Note: Descriptions are shown in the official language in which they were submitted.
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MASONRY WITH VERTICAL REINFORCED CONCRETE STRENGTHENING
Background
Current techniques for constructing larger buildings usually involve the use
of a load bearing
frame of steel or reinforced concrete, with attached cladding and/or masonry
infills. In the
case of masonry walls in such structures and elsewhere, it is necessary to
provide additional
strengthening where the area of the wall increases beyond certain limits. The
strengthening
is required to support the weight of the wall; to resist environmental loading
such as wind
forces, differences in air pressure and earthquakes; as well as to withstand
other dynamic
service loads such as crowd pressure, vehicle impact or explosions. The
required strength
for a given structure is governed not only by the laws of physics but also by
local building
regulations.
Traditionally where additional strength is needed, walls have been supported
by cross walls,
piers and areas of wall thickening. More recently windposts have been
developed, which are
used in most building walls (particularly interior walls), if their length
exceeds 4m. The
purpose of the windpost is to stiffen or strengthen the walling, in
circumstances of particular
lateral stress from wind induced pressure differences, crowd or other design
loads. A
windpost generally consists of a steel column secured at its top and base to
the building
frame or another suitable load-bearing structure. This form of construction
brings with it the
following disadvantages:
1. An expansion joint is required on either side of the windpost, where it
interfaces with
the adjacent masonry. Filler material is inserted between the post and the
masonry block
faces to form the joint.
2. Frame ties typically at 225mm centres must be provided between the masonry
and
the post on both sides.
3. Mastic will often be a specification requirement.
4. The windpost will require fire protection.
5. Loss of acoustic and thermal insulation.
6. The windpost typically requires four bolt fixings, two at the base and two
at the
soffit.
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7. The windpost must be erected before the walling and so isolated access
(e.g.
scaffolding) is required for safe work practice particularly at height.
Our invention seeks to replace the windpost and to achieve increased strength
and ductility
within the wall panel.
Summary of the Invention
According to the invention, there is provided a masonry infill in a load
bearing structure,
comprising hollow masonry units arranged to define a cavity extending through
adjacent
courses thereof, the cavity being filled with reinforced cementitious
material, a lower end of
the cementitious material reinforcement being secured to a load bearing
support; a body
being secured to the load bearing structure and receiving an upper end of the
cementitious
material reinforcement so as to permit longitudinal sliding movement of the
reinforcement
upper end in the body, whilst constraining movement of the reinforcement in a
direction
transversely of the infill.
The reinforced cementitious material strengthens the masonry infill against
transverse
loading/deflection and helps to secure the panel within the load bearing
structure. The
reinforced cementitious material (e.g. reinforced concrete) also helps to
transmit transverse
loads applied to the masonry to the load bearing structure above and the load
bearing
support below.
The load bearing support may be a foundation, or another part of the load
bearing structure,
for example a beam. The body may be secured to or within a beam which forms a
part of
the load bearing structure above or within the masonry infill.
On their exterior, the masonry course or courses containing the cementitious
material are
indistinguishable from the adjacent masonry. This can have aesthetic
advantages. The
reinforced cementitious material may be used instead of a wind post, without
requiring
expansion joints frame ties, mastic, fire protection, sound insulation or
dedicated isolated
access during construction.
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The reinforcing material may comprise steel bar (e.g. "rebar"). The optimum or
acceptable
relative section areas of the concrete and steel and the positioning of the
bars in the cavity
may be calculated in accordance with standard engineering principles for beams
and
columns subjected to point and/or distributed loading, taking into account
design service
conditions such as anticipated impact and wind loading, etc. The reinforced
cementitious
material will key to the interiors of the hollow blocks and their presence can
therefore be
taken into account when determining the size and position of the steel bars.
Allowance must
be made for any reduction in compressive strength caused by the presence of
any mortar
joints in the masonry. The masonry is preferably laid in mortar or like
bonding/bedding
material. Solid masonry units may be used in regions of the masonry infill
away from the
cavity.
In similar manner to the upper end, the lower end of the cementitious material
reinforcement
may be received in a body secured to the load bearing support so as to permit
longitudinal
sliding movement of the reinforcement lower end in the body, whilst
constraining
movement of the reinforcement in a direction transversely of the infill.
Alternatively the
lower end of the cementitious material reinforcement may be built into the
load bearing
support, e.g. fixed in concrete forming the load bearing support.
The body may comprise a socket in which the end (upper or lower, as
applicable) of the
cementitious material reinforcement is received. Where the load bearing
structure or load
bearing support is formed from concrete, the socket may be formed in a metal
body inserted
(e.g. cast) into the load bearing structure/support. Where the load bearing
structure or load
bearing support is a metal (e.g. steel) frame, the socket may be formed in a
cleat secured
(e.g. bolted) to the frame.
The cementitious material reinforcement may be a sliding fit in the socket
(e.g. there may be
a total radial clearance of lmm or less for a rebar of 16 mm diameter). This
allows relative
longitudinal movement to take place between the cementitious material
reinforcement and
the socket, thereby accommodating differential expansion between the masonry
infill and
the load bearing structure. Suitable boots, seals or sealant may be applied to
prevent the wet
cementitious material from entering the socket as the reinforced cementitious
material is
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cast. Under transverse loading of the masonry, the reinforcing bar ends engage
the interior
sides of the sockets and transfer the transverse loads to the load bearing
structure. Under
such loading, the bond beam and reinforcing bars will tend to bowso as to
produce a reactive
moment at the socket. Reaction forces from the sockets at the bar ends and the
stiffness of
the bond beam and surrounding masonry tend to restrain and prevent excessive
lateral
movement of the masonry.
The upper course or edge of the masonry infill may be secured to the load
bearing structure
by other means besides the attachment at the reinforcement. Fixings which are
conventional
in themselves, such as metal brackets and head restraints, can be used for
this purpose.
Mortar beds between courses may also be reinforced by means which are
conventional as
such, for example using metal wire or mesh.
Additionally or alternatively, reinforcements such as rebars or suitably
shaped elongate
metal brackets may be embedded in the cementitious material in the cavity,
with one or both
of their ends extending into the masonry bed joints. For example, such
brackets or
reinforcements may extend to one side, to both sides, or to either side
alternately, of the
cavity, in each course, in every other course, in every third course, etc,
depending upon the
degree of reinforcement demanded by the particular service conditions of the
masonry infill
concerned.
More than one reinforced cementitious material filled cavity as described
above can be
provided, thereby providing effective reinforcement of horizontally long
masonry infills, or
at free vertical edges of apertures formed in a masonry infill.
The cementitious material reinforcement may comprise shorter lengths secured
together end-
to-end or overlapped to provide effective longitudinal securement, so that the
hollow
masonry units do not have to be threaded over the entire length of the
reinforcement as the
infill is constructed. The first length of the cementitious material
reinforcement is secured
to the load bearing support, and further lengths are added upwardly as the
infill is built up.
The cavity can be filled with cementitious material to encase the
reinforcement as each
masonry course is laid; or after two or more courses have been laid; or after
the entire infill.
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is otherwise complete. It is preferred that the cementitious material is not
allowed to fully
cure between successive pours, to eliminate cold jointing and promote bonding
into a
unitary whole. Threaded connections can be used to secure the lengths of
cementitious
material reinforcement end-to-end, but generally the overlapping securing
method is
preferred.
The masonry infill may also comprise a reinforced cementitious material (e.g.
concrete)
casting extending parallel to a course of masonry units. For example the
reinforced
cementitious material casting may comprise a bond beam formed within a course
of hollow
masonry units. These units may have a U-shaped cross-sectional profile within
which the
reinforcement (e.g. rebars) is placed, and within which the cementitious
material of the bond
beam is contained whilst it cures and afterwards. One or both ends of the
reinforcement for
the casting may be secured to the load bearing structure. Bodies secured to
the load bearing
structure in a similar manner to those used to secure the upper end of the
above-described
cementitious material reinforcement, may be used to secure the or each end of
the
cementitious material casting to the load bearing structure.
One or more courses of masonry above and/or below the cementitious material of
the bond
beam may be tied into the cementitious materialby reinforcements extending
into the
cementitious material and into mortar filled spaces in or between the units of
masonry in
these courses. For example, rebar or suitably shaped elongate metal brackets
may be cast
into the cementitious material so as to extend into the vertical mortar joints
(perpends or
"perps") in the adjacent course or courses above and/or below. Where the
cementitious
material is cast in the gap between the limbs of a U-cross-sectioned block,
selected U-
shaped blocks may be provided with holes in their bases, allowing the rebar or
elongate
brackets to pass downwardly into perpends of the course below, as well as
upwardly from
between the limbs of the U into the course above. The rebar or brackets may be
assembled
from shorter lengths joined end-to-end as building of the infill progresses,
in similar way to
the advantageous form of cementitious material reinforcement described above.
In this way,
the rebars or brackets may extend through and tie several courses of masonry
above and/or
below to the cementitious material casting or bond beam. Where the rebars or
brackets pass
through these courses in regions away from perpends, they may be grouted or
mortared into
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vertical holes running through the masonry units concerned. The elongate
brackets may be
generally L-shaped, having a horizontal support foot which rests against the
blockwork
course below and stabilses the bracket against an adjacent block before it is
built into the
masonry.
It has been found that the reinforced cementitious material filled cavity
running through
masonry courses and with reinforcement ends secured to a load bearing support
and load
bearing structure as previously described, and/or the reinforced cementitious
material
casting extending parallel to the course of masonry units and having upwardly
and/or
downwardly extending rebars or brackets, as described above, both serve to
resist crack
propagation when the masonry infill is subjected to transverse loading.
In a further independent aspect, the invention therefore provides a reinforced
cementitious
material casting extending parallel to a course of masonry units, in which one
or more
courses of masonry above and/or below the reinforced cementitious material
casting are tied
thereto by reinforcements extending into the cementitious material and into
grout or mortar
filled spaces in or between the units of masonry in these courses, the
reinforcements being
formed from separate lengths with ends overlapped, or joined end to end, for
example joined
by threaded connections.
The invention correspondingly provides a method of constructing a masonry
infill in a load
bearing structure, the method comprising the steps of:
laying hollow masonry units to define a cavity extending through adjacent
courses of the
masonry infill and filling the cavity with reinforced cementitious material,
wherein a lower end of the cementitious material reinforcement is secured to a
load bearing
support;
a body is secured to the load bearing structure; and
an upper end of the cementitious material reinforcement is longitudinally
slidably received
in the body in use; the body constraining movement of the reinforcement in a
direction
transversely of the infill.
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Further features and advantages of the invention will be apparent from the
following
description of illustrative embodiments made with reference to the
accompanying schematic
drawings.
Brief Description of the Drawings
Figure 1 is a front view of a half-hollow block and modular rebar as may be
used as
components of an embodiment of the present invention;
Figure 2 is a plan view of the block and modular rebar of Figure 1;
Figure 3 is a front view of the lower part of a masonry infill embodying the
invention
constructed using the components shown in Figure 1;
Figure 3a corresponds to Figure 3, but shows an alternative method for
securing the modular
reinforcement together;
Figure 4 shows the complementary upper part of the masonry infill of Figure 3;
Figures 5 and 6 correspond to Figures 1 and 2 but show an alternative hollow
block as may
be particularly advantageous in constructing the upper part of the infill as
shown in Figure 3;
Figure 7 is a side view of a receptor cleat as may be used as a component of
an embodiment
of the present invention, a rebar lower end being shown received therein;
Figure 8 is a side view of a modified receptor cleat for receiving a rebar
upper end;
Figure 9 shows a transfer rod or bracket as may be used as a further component
of an
embodiment of the present invention;
Figure 10 shows a junction between a vertical concrete reinforcement embodying
the present
invention and a bond beam;
Figures 11 and 12 show further and alternative structural details of the bond
beam of Figure
10;
Figure 13 shows an embodiment of the invention serving as reinforcement
adjacent to an
opening in a blockwork wall;
Figure 14 shows alternative elongate metal brackets in use in a preferred
embodiment of the
invention;
Figure 15 is a perspective view of an elongate metal bracket as used in Figure
14, and
Figure 16 shows the bracket of Figure 15 used as a shear transfer member /
rebar positioning
bracket in a bond beam; parts of the blockwork being omitted to show
reinforcement details.
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Detailed Description of the Illustrative Embodiments
Figure 1 depicts a front elevation of a half-hollow masonry unit in the form
of a building
block 1 through which modular reinforcement (rebar) 2 can be placed vertically
in the
hollow portion 3.
Figure 2 is a plan view of the half-hollow block 1 shown in Figure 1 with the
vertical
reinforcement 2 located centrally within the hollow 3 and the hollow
backfilled with a
cementitious mix, e.g. 40 N/mm2 premixed concrete.
Figure 3 illustrates a section of the bottom of a bonded masonry infill wall
50 embodying
the invention. The wall is formed from the half-hollow blocks 1 described
above and
standard solid blocks 1 b bedded in mortar or similar material to form joints
I a. A receptor
cleat 5 is shown fixed to a floor or floor slab 16 forming a load bearing
support.
Alternatively the load bearing support may be a beam, for example part of a
building frame.
The lower end of a modular section of reinforcement 2 is placed into the
receptor cleat.
Alternatively this end may be cast directly into the load bearing support 16
where the latter
is made from concrete, for example. The bottom four courses of blocks are then
laid in the
normal manner, with the half-hollow blocks 1 placed over the reinforcement,
such that the
hollow aligns vertically with the block below to form a continuous vertical
cavity containing
the reinforcement. The modular reinforcement 2 is shown with a threaded
connector 4
screwed onto its threaded upper end. A threaded lower end of the next modular
reinforcement (not shown) is screwed into the connector to provide a
continuous and full
strength connection. Transfer rods or L-shaped brackets 9 are located in every
second bed
joint, with the shorter leg protruding out into the cavity which is then
backfilled with a
cementitious mix such as concrete. Transfer rods or L-shaped brackets 9 are
located in
every second bed joint, with the shorter leg protruding down into the cavity
which is then
backfilled with the cementitious mix. Other spacings of brackets/transfer rods
9 may be
used, as appropriate to the degree of reinforcement required. The
brackets/transfer rods
assist in transferring shear stress between the reinforced cementatious
material in the cavity
3 and the surrounding blockwork, e.g. under transverse loading of the wall.
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The structure shown in Figure 3a is similar to that shown in Figure 3, except
that the
sections of modular reinforcement, rather than being secured together with
threaded
connectors 4, are placed with their ends overlapping, preferably by tying the
next section of
reinforcement to the previous one before the resulting joint is encased in the
blockwork
being laid. Wire ties 2a or other suitable means are used to secure the
overlapped
reinforcement ends together temporarily before they are encased in and
permanently held
together by the cured cementitious mix. 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 50x
rebar
diameter may be typical. This form of joining the modular reinforcement
sections may be
used in place of the threaded connectors 4 wherever those are mentioned in
this document.
Figure 4 illustrates a section of the top of a bonded masonry infill wall
embodying the
invention. A receptor cleat 6 (which may be substantially the same as the
receptor cleat 5;
although other arrangements are also possible, as further discussed below in
conjunction
with Figures 7 and 8) is shown fixed to the soffit 18 of a load bearing
structure in which the
masonry infill 50 is being constructed. The upper end of a modular section of
reinforcement
2 is placed into the receptor cleat 6. The thread on the lower end 7 of this
reinforcement
section may be long enough to fully accommodate a connector 4 (not shown) so
that this
may then be screwed down onto the upper end of the modular reinforcement
section below
(not shown). A backing nut can be used if required, to form a rigid, play-free
joint.
Alternatively the uppermost connector 4 may be screwed up from the lower
reinforcement
section onto the adjacent uppermost reinforcement section. Yet alternatively,
the
overlapping joining method can be used for the sections of modular
reinforcement, as
described above with reference to Figure 3a. In that case, the upper end of
the uppermost
length of reinforcement 2 is poked into the receptor cleat 6 before the wire
ties 2a are
secured. The top four courses of blocks are then laid in the normal manner,
using half-
hollow blocks 8 with no end wall, placed into position around the
reinforcement so that the
hollow aligns vertically with that of the block below. The threaded end 7 of
the uppermost
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modular reinforcement section screws into the connector of the modular
reinforcement
below, or the two plain ends are overlapped (not shown in Figure 5), to
provide a continuous
and full strength connection. Transfer rods or L-shaped brackets 9 are again
located in every
second bed joint, with the shorter leg protruding down into the cavity which
is then
backfilled with the cementitious mix. Throughout the height of the infill,
other spacings of
brackets/transfer rods 9 may be used, as appropriate to the degree of
reinforcement required.
Figure 5 depicts a plan view of the half-hollow block 8 with no end wall, with
the vertical
reinforcement 2 located centrally within the hollow 3 and the hollow
backfilled with the
cementitious mix.
Figure 6 depicts an elevation of the half-hollow block 8 with no end wall
which can be
placed around the reinforcement 2 so that this extends vertically and
substantially centrally
in the hollow portion 3. The absence of the end wall ensures that this
placement remains
possible even when the corresponding reinforcement section 2 is secured at
either end,
between the cleat and the next lower reinforcement section.
Figure 7 depicts an example of a receptor cleat 5 for locating the vertical
reinforcement 2 in
the desired position within the cavity at the base of the wall formed by the
masonry infill.
The reinforcement is preferably located substantially in the centre of the
cavity formed by
the vertically aligned hollow parts of the hollow blocks 1. This particular
example shows a
receptor cleat 5 comprising a tubular socket 20 welded to a base plate 22
which can then be
fixed to the floor slab or other load bearing support 16, using appropriate
fasteners such as
bolts, expansion bolts, etc. The reinforcement fits snugly in the tubular
socket but this
allows for longitudinal sliding to accommodate shrinkage etc.
Figure 8 depicts an example of a modified receptor cleat 6 for locating the
vertical
reinforcement 2 at the desired location (e.g. substantially in the centre) in
the vertical cavity
at the head of the wall. This particular example shows a tube 24 welded to a
base plate 20
which can then be bolted or otherwise fixed with appropriate fasteners to the
soffit. The tube
wall has a semi-cylindrical cut-away portion extending from its free end
towards the base
plate, over a substantial portion of its length. The reinforcement sits within
the remaining
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semi-circular section 26 of the tube which gives it restraint against lateral
loading at least in
one direction, but allows sufficient access/tolerance to enable the modular
reinforcement 2
to be connected to the modular section below as well as accommodate head
deflections,
shrinkage, expansion etc. The uppermost modular reinforcement section can
therefore be
fitted to the adjacent section without the need to screw the connector 4 up
and then down or
down and then up as described above.
Figure 9 depicts a transfer rod or L-shaped bracket 9 which has a short leg 11
and a long leg
12 and a series of perforations 10 which, when built into a wall, allow the
mortar / concrete
etc to pass through, providing shear resistance. The bracket 9 may be used, as
shown in and
described with reference to Figures 3, 3a and 4
Figure 10 shows a portion of the masonry infill or wall 50 which accommodates
both a
reinforced concrete filled vertical cavity 3 and a course of hollowed out, U-
shaped cross-
section masonry units or blocks 30 for accommodating a bond beam 31. A pair of
horizontally extending rebars 32 are suspended one above the other in the open
channel
formed by the U-profile blocks 30 as this course is laid. The channel is
filled with concrete
or other cementitious material to form the bond beam and the next course can
then be laid.
L-shaped brackets or transfer rods 34 may extend from the horizontal channel
into the
perpends of the adjacent courses. These may be similar to the brackets 9 of
Figure 9. They
assist in transferring shear stress or other forces/stresses between the
reinforced concrete or
other cementitous material in the horizontal channel and the surrounding
blockwork. Holes
may be provided in the bases of the U-profile blocks 30 where required, to
allow the
downwardly extending limbs of the downwardly directed brackets to pass into
the perpends
of the course below. Solid blocks lb may be used in regions of the wall away
from the
reinforced concrete filled vertical cavity 3 and the bond beam filled
horizontal channel in the
U-profile blocks 30.
As shown in Figure 11, the ends of the rebars 32 are slidingly fitted into
tubular sockets 36
welded to a base plate 40 of a further cleat 38. In this respect, the cleat 38
is similar to the
cleat 5, and its base plate 40 may be fixed to an adjacent load bearing
structure, e.g. the
frame of a building, prior to fitment of the rebars and pouring of the bond
beam concrete. In
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this way, one or both ends of the bond beam may be secured to the load bearing
structure.
Where the load bearing structure is formed from concrete, the body of the
cleat may be cast
into this structure. Brackets 34 may be provided, similar to the brackets 9 of
Figure 9.
Figure 12 shows a modification of Figure 11, in which the brackets 34 are
replaced by L-
shaped transfer rods 2a, having threaded ends that may each be connected to
one or more
further modular rebar sections 2 in series, by threaded connectors 4.
Alternatively, some or
all of these joints may be formed by overlapping rebar ends, as described
above with
reference to Fig. 3a. In this way, the bond beam may be tied to one or more
adjacent
masonry courses, both above and below. Vertical holes may be provided in the
blockwork
where the rebar sections and transfer rods 2, 2a pass through away from
perpends, and into
which the rebar sections/transfer rods are grouted or mortared as the
blockwork is built up.
The lower transfer rods 2a may have their ends bent over or partly bent over
to form the
final L-shape after placement of the corresponding U-profiled block 30, or the
hole in the
base of the block and/or the radius of the bend in the rod 2a may be
configured to allow the
block to be threaded over the upper, free end of the rod 2a as the block 30 is
laid.
Figure 13 is similar to Figure 10, but shows the vertical cavity 3 filled with
reinforced
cementitious material e.g. concrete, used to strengthen the free vertical edge
of blockwork
adjacent to an opening 42, such as a window, door or service opening. Such
edge
strengthening may be required for higher transverse design loadings on the
blockwork, for
example loadings over 5 kPa. The vertical edge of the opening is formed by
hollow half
blocks lc which alternate course by course with the half hollow blocks 1, to
provide the
vertical cavity 3 extending through the courses adjacent to the opening 42.
Rather than
continuing upwardly as shown, e.g. to a soffit or other load bearing structure
and securing
cleat (not shown), the modular reinforcement 2 can terminate in the bond beam,
where
design loads allow. For example, L-shaped transfer rods 2a such as shown in
Figure 12 can
be used to terminate the vertically extending, modular reinforcement 2 in the
bond beam.
As another alternative, the bond beam may terminate in the course of blockwork
above the
opening 42 (e.g. at or slightly beyond the side of the cavity 3 opposite to
the opening 42) to
form a lintel above the opening 42. The lower end of the vertical edge
reinforcement can
similarly be terminated in a bond beam where appropriate, e.g. in the case of
a window or
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service opening. Likewise the upper or lower part of the reinforcement 2 shown
in Figure
can terminate in the bond beam; or indeed both ends of such a vertical
reinforcement can
terminate in a bond beam.
Figure 14 is similar to Figure 4, but shows alternative elongate shear
transfer brackets 9a.
These have a central portion embedded in the cementitious material in the
vertical cavity 3,
with opposed end parts extending into the blockwork on either side of the
cavity 3. The
vertical spacing of the brackets 9a can again be varied, depending upon the
degree of
reinforcement required. The length of the bracket can similarly be varied.
However, to reduce the overall number of parts required in constructing a
variety of
reinforced blockwork walls, the bracket 9a may be of a generally standardised
form as
shown on Figure 15. As shown, it has a short foot part 44 extending at right
angles to a
main shank 46. It is provided with apertures 10 similar to those of the
bracket 9, and for the
same purpose. A notch 48 is cut into the shank extending from one edge across
to the
midline, to accommodate inter alia the modular reinforcement 2. A similar
notch 52 is cut
into the opposite edge of the shank, for a purpose explained below.
The standard bracket 9a can also be used as a stress transfer member in a bond
beam, as
shown in Figure 16. The foot 44 is used to support the bracket with the shank
46 propped
vertically against an adjacent block le, immediately before the bracket is
built into the
blockwork. When built in, the foot lies in a bed joint and the adjacent part
of the shank lies
in a perpend. (As used in Fig. 14, of course, the foot 44 lies in a perpend
and the shank in a
bed joint. The foot is not necessary in the arrangement shown in Fig. 14, but
is preferred so
as to keep the different kinds of brackets required to a minimum). The
remainder of the
shank 46 extends through an opening 54 in the base of the U-profiled block
30a, so as to
traverse the cavity in which the bond beam is to be formed. The distal end of
the shank 46
projects upwardly beyond the top edges of the block 30a a significant
distance, so that it can
be built into a perpend of the next course of blockwork immediately above the
bond beam.
In this way, the courses of blockwork above and below the bond beam are tied
to the bond
beam, with the brackets 9a helping to transfer shear loads or other stresses
between the bond
beam and the surrounding blockwork. The notches 48 and 52 can be used to
accommodate
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and support bond beam rebars 32 in the correct position within the bond beam
cavity, before
the bond beam concrete or other cementitious material is cast and cured.
