the concrete deposited in the channel of the top chord.

The drawings illustrate a framing assembly for composite construction featuring open web structural steel joists, each composed of a channeled top chord 10, a bottom chord 11, and a web of zig-zag rod 12 extending between the chords and affixed thereto by welding, bolting or in any other suitable manner. While both the top and bottom chords as shown in FIG. 1 are of channel formation, it is essential that only the top chord be of this form in order to accommodate therein the metal chairs shown in FIG. 7.

As indicated in FIG. 6, the top chord 10 may be formed of an integral channel having a base 15, side walls 16, 16' extending upwardly therefrom in slightly tapering relation towards each other, with horizontal flanges 17, 17 extending outwardly from the upper ends of said walls 16, 16'. Dimples or depressions 18 may be formed in the flanges 17, 17' for the purpose of keying the concrete which is eventually poured thereover, in order to resist horizontal shearing forces in the completed construction. The substantially fiat tops of the structural steel joists permit easy handling, erection and walking thereon with relative safety.

While the top channel chord 10 is shown formed of a unitary length of sheet metal, the same may also be formed by separate angles, with the rod of the web extending therebetween as long as there is provided a channel depression for the reception of the bolster or continuous chair therein.

As may be seen from the framing plan shown in FIG. 3, the structural joists may be of continuous lengths which bridge the spacing between the girders G, for example, eighteen feet, and which girders are mounted on suitable columns. In the illustrated embodiment the girders are in the form of structural steel I-mernbers having a top flange 1, a bottom flange 2, and a vertical web 3. The insertion of the metal chairs following the setting up of the molding forms, makes possible the safe and easy mobility of the laborers therealong, with maximum safety. This is not the case when structural members are provided with shear connectors in the forms of upstanding studs or lug formations of the type disclosed in the patents to Singleton et al., No. 2,987,855, June 13, 1961, or Cueni et al., No. 2,340,176, January 25, 1944.

The molding forms P, which may be of plywood of thickness, are supported by frangible clips K of cast iron or similar material, of the type disclosed in applicants Patent No. 2,731,701. As shown in FIG. 6, these clips are formed of a main bar 25 overlying the top chord and having the hook 24 engaging one side thereof, while the supporting lug 27 projects laterally from the vertical web 26 extending downwardly from the opposite end of the bar 25.

As shown in FIG. 3, the supporting lugs 27 are disposed on opposite sides of each structural joist, which may be spaced slightly more than two feet from each other and which serve to support the molding forms F, about A below the top face of the top chord.

An especially effective shear connector is formed at the junctions of the structural joists with the top flange 1 of the girder G, which is clearly illustrated in FIGS. 1 and 2. An enlarged channel reinforcing and stresstransmitting member 31 extends from the end of the bottom chord 11 and is bent horizontally at the opposite end 30 into abutting relation with the bottom of the top chord 10. Each end block 30 is welded to the top flange 1 of the girder G, as indicated in FIG. 1, so that if the depth of the channel of the top chord 10 is 2 /2", the depth of the combined channel and block is 5". The block 30, in effect, supports the end of the structural joist J, and the additional depth thus imparted to the ends of the structural joists overlying the top flange 1 which becomes embedded in a correspondingly thicker mass of concrete which slopes downwardly from the main floor slabs on each side of the girder to cover the top flange thereof, serves as an effective shear connector for the girder. A special molding form P, formed of plywood, as are the forms F, extends between each edge of the flange 1 of the girder and the terminal edge of the molding form F adjacent thereto. This inclined molding form P may be supported by special clips C, which are mounted on the edge of the flange 1 of the girder, as disclosed in my co-pending application Serial No. 136,588, filed September 7, 1961, Patent No. 3,195,209, July '20, 1965. The bight of each hair pin, of #9 wire, for example, engages the hook of the clip C and the free ends of the pin are bent in to engage the edge of the girder remote from the clip. The supporting lug 37 for the sheet P is fractured by a hammer blow after the concrete is cured.

Companion clips C, having jaws 41, 42 on one end, embrace the opposite edge of the inclined molding form P and an arm 43 on the opposite end is adapted to rest upon the free edge of the molding form F. The lastmentioned clips C are formed of steel and are reuseable, and function as temporary connectors between the ends of the molding forms F and P.

In order to retain the wet concrete above the inclined molding forms P on the opposite sides of the open web of the structural joists, cardboard sheets 45 bridge this space and are fastened to the juxtaposed forms P by means of tack or nail fasteners 46, as illustrated in FIG. 5.

The metal chairs which are inserted in the channels of the top chords after the molding forms are set up, as shown in FIG. 1, may assume different lengths since these are products of standard manufacture and may run in lengths of from 5 to 10'.

The rod is supported by forked legs 21 terminating in outwardly directed ends 22 which may be pressed inwardly in order to insert the legs within the channel and which thereafter are sprung outwardly to be retained securely therein. If desired, the ends may also be pointed inwardly. The convergence of the side wall 16, 16' of the channel 10 enhances the secure retention of the bifurcated legs therein preparatory to the pouring of the concrete and the ultimate locking of the legs in the hardened concrete mass.

The spacing between the forked legs 21 along the length of the reinforcing wire 20 may be varied, depending upon the shearing stresses which may be encountered at the neck 47 of the concrete projection into the channel. Thus, the forked supporting legs may be spaced two inches apart adjacent the girders and this spacing may be increased to eight to ten inches at the midportions between the girders.

Following the insertion of the continuous chairs within the channels 10, a reinforcing mesh M may be laid upon the support wires 20, which may sag therebetween to a point above the molding forms, as is well known in the art. Upon the pouring of the concrete mass, this reinforcing mesh is embedded therein to reinforce the same and the metal chairs are also embedded within the concrete, including the continuous support Wire 20. The concrete mass is effectively keyed in the channel 10 by virtue of the trapezoidal contour thereof and the concrete also is keyed effectively to the horizontal flanges 17, 17 by virtue of the depressions and dimples 18 there- Many features of the construction described above may be used to the exclusion of others without sacrificing the benefits of the separate features. Thus, the structural joists with channel top chords may be used in conjunction with concrete girders in certain installations.

While I have described my invention as embodied in specific forms and as operating in specific manners for purposes of illustration, it should be understood that I do not limit my invention thereto, since various modifications. will suggest themselves to those skilled in the art, without departing from the spirit of my invention, the scope of which is set forth in the annexed claims.

I claim:

1. In an installation for erecting composite concrete and steel construction comprising a pair of spaced parallel structural steel girders and a plurality of transverse parallel structural joists supported therebetween at predetermined distances therealong, each of said joists having a top channel chord, a bottom chord and an open web extending therebetween, a supporting block for each end of said joists welded to the top of the girders to form a shear connector thereat, a separate insertable high chair reinforcement provided with spaced integral downwardly extending forked legs resiliently engaging the internal walls of the channel of each top chord, clips resting on the upper flanges of said joists, said clips having laterally projecting frangible supporting lugs and extending into the spaces between said joists for temporarily supporting horizontally disposed sheet molding forms between said joists, a sloping sheet-molding form adapted to bridge the space between the top of each girder and the end of the horizontal molding form adjacent thereto near the level of the upper flanges of the joists, supporting clips for the ends of said sloping form resting on the top of each girder and said end of said last-mentioned horizontal molding form, a reinforcing mesh supported by the parallel high chair reinforcements above said molding forms, and a mass of hardenable concrete material above said molding forms embedding therein said high chair reinforcements, forked legs and reinforcing mesh.

2. An assembly as set forth in claim 1 including light supporting panels bridging adjacent pairs of the sloping sheet-molding forms at said open webs of said structural joists to retain the moist concrete at this point until it is hardened.

3. An assembly as set forth in claim 2 wherein the supporting clips on the girder are frangible.

4. An assembly as set forth in claim 2 wherein the supporting clips on the girder are frangible while the supporting clips on the horizontal molding form are formed of steel and are reuseable.

5. An assembly as set forth in claim 1 wherein the top channel chord is of trapezoidal section with the base thereof wider than the top to key the hardened concrete therein more effectively.

6. An assembly as set forth in claim 5 wherein the downwardly extending forked legs diverge outwardly for seating at the widest portion of the channel chord.

7. An assembly as set forth in claim 1 wherein the supporting block for each end of the structural steel joist is connected with the bottom chord of the joist through the intermediary of an inclined stress-transmitting member.

8. Composite concrete and steel construction comprising a structural steel joist having a top channel chord, a bottom chord, and a web extending therebetween, a separate insertable longitudinal metal reinforcing rod provided with spaced integral downwardly extending forked legs resiliently engaging the internal vertical walls of said channel and detachably supported by said top chord, a reinforcing wire mesh resting on said metal rod, and a cementitious mass encompassing said wire mesh, reinforcing rod and forked legs, and keyed within the channel of the top chord.

9. Composite concrete and steel construction comprising an open-webbed structural steel joist having top and bottom chords with a zig-Zag bar extending therebetween, said top chord being of channel formation provided with a base and side walls extending upwardly therefrom, said side Walls tapering slightly towards each other from said base to the upper ends thereof, a discrete inser-table longitudinal metal chair reinforcing rod provided with spaced integral downwardly extending forked legs adapted to be sprung resiliently into said trapezoidally-shaped channel and to engage the internal side walls thereof, a reinforcing wire mesh resting on said metal rod, and a hardened mass of concrete material encompassing said reinforcing wire mesh, reinforcing rod and forked legs, and keyed within the channel of the top chord.

10. An assembly as set forth in claim 9 wherein said top chord is provided with horizontal flanges extending outwardly from the upper ends of said side walls, said flanges having spaced depressions therein filled with the concrete material keyed thereto to provide resistance to horizontal shearing stresses.

11. As assembly as set forth in claim 9 wherein said forked legs integrally connected with said chair rod are spaced at varying distances along the length of the joist in accordance with the varying shearing stress requirements along the length of the neck of the concrete projection within the channel of the chord.

12. Composite concrete and steel construction comprising a pair of spaced parallel structural steel girders and a plurality of transverse parallel structural steel joists supported therebetween at predetermined distances therealong, each of said joists having a top channel chord, a bottom chord and an open web extending therebetween, a supporting block for each end of said joist welded to the top of the girders to form a shear connector thereat, an inclined stress-transmitting member extending between each supporting block and bottom chord, a separate insertable longitudinal high chair reinforcement provided with spaced integral downwardly extending forked legs resiliently and detachably engaging the internal vertical walls of the channel of each top chord, a reinforcing mesh supported by the parallel high chair reinforcements, and a hardened mass of concrete material encompassing said reinforcing wire mesh, high chair reinforcements and forked legs, said mass being keyed into the channels of said top chords and having a substantially uniform depth for the major length of the joists and having the bottom surface sloping to a greater depth adjacent the tops of the girders whereat said mass also encompasses the supporting blocks above the girders and the end portions of said stress-transmitting members connected to said blocks.

References Cited by the Examiner UNITED STATES PATENTS 788,942 5/1905 Perrot 52687 1,155,411 10/1915 Flannery 52687 1,898,736 2/1933 Melvin 52-335 OTHER REFERENCES Architectural Record, October 1963, page 37.

FRANK L. ABBOTT, Primary Examiner.

RICHARD W. COOKE, JR., Examiner.

Claims (1)

1. IN AN INSTALLATION FOR ERECTING COMPOSITE CONCRETE AND STEEL CONSTRUCTION COMPRISING A PAIR OF SPACED PARALLEL STRUCTURAL STEEL GIRDERS AND A PLURALITY OF TRANSVERSE PARALLEL STRUCTURAL JOISTS SUPPORTED THEREBETWEEN AT PREDETERMINED DISTANCES THEREALONG, EACH OF SAID JOISTS HAVING A TOP CHANNEL CHORD, A BOTTOM CHORD AND AN OPEN WEB EXTENDING THEREBETWEEN, A SUPPORTING BLOCK FOR EACH END OF SAID JOISTS WELDED TO THE TOP OF THE GIRDERS TO FORM A SHEAR CONNECTOR THEREAT, A SEPARATE INSERTABLE HIGH CHAIR REINFORCEMENT PROVIDED WITH SPACED INTEGRAL DOWNWARDLY EXTENDING FORKED LEGS RESILIENTLY ENGAGING THE INTERNAL WALLS OF THE CHANNEL OF EACH TOP CHORD, CLIPS RESTING ON THE UPPER FLANGES OF SAID JOISTS, SAID CLIPS HAVING LATERALLY PROJECTING FRANGIBLE SUPPORTING LUGS AND EXTENDING INTO THE SPACES BETWEEN SAID JOISTS FOR TEMPORARILY SUPPORTING

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