US3325959A - Chair supports for building constructions - Google Patents

Description

June 20, 1967 I A. TORP 3,325,959

, CHAIR SUPPORTS FOR BUILDING CONSTRUCTIONS Filed May :5, 1965 INVENTOR:

AL F TORP.

United States Patent 2 Claims. (a. 52-689) This invention relates to chair supports for building constructions and, in particular, to chairs for the support of reinforcing steel bars utilised in such constructions.

While various types of supports have hitherto been employed in building construction, they can be largely divided into three main groups as follows:

I. Cement blocks are provided with a groove as a bed for the reinforcing bar or a cast-in binding wire or the like for fixing the bar. Such cement blocks especially of small (thin) sizes are readily subject to crushing and breakage. In addition the type of material does not permit any other than a rather primitive form of block with a correspondingly reduced sphere of application. The use of cement blocks is, therefore, quite small.

II. Chairs produced of round or flat steel: They are supplied most often galvanized. However, it appears that the galvanization does not often provide satisfactory rust protection since the zinc is attacked in the alkaline cement surroundings in conjunction with the effect of the atmosphere. It concerns the portions of the chair which bear against the forrnWork and thus project into the light. In outer walls these portions are especially exposed to rain as the water becomes alkaline when it comes into contact with the cement. A satisfactory rust protection, for example by burn-lacquering is prohibitive by reason of expense.

III. Foundation blocks of plastic: These are provided as a rule with flexible claws which grip around the reinforcing bar so as to secure the latter to the block. Standard reinforcing bars are at present 8, l0, l2, 16, 20 and 26 mm. None of these plastic blocks has the ability to grip each and all standard dimensions. This means that for one and the same block height there must be produced several sizes with varying claw dimensions. Plastic is cement-resistant. Between plastic and cement, therefore, no chemical reaction occurs, that is to say the plastic does not combine with the cement, so that a joint is formed. The thermal expansion of plastic is on average about seven times greater than that of cement. At lower temperatures the joints can, therefore, open correspondingly, something which is regarded as a disadvantage in cement technology.

According to the present invention a chair constructed for the support of a reinforcing steel bar utilised in building constructions, which comprises a supporting beam for arrangement transversely relative to said bar and having a height at least substantially equal to its breadth and a pair of plates formed integrally with said beam at respective ends thereof, said plates each having an upper portion in the form of an upstanding lug projecting above the beam and, projecting below the beam, a lower portion the bottom edge of which is adapted to bear against a foundation of the building construction, said chair having been cast from a corrosion-resistant metal alloy containing from 94.3 to 96.0 percent highly refined fine zinc, the balance being aluminium, copper, magnesium and incidental impurities.

Preferably, the plates have a greater mutual spacing at the bottom edge of the beam than at its top edge and are vertically disposed from said bottom edge of the beam down to the bottom edges of the lower portions thereof.

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The advantages of the metal alloy used to make the chair of the invention are as follows:

A. Good corrosion properties against usual external influences. The potential difference between chair and conventional reinforcing steel is not greater than about 0.5 volt, that is to say that in the possible presence of moisture in the cement corroding galvanic currents of practical significance can no longer arise. For comparison is 1mentioned reinforcing steel/rust free 18/8-steel 1.2 V0 t.

B. The cement combines chemically with the alloy so that between the chair and the cement there are no joints.

C. The alloy casts very readily, is cheap in use and has a rigidity index which is at the same level as steel 35. The chair is, therefore, reasonable in price. The zinc used to make the alloy is preferably refined to a degree of purity of at least 99.99 percent.

When portions of the plates are vertically disposed as indicated above, these portions will not be stressed to any degree worth mentioning as a result of dimension-increasing bending moments. This represents a not insignificant saving of material as is also the case due to the supporting beam standing edgewise and not on its broad side.

In order that the invention can be more easily understood, a convenient embodiment thereof will now be de scribed, by way of example, with reference to the accompanying drawings:

FIGURE 1 is a perspective View of a chair constructed in accordance with the invention, and

FIGURE 2 is an end view of the chair of FIGURE 1 with a reinforcing bar shown mounted thereon in dotted lines.

Reference numeral 1 denotes a transverse supporting beam provided with upstanding lugs 2 and 3. The beam 1 is joined at both ends to respective side plates 4 and 5, the bottom edges of which bear against the formwork or another foundation. In both plates, recesses 6 and 7 are made in the middle of the lower end for inserting a binding Wire. The recesses provide the cement at the same time with lateral access to the chairs inner portion and thereby contribute to oppose the formation of a hollow space here. The holes 8 and 9 are likewise for fixedly binding the reinforcing bar. The third binding possibility is to push the rope underneath the beam 1.

As shown in FIGURE 2, both of the side plates are given an outwardly bent shape so that the mutual spacing increases substantially from the upper edge to the bottom edge of the beam. The chair is provided thereby in an effective manner with the desired lateral stability. From the bottom edge of the beam and down to the structure against the formwork, the plates (the legs) are vertical so that on this Weak portion no bending moments of any significance worth mentioning arise with, in consequence, a corresponding saving in material. At the very bottom the legs can be given a greater thickness 10 and 11 if it is desired to increase the surface of the structure against the formwork.

The chairs bed grips one and all standard bar dimensions, of which the largest is shown dotted. The lugs 2 and 3 are made as low as possible but at the same time, sufficiently high to give the largest bar a dependable lateral support. In this way the breadth of the bed is reduced which involves reduction in the consumption of material and increase in lateral stability for the thinner bars which will not fill out the Whole of the bed. When the thinner bars are only able to bear against one lug, that is to say eccentrically on the chair, the chair nevertheless fulfills fully its purpose, namely to give the reinforcement the prescribed spacing from the formwork.

The chair is designed to be used in all conventional cement constructions in ordinary house buildings, that is to say in plates and beams of different kinds, walls, columns, flights of stairs etc. It often becomes necessary then, to be able to secure the reinforcing bar to the chair with a conventional binding Wire, which is an easy and dependable mode of fastening. (Unnecessary in plates.) It is then important that this can be done in the simplest and quickest manner all according as to how accessible the chairs are in each individual cement construct-ion.

That the chair which is mentioned above has not less than three binding possibilities is a practical advantage at the building location. It especially concerns high beam constructions and the like, when these are so narrow that the iron binder can not in the normal way reach down into the beam. He must then lie flat on the surface form- Work with arms and head down in the beam. The iron binding under such conditionsincluded herein fixedly binding of the chairsis of course inconvenient, and all experience indicates that the more binding possibilities the chair has, the better it is for the iron binder.

What I claim is:

1. In a chair constructed for the support of a reinforcing steel bar utilised in building constructions, a supporting beam for arrangement transversely relative to said bar and having a height at least substantially equal to its breadth and a pair of plates formed integrally with 25 said beam at respective ends thereof, said plates each having an upper portion in the form of an upstanding lug projecting above the beam and, projecting below the beam, 21 lower portion the bottom edge of which is adapted to bear against a foundation of the building con- 30 2. In a chair constructed for the support of a reinforcing steel bar utilised in building constructions, a supporting beam for arrangement transversely relative to said bar and having a height at least substantially equal to its breadth and a pair of plates formed integrally with said beam at respective ends thereof, said plates each having an upper portion in the form of an upstanding lug projecting above the beam and, projecting below the beam, a lower portion the bottom edge of which is adapted to bear against a foundation of the building construction, the improvement which comprises in the plates having a substantially greater mutual spacing at the bottom edge of the beam than at its top edge and being vertically disposed from said bottom edge of the beam down to the bottom edges Of said lower portions thereof and which further comprises in the chair having been cast from a corrosion-resistant metal alloy containing from about 94.3 to about 96.0 percent highly refined fine zinc, the balancebeing aluminium, copper, magnesium and incidenta1 impurities.

References Cited UNITED STATES PATENTS 1,123,107 12/1914 Darr 52689 1,260,494 3/1918 Widrner 52-689 1,378,202 5/1921 Voclpel 52689 1,773,918 8/1930 Mathews 52687 1,909,121 5/1933 Riley 52689 FOREIGN PATENTS 462,777 3/ 1937 Great Britain.

DAVID J. WILLIAMOWSKY, Primary Examiner. FRANCIS ZUGEL, Examiner.

Claims (1)

1. IN A CHAIR CONSTRUCTED FOR THE SUPPORT OF A REINFORCING STEEL BAR UTILISED IN BUILDING CONSTRUCTIONS, A SUPPORTING BEAM FOR ARRANGEMENT TRANSVERSELY RELATIVE TO SAID BAR AND HAVING A HEIGHT AT LEAST SUBSTANTIALLY EQUAL TO ITS BREADTH AND A PAIR OF PLATES FORMED INTEGRALLY WITH SAID BEAM AT RESPECTIVE ENDS THEREOF, SAID PLATES EACH HAVING AN UPPER PORTION IN THE FORM OF AN UPSTANDING LUG PROJECTING ABOVE THE BEAM AND, PROJECTING BELOW THE BEAM, A LOWER PORTION THE BOTTOM EDGE OF WHICH IS ADAPTED TO BEAR AGAINST A FOUNDATION OF THE BUILDING CONSTRUCTION, THE IMPROVEMENT WHICH COMPRISES IN THE CHAIR HAVING BEEN CAST FROM A CORROSION-RESISTANT METAL ALLOY CONTAINING FROM ABOUT 94.3 TO ABOUT 96.0 PERCENT HIGHLY REFINED FINE ZINC, THE BALANCE BEING ALUMINIUM, COPPER, MAGNESIUM AND INCIDENTAL IMPURITIES.

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