US1674476A - Chair for supporting and spacing concrete beam and slab reenforcing steel - Google Patents

Description

June 19, 1928.

W. E. MATHEWS CHAIR FOR SUPPORTING AND SPACING CONCRETE BEAM AND SLAB REENFORCING ST EEL Filed April 26, 1926 Sumac. W. E .blATHEWS.

the chair when'once in place, 'fsteel is confined to Patented June 19, 1928.

WILLIAM E. ivra'rnnws, OFBIRMINGHAM, A A AMA;

CHAIR FOR SUPPORTTNG AND SPACING. CONCRETE BEAM AND SLAB REENFORCING STEEL. I 1

Application filed April as, 1926. Serial No. 104','77a'- a chair for sup- My invention. relates to steel 1n porting and spacing the reenforcing concrete beams and slabs.

Theobyect of my 'lHVGDlLlOIl is to design a chair for supporting and. spacing concrete reenforcement that can be inexpensively manufactured, preferably as a light but very strong sheet metal stamping, and which will have the following distinctive advantages, namely:

The chair will be constructed so skeletonlike in its framework that it will cause a minimum of hindrance to the flowing of .the concrete around it It will support the reenforcing steel on a thus reducing to a plurality of pointed lugs,

showing minimum the amount of itself through the bottom surface of the concrete when the forms are removed;

It will act as a spacer as well as a chair, in that the points of the supporting lugs will bite into the forms, thus setting up very great resistance to lateral displacement .o

and, sincethe the chair by the upstands ,ing lugs, it will also remain where the steel man places it;

It will'be of ample ruggedness, unique in design and .being made of comparatively heavy gauge steel, it is abundantly safe against collapse under average working conditions, which are often very severe. During the pouring of the concrete slab work men are walking'over the steel While it rests on these chairs, sometimes even carrying heavy loads. This chair is designed to successfully withstand this punishment;

The chair isduplex in that while resting on one set of lugs" it is a chair for beam steel, and while resting on the other set of lugs itis a chairfor supporting and spacing slab steel. In either position the upstanding lugs serve to confine. the steel and insure against its dislodgment from the chair.

. The lengths of the two sets of lugs are in conformity with this duplex feature, the

chair resting OILItS longer lugs when sup.

porting beam steel and on its shorter lugs when supporting slab steel;

Vhen; used to support beam steel, this chair will automatically prevent the bars from coming too close to the side forms,and will also automatically compel a proper interval of space between any two adjacent bars in the same beam, thus insuring the .reenforcingbar in a. beam form.

angles to the plane of the floor on which the chair is placed, thu'seifectually eliminating all likelihood of honeycomb, or poorly filled aggregatepabout the point of rest of the chair. 1' V a My invention also contemplates broadly the stamping up from a metal plate of upturned and downturned lugs, each setlof lugs being adapted to form both guides and supports for the reenforcing bars andth'e lugs of one set being preferably longer thani those of the other set toadaptthe chair foruse with various kinds of reenforcements.

My invention also comprises the novel:details of construction and arrangements of parts, which in their preferred embodiments only are illustrated in the accompanying drawings which form a part of this specification, and in which ,Fig.1 1: is a perspective view showing-my improved chair in operating position supporting thereenforcing bars of a slab. Fig. 2 s a side elevation of the chair with the bars shown in dotted lines.

Fig. 3 is a plan view of the chair as shown in Fig. 2; and I Fig. 4- is a view corresponding to Fig. 2 showing the chair inverted andsupporting a Fig. 5' is a fragmental view showingv a modified. form of the chair shown in plan in liig, 3. I Similar reference numerals .refer to similar parts throughout the drawings.

In the embodiment of my invention illustrated, I show a concrete; slab 1 being poured over "thefboards 2 of its form and having imbedded inthe slab the crossed reenforcing bars 3 and 4: which at thelr mtersections are 10:; supported by my improved type of chair,

generally indicated by the numeral 5.. This chair in the preferred embodiment shown is formed from a stamping of sheet metal of the requisite gauge, according to the duty 110 g i p 1,674,476 rss PATENTTOFFICE- the chair is called contemplated for the chair. It is provided with downturned pointed lugs 6 which are provided by deforming and bending down the corners of the square blank from which the chair is stamped. These corners are bent down so as to have, in l'iorizontal cross section, a concavo-convex shape which materially increases their load supporting strength and resistance to lateral thrust. These lugs 6 have bottom points which e11- gage the form boards 2 and serve to hold the reenforcement in position thereon against slippage with the requisite space left under the bars to permit the concrete to flow around and envelop them to the extent required by standard practice. From the center of the blank I strike up four lugs 7 having pointed symmetrical tips 8, these being set 90 apart and in staggered relation to the downturned lugs 6. The center of the blank after the striking up of the lugs 7 may be left with the pointed projections in the center, as shown in Fig. 3, or if it is desired to produce a lighter and more skeleton like form of chair, the apices of the triangular shaped projections 9 left in the blank between the lugs 7 may be cut away to leave an octagonal space as shown in Fig. .5.

It will be noted that the lugs 7 are substantially longer and more closely spaced than the lugs 6. This arrangement is of advantage in that it enables the reenforcing bars for beams and slabs to be supported at different distances from the bottom of the form, with the shorter lugs 6 serving to sup port the bars for the relatively shallow slabs while the longer lugs 7 serve to support the bars for the deeper beams. Because the lugs 6 and 7 are relatively staggered the supported bar in each case will lie between the upturned lugs and with its axis above two of the downturned supporting lugs. This places the load in the correct position on the supporting lugs. Also since in the slabs upon to support intersecting bars there is advantage in having the longer lugs 7 upturned, as they will serve to position the superimposed bars, as will be more clearly seen in Fig. 2.

Generally, in beams the chair is not called upon to support intersecting bars and thus the shorter lugs are ample for the purpose, and, due to the arrangement of the lugs, spaces for larger bars are provided between the lugs 6 than between the lugs 7, which is proper because the reenforcement is general- 1y heavier for the beams than for the slabs.

The engagement of the sides of the chairs with adjacent chairs or bars or sides of beam the form 9 will serve to prevent the reenchanges in arrangement and substitution of.

equivalents may be made by those skilled in the art without departing from the-inven tion as defined in the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent, is v I 1. An invertible chair for concrete reenforcing steel, comprising a body portion havopposed sets of out-turned lugs relative- 111g ly staggered and spaced and each set adapted when downturned to support and when upturned to confine the 'reeni orcing steel.

2. A chair for concrete reeni'orcing steel, comprising a skeleton body portion having upturned lugs struck up from its center and having relatively shorter marginal lugs downstruck from its corners.

3. A chair for concrete reeniorcing' steel, formed of a sheet metal stamping having marginal downturned lugs and having the major portion of its center struck up 'to form upturned lugs, the lugs on one side being more widely spaced about the margin of the chair than the lugs on the other side.

4-. A chair for concrete reenforcing steel, formed of a sheet metal stamping having marginal downturned lugs and having the major portion of its center struck up to form supported lugs when inverted, the lugs on one side being longer than those on the other side and the lugs on one side being more widely spaced than those on the other side.

5. A chair for concrete reenforcing steel comprising a skeleton body portion having two oppositely extending sets of spaced lugs, the lugs of each set being turned at substantially right angles to the plane of the body portion, either set of lugs being adapted for supporting the chair or for receiving and confining the reenforcing steel, and the lugs of one set being longer than the lugs of the other set.

In testimony whereof I aflix my signature.

WILLIAM E. MATHEWS.

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