IMPROVEMENTS IN OR RELATING TO BAR CHAIRS

Abstract: A bar chair (10) suitable for use in building construction and appropriate for supporting reinforcing rods (30, 31) during formation of a concrete wall. The bar chair includes a central body portion (11) which may be a rod or stem and also a plurality of plate elements (12) which extend outwardly from the central body portion (11). In one type of bar chair (10) for supporting upper reinforcing rods (30, 31) the plurality of plate elements (12) all form support legs (12) which all extend from the central body portion (11) downwardly and outwardly to enable the bar chair (10) to straddle a lower reinforcing rod (27, 28) in use. In another type of bar chair (18) in accordance with the invention a base surface of the central body portion (19) and a base surface (23) of each plate element (20) are all oriented in a common plane. This latter type of bar chair (18) is suitable for supporting the lower reinforcing rods (27, 28).

Description: IMPROVEMENTS IN OR RELATING TO BAR,CHAIRS THIS INVENTION relates to an improved bar chair suitable for use in building construction. Conventional bar chairs are formed from wire and include two substantially ϋ shaped wire components welded to each other at mutually adjacent vertices and oriented at right angles to each other so as to form a substantially pyramid shaped wire frame. The wire frame therefore was 0 formed from an upper wire component overlying a lower wire component and the upper component was also provided with a relatively shallow recess for supporting a reinforcing rod. The abovementioned conventional bar chair was also provided with four feet which were dipped in a molten ---- ■ plastics material. In building construction and particularly in regard to formation of suspended slabs such as intermediate levels or floors of a building the usual practice was to mount a lower bar chair as described above at spaced intervals on a formwor base usually formed from • --- plywood so as to support a plurality of lower reinforcing rods. Then upper bar chairs were used which were mounted on the plywood base and straddled the lower reinforcing rods to support upper reinforcing rods. Subsequently a concrete pour was carried out to form the suspended slab. --5 Problems with conventional bar chairs as described above which occurred included the fact that during laying of the reinforcement rods on the bar chairs the wire feet had a tendency to protrude through the layer of plastics material Υf and pierce the plywood formwork base thereby creating rust problems which can be very costly to repair in restitution work. Thus after a period of time not only did the wire bar chairs rust but also the rust affected the reinforcing rods and thus the whole of the suspended slab was adversely effected which was very expensive to repair at a later date. It therefore is an object of the present invention to provide a bar chair which alleviates the abovementioned problems of the prior art. The bar chair of the invention suitably includes a substantially centrally located body portion and a plurality of outwardly extending plate-like support elements. Preferably each plate-like support element is oriented at right angles or radially with respect to the longitudinal axis of the centrally located body portion * in plan view. Each support element being plate-like will have a pair of opposed broad surfaces. If desired reinforcing or strengthening ribs will be provided on one or both broad surfaces and more preferably reinforcing " ribs will be provided on each broad surface adjacent an outer or free edge of the support elements. The centrally located body portion may form a rod or stem and may adopt any suitable cross-sectional shape such as being round, square or rectangular. Preferably however the centrally located stem is of round cross section and is integral with each outwardly extending support element. In this regard it is preferred that the bar chair be formed from plastics material, aluminium or other suitable rust-free material. The central located body portion may also be formed by a central plate if desired. In relation to a lower bar chair which supports lower reinforcing rods it is preferred that the centrally located stem have the same height as each outwardly extending support element although this is not essential. Suitably each base surface of the outwardly extending support elements and of the centrally located stem are oriented on a common horizontal plane. In regard to an upper or straddle type bar chair it is preferred that the outwardly extending plate-like support elements form support legs which all extend from a common body portion or centrally located stem. In this embodiment each support leg may extend downwardly and outwardly at an acute angle to the centrally located .stem. Reference may .now be made to a preferred embodiment of the present invention as shown in the attached drawings wherein - FIG 1 is a perspective view of a straddle type bar chair constructed in accordance with the invention; FIG 2 is a perspective view of a base or lower type bar chair constructed in accordance with the invention; and FIG 3 is a schematic view of a formwork assembly utilizing the bar chairs shown in FIGS 1 and 2; FIG 4 is a schematic view of a second type of bar chair constructed in accordance with the invention; FIG 5 is a schematic view of a third type of bar chair constructed in accordance with the invention; FIG 6 is a perspective view of a modified straddle type bar chair to that shown in FIG 1; and FIG 7 is a perspective view of the straddle chair of FIG 6 taken from a different angle. The bar chair 10 in FIG 1 includes a centrally located stem 11, plate-like support elements or legs 12, strengthening ribs 13 located at an outer or free edge 14, and opposed broad surfaces 15 of each support element 12. The stem 11 is of circular cross section. The base surfaces 16 of each support leg are all on a common horizontal plane and there are also provided internal strengthening ribs 17 of each support leg 12 as shown. The bar chair 18 shown in FIG 2 includes a centrally located stem 19 and plate like support elements 20 each having strengthening ribs 21 intermediate their ends. If desired there also may be provided a support base 22 which contacts the base surfaces 23 of each support element 20 having a peripheral rib 24. Alternatively support base 22 may be omitted and the base surfaces 23 contact a suitable formwork base as shown in FIG 3. The formwork assembly 25 shown in FIG 3 includes a formwork base 26 suitably constructed from plywood and a row of bar chairs 18 as shown at spaced intervals on base 26. Each bar chair 18 supports an array of longitudinal reinforcing rods 27 as well as transverse reinforcing rods 28. There is also shown a row of straddle type bar chairs 10 located at spaced intervals on base 26 which each support an array of longitudinal reinforcement rods 30 and transverse reinforcement rods 31. The concrete 32 when poured thereby forms a suspended slab assembly 33. It will also be appreciated that in some cases the centrally located stem 11 or 19 may be omitted and all support elements 12 or 20 abut or are attached to mutually adjacent inner portions 34 of each other which are all attached or integral with a central plate or body portion 34A. This arrangement is shown in schematic plan view in FIG 4 and another possible arrangement is shown in schematic plan view in FIG 5 wherein all support elements 12 or 20 have inner portions 34 merging at a common stem 35. It will be appreciated that many other variations on this theme are possible involving an assembly of outwardly extending plate-like support elements. The arrangement shown in FIGS 4 and 5 will be suitable for both base type and straddle type bar chairs. In FIGS 6-7 a similar type of straddle bar chair is shown as already illustrated in FIG 1. Thus it has a central stem 11, plate-like support legs 12, strengthening ribs 13 located at free end 14 and opposed broad surfaces 15 of legs 12. The base surfaces 16 of each support. leg 12 are all on a common horizontal plane and there are also provided internal strengthening ribs 17 of each support leg 12. There is also shown S-shaped reinforcing ribs 35 and feet 36.

Claims: The claims defining the invention are as follows: 1. A bar chair suitable for use in building construction including: a plurality of plate elements all extending outwardly from a substantially centrally located body portion. 2. A bar chair as claimed in claim 1 wherein the centrally located body portion is a rod or stem and each plate element extends radially outwardly therefrom. 3. A bar chair as claimed in claim 2 wherein the central stem is of round cross section and integral with each plate element. 4. A bar chair as claimed in claim 1 further including reinforcing ribs located on one or both broad surfaces of each plate element. 5. A bar chair as claimed in claim 1 wherein the plurality of plate elements all form support legs which all extend from the centrally located body portion downwardly and outwardly to enable the bar chair to straddle lower reinforcing rod(s) in use. 6. A bar chair as claimed in claim 1 wherein a base surface of the centrally located body portion and a base surface of each plate element are all oriented in a common plane. 7. A bar chair for use in building construction including a central stem and a plurality of plate elements extending outwardly therefrom wherein a base surface of the central stem and a base surface of each plate element are all oriented in a common plane. 8. A bar chair for use in building construction having a central stem and a plurality of plate elements forming support legs which all extend from the central stem downwardly and outwardly to enable the bar chair to straddle lower reinforcing rod(s) in use.

Inventors: HULL BARRY GARTH, HULL, BARRY, GARTH
Applicants: HULL BARRY GARTH, HULL, BARRY, GARTH
Application year: 1986
Main classification: E04C5
IPC codes: E04C5