US2691293A - Reinforced concrete slab - Google Patents

Description

Oct. 12, 1954 F. l.. PATTERSON AREINF'ORCED CONCRETE SLAB Filed April 5, 1949 Patented Oct. 12, 1954 UNITED STATES this trice l Claim. l

My invention relates generally to devices and materials used in the construction of concrete slabs, and more particularly to improved materials and devices that are embedded in the slab for locating and holding other members to the slab.

The construction of buildings having the iioor formed of a concrete slab has increased materially during recent years, since this form of construction offers many advantages. However, there are attendant disadvantages, including the dimculty of providing a smooth and level surface, particularly where a large area is to be covered in this manner. I-Ieretofore, it has been the practice to embed boards or timbers in the concrete with their upper surface at the desired level so that a smoothing member may be scraped across the upper surface of the soft concrete to provide a smooth and level surface of the proper height. These guide timbers must be removed before the slab or :door is finished, and the space they once occupied then lled with concrete to provide a smooth and unbroken expanse, This, of course, is an expensive procedure but because of the possible moisture and attendant rotting of the wood, it is not practical to leave the timber permanently in the slab.

Another difliculty in the forming of a large concrete slab of this nature has been in the location of anchor bolts embedded in the concrete to receive the sill or footing of a wal1 that rests against or bears upon the slab. Previously, the anchor bolts have been placed in the concrete after the latter has partially set, a line being stretched to indicate the proper location of the bolts, and the latter then being driven into the partially hardened concrete. The intrusion of the bolt into the concrete has displaced some of the latter so that a raised portion is formed adjacent the bolt, and while this may be removed, the labor` involved renders this impractical. As a result, the bearing edge of the Wall does not fit snugly against the slab, but instead is held a slight distance therefrom by the raised portions adjacent the bolts. This reduces the load-carrying ability oi the slab, and also means that the wall or similar member is less rigidly held. Furthermore, the placing of the bolts in this manner generally results in inaccuracies that prevent the use of a previously drilled sill, since the location of the individual bolts will vary an amount requiring that the sill be drilled on the job to align with the bolts as actually located.

To overcome these difficulties, I have developed the screed or structural element now to be described, intended to be permanently embedded in the slab to form an integral part thereof.

lt is therefore a major object of my invention to provide a screed for use in concrete and similar construction that becomes an integral part of the nished product. n

Another object of my invention is to provide a screed of this type of light weight and attractive appearance that is easily used under a wide variety of conditions.

It is a further object of my invention to provide such a screed that may easily be located in its exact and final position prior to the pouring ci any concrete, thereby facilitating checking of the work and general inspection of the job.

Still another object of my invention is to provide a screed particularly well adapted to the locating and holding of anchor bolts to which a wall or similar member will be attached.

It is a still further object of my invention to provide a screed that may be used to insure'the smooth and level qualities or a slab, whether or not anchor bolts or similar members are embedded therein.

These and otherobjects and advantages of my invention will become apparent from the following description of a preferred form thereof, and from the drawings illustrating that form in which:

Fig. 1 is a plan view of a slab in the process of being formed, showing the use of my screed;

Fig. 2 is a perspective view of a clip used in joining or attaching one section of screed to the conventional forms or to other sections of screed;

Fig. 3 is an enlarged view showing the method of using the clip to hold the screed to the form;

Fig. 4 is a cross-sectional view taken on theline dof Fig. 3 to show the location of my screed with respect to the upper surface of the con-A crete, and also to show the method of holding a bolt or similar element; and v f Fig.l 5 is a perspective view of a junction, such as that indicated in Fig. l, of four screed portions, one of the portions beingomitted, and an anchor bolt being shown.

Referring now to the drawings` and particularly to'Fgs. 1 and 5 thereof, it will be seen that my improved screed or structural element is shaped in the form of a strip lil, preferably of a medium gauge metal, that is bent or otherwise formed to provide a generally vertically extending web il having a generally horizontal ilange l2 at its upper edge. At its lower end, the web Il carries an angularly positioned leg i3, while another angularly positioned leg iii extends downwardly and rearwardly from the downward and forward edge of the upper leg I3. In crosssection, the legs I3 and I4 thus form a V-shaped section, with the vertex of the V pointing horizontally, away from the web I I. For reasons that are hereinafter discussed, the flange I2 projects from the flange II in the same general direction as thev upper and lower legs I3 and I4, and preferably, the free edge of the fiange is provided with a dcwnturned lip I5.

It will thus be realized that the screed I Il.

consists of a V-shaped section formed by the legs I3 and I4, with the upper end of the upper leg I3 joined to an angle section formed by the web II and flange I2. Whilethe screed may be formed of extruded material, in general, better results and greater resilience is secured if it is formed of sheet or strip metal that is bent or rolled to the desired shape.

At regular intervals along the length of the screed I0, I provide vertically aligned holes I6 in the upper and lower legs I 3 and I4, these holes preferably being somewhat elliptical to receive a vertically extending cylindrical member such asv a bolt IT. However, in order for the holes I6 in the upper and lower legs I3 and I4 to be properly aligned, it is necessary to squeeze or compress the V-shaped portion of the screed, as indicated in Fig. 4.

In that view, the normal or unstressed shape of the-screed I is indicated in phantom outline, while its stressed or compressed shape is indicatedvin full outline. By forming the holes I6 when the V-shaped portion is` compressed, the holes will be of the proper size to receive a member such as the bolt II the cross-section of which is slightly less'than the area of the hole, and ifthereafter released, the upper and lower edges ofthe holes will tend to return to their original position, therebyrinsuring the firm frictional gripping of theV bolt bythe legs I3 and I4.

Preferably, the holesy I6 are formed at fairly close intervals, such as every tworor three inches along the length of the screed I0. Since it is not anticipated thaty all of the holeswill be used to support members suchas anchor bolts I'I, most of the .remainingholes are unoccupied and permit the flowV of concrete fromone side of the screed to the other. Thus, the space between the upper andlower legs I3 and I4 is easily and l automatically filled with concrete asv the pouring ofthe. latter progresses, and consequently no voids are formed in the slab.

In; addition to the holes I formed in the legs I3 and I4, I prefer to form additional holes I8 in theweb II so that there is even greater opportunity for concrete to flow from one side of the screed IIJ to the other. This insures that the portions of concrete on each side of the screed I0 are joined together at a numberof points, the connections extending vthrough the openings I6 and I8, to insure the production of Aa single unitary slab. Furthermore, the angular positioning of the upper and lower legs I3 and I4 forms the equivalent of a tongue and groove joint between these portions, thereby further increasing the strength of this slab, In this connection, it is contemplated that the height of the screed I0, from the lower edge of the lower arm I4 to the upper surface of the flange I 2, will be materially less than the thickness of the slab of concrete,v and consequently Vrods and other rein-` `where the thickness of the slab approximates the height ofthe screed I0, the load and other structural demands usually do not require the use of reinforcing members.

To join sections of the screed together, as at corners, or where two shorter lengths must be joined to form a continuous straight run, I employ the clip illustrated in Fig. 2. As shown there, the clip 20 is formed of resilient strip material such as metal, and includes a body portion 2I having folded end portions 22 and 22a. Each of the end portions is formed as a continuation of the strip material of the body 2i, bent back upon itself to form a centrally projecting leg 23 that approaches but does not reach the center of the body portion, the end of that leg being bent outwardly to form an outwardly projecting leg 24 generally parallel to the body 2I. As a result, the clip 20 includes a pair of S-shaped sections that are joined together by the body 2I. A slit 25, extending substantially halfway across the body 2l, is formed in the middle of the latter, and a pair of clips may thus be placed together, in the manner indicated in Fig. 5, to provide a right angle connection for two or more screeds I0. The clips 2Q are completed by forming holes 26 passing completely through the S- shaped sections 22 and 22a to receive a nail in the manner hereinafter described.

To use the clip 2t in the joining of a pair of screeds I 0, the clip is placed so that the outwardly extending leg 24 is on the back or outside of the web II, and the centrally extending leg 23 is adjacent the inner or forward side of the web. The lip I5 fits over and engages the upper edge of the body portion 2 I, and the clip is then forced longitudinally of the screed III until the web II bears against the centrally located curve of the S-shaped section 22, as indicated in Fig. 3. The other portion or strip of the screed It that is to be joined to the first strip is then forced into engagement with the other end 22a of the clip 20, and the two strips are thus simply and quickly but rmly held together. If only two strips are to be joined together at an angle to each other, the clip 20 may easily be bent at its center, the slit 25 providing a zone or line of weakness that insures the proper location of the bend.

This last feature also renders it Very easy to attach the screed I0 to the conventional external forms used for concrete work. As indicated in Figs. 1 and 3, the screeds II] will normally extend generally perpendicularly from the external forms 3U, and are held to the latter by clips 2D. The latter, as previously suggested, are bent so that their ends are perpendicular, and one end 22 is clipped over-the web I I of the screed IU. The other end 22a of the clip 2i) is thus parallel to the face of the form 3G, and is held thereto by a nail passing through the hole 26 and driven into the form. Care should be taken to locate the flange I2 of the screed I0 so that it is substantially coplanar with the upper surface of the form 30, thereby providing a simple and convenient means for leveling and smoothing the upper surface of the concrete slab.

The method of joining two or more screeds II] has previously been described, and thus it is possible to form a complete grid of the screeds, corresponding to the location of the various walls and similar members that are to bear against the slab.

To support the screeds I0 intermediate the y connections to the form 30, I prefer to'I drive stakes or provide similar supporting members that pass through the holes IB in the legs I3 and I4. It will be appreciated, of course, that while the screeds I are sufficiently rigid and strong for the purpose intended, they must be supported intermediate their ends, particularly in the case of long spans. Generally, this will be accomplished by the use of stakes or similar supporting means, as suggested, that are passed through the holes I 6, and are firmly engaged by the screed I0 by the natural resilience of the latter, in the same manner as the anchor bolts I'I. It is not essential, and in general it is undesirable that the stakes extend to the upper surface of the flange I2, but instead they preferably stop just above the upper end of the upper leg I3. Care is taken in locating the stakes, of course, to make sure that they are not passed through holes I6 that are intended to receive an anchor bolt Il, but since the holes are located at frequent intervals, this is a simple matter.

After the screeds Ill have been properly located and supported, the anchor bolts I I may be inserted in the proper locations by compressing or squeezing together the legs I3 and I4 of the screed adjacent the desired holes I6. Normally, the bolts I'I will be inserted from below, since the bolts are customarily provided with a head or an angularly positioned section 3l to prevent the turning of the bolt when a nut is placed upon its upper end. The flange I2, it will be noted, is shaped and positioned to bear against one side of the bolt I'I to partially support and to insure the correct alignment of the latter.

At this time, the construction has proceeded to a point where it will readily be apparent if any errors have been made in the location or alignment of any of the screeds I0, or if any errors have been made in the location of the anchor bolts II. When it has been determined that all is in order, concrete 32 may be poured to form the slab, the upper surface of the concrete being leveled and smoothed to be flush with the upper surface of the flange I2. It will be appreciated that the screed or structural element I I) thus performs a very useful service in providing a simple and accurate method of smoothing and leveling the surface, in addition to supporting and aligning the anchor bolts I'I. In this connection, the screed or structural element I0 can very easily be used as a smoothing and leveling gauge in the case of large eXpanses, where no walls or similar members bear or rest against the slab. Under such circumstances, the anchor bolts I'I are omitted, and the surface of the slab is leveled with the upper surface of the flange I2 as previously described. It will be realized that the downwardly projecting lip I5 on the ange I2 tends to insure that the flange will remain horizontal, and will not be caught and bent upwardly so that it projects from the upper surface of the slab.

From the foregoing, it will be seen that I have provided a simple and inexpensive screed or structural element that is fully capable of achieving the objects and securing the advantages heretofore set forth. It will be realized that the screed or structural element may be formed in any one of a variety of manners, and from a wide variety of materials, the important requirements being that the material be resilient, and not tend to stain or otherwise discolor the slab.

While I have shown and described a preferred form of my invention, it will be apparent that modifications may be made within the broad outlines herein pointed out. Consequently, I do not wish to be restricted to the particular form or arrangement of parts herein described and shown, except as limited by my claim.

I claim:

A structural device embedded in a slab of cementitious material, said device including: a plurality of continuous strips of sheet material joined together and each having a flange positioned in the plane of the upper surface of the slab, a downturned edge along one side of said flange projecting downwardly therefrom into the space occupied by said slab, a web connected to and extending generally perpendicularly downwardly from the other edge of said flange and into said slab, said web having apertures therein through which said cernentitious material passes, and a resilient V-shaped portion having the edge of one side connected to said web, and the edge of the other side of the V-shaped portion being left free, the apex of said V-shaped portion projecting laterally from said web, and the sides of the V-shaped portion being provided with a series of holes alignable by forcing the free edge of the V-shaped portion toward said web prior to placement of said slab; resilient connectors joining said continuous strips together, each connector having a depth substantially equal to that of said web\and comprising a straight portion positioned against said web and reversely bent upon itself at each end, said reversely bent ends being again reversely bent, said reversely bent ends being engaged against the opposite sides of said webs at the adjacent ends of two strips, said connectors being transversely slotted from one edge to half their. depth intermediate the reversely curved bent ends thereof, whereby a pair of said connectors engage with each other at the junctions of a plurality of angularly related strips and hold said strips in said angular relation and the flanges of the strips in a common plane; and elements inserted through certain of said holes and projecting above and below said strips, said elements being held against displacement in the V-shaped portion prior to placement of said slab by the binding of said portion therewith when the free edge of said V-shaped portion adjacent said elements is released, the cementitious material of said slab filling all the holes in the strip.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 667,384 Brandt Feb. 5, 1901 1,398,852 Gilbert Nov. 29, 1921 1,505,220 Shay Aug. 19, 1924 1,666,613 Woods Apr. 17, 1928 1,668,858 Madsen May 8, 1928 1,741,585 Robertson Dec. 31, 1929 1,748,017 Goldenstar Feb. 18, 1930 1,818,404 Kaufman Aug. 11, 1931 1,874,591 Older Aug. 30, 1932 1,900,686 Averill Mar. 7, 1933 2,027,516 Burrell Jan. 14, 1936 2,123,425 Kelley July 12, 1938 2,240,427 Thomsen Apr. 29, 1941 2,262,704 Tompkins et al Nov. 11, 1941 2,379,179 Petersen June 26, 1945

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