GB2204620A

GB2204620A - Masonry support for cladding forming an outer skin of a cavity wall

Info

Publication number: GB2204620A
Application number: GB08809994A
Authority: GB
Inventors: David John Pratt; Michael Douglas Hoyland
Original assignee: EXPAMET U K Ltd
Current assignee: EXPAMET U K Ltd
Priority date: 1987-05-13
Filing date: 1988-04-27
Publication date: 1988-11-16
Also published as: GB8809994D0; GB8711225D0; NL8801224A

Abstract

A masonry support system for supporting an outer skin of masonry of a cavity wall in a multi storey building having a concrete or steel framed inner wall structure comprises a masonry support plate 10, 30 rigidly secured to brackets 11; 31, 32 having upper and lower abutment means 18; 37, 38 to receive a washer plate 12, 34. The washer plate has an inclined closed ended opening (Fig 4, 19), 35 which intersects an upright slot (16, Fig 1) 36 in a web (40, Fig 8), 31 of the bracket. A bolt stud projects through at the point of intersection from the inner wall structure and is tightened to secure the masonry support in position. Up and down adjustment is achieved by sliding the washer plate 12, 34 laterally between the abutments. Two embodiments are described, the first of which uses a vertical channel section bracket with the web 14 linked to side walls (15, Fig 3) forming bridging flanges across the cavity, the slide walls having slots 18 defining the upper and lower abutments for the washer plate. The masonry support plate forms parts of a cold formed angle section 10. Gussets 22 stiffen the angle section 10. The second embodiment includes a single cavity bridging flange 32 affording the lower abutment 37 and a perpendicular web 31 affording the slot 36 and upper abutment 38. The bridging flange 32 is welded to a flat plate 30 forming the masonry support plate. <IMAGE>

Description

TITLE: Masonry Support System This invention relates to a masonry support system for supporting an outer skin of masonry of a cavity wall having a concrete or steel framed inner wall structure.

This form of construction is typically used in buildings of more than two storeys such as office buildings.

In such buildings, the outer skin masonry needs to have its weight supported, usually at each storey level, by the inner structure. Currently, this is achieved by casting fixing elements such as bolt studs in the concrete, or welding them to the steel work, of the inner structure and subsequently attaching heavy duty cold formed angle to the face of the concrete or steel inner structure. One limb of the cold formed angle is secured against the inner structure and the masonry is then built up on the free edge of the other limb, leaving a cavity between the inner structure and the masonry outer skin.

To allow for the inevitable inaccuracy in positioning the fixing points on the inner structure of concrete or steelwork, the cold formed angle may have upright slots to receive the fixing bolts.

Alternatively, horizontal slots may be provided in the cold formed angle. Some form of vertical adjustment allowed at the inner structure fixing points for example by using cast-in, or welded on, upright channels with captive bolts adjustable for height in the channels, instead of merely using fixing bolts.

This latter alternative allows some adjustment in both vertical and horizontal directions.

In each of these methods, the mating parts (such as channels, bolts, washers, or angles) must have machined grooves to prevent sliping of the bolt fixings under the expected heavy load of masonry, typically a whole storey about 3 metres high.

A high bending moment is caused because the masonry is spaced by the cavity thickness from the inner structure. A thick and therefore expensive cold formed angle therefore needs to be used to support the load safely without deflection. The tendency towards wider cavities to contain extra insulation is aggravating this problem.

A damp proof means needs to be used since the cold formed angle closes off the cavity at each storey and particularly as mortar from the masonry above may tend to build up on the angle. The cold formed angle acts as an undesirable thermal bridge across the cavity, usually corresponding to the floor/ceiling level within the building.

In a recent proposal, a smaller cold formed angle is used, located more or less within the thickness of the outer skin masonry and connected to the inner skin by cavity bridging brackets, bolted to the usual fixing bolt studs. This proposal overcomes or reduces some of the disadvantages referred to above.

For adjustment purposes, each bracket has a pair of upright side walls with upright slots and an upright slot in the channel web for the bolt stud. A quadrilateral washer is located snugly between the walls to receive the bolt stud and vertical adjustment is achieved by fixing the height of this washer relative to the upright bolt receiving slot in the bracket web, using a separate wedge driven into the upright side slots above the quadrilateral washer.

No machined grooves are needed, so this proposed system reduces the cost as well as the weight of the hitherto used cold formed angle, but it has some drawbacks. The assembly of the special quadrilateral washer and the wedge requires some skill and judgement and the non-captive wedge is capable of being lost or mishandled by workmen. Perhaps more seriously, some damage to the structure or vibration in use might cause the loss of one or more wedges with possibly catastrophic results.

In this proposal, gussets have been welded in the cold formed angle at the bracket positions to counteract the extra torsional forces on the cold formed angle due to its spacing from the inner structure. These gussets project to the outer edge of the cold formed angle and interrupt the masonry coursing. To accommodate the gussets, it has been necessary to use a thin brick slip at the face of the masonry and infill behind the brick slip, or alternatively to slot the brick to accommodate the gusset plates.

It is an object of the present invention to provide a new or improved form of masonry support system for use in multi storey buildings which overcomes or reduces some or all of the disadvantages previously referred to.

According to the invention there is provided a masonry support system for attaching to a fixing bolt of an inner structure of a wall to provide support for a masonry outer skin of the wall, the masonry support system comprising; a rigid masonry support plate adapted to be located substantially within the thickness of said masonry outer skin; at least one bracket rigidly secured to said masonry support plate and comprising a web and at least one bridging flange, the web abutting the inner structure and being provided with an upright bolt-receiving slot adap ted to receive said fixing bolt, the bridging flange or flanges projecting into the cavity and being rigidly secured to the masonry support plate, the bracket defining upper and lower abutments adjacent the web;; and a washer plate which is a sliding fit between the upper and lower abutments, the washer plate having an oblique closed ended elongate opening adapted to receive said fixing bolt in use so as simultaneously to make the washer plate captive and to permit height adjustment of the bracket relative to the bolt by sliding the washer plate laterally.

The bracket may comprise an upright channel having said web and a pair of side walls constituting bridging flanges.

The upper and lower abutments may be defined by a pair of aligned upright adjustment slots in said side walls adjacent the web.

Alternatively, the bracket may comprise an upright web having a transversely centrally disposed bridging flange rigidly secured thereto.

The upright web may have an integrally formed abutment to provide said upper abutment.

The integrally formed abutment may be formed by pressing, piercing or half-shearing.

The integrally formed abutment may be provided centrally of the web or alternatively may be provided at the lateral edges of the web.

The integrally formed abutment or abutments may be strengthened by welding.

Alternatively, the web may have a separately-formed attached abutment or abutments.

In this case, the or each abutment may comprise a block or a hook.

The masonry support plate may be planar.

Alternatively, the masonry support plate may comprise one flange of a rigid angle section such as a cold formed angle.

The washer plate may have parallel upper and lower edges.

The oblique opening in the washer plate may be closer to one of said upper and lower edges than to the other.

The oblique opening in the washer plate may be inclined at an angle of approximately 150 to the parallel upper and lower edges of the washer plate.

A plurality of brackets may be rigidly secured to the masonry support plate at spaced positions along its length.

A plurality of generally triangular gussets may be secured within the angle of said rigid angle section.

The gussets may be of an area less than the enclosed area of the rigid angle section.

The maximum horizontal extent of the gussets is preferably less than one half of the width of the horizontal limb of the angle and most preferably is approximately one third of that width.

The gussets may be provided in pairs, welded to the rigid angle section at positions corresponding to the positions of securement of the walls of a channel section bracket.

Embodiment of the invention will now be described in more detail by way of example only with reference to the accompanying drawings in which; FIGURE 1 is a front elevational view of a first embodiment of masonry support embodying the invention.

FIGURE 2 is a side elevation partly in section of the masonry support in use.

FIGURE 3 is a plan view of the masonry support.

FIGURE 4 is a front elevational view of a washer plate.

FIGURE 5 is an elevational view of the washer plate in an inverted condition.

FIGURE 6 is a front elevational view of a second embodiment of masonry support.

FIGURE 7 is a plan view of the masonry support of Figure 7.

FIGURE 8 is a side elevation, partly in section, of the masonry support of Figures 6 and 7.

Referring firstly to Figures 1 to 5 of the drawings, the masonry support system to be used to support an outer masonry leaf of a cavity wall from an inner structure of concrete or steel work comprises three main parts, namely, a masonry support plate provided by an angle section 10, a bracket 11 and a washer plate 12.

The angle section 10 is preferably a cold formed angle of substantial thickness since the load to be carried is likely to be the weight of a whole storey of outer leaf masonry. The rigid angle section 10 is welded at 13 to a generally channel section bracket 11, best seen in Figure 3. The channel bracket 11 has a web 14 and a pair of bridging flanges constituted by generally parallel side walls 15 welded as referred to at 13 to the angle section 10. The web is provided with a closed ended upright slot 16 which is adapted to receive a bolt stud projecting from the inner structure of the building, for example from the concrete or steel work. The slot 16 is upright and has a width equivalent to that of the bolt shown in dotted line at 17 in the drawings.

Each of the side walls 15 also has an upright slot illustrated at 18. These slots are relatively narrow and are intended to receive the third part of the assembly which is a washer plate 12, the ends of the slots 18 forming upper and lower abutments to guide the washer plate 12. This is best seen in use in Figure 1 of the drawings and is illustrated in more detail in Figures 4 and 5 to be referred to below.

The slots 18 are provided immediately adjacent the web 14 of the bracket so that the washer plate 12, which is a close sliding fit in the slots 18, can be slid in from the side to the position shown in Figures 1 to 3 of the drawings.

Referring to Figure 1, it will be seen that the washer plate 12 has an obliquely angled closed ended opening 19 which is of sufficient size to enclose the bolt stud 17. The bolt stud 17 is therefore located at the intersection of the upright slot 16 of the channel web and the oblique opening 19 of the washer plate 12.

By moving the washer plate 12 laterally, this position of intersection is caused to move up or down the upright slot 16 and, in use, this adjustment is used to raise or lower the bracket 11 relative to the (fixed) position df the bolt stud 17.

Brackets 11 are provided along the length of the angle section 10 at intervals sufficient to support the expected load. Each of the brackets is attached at a respective stud and adjustment is made using a respective washer plate to accommodate any slight variation in height of the position of the bolt studs in the inner structure of the wall.

Referring to Figure 4 of the drawings, it will be seen that the washer plate 12 has parallel upper and lower edges 20 and 21, spaced at a distance equivalent to the height of the slots 18 in the bracket side walls so as to be a close sliding fit. The oblique closed ended opening 19 is positioned closer to the upper edge 20 than to the lower edge 21. It is inclined at an angle of 150 to the upper and lower edges. In use, lateral sliding of the washer plate shown in Figure 4 gives a range of possible bolt positions relatively close to the top edge of the washer plate; that is the bracket is hung relatively low. If the bracket needs to be hung higher; the washer plate can be inverted as shown in Figure 5 so that the opening 19 is then positioned closer to the new lower edge 20 than to the upper edge 21.

Returning to Figures 1 and 2 of the drawings, a pair of gusset plates 22 are welded to the rigid angle section 10 at the position of each bracket 11 in the example shown. These gusset plates are optional. They may be provided away from the bracket positions. Where provided, the gussets prevent flexure of the angle section and stiffen the assembly against torsional movement under load, bearing in mind the extra leverage caused by the load being spaced by the cavity width from its main point of support.

Each gusset is of generally triangular form although cropped short at the corner to permit it to be used with the non-square cold formed angle 10. The area of each gusset plate is substantially less than the enclosed area of the angle section 10 and its maximum horizontal extent to the point 23 is between one half and one third the extent of a horizontal limb 24 of the angle.

In the example shown, the cold formed angle does not extend completely to the edge of the masonry. Standard bricks 25 can be laid on the cold formed angle on a suitable mortar bed 26 and project only slightly forwardly of the end of the limb 24. In order to accommodate the gusset plates 22, a small portion, typically about one third of the width of the brick is 'chipped off the back corner of the brick when it is laid at the position of the bracket and gusset plate assembly. This is a relatively simple operatipn for a bricklayer to carry out and it will be seen that no other modification is needed to the brickwork and the coursing is uninterrupted.

This contrasts with the arrangement where relatively wide gusset plates are used extending close to the forward face of the masonry. In that case, special brick slips need to be used to conceal the position of the gusset plate and the part of the wall behind the brick slip is filled up with rubble and mortar, reducing the load bearing capacity locally and also requiring a degree of skill and judgement of the part of the bricklayer.

As stated above, the gusset plates could be omitted in suitable conditions of load.

The masonry outer leaf is continued in conventional fashion up to the level of the next storey where another angle 10 is found. An expansion joint 27 may optionally be used below the cold formed angle.

Referring particularly to Figure 3 of the drawings, it is noted that the angle section 10 lies substantially wholly within the thickness of the outer leaf masonry and the cavity 28 is substantially clear. The only obstructions in the cavity are the vertical disposed side walls 15 of the channel and these provide the only point at which mortar droppings could build up in the cavity or heat or moisture could be transferred across the cavity.

Thus, the arrangement shown does not provide a thermal bridge except at the localised positions of the brackets and even this amount of conduction of heat can be avoided by the use of a small insulating web placed behind the web 14 of the bracket adjacent the inner Structure of the wall.

The very stiff nature of the channel section bracket enables a relatively large cavity 28 to be used and almost all the cavity is clear for insulating material to be incorporated within the cavity. Similarly, the normal damp proofing action of the cavity is not interrupted except locally and it is possible to lay suitable damp proof membranes across the cavity above the brackets so that moisture tends to be shed towards the outer masonry leaf.

Wall ties may be incorporated in the wall to link the inner structure and the outer masonry leaf in generally known manner.

Reference has been made to a prior proposal in which a wedge was driven laterally into a slotted upright channel section bracket to provide fine adjustment of the height of the projecting bolt stud relative to the bracket. In that prior proposal, the wedge was not captive.

It will be noted that, once the washer plate of the present invention has been inserted into the slots 18 and the bracket and washer plate assembly presented to the bolt stud 17, the washer plate 12 remains captive and cannot be lost or dropped by the builder or shaken loose by damage to the bulding in use.

It is particularly to be noted that the washer plate 12 is a close sliding fit in the slots 18. This means that the bracket 11 cannot be forced to move from side to side with a pendulum motion about the fixed bolt stud 17 even in the event of severe damage to the building caused by for example an explosion or an impact. With the previously described system using a wedge inserted above the bolt, only the weight of the masonry held the bracket upright. Should the masonry load become unstable, the bracket was capable of rocking or pendulum movement about the bolt with consequent loss of stability to the entire structure.

Under tests, it has been found that the embodiment described above performs greatly in excess of the requirements for strength and resistance to bending. With this in view, a second embodiment is described with reference to Figures 6 to 8 of the accompanying drawings, this second embodiment being of relatively lighter weight and having features which make its use on site relatively easier.

Referring to Figures 6 to 8 of the drawings, the masonry support system in this case comprises a flat plate 30 which acts as a support for the outer leaf masonry, a bracket comprising an inner web 31 and a centrally disposed transverse flange 32 which projects across the cavity. The flange 32 is welded at 33 to the masonry support plate 30.

A washer plate 34 is provided as before with an oblique, closed ended opening 35. The upright web 31 of the bracket has an intersecting vertical slot 36. The washer plate 34 can be moved laterally and is guided by a lower abutment 37 formed by the top of the bridging flange 32, and an upper abutment 38 formed on the web 31.

The upper abutment 38 may be formed in various ways but, in the example shown, it is formed by pressing the material of the web forwardly, as most clearly seen in the sectioned part at the top of Figure 8. The abutment 38 is optionally supported by a weld 39.

The washer plate 34 can slide between the upper and lower abutments 37 and 38 with the same effect as that described previously in connection with the first embodi ment. However it will be noted that the washer plate 34 is only captive when a nut has been placed on the bolt stud.

The masonry support plate 30 can be extended to any chosen length to support the outer leaf masonry. It will be seen that only the bridging flange 32 actually spans the cavity, thereby reducing the possibility of mortar build up and avoiding the need for major damp proofing measures. A suitable cut-out 40 is provided in the lower edge of the bridging flange 32 to shed any moisture settling on the bracket.

The upper abutment 38 could be formed in various different ways, for example by pressing, piercing or half shearing it can be formed integrally with the remainder of the web 31. Alternatively, it could be a block or hook shaped member welded onto the face of the web 31.

In further alternatives, the single central abutment 38 could be replaced by a pair of abutments provided at the side edges of the web 31.

Claims

1. A masonry support system for attaching to a fixing bolt of an inner structure of a wall to provide support for a masonry outer skin of the wall, the masonry support system comprising; a rigid masonry support plate adapted to be located substantially within the thickness of said masonry outer skin; at least one bracket rigidly secured to said masonry support plate and comprising a web and at least one bridging flange, the web abutting the inner structure and being provided with an upright bolt-receiving slot adapted to receive said fixing bolt, the bridging flange or flanges projecting into the cavity and being rigidly secured to the masonry support plate, the bracket defining upper and lower abutments adjacent the web;; and a washer plate which is a sliding fit between the upper and lower abutments, the washer plate having an oblique closed ended elongate opening adapted to receive said fixing bolt in use so as simultaneously to make the washer plate captive and to permit height adjustment of the bracket relative to the bolt by sliding the washer plate laterally.

2. A masonry support system according to Claim 1 wherein the bracket comprises an upright channel having said web and a pair of side walls constituting bridging flanges.

3. A masonry support system according to Claim 2 wherein the upper and lower abutments are defined by a pair of aligned upright adjustment slots in said side walls adjacent the web.

4. A masonry support system according to Claim 1 wherein the bracket comprises an upright web having a transversely centrally disposed bridging flange rigidly secured thereto.

5. A masonry support system according to Claim 4 wherein the upright web has an integrally formed abutment to provide said upper abutment.

6. A masonry support system according to Claim 5 wherein the integrally formed abutment is formed by pressing, piercing or half-shearing.

7. A masonry support system according to Claim 5 or Claim 6 wherein the integrally formed abutment is provided centrally of the web.

8. A masonry support system according to Claim 5 or Claim 6 wherein the integrally formed abutment is provided at the lateral edges of the web.

9. A masonry support system according to any one of Claims 5 to 8 wherein the integrally formed abutment or abutments are strengthened by welding.

10. A masonry support system according to Claim 4 wherein the web has a separately-formed attached abutment or abutments.

11. A masonry support system according to Claim 10 wherein the or each abutment comprises a block.

12. A masonry support system according to Claim 11 wherein the or each abutment comprises a hook.

13. A masonry support system according to any preceding claim wherein the masonry support plate is planar.

14. A masonry support system according to any one of Claims 1 to 12 wherein the masonry support plate comprises one flange of a rigid angle section such as a cold formed angle.

15. A masonry support system according to any preceding claim wherein the washer plate has parallel upper and lower edges.

16. A masonry support system according to Claim 15 wherein the oblique opening in the washer plate is closer to one of said upper and lower edges than to the other.

17. A masonry support system according to any preceding claim wherein the oblique opening in the washer plate is inclined at an angle of approximately 150 to the parallel upper and lower edges of the washer plate.

18. A masonry support system wherein a plurality of brackets are rigidly secured to the masonry support plate at positions along its length.

19. A masonry support system according to Claim 14 wherein a plurality of generally triangular gussets are secured within the angle of said rigid angle section.

20. A masonry support system according to Claim 19 wherein the gussets are of an area less than the enclosed area of the rigid angle section.

21. A masonry support system according to Claim 20 wherein the maximum horizontal extent of the gusset is less than one half of the width of the horizontal limb of the angle.

22. A masonry support system according to Claim 21 wherein said maximum horizontal extent is approximately one third of the width of the horizontal limb of the angle.

23. A masonry support system according to Claim 2 and Claim 19 wherein the gussets are provided in pairs, welded to the rigid angle section at positions corresponding to the positions of securement of the walls of a channel section bracket.

24. A masonry support system substantially as hereinbefore described with reference to and as illustrated in Figures 1 to 5 of the accompanying drawings.

25. A masonry support system substantially as hereinbefore described with reference to and as illustrated in Figures 6 to 8 of the accompanying drawings.