US2294528A - Composite structural element - Google Patents

Description

P 1, 1942- w.A. WELLS 2,294,528

COMPOSITE STRUCTURAL, ELEMENT Filed Feb. 14, 1940 2 Sheets-Sheet 1 mafia 2 F99. I n 3.

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Patented Sept. 1, 1942 COMPOSITE STRUCTURAL ELEMENT William A. Wells, deceased, late of Seattle, Wash, by Robert D. Wells, executor, near Seattle, Wash, assignor to United States Loo-Bloc Corporation, a corporation of Washington Application February 14, 1940, Serial No. 318,859

'7 Claims.

This invention relates primarily to building structures, and more particularly to parts of a building such as the floor, ceiling, or roof, in which sheathing, flooring, or the like, is normally laid upon beams, rafters, or the like, stretching between supports.

Broadly speaking, it is the object of the present invention to provide a single composite element, of such size as can be conveniently manufactured and handled, incorporating in part a beam-like portion, which constitutes the principal support for the whole, when rested upon spaced supports in the remainder of the structure, and incorporating also a slab portion which constitutes a part of the covering in plan, to the end that no special or separate beams, joists, rafters, or the like need be provided to support the covering or horizontal portion, since the beam portions, integrally joined to and formed as part of the slab, constitute the sole needed support.

It is preferred that such a composite structural element be manufactured of concrete, for instance, as a cast monolithic piece, and since it must, in most instances, incorporate reinforcing material, particularly in the beam portion thereof, it is a further object of the present invention to provide a form for such a composite element which lends itself readily to such manufacture, with the reinforcement in place, and which may be made conveniently of substantially equal and sufficient density throughout, and without displacement, in the process of manufacture, of the reinforcing material. As an associated object it is a further object to provide a form of design and construction of such an element which may be readily cast in prepared molds and re- 'moved therefrom, and which may thereafter be conveniently handled and put in place.

It is a further object to provide such a struc tural element the principles of which, in various forms, may be incorporated at will in a roof element, in a floor element, or in a ceiling element.

It is a further object to provide such an element which is readily joined to other such elements and held in place in the structure, and to provide one which can be joined in such a way to adjoining elements that no cracks need be left, and which may therefore form a tight floor, ceiling, or roof.

It is a further object, especially in conjunction with floors and ceilings, to provide such an element which may be so assembled with other elements to constitute a floor and a subjoining ceiling, requiring the minimum of room, yet providing an open space which may be filled with insulating material, and which, whether insulating materials are provided or not, still leaves no contact between fioor elements and ceiling elements, to the end that transmissionof heat and sound through the composite structure is avoided to the largest degree possible.

With these and other objects in mind, as will appear hereafter, the invention comprises the novel structural element, the novel specific forms thereof, and the novel structures formed from such elements, all as shown in the accompanying drawings, described in this specification, and as will be more particularly defined by th claims which terminate the same.

In the accompanying drawings are illustrated the principles of this invention incorporated in various forms of execution, each as now preferred.

Figure 1 is an end view of such an element, formed as a roof element, and Figures 2 and 3 are side elevations, taken from opposite'sides of one end of the element, from the respective viewpoints illustrated by the lines 2--2 and 3-3 of Figure 1.

Figure 4 is an end View of several such elements, in the form of floor elements, and in assembled relation.

Figure 5 is a side elevation of one end of the floor element.

Figure 6 is an end view of a composite floor and ceiling construction, incorporating such elements, and Figure 7 is a plan view of the same.

Such an element must be sufiiciently light to be conveniently handled in manufacturing and shipping it, and in assembling it into a building, yet

it must be suiliciently strong, at least considered as a beam, to support the expected load thereupon when supported between two spaced-apart supports. Since it also incorporates a slab portion, it must be suiiiciently strong that the slab portion is afforded adequate support from the beam portion throughout its entire extent. Added to the above, it must be so designed that it is simple to construct and to handle during construction.

It has been found that these ends are best served if the beam portion of the element, at least in a floor element, is not made of sufficient strength that by itself, and unaided, it will support the entire expected load between the bearing points of the beam, but rather the beam is divided, and two half-beams are constructed, which in the aggregate will afford adequate strength to the floor, for instance, but either of which of itself affords less than sufilcient strength, considered as a beam. The same ends are further served if the slab portion of the element be formed at one side only of the beam portion, and cantilevered at this side of the beam, so that its support is from the beam, except at its ends, and at its ends it is preferred that a common bearing pad be provided for the slab and for the beam. In roof and ceiling elements there is little added load to be expected, hence the beam need only be sufficiently strong to carry its own weight and the weight of the slab. Since the beam must have adequate and effective depth, consistent with economical design on long spans, and must have a volume of concrete sufficiently reduced to permit easy handling and fabrication, it follows that the beam ends should be inclined upwardly towards the level of the bearing pad, that is, the beam must be reduced in depth adjacent the ends, or adjacent the bearing pads, but this does not appreciably reduce its effective strength, since the bending moment at these points is the minimum.

In order that the height over-all of the structural element be a minimum, and confined only to the necessary height of the beam portion, the slab portion is not superimposed upon the beam portion, but rather is depressed so that its upper surface lies flush with the upper surface of the upper chord of the beam, thereby in effect merging together the slab and the beam at their junction, and reducing the over-all height of the beam, and therefore the amount of steel and the amount of concrete, and its weight. By thus reducing its weight a further reduction is possible in the amount of steel and in the amount of concrete without reduction of the necessary strength of the structural element.

It will be borne in mind that such elements will be designed and constructed for use under varying circumstances, and that no precise mensions or sizes can be given, since these will vary in accordance with the different conditions under which the element is employed. It will be understood, also, that the forms, shapes, and dimensions shown, and the proportions, and pure 1y illustrative.

The element is shown in the form of a roof element in Figures 1, 2, and 3. Such a roof element is intended to be extended from an end wall or gable to an opposite end wall or support, and is therefore of appreciable length, and considerably less width than length. It is intended to be supported without the aid of rafters, joists, or the like, the place of these elements being taken by the beams incorporated in the elements themselves. Thus the beam portion l is shown as provided with the reduced end I!) for support at S upon an end Wall or other form of bearer, whereas its intermediate portion H is of considerably greater depth. The beam as a Whole incorporates reinforcing elements suitably formed, arranged, and joined together to afford the desired strength to the beam, coupled with the concrete of which it is formed, and in Figure 3 this reinforcing, generally illustrated by the numeral 3, includes an upper chord Bil, a lower chord 3i, and suitable tie members 32. It will be noted that the upper chord 30 lies substantially in th upper surface of the beam.

cantilevered out at one side from the beam portion l is the slab portion 2. In the roof element this slab portion slopes downwardly. At its junction with the beam its upper surface coincides generally with the upper portion of the upper chord of the beam, but for the purpose of effecting a tight joint between adjoining elements of this type a batten 4 may be extended upwardly above the upper surface of the slab element 2, this batten including, if desired, a part of the reinforcing of the beam and being in effect a part of the beam itself. A similar complemental batten it extends downwardly from the outer end of the slab 2.

The under surface of the reduced portion In of the beam constitutes a bearing pad, as indicated at 5, to rest upon the bearer or wall S. The slab portion likewise has a bearing pad beneath its end, as indicated at 59, and these two bearing pads 5 and 50 are preferably coplanar and merge into one another, so that when they rest upon a level surface they support mutually the ends of the beam and the ends of the slab. In the roof element, where the slab 2 is inclined, as shown in Figure 1, a gable portion 52 may be employed to fill the angle above the bearing pad 56 and the upper surface of the slab 2.

As will now be evident, such roof elements are supported upon stepped end walls or gables, and thus supported, extending between the end walls, the weight of the roof is supported almost entirely by the individual beams l. Each successive element is offset laterally from the overlaps the element below, the batten 40 of the upper one extending downwardly and outwardly beyond the batten at of the element below. Suitable sealing material or resilient pads may be supported between their contacting surfaces to keep out the weather. Thus formed, the roof is made up without the necessity of placing joists, rafters, stringers, sheathing, or other supports, since the roof incorporates beams that support themselves and the slab elements that form the cover of the roof, and no other support is needed.

The same principles may be incorporated in floor elements, as shown in Figures 4 and 5. Herein the primary difference in the structure of the individual elements over the roof elements described is that the slab 2 is horizontal instead of sloping. It may also incorporate reinforcing material, as indicated at 33, but so also may reinforcing material be incorporated in the slab portions of the roof elements, if needed. It is also desirable in the floor elements (as also in other types of element if needed) to provide integral braces 23 at intervals, to assist in supporting the intermediate portions of the slab 2 from the beam I.

Such floor elements are preferably placed somewhat diiferently than the roof elements. When the roof elements are placed it is not to be expected that they will be disturbed, nor that loads other than those generated by the weight of the elements themselves will be imposed upon them. With floors, however, this is different, and it is normally expected that loads will rest upon the floor. If the beam portions I were made sufficiently strong that each beam would be able to sustain all loads that would normally be placed upon it, the elements would be excessively heavy; therefore each beam portion is made of less strength than necessary to take the expected loads, and two such elements are placed in such way that their beam portions adjoin, and thereby mutually assist in supporting each a part of the others load.

Such floor elements, supported by the bearing pads 5 and 59 from a suitable support S, extend across to some opposite support, and they are held in this position by suitable means. For instance, two such elements which adjoin, side by side, may be held together by tie rods 5, received in grooves 51 extending across the ends of the elements, the heads 60 whereof are abutted against suitable shoulders at the edges of the elements. The elements may thus be coupled together in pairs, or each such element may be joined in this fashion, or in any suitable fashion, to each of the two elements at the opposite sides thereof.

It is hardly possible to form the elements so accurately that they will abut along their edges without possibility of leakage. It is preferred, therefore, that they be spaced slightly apart, and that means be provided for positively closing the crack between them, throughout their length, to the end that grouting may be put in place and the crack thus closed. The elements are therefore formed along each edge of the slab with grooves 2| and 22, and in the complemental longitudinally extending passages formed by two such grooves, when adjoining, there is placed a trough or channel I which is drawn tightly against the upper shoulder of this passageway, by spaced screws or bolts 10, the heads of which are received in the grooves 22, and in this fashion the crack between any two adjoining elements may be closed, and thereafter grouting may be run into the crack to completely fill it, and to leave a flush floor.

The floor elements may likewise be employed as ceiling elements, merely by inverting them top for bottom, and they are shown so used in Figure 6. The only difference lies. in the manner of closing the crack between them, in that when they are used as ceiling elements the trough or channel 1 is received in the grooves 22, instead of the grooves 2i, and the heads of the clamping screws are now received in the grooves 2!.

Such elements may be assembled into a composite floor and ceiling structure, which takes but little space, and which, without any physical contact which might conduct heat or sound through the structure, provides a dead air space or a space which can be filled with insulating material. Such a composite structure is shown in Figures 6 and '7. It is to be noted that in the floor construction where two beams I are placed adjoining, the slabs 2 of the corresponding elements extend in opposite directions, and the free edge of the slab 2 of one element adjoins the free edge of the slab 2 of another element, and in this interval, staggered between the beams of the floor element, are placed the beams i of the ceiling elements. In such fashion the depth of the composite ceiling and floor structure is kept to a minimum, and yet physical contact is avoided between the ceiling and the floor.

While the method of molding such elements has not been disclosed herein, it will be appreciated that such elements can be readily molded in prepared molds, and the angle sections can be poured from the sides with the reinforcing accurately placed, thus overcoming the impracticability of thin concrete sections in which it is normally impossible to maintain either a uniform density of the concrete or a fixed position of the reinforcing when poured from the edge. The method of constructing these elements is, however, a separate invention, which is not herein claimed.

What is claimed as the invention is:

l. A structural assembly comprising a plurality of cast monolithic structural elements each comprising a beam disposed generally in a vertical plane and of a length to rest upon two spaced-apart supports, and a slab cantilevered from the side of the beam, horizontal grooves across the end of each element, and tie rods bearing in the outer edges of a group of assembled elements, and received in said grooves, to tie the elements into the group and to hold them in assembled relation.

2. A floor assembly comprising a plurality of cast monolithic structural elements, each comprising a beam disposed in a generally vertical plane, and of a length to rest upon two spacedapart supports, a slab cantilevered from the upper side of the beam, and means disposed lengthwise the adjoining edges of the elements, below the floor level, to close the crack therebetween.

3. An assembly as in claim 2, the adjoinin edge of each element being longitudinally grooved, below the floor level, and wherein said crack-closing means comprises a closure plate received in such grooves and spanning the crack between the elements, whereby to retain grouting to fill such crack.

4. A floor assembly including cast monolithic structural elements each comprising a beam disposed in a generally vertical plane, and of a length to rest upon two spaced-apart supports, a slab cantilevered from the side of the beam, at its top, and of a thickness to define a downwardly facing shoulder, the opposite side face of the element being grooved in the plane of such shoulder to define a similar and registering downwardly facing shoulder, a groove along the opposite longitudinal edges of the element, above said shoulder and below the top of the slab, to define upwardly facing registering shoulders, a closure plate engageable beneath the downwardly facing shoulder and bridging the gap between two adjoining elements, and bolts engaged with the closure plate, through the crack between such elements, and disposed with their heads restin upon the upwardly facing shoulder and generally below the top surface of the slab and beam.

5. A cast monolithic structura1 element comprising a reinforced beam of adequate depth in proportion to its length, and terminating in bearing pads at each end of reduced depth, a cantilever slab section projecting at one side only of the beam, of lesser width than length, said slab section sloping downwardly from the upper chord of the beam, when the beam is disposed in a normal vertical plane, to about the level of the under side of the bearing pads, and said pads extending laterally of the beam to join the slab section at each end, and constituting a common support for the beam and slab at each end.

6. A cast monolithic structural element comprising a reinforced beam of adequate depth in proportion to its length, and terminating in bearing pads at each end of reduced depth, a cantilever slab section projecting at one side only of the beam, of lesser width than length, said slab section sloping downwardly from the upper chord of the beam, when the beam is disposed in a normal vertical plane, to about the level of the under side of the bearing pads, and said pads including a vertically disposed gable portion extending laterally of the beam to join the slab section at each end, whereby the pads constitute a common support for the beam and slab at each end, level upon its under bearing surface.

7. A floor and ceiling assembly comprising a plurality of alike, independently cast monolithic elements disposed in two adjacent horizontal planes, each of said elements including a horizontal slab and a beam disposed at one side only of the slab, and having a bearing pad common to the slab and beam at each end, the upper chord of the beam, in the upper plane, lying substantially flush with the upper surface of the slab, the opposite chord of the beam, throughout the major portion of its length, lying beneath the plane of the pads bearing surfaces, but being inclined upwardly towards and merging into the bearing pads at each end, the elements in the lower plane being inverted, top for bottom, with relation to those in the upper plane, and the two planes being so spaced as to cause the upper chord of the beam of an element in the lower plane to project above the level 01 the lower chord of the beam of elements in the upper plane, but not to the level of the lower surface of the slab of such upper element, the elements in the two planes being disposed to stagger their beams, whereby to provide independently supported and substantially flush floor and ceiling assemblies, having no portions in contact, but spaced apart for insulation.

ROBERT D. WELLS, Executor of the Estalte of William A. Wells, De-

ceased.

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