US3251167A

US3251167A - Composite concrete floor construction and unitary shear connector

Info

Publication number: US3251167A
Application number: US270882A
Authority: US
Inventors: Bernard E Curran
Original assignee: HH Robertson Co
Current assignee: HH Robertson Co
Priority date: 1963-04-05
Filing date: 1963-04-05
Publication date: 1966-05-17
Anticipated expiration: 1983-05-17

Description

May 17, 1966 a CURRAN 3,251,167

COMPOSITE CONCRETE FLOOR CONSTRUCTION AND UNITARY SHEAR CONNECTOR Filed April 5, 1963 3 Sheets-Sheet l INVENTORT Bf/P/VJFD E CVP/Rd/V I 76. 4 BY May 17, 1966 B. E. CURRAN COMPOSITE CONCRETE FLOOR CONSTRUCTION AND UNITARY SHEAR CONNECTOR Filed April 5, 1963 5 Sheets-Sheet 2 May 17, 1966 B E, CURRAN 3,251,167

COMPOSITE CONCRETE FLOOR CONSTRUCTION AND UNITARY SHEAR CONNECTOR Filed April 5, 1963 3 Sheets-Sheet 5 United States Patent 3,251,167 COMPOSITE CONCRETE FLOUR CONSTRUCTRON AND UNHTARY SHEAR CONNECTOR Bernard E. Curran, Sewicldey, Pa, assiguor to H. H.

Robertson Company, Pittsburgh, Pin, a corporation of Pennsylvania Filed Apr. 5, 1963, Ser. No. 270,882 4 (Claims. (Cl. 52--32'7) This invention relates to floors of a building. More particularly, this invention concerns steel frame buildings having corrugated sheet metal flooring which is covered with a layer of concrete. The invention is specifically directed to novel apparatus and a combination thereof with steel framing, sheet metal flooring and concrete which achieves over-all composite coaction of the concrete with the metal building elements.

PRIOR ART There are two general categories of modern building techniques: (a) those buildings which utilize reinforced concrete flooring; (b) those buildings which utilize steel framing and sheet metal flooring.

(a) Reinforced concrete constrncti0n.-Reinforced concrete construction utilizes molding elements which may be metal, lumber, plastic and the like. These molding elements are assembled in a meticulous manner to prescribe the ultimate shape of the proposed building. The interior molding chambers are filled with reinforcing elements, usually steel wire or rods, in a precise, prearranged array. Wet plastic concrete is poured into the molding cavity and allowed to cure or harden. Thereafter the molding elements are removed to expose a concrete covered structure which derives its strength in part from the concrete itself and in part from the preassembled reinforcing elements which are buried within the structure and hidden from view by the concrete.

A minor fraction of the reinforced concrete buildings are constructed in somewhat different sequences which may include precasting of floors at remote locations, the use of permanent forms, and the like. In general, however, the principal distinguishing feature of a reinforced concrete construction is the reliance upon the concrete itself to supply a major contribution to the load-bearing properties of the resulting building. The concrete is required to sustain the compressive stresses While the reinforcing elements sustain the tensile and shear stresses.

(b) Steel fnaming and sheet metal flooring-This construction utilizes a building skeleton which is formed from vertical steel columns and horizontal steel beams and girders. Corrugated sheet metal flooring sections are secured to the horizontal beams and girders to serve as the load supporting element of the building floors. A layer of concrete is normally poured above the corrugated sheet metal flooring elements to rigidize the structure and serve as a walking surface for the occupants of the building. In the typical construction, the sheet metal flooring sections are required to provide all of the loadbearing requirements of the building including the support of the weight of the concrete layer itself. The concrete is considered to contribute no loadbearing properties whatsoever to the resulting structure.

(0) Recent proposals.Recently it has become recognized that the concrete layer which accompanies sheet metal flooring has a capacity for sustaining some of the compressive stresses which exist in the resulting floor. Numerous proposals for tying together the concrete layer with the sheet metal flooring have been presented within the past several years. The essential ingredient of these proposals has been the provision of shear-transferring elements which will allow the concrete layer to sustain compressive loading and will protect the concrete layer from exposure to severe shear stresses.

All of these recent proposals have recognized that the corrugatedsheet metal flooring will be deflected vertically between its supported ends as a load is applied to the floor. By compelling the concrete layer to sustain some of the compressive stress resulting from the load, the developed tensile stresses in the sheet metal flooring are lessened. Thus, from one viewpoint, these recent proposals have sought to reduce the vertical deflection of the corrugated sheet metal flooring by developing composite coaction between the concrete layer and the sheet metal flooring sections.

THE PRESENT INVENTION Inherent in all of the recent proposals is an unstated assumption that the transverse girders and beams which support the corrugated sheet metal flooring are considered as rigid, unmoving support elements. I have come to realize that the horizontal beams and girders transverse of the longitudinal corrugations of the sheet metal flooring will themselve be deflected when a load is applied to the resulting floor.

These transverse beams and girders are exposed to compressive stresses in the upper fibers and to tensile stresses in the bottom fibers. The concrete layer above the transverse beams and girders is capable of substaining some of the compressive stresses. However, the potential of the beam to sustain a tensile loading far exceeds the potential of the concrete layer to sustain a compressive load. By artifically auguinenting the compressive stress resistance within the concrete layer, the inherent strength of the concrete layer can be exploited.

As a consequence, the transverse beam will not be fully stressed and hence its deflection will be reduced. Alternatively a lighter transverse beam may be selected which will be more fully stressed without exceeding allowable deflection limits.

OBJECTS It is therefore a purpose and object of the present invention to provide a building construction utilizing steel framing, corrugated sheet metal flooring and a concrete floor covering having composite coaction between the sheet metal flooring and the concrete according to recent developments in the art and also having composite coaction between the steel framing and the concrete layer.

A further object of the invention is to provide novel apparatus which is useful in combination with a steel building skeleton, corrugated sheeet metal flooring and the concrete covering thereof.

A consequence of this invention, and therefore, an object thereof, is the provision of a building which utilizes steel framing and corrugated sheet metal flooring which will require substantially less total steel than such buildings have heretofore required.

A further consequence of the present invention, and therefore an object thereof, is the appreciation and exploitation of the fact that the use of less steel weight in a building reduces the over-all weight of the building and therefore in turn further reduces the bulkiness of subjacent steel framing which is required to support the building.

The present invention involves novel unitary composite connector elements which are rigidly secured to a hori zontal beam or girder of a builiding and which extend above a corrugated sheet metal flooring section and which further are entirely embedded within a concrete layer subsequently poured above the corrugated sheet metal flooring sections. These unitary composite connector elements include:

(a) A longitudinal compression member which may be a strap or bar which is horizontally disposed directly above and spaced apart from a horizontal beam of a building:

(b) A plurality of spaced-apart bearing elements which have bearing surfaces disposed transverse to the longitudinal axis of the compression member and which also serve to connect the compression member directly to the horizontal girder or beam;

(c) Some hold-down means which are associated with either the compression member or the bearing elements or both.

The present invention, its objects and advantages, will be more clearly understood from the following detailed description by reference to the accompanying drawings in which:

FIGURE 1 is a fragmentary perspective illustration of a typical modern building involving a steel framework and corrugated sheet metal flooring.

FIGURE 2 is afragmentary perspective illustration of horizontal beams, girders and typical sheet metal flooring sections.

FIGURE 3 is a cross-section of a typical floor taken along the lines 3-3 of FIGURE 2 and showing a typical deflection in a sheet metal flooring section. A layer of concrete has been added.

FIGURE 4 is a cross-section taken along the line 44 of FIGURE 2 illustrating a typical floor and the beam deflection which would occur in a completed building. A layer of concrete has been added.

FIGURE 5 is a fragmentary perspective illustration of a unitary composite connector according to the present invention showing its construction and manner of connection with a horizontal beam and a typical sheet metal flooring section which are illustrated in phantom outline.

FIGURE 6 is a cross-sectional view similar to that of FIGURE 4 showing the deflection which develops in a typical building utilizing the present invention in the embodiment shown in FIGURE 5.

FIGURE 7 is a fragmentary perspective illustration of an alternative embodiment of the unitary composite connector element of this invention otherwise similar to the showing of FIGURE 5.

FIGURE 8 is a cross section illustration similar to FIGURE 6 showing the deflection which develops in a typical building utilizing the present invention in the embodiment shown in FIGURE 7.

FIGURE 9 is a fragmentary perspective illustration of a typical bay of a building showing the interrelationship of beams, girders, sheet metal flooring sections and the present unitary composite connector elements.

FIGURE 1 illustrates the essential structural elements of a modern building including vertical columns 11, horizontal beams or girders 12, corrugated sheet metal flooring 13, and a floor covering comprising a layer of concrete 14. s

As shown in FIGURE 2, the horizontal girders 12 have a plurality of horizontal beams 15 secured thereto, he

quently by means of welding angles 16. A corrugated sheet metal flooring section 17 is shown secured across two of the horizontal beams 15 by means of spot welds 18. The corrugated sheet metal flooring section 17 is of the type known in the building industry as cellular metal flooring. It comprises two sheet metal elements, a relatively fiat bottom element 19 and a corrugated upper element 20. The bottom element 19 and upper element 20 are secured together by means of a plurality of spot welds disposed along the contiguous portions. The corrugated flooring section 17 includes a plurality of longitudinal cells 21 which serve as raceways for distribution of electrical wiring, as conduits for distribution of conditioned air throughout a building, and the like.

The corrugated sheet metal flooring section 17 also serves as a principal structural element of the resulting building. As seen in FIGURES 2 and 3, the flooring sec tion 17 spans the distance between the adjacent horizontal beams 15. In FIGURE 3, the flooring section 17 is covered with a layer of concrete 23.

Another form of corrugated sheet metal flooring comprises only the corrugated sheet element 20, without any additional bottom element 19. Such corrugated sheet metal flooring is frequently identified as corrugated floor decking. It is not uncommon in the building industry to provide so-called blended floor constructions which utilize a blend'of the cellular metal flooring as illustrated in FIGURE 2 along with the floor decking which does not provide cellular passageways.

The present invention is applicable to those floor constructions which utilize all cellular flooring sections, those which utilize all corrugated floor decking, and also those which utilize the blended system.

Various techniques (none of which are shown in FIG- URE 3) may be employed to improve the bonding between the corrugated sheet metal flooring sections 17 and the layer of concrete 23 whereby a composite coaction will be developed between the concrete and sheet metal. If the floor of FIGURE 3 is considered to be supporting a load represented by the arrows labeled A, the entire load and also the weight of the concrete layer 23 will be borne by corrugated sheet metal flooring sections 17 according to conventional construction principles.

However, where composite coaction has been developed between the concrete layer 23 and the flooring sections 17, the imposition of loads represented by the arrows labeled A will create compressive stresses in the concrete layer 23 and tensile stresses in the flooring section 17 so that the load is shared by the concrete layer 23 and the flooring section 17. To effect such composite coaction, some shear transferring elements (not shown in FIGURE 3) are essential for transferring the shear stresses between the concrete layer 23 and the flooring section 17. Such shear connectors have been developed in various sources within the past several years.

These various techniques for developing composite coaction between the corrugated sheet metal flooring and the concrete layer are not themselves a part of the present invention. However, the present invention has its primary utility in combination with building constructions which utilize such techniques.

The phenomenon which appears to have been overlooked by the recent workers in the building arts is illustrated in an exaggerated cross-section view in FIGURE 4. The horizontal beam 15 actually is not rigid and unyielding as has been tacitly assumed heretofore. Instead, the horizontal beam 15 deflects upon loading in the same manner as does any other beam which is subjected to loading. To date the so-called composite co-action flooring proposals have not taken into consideration the fact that the concrete layer must act compositely with the horizontal beam 15 as well as act compositcly with the metal flooring section 17.

The present invention provides a unitary composite connector element for achieving coaction between the concrete layer 23 and the beam 15.

Figures 5 and 6 A preferred unitary composite connector element 30 is illustrated in FIGURES 5 and 6. The connector includes an uninterrupted longitudinal member 31 consisting of a strap having a longitudinal groove 32 over its entire length. The connector element 30 also includes a corrugated member 33 consisting of alternating crests 34 and valleys 35 which are spaced apart by generally vertical web portions 36. The corrugated member 33 preferably is formed from a metal strap having a width which is only a minor fraction of its length. The corrugated element 33 likewise has a reinforcing groove 37 extended over its entire length. The

longitudinal grooves

32, 37 are not essential, but it contributes compressive rigidity to the members 31, 33. The longitudinal member 31 and the corrugated member 33 preferably are fabricated from steel sheets having a thickness from about 16 gauge to about one-quarter inch.

The upper element 31 and lower element 33 are secured together along the crest portions 34 by means of spot welds 38.

The valley portions 35 are welded directly to the horizontal beam by means of plug welds 39 which extend through the contiguous abutting sheets 19, of a sheet metal flooring section 17.

Thus, the present composite connector element 30 is a unitary structure which is secured directly to a horizontal beam at spaced points, i.e., at the valleys 35. The upper element 31 is an uninterrupted longitudinal compression member which is capable of resisting a lengthwise compressive load. The undersurface of the crest portions 34 is spaced from about one-half inch to about three inches above the upper sheet metal surfaces of the cells 21 according to the depth of the concrete layer 23 which covers and entirely surrounds the present unitary composite connector element 311. The concrete layer 23 extends as a unitary mass between the undersurface of the crest portions 34 and the upper surface of the longitudinal cells 21. The crest portions 34 thus serve as hold-down elements. The vertical web portions 36 present surfaces which are transverse to the axis of the beam 15, and hence transverse to the axis of the longitudinal compression member 31. When a load is applied to the resulting floor, the concrete bears against the generally vertical web portions 36 in compression and shares the compressive stresses along with the uninterrupted longitudinal member 31.

As the concrete above the top surface of the metal flooring experiences compression, the concrete beneath the top surface may be free of stress or may even be exposed to tensile stresses. A shear stress develops within the concrete as a result of these stress variations. The generally vertical web portions 36 interrupt the concrete and receive these shear stresses for transfer downwardly dicrete layer 23 away from the horizontal beam 15.

A further phenomenon which has been manifested in composite concrete construction is the tendency of the concrete layer 23 itself to rise up as a mass and separate away from the subjacent sheet metal flooring section 17. This tendency relative to the beam 15 is offset with the present unitary composite connector elements by virtue of the fact that a substantial quantity of the concrete layer 23 is disposed in compression beneath the crest portions 34 of the connector element 31 Thus the corrugated element 33 itself serves as a hold-down means to resist any tendency for physical separation of the concrete layer 23 away from the horizontal beams 15.

Figures 7 and 8 Another embodiment of the present unitary connector element 40 is shown in FIGURES 7 andS. The connector element 40 includes a corrugated strap 41, continuous rods 42, and outwardly flanged, open-end-up channels 43.

The corrugated strap 41 includes alternating crests 44 and valleys 45 which are separated by generally vertical web portions 46. The flanged channels 43 include a base 47, vertical legs 43 and outwardly flanged legs 49. Aligned holes 50 are provided in the vertical legs 48 to receive the continuous bars 42.

The base 47 is welded to the crest 44 of the corrugated strap member 41. Likewise the continuous bars 42 are welded to the vertical legs 48 so that the over-all connector element 40 is a unitary structure.

The corrugated strap 41 and the channels 43 may be formed from sheet steel having a thickness from about 16-gauge to about one-quarter-inch. The continuous rods 42 may be ordinary concrete reinforcing rods or other rods having a diameter from about 0.1 inch to about 1.5 inches. While two rods are shown in FIG- URE 7, one rod will sufiice in many instances while more than two rods may be desirable in other instances.

As best seen in FIGURE 8, the under-surface of the corrugated strap member 41 can assume the upper shape of the corrugated sheet metal flooring section 17. The presence of the outwardly flanged legs 49 provides the necessary hold-down feature to resist the tendency of the concrete layer 51 to separating away from the metal flooring components.

The continuous bar members 42 preferably consist of reinforcing rods. They are positioned above the neutral axis of the resulting flooring structure and serve thereby as compression sustaining elements of the composite structure.

Normal concrete layers do not possess sufiicient compressive strength to provide maximum cooperation with the tensile stresses which can be developed in the steel beams beneath the concrete. For this reason, the compression-resistance of the concrete must be augmented with the uninterrupted compression member 42.

The valley portions 45 of the unitary connector element 40 are secured directly to a subjacent beam 15 by means of plug welds 52.

The general usage of the present unitary shear connector elements is illustrated in FIGURE 9 which is a fragmentary perspective illustration of a bay of a typical modern building. The columns 11 are connected by means of girders 12. Extended between the girders 12 are a plurality of beams 15. A plurality of corrugated sheet metal flooring sections 17 are interconnected and assembled in side-by-side and end-to-end relation across the girders 12 and beams 15. The metal flooring sections 17 are welded to the beams 15 and girders 12.

The present unitary

shear connector elements

30, 40 are assembled above the metal flooring sections 17 and are secured directly to the beams 15 or girders 12 by means of plug welds which extend entirely through the metal flooring sections 17.

The present unitary connector elements; 30, 40 also may be provided axially parallel with the lengthwise corrugations of the flooring sections 17 as indicated by the numeral 30' and 40'. These additional unitary connector elements 30', 4t) serve the identical purpose as the

connector elements

30, 40, i.e., to tie the concrete layer directly to the structural steel framing of the resulting building.

GENERAL The two

connector elements

30, 40 which have been illustrated and described, have the following features in common and in accordance with this invention:

(1) Both possess a continuous longitudinal element (31, 42) have an uninterrupted axis parallel with the axis of the subjacent beam and located above the sheet metal flooring;

(2) Both possess bearing elements which extend above the sheet metal flooring to provide bearing surfaces (36,

48) transverse to the axis of the beam and hence transverse to the axis of the longitudinal element; the bearing elements are connected directly to the subjacent beams whereby shear stresses from the concrete layer are transferred directly to the subjacent beam without being transferred through a sheet metal flooring;

(3) Both possess hold-down elements (34, 49, 42) which are separated vertically from the subjacent beams by means of a mass of concrete which is integral with the concrete covering;

(4) All of the elements recited in paragraphs (1), (2) and (3) are assembled into a unitary structure;

(5) The over-all connector elements (30, 40) are integrally connected to the subjacent beam.

The benefits of the present invention accrue when all of the above five enumerated factors are combined in a building structure.

I claim:

1. In a' building having horizontal beams, sheet metal flooring secured to the said beams, a concrete floor covering thereabove, and shear-transferring means associated with the said concrete floor covering and the said sheet metal flooring whereby the said sheet metal flooring and the said concrete floor covering coact compositely, the improvement in the floor assembly comprising:

a unitary composite-connector element rigidly secured to the upper surface of a said beam and embedded in the said concrete above and below the neutral axis of the said floor and comprising:

(a) a longitudinal compression member having an uninterrupted linear axis parallel to the longitudinal axis of the said beam and vertically spaced above and apart from the said sheet metal flooring and also spaced above the said neutral axis of the said floor;

(b) a plurality of spaced-apart bearing elements each having a bearing surface which is transverse to the said uninterrupted axis and the said bearing elements being disposed along substantially the entire length of the said uninterrupted axis, said bearing elements being secured to the said longitudinal compression member and also being secured to the said beam;

(c) the said compression member (a) and the said bearing elements (b) comprising a unitary structure;

the said concrete comprising an integral mass ,sur-

rounding the said compression member (a) on all sides and surrounding the said bearing elements (b) whereby the said concrete and the said longitudinal compression member (a) are maintained in compression above the said sheet metal flooring; and the said bearing elements (b) are maintained in bearing engagement with the said concrete;

whereby overall, the said concrete and the said beam and sheet metal flooring coact as a composite structure.

2. In a building having horizontal beams, sheet metal flooring secured to the said beams, a concrete floor covering thereabove, and shear-transferring means associated with the said concrete floor covering and the said sheet metal flooring whereby the said sheet metal flooring and the said concrete floor covering coact compositely, the improvement in the floor assembly comprising:

(a) a longitudinal compression member having an uninterrupted linear axis parallel to the longitudinal axis of the said beam and vertically spaced above and apart from the said sheet metal flooring and also spaced above the said neutral axis of the said fioor;

(b) a plurality of spaced-apart bearing elements (c) a hold-down element secured to said bearing elements and extending generally horizontally and being spaced vertically apart from the upper surface of the said sheet metal flooring to provide a space therebeneath for the integral mass of concrete;

((1) the said compression member (a) and the said bearing elements (b) and the said hold-down element (c) comprising a unitary structure;

the said concrete comprising an integral mass surrounding the said longitudinal compression member (a) on all sides, surrounding the said bearing elements (b), and filling the said space between the said hold-down elements and the upper surface of the said sheet metal flooring, whereby the said concrete and the said longitudinal compression member (a) are maintained in compression above the said sheet metal flooring; and whereby the said bearing elements (b) are maintained in bearing engagement with the said concrete; and whereby the said concrete is prevented from separating apart from the said sheet metal flooring and the said beam;

3. A composite connector element for use in a building comprising:

(a) a longitudinal compression member having an uninterrupted linear axis;

(b) a corrugated member having a plurality of alternating crests and valleys connected by generally vertical web portions which are transverse to the said linear axis, said corrugated member being formed from a strap of metal having a width which is only a minor fraction of its length;

(0) each of the said crests having secured to the upper surface thereof an open-end-up channel section having a base and a pair of generally vertical legs;

the said generally vertical legs having an aperture and being disposed transverse to the said linear axis;

the said compression member being extended through each aparture and being secured to' each of the said legs;

whereby the said corrugated member, the said compression member and the said channel sections comprise a unitary structure.

4. In a building having horizontal beams and a concrete floor supported by said horizontal beams, the improvement in the floor assembly comprising:

a unitary composite connector element rigidly secured to the upper surface of a said beam and embedded in the said concrete above and below the neutral axis of the said floor and comprising:

(a) a longitudinal compression member having an uninterrupted linear axis;

(b) a corrugated strap of metal having a plurality of alternating crests and valleys connected by generally vertical web members and having a width which is a minor fraction of its length, said valleys being directly connected to the said beam, and the said crests being spaced above the said beam;

(c) an open-end-up channel section having a horizontal base and a pair of generally vertical legs secured to the said crests with the said vertical legs being transverse to the said linear axis;

9 10 the said generally vertical legs having an aperture and References Cited by the Examiner the liaid gompretzssion nerbnher being ertlendedfihrfiiglh UNITED STATES PATENTS eac sa1 aper ure an emg secure 0 eac o e said legs, whereby the said compression member is gtewart i (1 above the said crests and the said corrugated 5 tewart 5 4 8 2,924,310 2/1960 Colbath 52-578 member, the said compression member and the said channel sections comprise a unitary structure; FOREIGN PATENTS the said concrete comprising an integral mass surround- 331,402 7/ 1958 Switzerland.

in the said com ression member and the said vertilegs; p 10 RICHARD W. COOKE, JR., Primary Examiner.

whereby over-all, the said concrete and the said beam CHARLES E. OCONNELL, FRANK L. ABBOTT,

and the said composite connector element coact as a Examiners. composite structure. D. R. COMUZZI, Assistant Examiner.

Claims

1. IN A BUILDING HAVING HORIZONTAL BEAMS, SHEET METAL FLOORING SECURED TO THE SAID BEAMS, A CONCRETE FLOOR COVERING THEREABOVE, AND SHEAR-TRANSFERRING MEANS ASSOCIATED WITH THE SAID CONCRETE FLOOR COVERING AND THE SAID SHEET METAL FLOORING WHEREBY THE SAID SHEET METAL FLOORING AND THE SAID CONCRETE FLOOR COVERING COACT COMPOSITELY, THE IMPROVEMENT IN THE FLOOR ASSEMBLY COMPRISING: A UNITARY COMPOSITE-CONNECTOR ELEMENT RIGIDLY SECURED TO THE UPPER SURFACE OF A SAID BEAM AND EMBEDDED IN THE SAID CONCRETE ABOVE AND BELOW THE NEUTRAL AXIS OF THE SAID FLOOR AND COMPRISING (A) A LONGITUDINAL COMPRESSION MEMBER HAVING AN UNINTERRUPTED LINEAR AXIS PARALLEL TO THE LONGITUNDINAL AXIS OF THE SAID BEAM AND VERTICALLY SPACED ABOVE AND APART FROM THE SAID SHEET METAL FLOORING AND ALSO SPACED ABOVE THE SAID NEUTRAL AXIS OF THE SAID FLOOR; (B) A PLURALITY OF SPACED-APART BEARING ELEMENTS EACH HAVING A BEARING SURFACE WHICH IS TRANSVERSE TO SAID UNINTERRRUPTED AXIS AND THE SAID BEARING ELEMENTS BEING DISPOSED ALONG SUBSTANTIALLY THE ENTIRE LENGTH OF THE SAID UNINTERRUPTED AXIS, SAID BEARING ELEMENTS BEING SECURED TO THE SAID LONGITUDINAL COMPRESSION MEMBER AND ALSO BEING SECURED TO SAID BEAM; (C) THE SAID COMPRESSION MEMBER (A) AND THE SAID BEARING ELEMENTS (B) COMPRISING UNITARY STRUCTURE; THE SAID CONCRETE COMPRISING AN INTEGRAL MASS SURROUNDING THE SAID COMPRESSION MEMBER (A) ON ALL SIDES AND SURROUNDING THE SAID BEARING ELEMENTS (B) WHEREBY THE SAID CONCRETE AND THE SAID LONGITUDINAL COMPRESSION MEMBER (A) ARE MAINTAINED IN COMPRESSION ABOVE THE SAID SHEET METAL FLOORING; AND THE SAID BEARING ELEMENTS (B) ARE MAINTAINED IN BEARING ENGAGEMENT WITH THE SAID CONCRETE; WHEREBY OVERALL, THE SAID CONCRETE AND THE SAID BEAM AND SHEET METAL FLOORING COACT AS A COMPOSITE STRUCTURE.