Patent Publication Number: US-2011072751-A1

Title: Masonry bracket, system and construction method

Description:
FIELD OF THE INVENTION 
     The present invention concerns reinforcing devices for masonry walls. In particular, the reinforcing devices are brackets transferring stress such as shear forces between masonry courses. The brackets in the present invention are intended to be used in masonry walls comprising reinforcement. 
     RELATED ART 
     In large buildings, masonry block walls are typically used as an infill for a load bearing framework. The load-bearing framework generally comprises a number of load-bearing steel and/or concrete columns and beams, between which panels of masonry blockwork are formed. Larger spans of masonry wall between the load-bearing columns, or walls with openings (e.g. for doors or windows) are more susceptible to forces perpendicular to the plane of the wall such as those exerted by wind. Excessive forces may cause failures in the structural integrity of the wall which can result in cracking or failure. 
     It is therefore desirable to introduce reinforcing elements that have the effect of subdividing the masonry wall panel in to smaller sub panels and also transferring wind forces, transverse pressure differences, impacts or similar lateral loads to the load bearing framework. One common method of approaching this problem is to install vertical steel windposts within the masonry wall panel at intermediate points between the load-bearing columns. Such windposts typically extend from the bottom to the top of the masonry wall with a head portion and a foot portion secured to the beams or concrete floor slab/soffit of the framework. Windposts are typically large and cumbersome in nature making them difficult to install. Because of their cumbersome nature, windposts are also difficult to handle and are not desirable from a health and safety standpoint, where good practice and/or regulations require that building components carried by hand be of particular maximum manageable weights, typically 20 kg or less. Windposts are also expensive, have significant procurement lead in times, and after installation, quite often require further treatment to enhance their aesthetic, fire resistance, thermal insulation and/or acoustic properties. 
     Another method of subdividing a masonry wall panel into sub panels is to provide a horizontal reinforced concrete beam (known as a bond beam) that extends between and connects to adjacent load-bearing columns. Such bond beams are referred to in patent document GB2442543. The bond beam is typically housed within a hollowed masonry course within the masonry wall and is reinforced by one or more reinforcing bars (“rebars”) cast into the concrete. At least some of the hollowed masonry blocks may have a hole in the bottom that allows a masonry course connecting member to be driven into a perpend of a masonry course immediately below. The connecting member allows shear forces to be transferred between the courses concerned, effectively tying adjacent courses to the bond beam course, further enhancing the strength and cracking resistance of the masonry panel as a whole. 
     Once the rebar and connecting members are in place the hollowed masonry course is typically filled with concrete to form the bond beam. In such a bond beam, the quantity and location of the rebars is critical to the strength and bending moment resistance of the bond beam itself, and hence the characteristic design load of the wall. Several devices exist that can be used to locate a rebar within a concrete casting at one or more specific positions. 
     One such device is described in patent document U.S. Pat. No. 6,629,394 which discloses a rebar hanger for suspending rebars comprising a form hook for hooking on top of a concrete form, a first rebar hook for supporting a first rebar that extends away from the lower end of an inner section of the form hook and a second rebar hook for supporting a second rebar that extends downwardly and inwardly from the inner end of a brace. 
     Another such device is described in patent document U.S. Pat. No. 5,907,939 which discloses a reinforcing bar hanger comprising a pair of supporting arms contacting a supporting block and vertically extending hanger members terminating in a rebar cradle for receiving and supporting a rebar to be positioned within the wall. 
     Alternatively for short spanning walls, the rebar can simply be positioned within cleats or similar securing brackets fixed to the load-bearing columns or within suitably sized holes formed in the supporting load bearing column Either method would provide sufficient transfer of transverse forces between the rebar and the load bearing columns. The rebar can also be positioned by casting the bond beam in stages such that a bed of concrete or similar is placed to the appropriate height within the hollow of the block before placing the rebar. However this is more labour intensive and time consuming than casting the bond beam in a single pour. It may also introduce structural weaknesses into the bond beam if the separately cast sections do not fully knit together, or the rebar is moved laterally whilst the next layer of concrete is being placed and vibrated. 
     SUMMARY OF THE INVENTION 
     The present invention provides a masonry wall reinforcing bracket comprising an elongate inter-course stress transfer member, the stress transfer member comprising a rebar cradling feature. The stress transfer member may comprise a plate operative to be located within at least a perpend of a masonry wall. The stress transfer member may act for example to transfer shear stress between a bond beam and adjacent masonry courses, or to transfer stress between a bond beam and a vertically extending reinforcing structure built into the wall. 
     The bracket may further comprise a supporting member that protrudes perpendicularly to the length of the stress transfer member. The supporting member may comprise a plate operative to be located within a bed joint of the masonry wall. The supporting member may be a stabilising foot. 
     The present invention further provides a masonry wall tie bracket comprising: a rebar cradling feature for accommodating a rebar; and, an adaptor configured to secure the bracket to an elongate reinforcing member. Typically the adaptor may comprise a socket for receiving an end of a vertical rebar or a spigot for inserting into the top of a pillar within the masonry wall. The pillar may be a steel column of any suitable section, such as a box section or other tubular or I or U section or solid. 
     Other preferred features of the present invention are as set out in the dependent claims. Illustrative embodiments of the invention are described below with reference to the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1   a  to  1   e  show a bracket embodying the present invention, the bracket being shown in relation to the surrounding masonry blockwork, rebars and rebar end securing cleats. 
         FIG. 2  shows another form of bracket embodying the present invention. 
         FIGS. 3 and 3   a  show further brackets embodying the present invention where the brackets comprise cradling features located in different masonry courses. 
         FIGS. 3   b  and  3   c  are front and side views respectively of a yet further bracket; 
         FIG. 4  shows a cleat which may be used together with the masonry wall reinforcing brackets of the present invention. 
         FIGS. 5 and 6  are respectively front and side views of a cleat mounting adaptor that may be used together with brackets embodying the invention. 
         FIGS. 7   a  and  7   b  are side and front views respectively of a tie bracket of the present invention 
         FIG. 7   c  is a vertical rebar cleat according to one aspect of the present invention 
         FIGS. 8   a  and  8   b  show a vertical rebar being mounted into the tie bracket and cleat of  FIGS. 7   a - 7   c.    
         FIGS. 9   a  and  9   b  show another tie bracket of the present invention. 
         FIG. 10  shows the tie bracket of  FIGS. 9   a  and  9   b  being inserted into a vertical reinforcement post. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1   a - 1   e , the present invention provides a masonry wall reinforcing bracket  2  comprising an elongate stress transfer member  4  adapted and configured to extend between at least two courses  30  of masonry in use. The stress transfer member  4  further comprises one or more rebar cradling features  6 . The cradling feature  6  is operative to support and locate a rebar  8  within a masonry wall  10 , e.g. to allow it to be cast into a bond beam  12  formed within a course of hollowed masonry units  14 . The bracket  2  is formed from a material that is stronger in tension and shear compared to the bond beam matrix material (i.e. concrete, usually) and mortar. Such a bracket  2  material could be steel or another metal, or a metallic or non metallic composite material. 
     As shown, the stress transfer member  4  extends between at least two immediately adjacent masonry courses  30 , but it may in principle extend through any number of masonry courses  30 . In use the stress transfer member may extend outwards to one side of the bond beam only. For example, a series of brackets may be provided extending from the bond beam into the adjacent masonry course alternately above and below. Alternatively, a central portion of the bracket may be embedded in the bond beam in use, with end portions projecting into adjacent masonry courses above and below the bond beam. The projecting portions may be symmetrically or asymmetrically disposed with respect to the reinforced concrete core of the bond beam. By having the stress transfer member  4  extending between adjacent masonry courses  30 , shear forces applied to the wall  10  may be transferred between masonry courses  30  and more effectively between the masonry and the bond beam, to mitigate cracking and masonry course  30  separation, ultimately dividing the wall  10  into sub-panels and increasing the characteristic design load of the wall  10 . 
     Typically a masonry wall  10  is formed with bonded masonry whereby the perpends  22  between masonry units in one course  30  are offset horizontally from equivalent perpends  22  in the adjacent masonry course  30 . The stess transfer member  4  of the bracket  2  in the present invention extends at least into a perpend  22  or a specially formed hole  16  in one masonry course  30  and at least partially into a hollowed block  14  of an adjacent masonry course  30 . The bracket  2  and hollowed masonry block  14  form part of a combined masonry system. The hollowed block  14  typically comprises a hole  16  in its base through which the stress transfer member  4  extends to protrude into the cavity  18  of the hollowed masonry block  14  from below, as the hollow block is laid and afterwards. The open top of the cavity  18  allows the bracket to extend from within the hollowed block into the masonry course above. The part of the stress transfer member  4  extending into the cavity  18  of the hollowed masonry block  14  comprises one or more rebar cradling features  6 . 
     Once the stress transfer member  4  protrudes into the cavity  18 , a rebar  8  may then be located within the rebar cradling feature  6 . The present invention therefore provides a combined rebar cradling feature  6  and inter-masonry course stress transfer mechanism integrated into a single bracket  2 . Personnel building a masonry wall  10  reinforced by a rebar  8  therefore only have to incorporate into the masonry wall  10  a single bracket  2  in order to facilitate rebar  8  positioning and stress transfer between adjacent masonry courses  30 . By having a single bracket  2  performing the functions of rebar cradling and stress transfer, the build time of a shear strengthened (or otherwise strengthened) masonry wall  10  and the number of building components required to form the wall  10  is reduced, which reduces overall building costs. 
     Typically, hollowed masonry blocks  14  are used to form part of a hollowed masonry course which houses one or more rebars  8  supported by one or more rebar cradling features  6  on one or more brackets  2  embodying the present invention. The brackets  2  are typically distributed horizontally at the same vertical level along the length of the wall  10 , but may also be distributed at other locations throughout the wall  10 . The rebar  8  typically extends the full horizontal length of the masonry wall panel and connects to the end load-bearing columns  20  using one or more cleats  26  (see  FIG. 4 ). Because the rebar  8  and stress transfer member  4  are mechanically linked, transverse forces applied to the masonry panel are distributed through masonry courses  30  linked by the stress transfer member/s  4  to the rebar  8 . 
     The bracket  2  may also comprise a supporting member  28 . Preferably the supporting member  28  protrudes perpendicularly to the length of the stress transfer member  4  and is typically intended to be located within a bed joint  24  of the masonry wall  10 . Such a supporting member  28  when located in a bed joint  24  provides a height alignment reference for the bracket  2 , and preferably acts as a foot for easy placement, support and lateral positioning of the bracket on top of an existing course  30  of blocks, immediately before the bracket is built into the blockwork. The foot  28  rests on the bed joint  24  below, and the stress transfer member can be propped against the exposed header face of the most recently laid block, preferably being pressed into pre-applied mortar (see  FIG. 1   a ). When the bracket  2  is in position, the one or more rebar cradling features  6  are located in alignment and at the correct uniform spacing from the bases of the hollowed masonry units  14  to support the one or more rebars  8  ( FIG. 1   c ). Since any further brackets  2  along the length of the masonry wall  10  may also locate their supporting members  28  in the same bed joint  24 , all the cradling features  6  may be vertically aligned with respect to one another providing a constant level distributed supporting platform for the one or more rebars  8 . 
     Preferably the supporting member  28  and/or the stress transfer member  4  may take the form of plates that correspondingly allow the supporting member  28  to be accommodated within a bed joint  24 , and the stress transfer member  4  to be accommodated within a perpend  22  of a masonry wall  10 . The bracket  2  may be formed from a single sheet or strip of material thus allowing multiple brackets  2  to be made in a simple manufacturing process. 
     The bracket  2  also preferably comprises one or more apertures  32  in the stress transfer member  4  and/or the supporting member  28  that operate to allow masonry block binding material to pass through the bracket  2 . By allowing masonry block binding material, typically mortar, to pass through the bracket  2 , the bracket  2  is anchored within the structure of the masonry wall  10 . 
     Masonry walls  10  may in certain circumstances require vertically extending reinforcement structures incorporated within or connected adjacent to the masonry walls  10 , for example, either side of a door or window to provide extra reinforcement around nominally weakened areas of the wall. Such structures are typically formed from steel or other metals or metal alloys. In principle, the vertical extending structures may take any form, but more typically take the form of vertical rebars  70  similar to the horizontal rebars  8  used in the aforementioned bond beam  12 , or vertical reinforcement pillars  78  typically formed from a hollow metal tubing. It is desirable in masonry walls  10  to mechanically tie in and link the horizontal rebars  8  (thus the one or more bond beams  12 ) of a masonry wall  10  to the vertical reinforcement structures in order to distribute the shear forces acting upon one localised part of the wall to other parts of the wall  10 . The present invention therefore further provides a masonry wall tie bracket  62  comprising a first portion  64  with a rebar cradling feature  6  for accommodating a rebar  8  and a second portion with an adaptor  66  configured to secure the bracket  62  to an elongate reinforcing member. The tie bracket  62  may transversely interlink and mechanically couple the horizontal rebars in the bond beam to one or more elongate vertical reinforcement structures/members, although in principle the adaptor  66  may be configured to secure the bracket  62  to other elongate reinforcing structures that are not vertical. 
     The following are illustrative examples of the present invention. The features and methods of any example or embodiment may be used in any compatible combination or permutation with those of any other example or embodiment described throughout this document. 
     The first example is a bracket  2  as shown in  FIGS. 1   a - 1   e  for use in a bonded masonry wall  10 . The bracket  2  in this example comprises a supporting member  28  wherein the supporting member  28  is a stabilising foot attached to the bottom end of the stress transfer member  4 . The stress transfer member  4  and the stabilising foot of the bracket  2  in this example are respective limbs of a steel strip that has been bent into an L shape. Both the foot and the transfer member  4  comprise apertures  32  allowing masonry block binding material to pass through the bracket  2 . It is however envisaged that the foot or transfer member  4  of the bracket  2  may equally not comprise such apertures  32  in this example. 
     The foot is located in a bed joint  24  beneath a first ‘bottom’ masonry course  30 . When the bottom masonry course  30  is being formed, the bracket  2  is placed within the next perpend  22  due to be formed between an existing laid block of the bottom masonry course  30  and the next adjacent block of the course  30  due to be laid. The foot therefore serves in use to allow the bracket  2  to stand or be propped against the most recently laid block whilst the next block of the bottom masonry course  30  is being laid. 
     When the bracket  2  is placed in this manner it is fully surrounded and intimately embedded within the masonry block binding material. This is in contrast to the prior art which requires the stress transfer member to be driven down into a perpend  22  of the masonry course  30  below. Driving a member down into an already laid binding material is undesirable as, for example, anchoring holes or indentations formed in the member are not guaranteed to be completely filled by the binding material due to the possible formation of air gaps resulting from the driving action. Air gaps weaken the perpend  22  as well as weakening the mechanical bond between the stress transfer member and the binding material. The problem is exacerbated by the fact that the binding material in the perpends  22  may have already set or cured to an undesirable extent at the time the brackets are driven into the perpends  22 . This means that there cannot be any substantial delay between laying the course  30  containing these perpends  22 , laying the course  30  of hollowed masonry units  14  and driving in the stress transfer members  4 . The same problem does not arise with the reinforcing bracket  2  illustrated in this example, which can be built into the bottom course  30  at any time prior to laying of the bond beam course  12 , without adverse effect. 
     The stress transfer member  4  extends completely across the full depth of the masonry blocks of the bottom masonry course  30  and resides within a perpend  22  existing between two blocks of the bottom course  30 . The foot is accommodated in the bed joint  24  underneath a block of the bottom course  30 . 
     The stress transfer member  4  of the bracket  2  further extends upwards into a second or ‘bond beam’ course  12  of the bonded masonry wall  10 . The bond beam course  12  is formed of hollowed masonry blocks  14  laid on top of the bottom course  30  with a further bed joint  24  in between. When the wall  10  around the bracket  2  is complete the foot acts to hold the bottom course  30  to the bond beam course  12  and any other subsequent laid course  30  mechanically linked by the stress transfer member  4 . 
     The stress transfer member  4  protrudes through an aperture  16  in the base of a hollowed block  14  of the bond beam course  12  and into the cavity  18  formed from the hollowed centre of the hollowed block  14 . The part of the stress transfer member  4  that protrudes into the cavity  18  of the hollowed block  14  comprises two rebar cradling features  6 . The stress transfer member  4  of the bracket  2 , in this example, also protrudes into the perpend  22  of a course  30  immediately above the hollowed masonry course  14 , although it is entirely feasible that a stress transfer member  4  may in principle vertically extend through any number of adjacently laid masonry courses  30 . 
     Each rebar cradling feature  6  may be an inwardly recessed slot  34  with an opening along a long edge  38  of the stress transfer member  4 . Each slot  34  may further comprise a retaining lip  36  serving to provide confinement of the rebar  8  in directions traverse to the wall  10 . Each slot  34  is sized such that a rebar  8  may enter the slot  34  and pass over the retaining lip  36  into a retaining section of the slot  34 . The slots  34  in this example are open into opposing long edges  38  of the stress transfer member  4  and are separated vertically along the length of the stress transfer member  4 . Thus in this example the bracket  2  acts to cradle two rebars  8 . Each slot  34  comprises a stopping edge  40  at the inner end of the slot  34  opposite to the retaining lip  36  and opening. The stopping edges  40  of the two slots  34  in this example therefore face in opposing directions. 
     Once both rebars  8  are located in the cradle features of the stress transfer member  4 , the hollowed block  14  may be filled with a suitable material (e.g. concrete or similar cementitious material) to solidify in the hollowed block  14 , cement the rebar  8  and bracket  2  in place, and form a compression resistant matrix in which the rebars and mid-portions of the brackets are embedded. The cradling features  6  are located relative to the supporting member  28  so that the rebars  8  are positioned at the correct location within the hollow of the bond beam course  14  as required according to the design of the finished bond beam. 
     The bracket  2  in this example is made from steel strip or sheet steel cut to an elongate rectangular shape. The foot is formed by simply bending the rectangle or strip at one end to make an L shape. By having the foot and stress transfer member  4  of the bracket  2  formed from the same piece of steel, the bracket  2  may be formed cheaply and simply. Typically the steel has a thickness between 3 to 4 mm. The width of the bracket  2  is ideally not wider than the plan width of the masonry blocks so that when the bracket  2  is introduced into the masonry wall  10  structure it is hidden from the outside. Preferably the material of the bracket  2  does not occupy an excessive proportion of the perpend  22  horizontal cross-section, so that sufficient binding material is present to form a strong mechanical bond with the bracket  2 , and/or so that the bracket  2  does not form a significant plane of weakness in the perpend  22 . At least the part of the stress transfer member  4  that extends through the hollowed block base aperture  16  has a width that allows a rebar  8  to be slid down between the inner sides of the hollowed block  14  and the outer edge  38  of the shear transfer member  4  into the recessed slot opening/s. 
     The foot in this example protrudes outwardly from the stress transfer member  4  in a single direction. This provides a clearly identifiable directional alignment feature to the bracket  2 . When bricklayers are placing subsequent brackets  2  further along a masonry course  30 , they may simply align the feet in the same direction as the previously placed brackets  2  such that the equivalent cradling slots  34  are correctly aligned vertically and horizontally with respect to each other, with corresponding slots all facing in the same direction. 
     Typically the widths of the foot and stress transfer member  4  are between 30 to 60 mm, preferably 40 mm. The length of the stress transfer member  4  is typically 500 to 700 mm, preferably 610 mm and the length of the foot is typically between 40 to 100 mm, preferably 70 mm. 
     Following from the first example is a second example embodying the present invention as shown in  FIG. 2 . Instead of a stabilising foot, the bracket  2  comprises one or more perpendicularly protruding supporting members  28  along its length, spaced from the ends of the stress transfer member  4 . 
     The supporting members  28  in the second example are intended to be accommodated within a masonry wall bed joint  24 . Similarly to the first example, the supporting members  28  in the second example provide height reference to the bracket  2 , which gives corresponding height reference to the at least one rebar  8  located in the supporting cradles  6  of the bracket  2 . 
     Following from the previous examples is a third example embodying the present invention as shown in  FIG. 3 . In this example, brackets  2  (not shown) similar to those of the first example are utilised within the masonry wall  10 . Some of the brackets in this example are extended length brackets  3  that comprise stress transfer members  4  that extend into two hollowed masonry block courses  14 . The stress transfer members  4  of these extended length brackets  3  comprise at least two sets of rebar cradling features  6  (two sets of one bar each, as shown), each cradling set located at different positions along the length of the shear transfer member  4  to coincide with the cavities of the separate hollowed masonry block courses  14 . Thus the extended length brackets  3  are intended to engage with two sets of one or more rebars  8 , each rebar  8  set being disposed within a different hollowed masonry course  14 . 
     Such an extended length bracket  3  provides stress transferring mechanical connection between two sets of one or more rebars  8 . Such a bracket  3  may be useful for interconnecting rebars  8  running at different height levels, for example, when one set of rebars  8  cannot extend fully between adjacent load-bearing columns  20  due to the presence of an opening  42  in the masonry wall  10  such as a door or a window. The extended length bracket  3  thus provides a means to interlink one or more rebars  8  running at height levels not horizontally inline with the wall opening  42  to one or more rebars  8  interrupted by the opening  42 .  FIG. 3   a  shows another extended length bracket  3  with two sets A, B of rebar cradling features  6  and two cradling features in each set. This can be used for example to form a stress transfer connection between two bond beams positioned one above the other, each bond beam comprising two rebars. Parallel bond beams such as this may be used for example to support cantilevered loads attached to a wall, with load supporting frames or brackets spanning between and anchored to the bond beams. Of course, other numbers of sets of rebar cradling features and other numbers of rebar cradling features within each set can be provided as desired and to suit different purposes as required. 
       FIGS. 3   b  and  3   c  show another form of bracket  2   a  for use where the bond beam is to be tied into adjacent blockwork for stress transfer on one side only, e.g. where the bond beam forms a lintel above an opening such as for a window or door. The stress transfer member  4  is made shorter than that shown in  FIGS. 1   a - 1   e  and the rebar cradling features  6  are positioned relative to the foot  8  so that the foot  8  rests on the floor of the cavity  18  in the hollowed blocks so as to position the rebar cradling features at the correct height. The upper end of the stress transfer member  4  therefore extends into the course above, similarly to the example of  FIGS. 1   a - 1   e , but no part of the bracket  2   a  extends downwardly of the bond beam. To prevent the foot  8  of the bracket  2   a  from being incorrectly built into a bed joint in the manner of the bracket  2  (instead of resting on the base of the cavity  18  as intended) the end of the foot is split into two parts with one part  8   b  being angled upwardly with respect to the other part  8   b . The tips of the parts  8   a ,  8   b  are separated by a distance (e.g. 20 mm) greater than the mortar joint thickness (which is typically 10 mm). The foot is therefore too wide to be built into a mortar joint. 
     In any of the previous examples there may also be included a cleat  26  which mechanically joins an end of a rebar  8  to a load bearing column  20  (see  FIGS. 1   e  and  4 ). The cleat  26  comprises a backplate  44  from which at least one rebar securing feature  46  protrudes outwardly and acts as a pocket to securably house the end section of a rebar  8 . 
     A typical cleat rebar securing feature  46  would be a cylindrical tube as shown in  FIG. 4 . The rebar is a sliding fit within the tube to allow longitudinal movement of the rebar, e.g. to accommodate thermal movement or shrinkage of the blockwork infill in the load bearing framework. Instead of the column  20 , the baseplate may be secured by suitable fasteners to any other suitable load bearing structure, for example to provide a bond beam reinforced masonry infill similar to those described in our UK patent specification nos. 2440531 and 2442543. 
     The back plate of the cleat  26 , may have a hole  48  formed in line with the bore of the tube. The back plate hole  48  is sized such that the rebar  8  to be housed in the securing feature  46  may pass through the hole  48 . In this manner, the entire cleat  26  may be fed over the rebar  8 . Because the rebar  8  may pass all the way through the cleat  26 , the back plate of the cleat  26  does not hinder the placement of the rebar  8  when being maneuvered into its final operating position. Once the rebar  8  is located into its final operating position, the cleat  26  may then brought into contact and secured to the load bearing columns  20 . The securing feature  46  of the cleat  26  protrudes outwardly from the back plate into the masonry wall  10  to an extent that it can secure the rebar  8  once the cleat  26  is secured to the column  20  and the rebar  8  is in its final operative position. 
     A similar hole  50  may also be formed in the load bearing column  20  coinciding with the position of the back plate hole  48  to further facilitate lateral movement of the rebar  8  when the rebar  8  is being placed into its final operative position. This is advantageous, for example, when a cleat  26  is already fixed to the load bearing column  20  before the rebar  8  is in its final operative position. In this manner, the cleat  26  and column  20  form a cleating system. 
     Alternatively, the rebar can be provided in at least two separate lengths. An end of each length can be poked into a respective cleat pocket without the need to form a hole in the back plate  44  or in the column  20 . The rebar ends are poked almost fully home, merely leaving a suitable clearance between the rebar end and the base of the pocket to allow for the anticipated relative movement. The remainder of the rebars can then be manoeuvred into the bracket cradling features  6 , e.g. over the retaining lips  36  and into the retaining sections of the slots  34 . The lengths of the rebar sections are such that their free ends overlap in this position. The overlapping ends can be secured together by wire ties or the like, to hold them in the correct position whilst the bond beam concrete is poured, compacted and cured in the hollowed masonry block course  14 . The length of the overlap is made sufficient so that tensile stress in one section of reinforcement can be transmitted via shear stress at the interface to the surrounding cementitious matrix and then to the next section of reinforcement, without shear failure occurring between the matrix and the reinforcement ends (i.e. without the reinforcement ends pulling out of the cured cementitious mix). The length of overlap may be as specified in local building codes. For example 50× rebar diameter may be typical. The overlapping section is preferably placed away from regions of maximum rebar tensile stress, e.g. away from the region of maximum bending moment in the bond beam. Thus a rebar end overlap in the central region of its span should preferably be avoided in the case of a bond beam spanning a continuous blockwork infill wall subject to a uniform pressure difference between its inner and outer faces. Similarly the overlap should preferably be placed away from stress concentrations arising from nearby discontinuities in the blockwork such as those caused by openings in the blockwork. The overlap can be accommodated in the space between adjacent brackets, so that specially modified bracket rebar cradling feature/slot profiles are not needed. 
       FIGS. 5 and 6  show a mounting adaptor  52  for a cleat which in turn receives rebar ends. Thus the cleat may be as shown schematically in  FIG. 4 . Preferably the cleat is of the kind for receiving a pair of rebar ends one above the other; generally as shown in our UK patent no. 2442543. The cleat mounting holes  18 ,  23  shown in that patent may be elongated transversely of the base plate rather than being generally circular as shown. This allows for increased adjustability when fixing the cleat to a load bearing structure. The adaptor  52  has a base plate  54  with four mounting holes  58  as shown, for receiving fasteners suitable for securing the adaptor to a load bearing structure. These fasteners may be, for example, bolts in the case of a steel structure or expansion bolts in the case of a reinforced concrete load bearing pillar or wall slab. The mounting holes  58  are elongated longitudinally of the base plate, to permit height adjustment of the adaptor. 
     The mounting adaptor  52  further comprises a cleat receiving flange  56  welded to and extending perpendicularly from the base plate  54  at its longitudinal midline. The cleat receiving flange  56  has a pair of horizontally elongated mounting holes  60  suitably spaced to receive fasteners (e.g. nuts and bolts) for securing the cleat to it. Therefore the mounting adapter  52  allows a bond beam containing blockwork wall to be built alongside and secured to a load bearing structure such as a pillar, column or wall slab; ends of the bond beam rebars being secured to the load bearing structure via the cleat and mounting adaptor. Where the blockwork wall continues away from the load bearing structure in either direction, a pair of cleats may be mounted back-to-back on either side of the receiving flange  52 . These can thus receive rebars of a pair of bond beams aligned end-to-end. This contrasts with a masonry infill secured to a load bearing structure to which the cleat is directly mounted, in which the infill is in line with the load bearing structure, rather than to one side of it. The cleat and mounting adaptor can be combined into a unitary welded assembly, for example with tubular cleat pockets welded directly to one or both sides of the receiving flange  56 . 
       FIGS. 7   a  and  7   b  show an example of a tie bracket  62  of the present invention comprising a first elongated portion  64  similar to the stress transfer member  4  shown in  FIGS. 1   a - e ,  3  and  3   a . The first portion  64  comprises one or more rebar cradling features  6  similar to those described above and shown in  FIGS. 1   a - e ,  3  and  3   a , except that the retaining lip  36  is located at the top of the slot  34  so that the tie bracket  62  hangs from the one or more horizontal rebars as shown in  FIGS. 8   a  and  8   b . The tie bracket  62  also comprises a second elongated portion that acts as an adaptor  66  configured to secure the bracket  62  to an elongate reinforcing member. The adaptor  66  is nominally disposed beneath the first portion, and acts as a socket to sit on top of and house a vertical rebar  70  as shown in  FIGS. 8   a  and  8   b . In principle, however the cradle retaining lip  36  may be located at the bottom of the slot  34  and/or the adaptor  66  may extend upward from the first portion to house the bottom of a vertical rebar. Typically the tie bracket  62  is formed from a rigid material such as steel or other metal. 
     The adaptor  66  as shown in  FIGS. 7   a - b  and  8   a - b  comprises a cylindrical tube adaptor with a cylindrical hole  68  with a closed top end and an open bottom end. The bottom end opening of the tube and the internal diameter of the tube are sized to accommodate a vertical rebar  70  so that the adaptor  66  can be slid on to the vertical rebar  70  and form a tight (close sliding) fit. When the tie bracket  62  has been located on to the vertical rebar  70 , the first portion  64  comprising the rebar cradling features  6  stands proud from the top end of the vertical rebar  70 . In principle however, the tubular adaptor  66  may be formed from any suitable rigid material and may be of any cross-sectional shape that fits a vertical rebar  70 . A cylindrical vertical rebar  70  and a cylindrical tubular adaptor have the advantage that once the adaptor is located upon the rebar, the tie bracket  62  can be rotated about the longitudinal axis of the vertical rebar  70 . Having the tie bracket  62  rotatable about the rebar  70  and a generally flat transverse cross-section to the first portion, allows a person building the masonry wall  10  to lay the masonry bond beam blocks and locate the horizontal rebars  8  in position with the long dimensions of the tie bracket  62  transverse cross-sections initially aligned longitudinally of the bond beam cavity  18 , for ease of positioning the horizontal rebars  8 . Once the horizontal rebars  8  are in position, each tie bracket  62  is then simply rotated so that the rebar cradling features  6  can hook over and hang the tie bracket  62  off the horizontal rebars  8 . 
     Similarly to the brackets described previously, the first  64  and/or second portion of the tie bracket  62  may also comprise one or more apertures  32  that operate to allow masonry block binding/filling material to pass through the tie bracket  62  and thus anchor the tie bracket  62  within the structure of the masonry wall  10  and to the vertical rebar  70 . Once the tie brackets  62  have been rotated into position over the horizontal rebars  8  as described above, they are preferably shaken, vibrated or tapped downwardly to ensure close engagement with the horizontal rebars  8  and penetration of the binding/filling material such as wet concrete into the bracket apertures  32 . 
     The present invention also provides a vertical rebar cleat  72  which is shown in  FIG. 7   c . The cleat  72  comprises a base plate  74  typically with fixing holes and an outwardly extending tubular portion  76 . The tubular portion  76  is similar to that of the adaptor  66  of the tie bracket  62  and protrudes outwardly normal from the plane of the base plate. The tubular portion of the vertical rebar cleat  72  comprises cylindrical hole  68  that is sized to accept and closely fit a vertical rebar  70 . Typically, the cleat  72  is placed upon and affixed to a horizontal supporting structure that supports the masonry wall. Preferably the vertical rebar cleat  72  is sized in the plane of the base plate  74  to allow the cleat  72  to be fully accommodated within a vertical through-hole made within a masonry block. When used in a preferred method of constructing a masonry wall, the cleat  72  is positioned so that the vertical through hole of a block in the first course of masonry block work sits over and surrounds the cleat  72 . A vertical rebar  70  is then inserted into the tubular portion  76  of the vertical rebar cleat. Successive masonry block courses are then subsequently formed over the first masonry course, wherein the masonry block of each masonry course immediately above the rebar  70  comprises a through hole to accommodate the vertical rebar  70 . 
     For masonry walls  10  where the one or more horizontal bond beams  12  are to be formed within courses not immediately adjacent to the bottom masonry block course, several vertical rebars  70  may be required to be tied together to form a composite vertical rebar extending up to and into the bond beam masonry block course. Tying together several shorter rebars  70  rather than having a single long vertical rebar  70  extending over multiple masonry block courses is advantageous because a person building the masonry wall with a single long vertical rebar  70  will have difficulty sliding the masonry blocks with the vertical through holes over the rebar  70 . The blocks would need to be lifted up and over the vertical rebar  70  so that the vertical though hole of the block accommodated the rebar  70 . By successively tying one or more shorter vertical rebars  70  together, for example no longer than the depth of 2 masonry courses, the person laying the masonry courses can place the blocks with the vertical through holes over the shortened vertical rebar  70  in a simpler manner and then, once the masonry block is in place, tie another vertical rebar  70  to the existing rebar  70  so that the rebar  70  is extended on a progressive course by course basis. 
     Vertical rebars  70  may be tied together via a number of methods including simple tying using one or more wires or clips to form an overlap joint complying with accepted building regulations or practice, or by using joining brackets with two or more connected rebar accommodating tubular portions, similar to the adaptor  66  of the tie bracket  62  in  FIGS. 7   a - b . The tubular portions of such joining brackets may either be located end on or adjacent to each other, each tubular portion having respective open and closed ends in opposite configuration to the other tubular option so that the joining bracket may accommodate rebars  70  inserted into the joining bracket from opposite directions. 
     In a preferred method of constructing a masonry wall  10  with one or more horizontal rebars  8  and one or more vertical rebars  70 , the masonry wall  10  is nominally built course by course as described above. In each course, the masonry block/s in-line with the vertical rebars are threaded over the vertical rebars so that the rebars protrude through the vertical though holes of the blocks. Once the block is laid and the vertical rebars protrude through the through hole, other vertical rebars may be secured to the existing vertical rebars to form a composite extended rebar as described above. When the masonry blocks accommodating the vertical rebars are in place and any required vertical rebar extensions are attached, the block may be filled or bonded in accordance with the general construction of the masonry course. For the adjacent masonry course  30  immediately below the intended bond beam course  12 , the vertical rebars  70  protruding into the course are designed or cut to end beneath the start of the subsequent bond beam course  12 . Preferably the top end of the vertical rebars  70  stop within the block of the masonry course but may in principle extend into the bed joint  24 . The adaptors  66  of the tie brackets  62  are then placed upon the end of the vertical rebars  70  so that the tie brackets  62  securably engage the vertical rebars  70  such that the first portions  64  of the tie brackets  62  protrude into where the next bond beam masonry course is to be laid. As stated above, preferably the long dimension transverse cross-section of the tie brackets  62  are initially aligned longitudinally of the bond beam cavity  18 . Once the adjacent masonry course below the bond beam course  12  is finished, the hollowed masonry blocks  16  of the bond beam course  12  are laid upon a bed joint  24 , together with any other shear transfer brackets  2  according to the present invention as described above. The hollowed masonry blocks  16  of the bond beam course are as described above and preferably comprise a U-shaped longitudinal cavity. The masonry blocks immediately above the tie brackets  62  comprise a vertical through hole sized to accept and allow the tie brackets  62  to protrude through the through hole into the cavity of the U-shaped masonry blocks  14 . The vertical through hole may be similar to the hole  16  in the base of the hollowed masonry block  14  as described above, or any other suitable hole such as one formed by removing a portion of the base at one end of a hollowed masonry block  14 . Where the vertical rebars extend upwardly from the bond beam, the open tops of the U-blocks allow the brackets  62  to pass upwardly from the bond beam space directly into the hollow block interiors in the course above. Alternatively the tie brackets  62  may be fitted onto the vertical rebars  70  after the hollowed masonry blocks  14  of the bond beam course have been put in place. Once all of the masonry blocks of the bond beam course  12  are in position, the horizontal rebars  8  are located into the rebar cradling features  6  of the shear transfer brackets  2  and the rebar cradling features  6  of the tie bracket  62  are hooked onto the horizontal rebars  8  by lifting and rotating the tie bracket  62 . The vertical through holes of the hollowed masonry blocks  14  and corresponding blocks of the adjacent course below are then backfilled with wet concrete. The longitudinal U shaped cavity  18  formed by the hollowed masonry blocks  14  is then filled with concrete to form the completed bond beam  12 . 
       FIGS. 9   a  and  9   b  show another example of tie bracket  62  similar to the tie bracket  62  shown in  FIGS. 7   a - b  and  8   a - b . In this alternative version of the tie bracket  62 , the adaptor  66  is a spigot adapted to secure the tie bracket  62  to a vertical reinforcing post or pillar  78 . Similarly to the tie bracket  62  shown in  FIGS. 7   a - b  and  8   a - b , the first portion  64  of the tie bracket  62  shown in  FIGS. 9   a - b  and  10  comprises rebar cradling features  6  with retaining lips  36  at the top of the cradle  6  that operate to allow the tie bracket  62  to hang upon horizontal rebars  8 . In this example of a tie bracket  62 , the adaptor is configured to be located and housed within the hollow interior of a typically tubular vertical reinforcing pillar  78 , e.g. having a rectangular cross-section and a corresponding rectangular cross-sectioned inner hole. In principle however, a tie bracket  62  may be adapted to be placed over the pillar in a similar fashion as the tie bracket  62  in  FIG. 7   a - b . The adaptor of the tie bracket  62  in the example shown in  FIGS. 9   a - b , as further shown in  FIG. 10 , is inserted into the hollow interior of the vertical reinforcing pillar  78 . The tie bracket  62  may also comprise an at least partially circumferential stopping lip  80  with at least one cross-sectional dimension greater than a corresponding dimension of the pillar hole. The adaptor  66  of the tie bracket  62  is inserted into the pillar  78  until the stopping lip  80  comes into contact with the top of the pillar  78 . 
     Preferably, the cross sectional shape of the adaptor  66  may be made to fit into a variety of vertical reinforcing pillars  78 . Where the cross-section of the adaptor  66  does not form a close fit with the inner cross-section of the vertical pillar, spacing strips  82  may be attached to the adaptor  66  of the tie bracket  62  by welding or any other suitable fixing method so that the adaptor  66  forms a close fit with the inner hole of the vertical reinforcing pillar  78 . 
     A masonry wall  10  with one or more horizontal rebars  8  and vertical pillars  78  is constructed in a similar manner to the preferred construction method of a masonry wall  10  with vertical  70  and horizontal  8  rebars as detailed above. When constructing a wall  10  with horizontal rebars  8  and vertical pillars  78  the masonry blocks of each course must have vertical through holes sized to accommodate the vertical pillars  78 . The top ends of the pillars  78  finish below the hollowed blocks  14  of the bond beam  12  course, either in the course immediately beneath the bond beam  12  course or within the bed joint  24  between them. Each tie bracket  62  is fitted onto the end of its pillar  78  such that at least the first portions  64  of the tie brackets  62  protrude into the hollowed masonry blocks  14 . Preferably, only the first portions  64  of the tie brackets  62  protrude through into the hollowed masonry blocks  14  of the bond beam  12  course, the stopping lips  80  residing either in the bed joint  24  or within the vertical though hole of the adjacent masonry blocks below. 
     
       
         
           
               
            
               
                   
               
               
                 Table of referenced features. 
               
            
           
           
               
               
            
               
                 Reference 
                 Feature 
               
               
                   
               
            
           
           
               
               
            
               
                 2 
                 Bracket 
               
               
                 3 
                 Extended length bracket 
               
               
                 4 
                 Stress transfer member 
               
               
                 6 
                 Rebar cradling feature 
               
               
                 8 
                 Rebar 
               
               
                 10 
                 Masonry wall 
               
               
                 12 
                 Bond beam 
               
               
                 14 
                 Hollowed masonry block 
               
               
                 16 
                 Hole in the base of a masonry block 
               
               
                 18 
                 Cavity 
               
               
                 20 
                 Load bearing columns 
               
               
                 22 
                 Perpends 
               
               
                 24 
                 Bed joint 
               
               
                 26 
                 Cleat 
               
               
                 28 
                 Supporting member 
               
               
                 30 
                 Adjacent masonry courses 
               
               
                 32 
                 Apertures 
               
               
                 34 
                 Slot 
               
               
                 36 
                 Retaining lip 
               
               
                 38 
                 Opposing long edges 
               
               
                 40 
                 Stopping edges 
               
               
                 42 
                 Opening 
               
               
                 44 
                 Back plate 
               
               
                 46 
                 Rebar securing feature 
               
               
                 48 
                 Back plate hole 
               
               
                 50 
                 Hole in load bearing column 
               
               
                 52 
                 Mounting adaptor 
               
               
                 54 
                 Cleat base plate 
               
               
                 56 
                 Cleat receiving flange 
               
               
                 58 
                 Mounting holes 
               
               
                 60 
                 Elongate mounting holes 
               
               
                 62 
                 Tie bracket 
               
               
                 64 
                 Tie bracket first portion 
               
               
                 66 
                 Adaptor 
               
               
                 68 
                 Cylindrical hole 
               
               
                 70 
                 Vertical rebar 
               
               
                 72 
                 Vertical rebar cleat 
               
               
                 74 
                 Vertical rebar cleat base plate 
               
               
                 76 
                 Outwardly extending tubular portion 
               
               
                 78 
                 Vertical reinforcing post 
               
               
                 80 
                 Stopping lip 
               
               
                 82 
                 Spacing strips