U.S. patent number 11,384,534 [Application Number 16/981,906] was granted by the patent office on 2022-07-12 for building reinforcement and insulation.
This patent grant is currently assigned to William George Edscer. The grantee listed for this patent is William George Edscer. Invention is credited to William George Edscer, John Jones.
United States Patent |
11,384,534 |
Edscer , et al. |
July 12, 2022 |
Building reinforcement and insulation
Abstract
A method is provided for securing external wall insulation (EWI)
panels to the outer walls of a high rise building of large panel
construction. The method involves first identifying the location of
internal voids in outermost floor/ceiling panels of the building;
and then creating continuous passages through the outer
load-bearing wall panels of the building into the located internal
voids, with each such passage forming a tie bar anchorage hole
extending into the adjacent floor/ceiling panel. Down the length of
each tie bar anchorage hole is inserted a tie bar that has, at an
inner end portion, an anchorage, and at an outer end portion, an
externally screw-threaded portion that projects from the outer
load-bearing wall panel. A pattress plate is located at the outer
end of each anchorage hole, with the externally screw-threaded
outer end portion of each tie bar extending through the associated
pattress plate.
Inventors: |
Edscer; William George (East
Sussex, GB), Jones; John (East Sussex,
GB) |
Applicant: |
Name |
City |
State |
Country |
Type |
Edscer; William George |
East Sussex |
N/A |
GB |
|
|
Assignee: |
Edscer; William George (East
Sussex, GB)
|
Family
ID: |
1000006425269 |
Appl.
No.: |
16/981,906 |
Filed: |
March 19, 2019 |
PCT
Filed: |
March 19, 2019 |
PCT No.: |
PCT/GB2019/050766 |
371(c)(1),(2),(4) Date: |
September 17, 2020 |
PCT
Pub. No.: |
WO2019/180421 |
PCT
Pub. Date: |
September 26, 2019 |
Prior Publication Data
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|
|
|
Document
Identifier |
Publication Date |
|
US 20210115667 A1 |
Apr 22, 2021 |
|
Foreign Application Priority Data
|
|
|
|
|
Mar 20, 2018 [GB] |
|
|
1804422 |
Aug 28, 2018 [GB] |
|
|
1813965 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
E04F
13/08 (20130101); E04B 2/94 (20130101); E04B
1/043 (20130101); E04B 1/215 (20130101) |
Current International
Class: |
E04B
2/94 (20060101); E04F 13/08 (20060101); E04B
1/21 (20060101); E04B 1/04 (20060101) |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
|
|
|
|
663813 |
|
Jan 1988 |
|
CH |
|
206091171 |
|
Apr 2017 |
|
CN |
|
2291324 |
|
Jun 1976 |
|
FR |
|
1256313 |
|
Dec 1971 |
|
GB |
|
1256313 |
|
Dec 1971 |
|
GB |
|
H11124980 |
|
May 1999 |
|
JP |
|
1019055 |
|
Mar 2003 |
|
NL |
|
2017629 |
|
Apr 2018 |
|
NL |
|
WO-2013173887 |
|
Nov 2013 |
|
WO |
|
Other References
International Search Report (Form PCT/ISA/210) for International
Patent Application No. PCT/GB2019/050766, issued from the European
Patent Office, dated Jun. 19, 2019, 3 pages. cited by applicant
.
Written Opinion of the International Searching Authority (Form
PCT/ISA/237) for International Patent Application No.
PCT/GB2019/050766, issued from the European Patent Office, dated
Jun. 19, 2019, 5 pages. cited by applicant .
Combined Search and Examination Report for Great Britain
Application No. GB1903748.0, published by the United Kingdom
Intellectual Property Office, dated Sep. 18, 2019, 5 pages. cited
by applicant .
Search Report for Application No. GB1813965.9, published by the
United Kingdom Intellectual Property Office, dated Nov. 23, 2018, 3
pages. cited by applicant.
|
Primary Examiner: Cajilig; Christine T
Attorney, Agent or Firm: Kilyk & Bowersox, P.L.L.C.
Claims
The invention claimed is:
1. A method of securing external wall insulation (EWI) panels to
outer walls of a high rise concrete frame building, which
comprises: creating continuous passages through outer load-bearing
wall panels of the building into adjacent floor/ceiling panels,
each such passage forming a tie bar anchorage hole extending at
least 300 mm into the adjacent floor/ceiling panel; inserting into
each tie bar anchorage hole a tie bar which has at an inner end
portion an anchorage received in the associated tie bar anchorage
hole and which has at an outer end portion an externally
screw-threaded portion which projects from the outer load-bearing
wall panel; locating a pattress plate at an outer end of each tie
bar anchorage hole, with the externally screw-threaded outer end
portion of each tie bar extending through an aperture in the
associated pattress plate, and securing the pattress plates in
position in or against the outer load-bearing wall panels;
anchoring each tie bar in its tie bar anchorage hole by extruding a
grouting compound past the associated pattress plate or through an
eccentric grout hole in the associated pattress plate and into the
outer end of each tie bar anchorage hole around the tie bar, and
allowing the grouting compound to set; securing to the externally
screw-threaded outer end portions of the tie bars a metal framework
for supporting external wall insulation for the building; and
securing to the metal framework EWI panels to clad the
building.
2. The method according to claim 1, wherein the building is a
building of large panel system construction.
3. The method according to claim 1, wherein the floor/ceiling
panels adjacent to the outer load-bearing wall panels of the
building are solid concrete panels, and the step of creating
continuous passages through the outer load-bearing wall panels of
the building into the adjacent floor/ceiling panels comprises
drilling core holes through the load-bearing wall panels and into
the floor/ceiling panels to create a depth of the tie bar anchorage
holes.
4. The method according to claim 1, wherein the floor/ceiling
panels adjacent to the outer load-bearing wall panels of the
building are precast concrete panels having internal voids
preformed therein, and wherein the step of creating continuous
passages through the outer load-bearing wall panels of the building
into the adjacent floor/ceiling panels comprises drilling core
holes through the load-bearing wall panels to connect with the
internal voids or with some of the internal voids, and, if
necessary, extending the core holes into the floor/ceiling panels
to create a depth of the tie bar anchorage holes.
5. The method according to claim 4, wherein a preliminary step in
the method is provided and comprises identifying, from the outside
of the building, the location of the internal voids.
6. The method according to claim 5, wherein the preliminary step
comprises establishing an approximate location of at least one of
the internal voids in the outermost floor/ceiling panels of the
building by X-ray scanning.
7. The method according to claim 5, wherein the preliminary step
comprises establishing the precise location of at least one of the
internal voids in the outermost floor/ceiling panels of the
building by drilling one or more pilot holes through the outer wall
panels of the building until the precise location of the internal
void or the internal voids in the adjacent floor/ceiling panels is
or are identified.
8. The method according to claim 4, further comprising placing
alongside but spaced from each tie bar within the internal voids of
the hollow floor/ceiling panels one or more reinforcing bars which
become encased in the grouting compound when the grouting compound
is injected into the floor/ceiling panel voids which provide the
tie bar anchorage holes.
9. The method according to claim 1, wherein, in the step of
creating continuous passages through the outer load-bearing wall
panels into the adjacent wall/ceiling panels to form the tie bar
anchorage holes, each continuous passage commences with a drilling
of a pattress core hole partially through the outer wall panel from
the outside of the building followed by a drilling of a smaller
diameter core hole from a base of the pattress core hole through a
remainder of the outer load-bearing wall panel to connect with
internal voids in the floor/ceiling panels, and, in the step of
locating a pattress plate at the outer end of each tie bar
anchorage hole, each pattress plate is a cylindrical pattress plate
which is received as a close fit in its associated pattress core
hole in the outer load-bearing wall panel, abutting the outer
load-bearing wall panel at a shoulder formed between the inner end
of the pattress core hole and the associated smaller diameter
hole.
10. The method according to claim 9, wherein the floor/ceiling
panels adjacent to the outer load-bearing wall panels of the
building are precast concrete panels having internal voids
preformed therein, and wherein the step of creating continuous
passages through the outer load-bearing wall panels of the building
into the adjacent floor/ceiling panels comprises drilling core
holes through the load-bearing wall panels to connect with the
internal voids or with some of the internal voids, and, if
necessary, extending the core holes into the floor/ceiling panels
to create a depth of the tie bar anchorage holes, and wherein the
pattress core holes extend coaxially with the internal voids in the
floor/ceiling panels.
11. The method according to claim 1, wherein each tie bar anchorage
hole extends at least three meters into the respective
floor/ceiling panel.
12. The method according to claim 11, wherein each tie bar
anchorage hole extends at least four meters into the respective
floor/ceiling panel.
13. The method according to claim 1, wherein the anchorage of each
tie bar comprises a washer secured to the inner end portion of the
tie bar, the washer having a size and shape substantially the same
as those of the tie bar anchorage hole in which it is received.
14. The method according to claim 1, wherein a tubular fabric
sleeve is placed around at least the anchorage end portion of each
respective tie bar before the respective tie bar is inserted into
the respective tie bar anchorage hole, and the grouting compound is
extruded into the tie bar anchorage holes between the tie bars and
the associated sleeves so that the grouting compound expands the
sleeves and, on permeating through the fabric of the sleeves, bonds
to the concrete of the associated floor/ceiling panel.
15. The method according to claim 1, wherein the metal framework
comprises an array of vertical rails carried by anchorage brackets
secured fast against the pattress plates by nuts screwed onto the
externally screw-threaded outer portions of the tie bars, and an
array of horizontal rails attached to the vertical rails.
16. The method according to claim 1, wherein the metal framework
comprises an array of vertical rails carried by anchorage brackets
formed integrally with the pattress plates, and an array of
horizontal rails attached to the vertical rails.
17. The method according to claim 15, wherein each vertical rail
comprises a pair of generally U-shaped cold rolled steel sections
clamped back to back against opposite sides of flange portions of
the anchorage brackets.
Description
FIELD OF THE INVENTION
The invention relates to a method of reinforcing and insulating a
certain class of existing high rise modular building. The buildings
to be reinforced and insulated in this way are all concrete frame
buildings, but the method is most advantageously applied to large
panel system buildings. These are systems in which load-bearing
precast concrete wall slabs are erected edge to edge and topped
with precast concrete floor/ceiling slabs which are secured edge to
edge to the tops of the load-bearing wall slabs. Each floor/ceiling
slab forms part of the ceiling of the storey defined by the
interconnected wall slabs and part of the floor of the next higher
storey of the building. One well documented collapse of such a
large panel system high rise building in the United Kingdom was the
partial collapse of the Ronan Point tower block in 1968, when an
internal gas explosion blew out part of an external wall, leading
to the disproportionate collapse of one corner of the tower block.
It is understood that the partial collapse of the building became
disproportionate in part because the outer walls and many of the
floor/ceiling slabs immediately above the explosion were no longer
supported by the external wall blown out by the explosion, and in
part because the weight of falling masonry brought down the outer
walls and many floor/ceiling slabs of the storeys immediately
beneath the damaged load-bearing external wall. The damage to the
building therefore extended both above and below the explosion
site.
A more recent high rise tower block tragedy in the United Kingdom
was the Grenfell Tower fire in 2017, when a fire swept upwardly
through a tower block, feeding principally, it is believed, through
the external wall insulation ("EWI") panels that had been added as
cladding over the external walls of the building.
Despite the Grenfell Tower fire tragedy, it is still desirable to
face tower block buildings with EWI panels to improve their thermal
insulation and appearance. This invention is based on the
observation that however close the external cladding panel is to
the large panel external wall of the building on which it is hung,
there is inevitably a cantilever effect pulling the large panel
external wall away from the building. Therefore, hanging EWI panels
on the outside of a large panel building increases the possibility
of disproportionate collapse of the building if an external large
panel wall should be damaged. This increased possibility of
disproportionate collapse is at its greatest when the EWI panels
are heavy panels, such as precast concrete EWI panels, but still
exists even when the EWI panels are lightweight panels such as
those based on the use of mineral wool which has a nil fire
rating.
It is an object of this invention to provide a method of securing
EWI panels to concrete frame buildings, and particularly to large
panel system buildings, while simultaneously adding to the
structural strength and integrity of the buildings to reduce the
risk of disproportionate collapse should there be an internal
explosion or other cause of structural failure of any of the
EWI-clad external load-bearing walls.
SUMMARY OF THE INVENTION
The invention provides the method of claim 1 herein. The method can
be considered as comprising four main stages: creating the tie bar
anchorage holes through the external wall panels on which the EWI
panels are to be added as cladding and into the adjacent outermost
floor/ceiling panels of the building; securing in position the tie
bars and pattress plates; building the metal framework bolted to
the exposed threaded ends of the tie bars; and securing to the
metal framework the EWI panels to clad the building and enhance the
thermal insulation of the building.
In the first of the above four stages, the continuous passages
which form the tie bar anchorage holes are preferably drilled as
core holes from the outside of the building. The accurate location
of the drilling of the core holes is paramount. They are to be the
start of the tie bar anchorage holes which extend some considerable
depth into the adjacent floor/ceiling panels, and yet the edges of
the floor/ceiling panels are not visible from the outside of the
building. Much can be learned from the original building plans
which ought to show the full specification and location of the
floor/ceiling panels. In the case of large panel system buildings,
the floor/ceiling panels are precast panels which may be solid
reinforced concrete panels or may be formed with axially elongate
voids to reduce the overall weight of individual panels. In the
case of other concrete frame buildings the floor/ceiling panels may
have been cast in situ as solid reinforced concrete over temporary
shuttering. In either case the location of the reinforcing steel
bars should be identified for example by carrying out a
three-dimensional imaging survey of the floor/ceiling panels, so
that the internal steel reinforcement can be avoided during the
drilling of the tie bar anchorage holes. But more than that: if the
floor/ceiling panels are precast panels with axially elongate
internal voids, then the location, size and shape of those voids
should be known in order for the tie rod anchorage holes to take
maximum advantage of those voids. The location or approximate
location of the voids may initially be established from the
building plans and possibly from an X-ray scan of the building
taken through the outer walls. Preferably a series of pilot holes
is drilled through the load-bearing outer walls and into one or
more of those voids, so that the size and shape of the voids may be
established with precision, for example using a bore scope. If the
axial voids extend perpendicularly to the outer wall through which
the core holes are drilled, then careful alignment of those core
holes with the ends of the voids can ensure that the core holes and
voids together form the tie bar anchorage holes which extend into
the floor/ceiling panels for the necessary depth. If the axial
voids extend other than perpendicularly, for example parallel to
the outer wall panel or diagonally thereto, then the core holes
must be drilled into the floor/ceiling panels across a number of
voids, by drilling through the concrete walls separating the axial
voids until the desired depth of each tie bar anchorage hole is
achieved. That depth is at least 300 mm, advantageously more than
three metres and preferably more than four metres.
If the floor/ceiling panels are solid concrete without the above
internal voids, then the core drilling through the outer wall
panels is simply continued through the floor/ceiling panels until
the necessary depth of tie bar anchorage hole is achieved.
If the pattress plates are (in the second of the above four stages)
to be secured against the outer faces of the load-bearing wall
panels, then those core holes are simple core holes less than the
size of the pattress plates, drilled from the outer faces of the
wall panels into the adjacent floor/ceiling panels. Generally,
however in a large panel system building the wall panels comprise
inner and outer leaves separated by an insulating layer, in which
case the inner leaf is the load-bearing element which supports the
adjacent floor/ceiling panel. In that case the core holes drilled
from the outer face of the wall panels are pattress core holes
sized to receive the pattress plates, and the pattress plates are
preferably secured within those pattress core holes to bear against
the inner load-bearing leaves of the wall panels. In such a case
the drilling of the core holes commences with the drilling of
pattress core holes from the outside faces of the wall panels as
far as the inner leaves of the wall panels, so that when the
pattress plates are inserted into those core holes they bear
against the inner leaves. Preferably those pattress core holes are
of a diameter to receive as a close fit cylindrical pattress
plates, and are drilled to a depth to receive the cylindrical
pattress plates fully within the pattress core holes so that the
pattress plates do not project from the outer faces of the wall
panels.
The second of the above four stages is to secure in position the
tie bars and the pattress plates. Each tie bar preferably has a
length of at least 300 mm, advantageously more than three metres
and preferably more than four metres, so that it can extend well
into the associated tie bar anchorage hole, and has at one end
portion an anchorage such as a washer of substantially the same
size and shape as the tie bar anchorage hole. That washer may for
example be secured to the tie bar by cutting or rolling a screw
thread at the inner end portion of each tie bar, passing the washer
over that threaded inner end portion and clamping the washer
against a shoulder of the tie bar with a nut. The tie bar is then
inserted down the associated tie bar anchorage hole until only the
externally screw-threaded outer end of the tie bar extends from the
outer wall panel. Preferably before insertion of each tie bar down
its anchorage hole a fabric sleeve is placed around at least the
inner end portion of the tie bar so that when the tie bar is pushed
down the anchorage hole it carries with it the fabric sleeve. Wire
spacers may be provided at intervals along the length of the tie
bars to hold the tie bars generally centrally in the tie bar
anchorage holes in the floor/ceiling panels and to hold the fabric
sleeves apart from the tie bars to encourage the flow of grout, in
the next step of the method, down the full length of the tie
bars.
After insertion of the tie bars in the tie bar anchorage holes, a
pattress plate is placed over the projecting outer end of each tie
bar. Each pattress plate has an aperture through which the
externally screw-threaded outer end portion of the tie bar passes.
When the pattress plates are received in pattress core holes formed
in the wall panels, they are preferably recessed to a depth so that
their outer faces lie flush with or do not project from the outer
faces of the wall panels. The pattress plates may be of unitary
construction, in which case the depth of the pattress core holes is
preferably accurately controlled so that when the inner face of
each pattress plate abuts the end of its pattress core hole the
outer face of that pattress plate lies flush with or do not project
from the outer face of the outer leaf of the wall panel. That,
however, requires very accurate depth control in the drilling of
the pattress core holes, and it is therefore often preferable to
form the pattress plates as two axially spaced elements, an inner
element and an outer element. The inner element is the element
which bears against the end of its pattress core hole to restrain
that wall panel from any outward movement which could potentially
relinquish support for the adjacent floor/ceiling panel. The outer
element is subsequently adjusted, as described below, to bring it
into the desired planar alignment with the outer face of the outer
leaf of the wall panel.
In the case of circular pattress plates located in pattress core
holes, the aperture through which the externally screw-threaded
outer end portion of the tie bar passes may be central, or may be
slightly offset from centre to receive the externally
screw-threaded outer end portion of the tie bar if that end portion
should be slightly off-centre (for example due to slight sagging of
the tie bar over its length). If desired, the aperture may be
elongate, extending radially outwards from the axial centre of each
such circular pattress plate so that by rotating the pattress plate
in its pattress core hole that aperture can be aligned with the end
of the tie bar even if the tie bar has sagged so that its end is no
longer axially central of the pattress core hole. Further rotation
of the pattress plate can then if desired lift the end of the tie
bar to an axial centre. An alternative method of bringing the
aperture in the pattress plate into alignment with a potentially
misaligned projecting end of the tie bar is for the pattress plate
or pattress plate element to be made as inner and outer rings, one
rotatable relative to the other about an eccentric axis. The
aperture through which the externally screw-threaded outer end
portion of the tie bar passes is a preferably eccentric aperture in
the inner ring so that rotation of the inner and/or outer ring
moves the aperture in an orbital path and the rotation can be
adjusted until the aperture is aligned with the projecting end of
the tie bar.
To complete this second stage in the method of the invention, the
tie bars and pattress plates are firmly anchored in place using a
grouting compound. Each pattress plate should be held in position,
for example with a nut threaded onto the projecting end of the
associated tie bar or by a screw thread of the pattress plate
itself. Then grout is extruded into the tie bar anchorage holes,
past the pattress plate or pattress plate element or through an
eccentric grout hole in each pattress plate or pattress plate
element. In order to fill the tie bar anchorage holes completely
with grout, and in order to exclude any air pockets, the grout is
preferably injected down a flexible injection tube which passes
past the pattress plate or pattress plate element or through the
eccentric grout hole in the pattress plate or pattress plate
element and extends right down to the anchorage ends of the tie
bars. The tie bar anchorage holes are therefore filled with grout
from the innermost ends, and the flexible injection tube is
preferably removed during the grout injection. In this second of
the above four stages it may be desirable to ensure that each tie
bar is held in place in its tie bar anchorage hole with a
preliminary extrusion of some of the grouting compound around the
anchorage at the innermost end of the tie bar, allowing that
grouting compound to set or partially set, to hold the tie bar in
place before proceeding. The grouting compound may be cementitious
or resinous and is forced past the pattress plates or through the
grout holes in the pattress plates until it fills the space between
the tie bars and the tie bar anchorage hole internal walls. If the
tie bars are surrounded or partially surrounded by fabric sleeves,
then the grouting compound is extruded into the tie bar anchorage
holes between the tie bars and the sleeves and, permeating through
the fabric of the sleeves, bonds to the concrete of the associated
floor/ceiling panel. The sleeves prevent wastage of the grouting
compound by restricting its flow into voids in the floor/ceiling
slabs.
Whatever method is used to fill the tie bar anchorage holes with
grout, it is desirable to be able to confirm that no voids have
been left within the anchorage holes during the grouting process.
Preferably when the grout has set sufficiently, the pattress plate
is removed from the tie bar and a visible inspection carried out to
confirm that the grout completely fills the anchorage holes before
the pattress plate is once again placed in position on the threaded
outer end of the tie bar.
Once the grouting compound has set, the tie bars and pattress
plates are securely anchored to the building structure. Preferably
the tie bars are made from deformed steel reinforcing bar stock, so
that the anchorage is very secure and strong. After this stage of
the process is completed there is preferably a period of waiting,
for example of 7 to 14 days, for the grouting compound to set
fully. Preferably the security of the tie anchorage is tested after
this period to demonstrate that it resists a pull-out test using a
test force which depends on the engineer's design. That should be
sufficient to show that the tie bars are firmly anchored in place
in the anchorage holes in the floor/ceiling slabs and the pattress
plates are firmly anchored in place in the pattress core holes
formed in the wall slabs. Then the pattress plates can be firmly
secured to the tie bars by tightening to a desired torque rating a
holding nut threaded onto the projecting end of each tie bar.
If the pattress plates comprise inner and outer elements of which
the outer element is adjustable so as to bring its outer face
precisely flush with or slightly recessed relative to the outer
face of the associated wall panel, then all that has been described
above concerning the anchorage of the pattress plates should be
read as describing the anchorage of the inner element of the
composite pattress plate. The outer element is subsequently placed
over the projecting threaded end of the tie bar and adjusted to
bring it into the desired alignment with the outer face of the wall
panel. That adjustment may be by placing spacers and/or shim
washers on the projecting end of the tie bar before placing the
pattress plate outer element in position, to bridge an axial gap
between the inner and outer elements of the pattress plate and to
bring the outer element of the pattress plate into the desired
planar alignment with the outer leaf of the wall panel, or it may
be by having the outer element of the pattress plate screw-threaded
onto the threaded end of the tie bar so that rotation of that outer
element of the pattress plate can cause it to be moved outwardly or
inwardly until it achieves the desired accurate planar alignment.
Preferably any space between inner and outer elements of such a
composite pattress plate is filled with a cementitious or resinous
grout before the second of the above four stages is complete.
The next stage in the method is the securing of a metal framework
to the exposed ends of the tie bars. Brackets may be formed
integrally with the pattress plates, and if so the pattress plates
are secured firmly to the tie bars by retention nuts threaded onto
the externally screw-threaded outer ends of the tie bars and
tightened to a desired torque rating. The metal framework is
subsequently secured to those integral brackets. If the pattress
plates have no such integral brackets, then initially separate
mounting elements are placed over the projecting threaded ends of
the tie bars and secured in place with retention nuts which are
threaded onto the externally screw-threaded outer ends of the tie
bars and ultimately tightened to the desired torque rating. Each
mounting element comprises a plate portion which in use lies flat
against and bears against the outer surface of the associated
pattress plate. Each plate portion is provided with a mounting
hole, which may be round or elongated, through which the externally
threaded end portion of the associated tie bar extends before
receiving the retention nut. The core holes should have been
drilled in a vertical and horizontal array, but those mounting
holes may be sized for final adjustment of the mounting elements
and their supported metal framework to improve and perfect the
vertical and horizontal alignment before tightening the retention
nuts. Before that final tightening, to each bracket or mounting
element is secured a rail of the metal framework, and the framework
is built up on site by connection together of vertical and
horizontal rails. Preferably the vertical rails are first secured
to the brackets or mounting elements, and the horizontal rails
subsequently secured to the vertical rails. The vertical rails may
be in flush contact with the outer faces of the wall slab or may be
spaced slightly from those outer faces with a spacing (for example
5 to 10 mm) deemed desirable and acceptable by a structural
engineer. If desired such a spacing may be bridged at intervals
with metal shims or plates contacting both the outer wall of the
building and the vertical rails. That alignment or spacing can be
easily controlled when the pattress plates have been recessed into
pattress core holes in the wall panels and precisely adjusted until
their outer faces are flush with or marginally recessed relative to
the outer faces of the wall panels.
If the pattress plates have integral brackets or if the mounting
elements have similar brackets extending from their plate portions,
then flange portions of those brackets are preferably oriented
vertically to carry vertical rails of the metal framework. Those
vertical rails may be arranged in pairs, back to back one on each
side of the flange portions of the brackets, and secured to the
brackets by bolts, rivets or other securing means. If the pattress
plates do not have integral brackets, then the plate portions of
the mounting elements may alternatively have tapped mounting holes
so that the vertical rails can be attached directly to the mounting
elements by set screws.
Vertically adjacent vertical rails of the metal framework are
preferably connected to each other by plates which span pairs of
adjacent vertically aligned rails. Such plates are preferably first
bolted to one vertical rail through pre-drilled holes and then
connected to the adjacent rail by bolts passing through holes
drilled in situ through both the plate and the adjacent vertical
rail. The in-situ drilling is a means of ensuring that a very
precise spacing of the vertical rails can be achieved when the
rails have been adjusted to an accurate vertical alignment.
Horizontal metal rails are secured to the array of parallel
vertical rails to complete the metal framework. Additional diagonal
bars may be added, to improve the rigidity of the metal
framework.
Each retention nut secures its bracket or mounting element to the
associated tie bar, and after accurate alignment of the metal
framework the retention nuts may be tightened to a desired torque
rating to avoid further movement. The torque applied may itself be
sufficient to prevent loosening of the framework over time, or
additional means may be employed to achieve that end. For example,
the retention nuts may be self-locking nuts; or they may be capped
by locking nuts which are applied and tightened after the framework
is in place; or they may be castellated nuts held against rotation
by anchor pins; or the tightened retention nuts may be sprayed with
a galvanizing coating which acts both to prevent rusting of the
threaded joint and to prevent the retention nuts from slackening
over time.
At the completion of this third stage in the method of the
invention, the metal framework is securely and accurately anchored
to the face of the large panel building. The final step of the
method is to hang EWI panels on that framework. Any secure fixing
method may be used, consistent with the precise EWI panels chosen.
The EWI panels may be concrete external cladding panels with fire
resistant thermal insulation or may be more lightweight thermal
insulating panels.
All of the metal components utilized in the method of the
invention, including the tie bars, pattress plates, brackets, nuts
and metal framework, may be rendered corrosion resistant for
example by being made from stainless steel or by being galvanized.
The galvanization, if applied, may be by zinc plating, hot dip
galvanization or sherardization.
Significant advantages of the method of the invention are that the
building has not only been clad with securely supported and
accurately positioned EWI panels which improve the appearance and
the thermal insulation of the building, but also it has been
considerably strengthened against potential disproportionate
collapse. Not only are the EWI panels supported by tie bars
anchored to both the external wall panels and the floor/ceiling
panels, but also the external wall panels of the large panel
structure are far more securely anchored to the floor/ceiling
panels than before the EWI cladding is applied. The anchorage
together of the wall panels and the floor/ceiling panels of the
large panel construction is no longer simple edge-to-edge
anchorage. The tie bars extend some considerable distance into the
floor/ceiling panels around the edge of the building, providing an
anchorage well into the width of the building which is an excellent
countermeasure to prevent or reduce disproportionate collapse.
The insertion of a single tie bar as described above into each tie
bar anchorage hole establishes a secure anchorage of the wall
panels to the floor/ceiling panels of the building, but does not
materially affect the bending resistance of the floor/ceiling
panels. Particularly when the floor/ceiling panels are hollow
precast panels with internal voids, it may be desirable as part of
the method of the invention to strengthen the panels around the
peripheral outer wall of the building to protect against
disproportionate collapse of the building caused by bending
distortion of those hollow panels. This may be achieved by placing
alongside but spaced from each tie bar within the internal voids of
the hollow floor/ceiling panels one or more reinforcing bars which
are then surrounded by the grouting compound in the second stage of
the method of the invention when that grouting compound is injected
into floor/ceiling panel voids which provide the tie bar anchorage
holes. The reinforcing bars may be supported by spacer elements at
least some of which are mounted on the tie bars, and the cage of
reinforcing bars and spacer elements should be sized to permit its
insertion into the internal voids of the hollow floor/ceiling
panels through the core holes drilled from the outside of the
building. The connections between the reinforcing bars and spacer
elements should be secure connections such as screw threads, grub
screws or welded joints. The spacer element located at the
innermost end of the tie bar is the anchorage referred to in claim
1 herein and is securely attached to the tie bar by threading or
similar other secure means. However all of the spacer elements have
an anchorage function in addition to supporting and positioning the
reinforcing bars, in that they contribute to the secure bonding of
the grout to the concrete internal walls which define the voids in
the hollow floor/ceiling panels. They act to restrict the grout
flow to ensure that the grout consolidates and backs up against
those concrete internal walls and by doing so ensures that the
internal voids in the floor/ceiling panels are completely filled
with grout for the entire length of the tie bars and anchorage
bars. The total encapsulation of all of the spacer elements by the
high strength grout ensures that the spacer elements cannot move
and become a composite part of the tie bar anchorage construction,
capable of resisting any reasonable specified load). The
reinforcing bars are preferably made from distressed deformed steel
reinforcing bar stock, as are the tie bars, to secure a good bond
with the grouting compound after it sets. Alternatively, they may
be completely threaded, for example using Gripbar.RTM. stock as
manufactured by Stainless UK Ltd, enabling them to be
screw-threaded to all of the spacer elements as well as providing a
good bond to the grouting compound.
Preferably a cluster of two, three or four such reinforcing bars is
arranged around each tie bar, held by the spacer elements near the
top and bottom of the internal voids in the floor/ceiling panels.
Of course, the spacer elements must be sized sufficiently small to
enable them to be inserted into the tie bar anchorage holes,
passing through the core holes drilled from the outside of the
building. Furthermore, the spacer elements must include apertures
or recesses to allow the flow of grout to each side of each spacer
element during the second stage of the method of the invention, so
that on completion of the second stage the tie bars, the
reinforcing bars and the spacer elements are all completely
surrounded by the grout. That ensures that after the setting of the
grout the floor/ceiling panels are significantly strengthened
against bending deformation for the entire length of the
reinforcing bars.
BRIEF DESCRIPTION OF DRAWINGS
Drawings: The invention is illustrated by the drawings of
which:
FIG. 1 is a photograph of a tower block building of large panel
construction;
FIG. 2 is a section through one corner of a junction between
external wall panels and a floor/ceiling panel of the building of
FIG. 1;
FIG. 2a is a section through the floor/ceiling panel, showing
internal voids formed in each such panel;
FIG. 3 is a section similar to that of FIG. 2 but in a plane
displaced from the former so that the section passes through one of
the voids shown in FIG. 2a;
FIG. 4 shows the section of FIG. 3 with the pattress core hole
drilled partially through the external wall panel and shown
shaded;
FIG. 5 is the section of FIG. 4 but with a further core hole
drilled and shown shaded, joining the pattress core hole to an
internal void in the floor/ceiling panel;
FIG. 6 is the section of FIG. 5 showing the insertion of a tie bar
and sleeve through the pattress core hole and into the void;
FIG. 7 is the section of FIG. 6 after insertion of a pattress plate
into the pattress core hole, with the tie bar extending through a
central aperture in the pattress plate, and after extrusion of a
grouting compound into the sleeve surrounding the tie bar;
FIGS. 7a and 7b are sections similar to that of FIG. 7 but
demonstrating the option of a two part pattress plate of which an
inner element is shown in place in FIG. 7a and both inner and outer
elements are in place in FIG. 7b, separated by a spacer and shim
washer;
FIG. 7c is a perspective view of a tie bar which has attached
thereto a cluster of four reinforcing bars, to achieve additional
strengthening of the floor/ceiling panels into which it is inserted
according to the invention;
FIG. 8 is a front view of the pattress plate of FIG. 7;
FIG. 8a is a front view of an alternative design of pattress
plate;
FIGS. 8b and 8c are front views of another alternative design of
pattress plate, being a two-part pattress plate shown with the
parts in two different angular conditions to show how the tie bar
receiving hole can be adjusted to a range of off-centre
locations;
FIG. 9 is the section of FIG. 7 after the grouting compound has set
and after an anchorage bracket for the external framework has been
bolted to the tie bar;
FIG. 10 is a perspective view of the anchorage bracket of FIG.
9;
FIGS. 11, 12 and 13 are front, side and top views of the anchorage
bracket of FIG. 10;
FIG. 10a is an exploded perspective view of the anchorage bracket
of FIG. 10 before all of its components are welded together;
FIG. 14 is a schematic illustration of the connection of the
support framework to the anchorage brackets;
FIG. 14a is a modification of FIG. 14 showing an additional support
flange or projection for supporting an optional diagonal brace
member of the support framework;
FIG. 14b is a plan view of a mounting plate assembly for use as a
bracket to attach the vertical rails of a metal framework to the
tie bar of any of FIGS. 2 to 9;
FIGS. 14c and 14d are plan views of two alternative mounting plate
assemblies similar to that of FIG. 14b; and
FIG. 15 is a front view of a part of the support framework,
including optional diagonal brace members, in position on the face
of the building.
DETAILED DESCRIPTION OF EMBODIMENTS
Embodiments of the present invention will now be described by way
of example only and with reference to the accompanying
drawings.
Referring first to FIG. 1, there is shown a tower block building to
be clad and reinforced against disproportionate collapse according
to the method of the invention. The building is of large panel
construction, and FIGS. 2 and 3 show how the external wall panels 1
and floor/ceiling panels 2 of the building are bolted edge to edge
in the large panel construction method. The wall panels 1 include
internal thermal insulation layers shown schematically as 3, which
separate each external wall panel 1 into inner and outer leaves. It
is the inner leaf which is load-bearing, in that it supports the
adjacent floor/ceiling panel 2. The floor/ceiling panels 2 rest on
top edges of the external wall panels 1 with an array of bolts 4
connecting the inner leaf of each external wall panel 1 both to the
inner leaf of the wall panel 1 immediately above and to the
adjacent floor/ceiling panel 2. A draught seal 5 is shown, and the
spaces between the panels after erection are filled with dry-pack
mortar 6.
FIG. 2a shows the internal construction of the floor/ceiling panels
2 which are Bison (Trade Mark) precast planks. The floor/ceiling
panels 2 are formed from reinforced concrete, and to reduce the
total weight of each panel the panels in this illustrative example
of the invention are formed with pre-cast voids 7 at intervals
along the length of each panel. One such void 7 is shown in the
section illustrated in FIG. 3, which shows an external wall panel 1
lying perpendicular to the longitudinal axes of the voids 7. Around
the corner of the building the external wall panels 1 would lie
parallel to the longitudinal axes of the voids 7, so that a similar
section to that of FIG. 3 but taken around the corner of the
building would show the succession of voids in the floor/ceiling
panel 2, as illustrated in FIG. 2a.
FIG. 4 illustrates the first core hole drilling step in this
illustrated embodiment of the invention, which involves the
drilling of a pattress core hole 8 through the outer leaf of the
external wall panel 1, directed axially towards one of the voids 7
in the floor/ceiling panel 2. The location of that void 7 cannot be
seen from the exterior of the building before drilling commences,
but can be established from the specification of the floor/ceiling
panels 2, or from X-ray inspection of the building. If desired, a
series of preliminary exploratory pilot holes can be drilled
through the exterior wall panel 1 and into the floor/ceiling panel
2 and voids 7 before drilling the core hole 8, to establish the
precise pattern and location of the floor/ceiling panels 2 and
their voids 7. Alternatively if the approximate location of the
voids 7 is first established for example by reference to initial
plans of the building and/or by X-ray scanning, the pattress core
holes 8 may be drilled part-way through the external wall panels 1
towards those approximate void locations, and the precise pattern,
size and location of the voids may be established by drilling one
or more pilot holes through the remaining thickness of the external
wall panels 1 from the base of one or more of the pattress core
holes 8. The pattress core hole 8 is shown cross-hatched in FIG. 4
purely to enable the reader easily to identify the location and
extent of that hole. The pattress core hole 8 will eventually
receive and locate a pattress plate, but that plate is not placed
in position until later in the method of the invention.
The next step in the method of the invention is illustrated in FIG.
5, and involves the removal of a second core of concrete from the
base of the pattress core hole 8 so as to connect to the adjacent
void 7. That second core of concrete is shown cross-hatched in FIG.
5 and numbered 9. Of course, if the pattress core hole had been
bored completely through the wall panel 1 rather than partially
therethrough, it would not have been necessary to remove the second
core 9. If the wall panel 1 had been on an adjacent external wall
of the building, so that it lay other than perpendicularly to the
line of the voids 7 in the floor/ceiling panels 7, then the second
core hole would have had to extend into the floor/ceiling panel 2
through each in turn of the concrete walls separating adjacent
voids 7, for the full length of the tie bars which are to be
received in and anchored to the floor/ceiling panels 2 in the
subsequent steps of the method of the invention. The second core
holes and voids 7 together form tie bar anchorage holes for those
tie bars. If the floor/ceiling panels 2 had been solid panels
without voids 7, the second core would have had to be drilled
through the inner leaf of the wall panel 1 and into the solid
concrete of the floor/ceiling panel 2 for the full depth of the
resulting tie bar anchorage hole. For all such drilling of core
holes laser-guided drilling rigs are preferably used, with diamond
edged core drills.
FIG. 6 shows the next step in the method which commences with the
insertion, into each tie bar anchorage hole, of a tie bar 10. The
tie bar 10 may be made from standard deformed steel reinforcing bar
stock, with external screw threads rolled into its ends 11 and 12.
The screw-threaded end 11 carries an anchorage for anchoring the
tie bar 10 in its tie bar anchorage hole, comprising a nut 13 which
clamps a washer 14 against a shoulder of the tie bar 10. The
screw-threaded end 12 extends from the pattress core hole 8. Before
the tie bar 10 is passed down the core holes 8 and 9 and into the
void 7 an optional fabric sleeve 15 may be placed around the end 11
and washer 14 and around a number of wire spacers 16 spaced along
the tie bar 10 to hold the sleeve 15 away from the tie bar 10. The
sleeve 15 need not extend the complete length of the tie bar 10. It
is sufficient that it is around the anchorage end 11. The wire
spacers 16 also serve to hold the tie bar 10 generally centrally in
the void 7, resisting excessive sagging of the tie bar 10.
A circular pattress plate 17 is then placed around the end 12 of
the tie bar 10 and into the pattress core hole 8, as illustrated in
FIG. 7. The pattress plate 17 has an aperture through which the tie
bar 10 passes. For example, that aperture may be a central axial
bore (not separately illustrated) or it may be a radial extending
slot 18, as shown in FIG. 8, through which the tie bar 10 passes.
The radial extent of the slot ensures that even if the end 12 of
the tie bar 10 is eccentric in its pattress core hole (for example
because the weight of the tie bar 10 has caused it to sag or bend)
it can be threaded through the slot in the pattress plate 17. Once
the pattress plate 17 is in its core hole 8 as shown in FIG. 7 it
can if desired be rotated to move the tie rod to the axial centre
of the pattress core hole 8. Alternatively the pattress plate may
have a number of discrete apertures 18a at different distances from
its axial centre, as shown in FIG. 8a, and the tie bar 10 may then
be passed through whichever of those is conveniently aligned with
the end of the tie bar 10. A further alternative is illustrated in
FIGS. 8b and 8c. Such a pattress plate 17 is formed as two parts,
numbered 17a and 17b. Part 17a is a circular plate the diameter of
the pattress core hole 17 but has an eccentric circular recess 17c
formed therein. The axis of the part 17a is shown as X. The part
17b is a circular plate the same diameter as the recess 17c and can
rotate in the recess 17c. Eccentric apertures 18b are formed in the
part 17b. Rotation of the part 17a in its pattress core hole 17 in
the direction of arrow A causes the central axis of the part 17b to
precess around the central axis of the pattress core hole 17, and
rotation of the part 17b in the recess 17c in the direction of
arrow B causes the apertures 18b to precess around the central axis
of the recess 17c. Suitable rotation of the two parts 17a and 17b
therefore causes an orbital movement of the apertures 18b and by
such movement it is possible to align one of the apertures 18b with
the end 12 of the tie bar 10 even if the end 12 is eccentric in the
pattress core hole 17. FIGS. 8b and 8c show different rotational
conditions of parts 17a and 17b after rotation in the direction of
the respective arrows A and B.
There is another hole formed in the pattress plate 17 of FIGS. 7, 8
and 8a. That is an eccentric grout injection hole. Any one of the
three apertures 18b of FIGS. 8b and 8c that is not used to receive
the tie bar 10 can be used as that grout injection hole of FIGS. 8b
and 8c. While the pattress plate 17 is held firmly in position by a
holding nut (not shown in FIG. 7) threaded onto the threaded
projecting end 12 of the tie bar 10, a grouting compound is
extruded down a flexible grout injection tube (not shown in the
Figures) which extends through the grout injection hole and down
through the sleeve 15 to the end 11 of the tie bar 10. Filling the
void 7 with grout therefore proceeds from the innermost end 11 of
the tie bar 10, back towards the pattress plate 17. The flexible
grout injection tube is withdrawn during grout injection. The
sleeve 15 stops the grouting compound from flowing beyond the
anchor 13, guides the grouting compound along the void 7 and
expands under the pressure of the grouting compound so that the
sleeve becomes pressed against the internal walls of the void. The
grouting compound permeates through the sleeve material and adheres
to the internal walls of the void, but the sleeve 15 prevents the
grout from flowing freely into any internal spaces along the length
of the tie bar 10 and at the end 11 of the tie bar 10.
The pattress core hole into which the pattress plates of FIG. 7 or
8 to 8c are received is drilled for a precise controlled depth into
the wall panel 1, that depth being designed to bring the outer face
of the inserted pattress plate into coplanar vertical alignment
with the outer face of the wall panel 1 or into an alignment that
is recessed for a precise predetermined amount into the wall panel
1, that amount being as specified by a structural engineer and
being dependent on the design of the bracket or other mounting
elements used to support the metal framework for the EWI panels. An
alternative to the very precise depth drilling of the pattress core
hole is illustrated in FIGS. 7a and 7b and utilizes a composite
pattress plate that can be utilize any of the alternative pattress
plate shapes of FIGS. 7 and 8 to 8d. Such a composite pattress
plate comprises two pattress plate elements 17a and 17d. The
injection of grout is as described above but is carried out in two
stages. In the first stage, illustrated in FIG. 7a, only the inner
pattress plate element 17a is inserted into the pattress core hole
and held in position against the inner leaf of the wall panel by a
holding nut 22. The grout is injected down its injection tube until
the associated tie bar anchorage hole is filled. When the grout has
set sufficiently, the holding nut 22 may be unscrewed and if
desired the pattress plate element 17a removed to carry out a
visual inspection to confirm that the tie bar anchorage hole has
been completely filled. Then as shown in FIG. 7b the pattress plate
inner element 17a once again placed in position, and if desired
held in place by replacement of the holding nut 22 (optional, so
not shown in FIG. 7b) tightened to a predetermined torque. A
tubular cylindrical metal spacer 17b, a shim washer 17c and the
pattress plate outer element 17d are then placed around the
protruding end 12 of the tie bar 10, and the alignment between the
outer end of the pattress plate element 17d and the plane of the
wall panel 1 is carefully checked. The shim washer 17c can be
exchanged for another of different thickness or supplemented with
additional shim washers of suitable thickness until the pattress
plate element 17d extends to a precise plane flush with or a
predefined distance behind the wall panel outer face. The holding
nut 22 (or a second holding nut 22 if the pattress plate inner
element 17a has been held in place by its own holding nut as
indicated above as a possible option) is then threaded onto the end
12 of the tie rod 10, to hold the entire pattress plate assembly
17a to 17d in place. Finally the void around the spacer 17b is
filled with grout by injecting the grout through an eccentric grout
hole (illustrated but unreferenced) in the pattress plate outer
element 17d.
FIG. 7c illustrates how the tie bar 10 can support one or more
reinforcing bars 10a of standard deformed steel. A cluster of four
such reinforcing bars is shown in FIG. 7c, but fewer or more such
bars may be used, each spaced from the tie bar 10 and held in
position by spacer elements 10b. The spacer elements 10b hold the
four reinforcing bars 10a illustrated in FIG. 7c near the top and
bottom of the voids 7 in the floor/ceiling panels 2 so as to
achieve maximum reinforcement. The spacer elements 10b along the
length of the reinforcing bars 10a may be made from plastics
material, for example nylon, or from metal, for example steel,
since their primary function is to hold the reinforcing bars in
position until they are encased in the grouting compound 20
injected down voids 7 which provide the tie bar anchorage holes.
Their presence avoids the need for the wire spacers 16 discussed
previously because the spacer elements 10b also hold the tie bars
10 centrally in the voids 7, and hold the sleeve 15 (if present)
away from the cage of tie bars and reinforcing bars. The spacer
element 10b at the innermost end of the tie bar 10, however,
doubles as the anchor 14 of FIG. 6, and should preferably be of
steel and is securely fastened to the tie bar 10 by a nut similar
to the nut 13 of FIG. 6 or by being screw-threaded directly onto
the threaded end of the tie bar 10. Similarly the spacer elements
10b at the ends of the reinforcing bars 10a are preferably of steel
and are securely connected to the reinforcing bars by nuts or by
direct screw threads. The other spacer elements 10c spaced at
intervals along the length of the reinforcing bars 10b are
preferably connected to the reinforcing bars 10a by grub
screws.
Once the injected grouting compound has set, the reinforcement
provided by the bars 10a adds very significantly to the strength of
the floor/ceiling panels, providing additional strength to resist
bending deformation of those floor/ceiling panels along the length
of the reinforcing bars 10a. Furthermore, the security of the
anchorage of the tie bars in the tie bar anchorage holes is
significantly increased by the presence of the spacer elements 10b.
The structural integrity of the building is thus much enhanced by
the inclusion of the reinforcing bars 10a. In FIG. 7c the
reinforcing bars 10a are shown as being longer than the tie bar 10
so that they extend into the voids 7 beyond the ends of the tie
bars 10, but they may if desired extend into the voids 7 for the
same distance as the tie bars 10 or for a lesser distance. Of
course, when the grouting compound is injected into the voids 7 it
should be injected as far as the innermost end of both the tie bars
10 and the reinforcing bars 10a. If a sleeve 15 is used to surround
the tie bar/reinforcing bar assembly, it should extend around the
innermost spacer element 10b and the innermost end of the tie bars
10 and the reinforcing bars 10a.
The injection of the grouting compound around the reinforcing bars
10a is slightly more complicated than the grout injection when no
such reinforcing bars are used. A similar rigid or flexible grout
injection tube may be used, so that the grouting compound fills the
void 7 around the reinforcing bars 10a and tie bar 10 starting at
the innermost end of the tie bar/reinforcing bar assembly. That
injection tube (not illustrated) passes initially past the spacer
elements 10b which have peripheral cut-away portions 10c to allow
for the insertion of the grout injection tube to the innermost end
of the tie bar/reinforcing bar assembly. The injection tube is
withdrawn as the grouting compound is injected, but care needs to
be taken to ensure that no unfilled spaces are left in the voids 7
during the grout injection. One method of achieving that is for the
injection tube to be marked with the distances spacing apart the
spacer elements 10b along the length of the reinforcing bars 10a.
As the injection of grout proceeds and the injection tube is
withdrawn, that withdrawal can be paused as each such marking is
revealed, and the grout injection continued for a period without
moving the injection tube, so as to be certain that the void 7 is
completely filled back to each in turn of the spacer elements 10b.
The grout injection pressure assists the withdrawal of the
injection tube. The grout injection pressure can be monitored as a
guide to indicate when each section of the void 7 is completely
filled. When the grouting compound has set, the spaced apart
reinforcing bars 10a create a highly beneficial strengthening of
the floor/ceiling panels 2 both to enhance the anchorage of the tie
bars 10 in the tie bar anchorage holes and to resist bending
stresses around the periphery of the building. To ensure that the
grout achieves a high strength bond with both the reinforcing bars
10a and the internal surface of the voids 7 the tie bar anchorage
holes may be pre-wet before the grout is injected to prevent
moisture in the grout being absorbed by the concrete. This allows
the grout to cure completely, with a good bond to both the concrete
floor/ceiling panels 2 and the reinforcing bars 10a.
Whichever of the above alternative pattress plates is used, and
whether or not the reinforcing bars 10a of FIG. 7c are included,
when the grouting compound 20 has set, each tie bar 10 is securely
anchored in the floor/ceiling panel 2 by a cementitious or resinous
grout bond which extends continuously from the pattress plate 17 to
the anchorage 14 of FIG. 7 or to the innermost end of the tie
bar/reinforcing bar assembly of FIG. 7c, with the externally
threaded end portion 12 of each tie bar 10 projecting from its
pattress plate 17. The security of that anchorage is preferably
tested before the metal framework is attached to the tie bars 10,
and the results of that testing for each in turn of the tie bars 10
is preferably retained for the lifetime of the building as an
accurate record of the competence of the reinforcement. Then
anchorage brackets can be attached to the projecting externally
threaded ends 12 of the tie bars 10 and held in place by nuts 22.
The anchorage brackets may be any suitable size and shape to secure
in position a metal framework for supporting external wall
insulation (EWI) panels for the building.
One such anchorage bracket, to suit the metal framework of FIGS. 14
and 15, is illustrated as bracket 21 in FIGS. 10 to 13. The bracket
21 comprises a plate portion 23 and a pair of flange portions 24.
FIG. 10a illustrates one possible method of construction of the
anchorage bracket 21, with each flange portion 24 being provided
with a tenon portion which is received in a mortise slot in the
plate portion 23 before being welded in place. Instead of the tenon
portions illustrated in FIG. 10a, discrete stud portions of the
flange portions 24 may be welded into spaced apart bores in the
plate portions 23. Each anchorage bracket 21 is of a size and shape
to support a vertical rail of a support framework. In FIG. 14, that
vertical rail comprises a pair of cold rolled steel sections 25
clamped back to back against opposite vertical sides of the flange
portions 24 of the bracket 21. The vertical rails are fastened to
the brackets 21 by bolts (not shown) passing through holes
(circular or elongate) in the flange portions 24. Each vertical
rail 25 is of generally U-shaped section and comprises a central
web and inner and outer flange portions of which an inner flange
portion lies against the vertical outer wall of the building and an
outer flange portion is spaced from the outer wall of the building.
Although not shown in FIG. 14, the inner flange portion of each
steel section 25 would be cut away slightly as shown in FIG. 14a to
accommodate the thickness of the plate portions 23 of the brackets
21. An alternative method, not illustrated, of mounting similarly
shaped vertical rails 25 on the threaded end portions of the tie
bars uses an alternative design of bracket 21. Such a bracket 21 is
a metal plate secured to the tie bar by the holding nut 22. The
metal plate bracket 21 would be of a sufficient thickness that set
screws passing through holes formed in the inner flange portion of
the vertical rail 25 can be securely retained in threaded holes
formed in the face of the metal plate bracket which is held against
the outer wall of the building by the holding nut 22. To assemble
and secure in place those vertical rails, each vertical rail is
positioned with its upper end over the metal plate bracket and
secured to the metal plate bracket using the above set screws. A
connecting plate is then bolted to the outer flange portion of the
vertical rail, to overlie the outer flange portion of the next
higher vertical rail. When the vertical rails are accurately
positioned, with their positioning and alignment preferably checked
by lasers, adjacent pairs of vertical rails can be secured to one
another by bolts passing through holes drilled on-site through the
overlying connecting plates and outer flange portions of the
vertical rails.
If desired, each vertical rail or selected vertical rails may be
supported at locations between adjacent anchorage brackets by
additional support brackets connected to the external wall panels
of the building. Such intermediate support (not illustrated in the
drawings) adds to the rigidity and security of the vertical rail
assembly. If the external wall panels are composite wall panels
with inner and outer leaves, then the additional support brackets
may be connected to the outer leaves only, or may be recessed into
the outer leaves and also connected through to the inner leaves of
such composite wall panels to connect both the inner and outer
leaves of the outer wall of the building to the metal framework at
positions between adjacent anchorage brackets.
If desired, the mounting brackets 21 which secure in place the
vertical rails 25 of the metal framework may incorporate means for
precise and controlled vertical and horizontal adjustment of the
vertical rails before the final positioning and alignment of those
vertical rails is checked as described above. The tie bars 10 have
been set in position before the vertical rails are attached, but
those tie bars 10 may not have the precise degree of accurate
vertical and horizontal alignment required of the metal framework.
Therefore, the mounting brackets may be mounting plate assemblies,
incorporating some degree of adjustability between central portions
which are secured in place by the tie bars and outer portions which
support the vertical rails 25. For example the outer portions may
be rotatable relative to the inner portions about an eccentric
axis, so that with the inner portions in fixed positions clamped to
or integral with the pattress plates 17 and tie bars 10, the outer
portions can be rotated about that axis eccentric to the tie bar 10
axis until the desired horizontal and vertical alignment is
achieved. If desired the angular rotation may be a free rotation to
any angle, as illustrated in FIG. 14b, or it may be to a series of
predefined angular increments, as illustrated in FIGS. 14c and 14d.
In FIG. 14b the mounting bracket is numbered 21a and is in three
parts. A central part 21a is locked fast to the tie bar 10 by the
holding nut 22. The central part 21a' incorporates an eccentric
stepped circular recess 101 receiving a ring part 21a'' and the
ring part 21a'' itself incorporates an eccentric stepped circular
recess 102 which receives an outer ring part 21a''. The recesses
101 and 102 are stepped so that they permit rotation of the ring
parts 21a'' and 21a'' while preventing them from moving outwardly
away from the pattress plate 17 and from outer wall 1 of the
building. Rotation of the ring parts 21a'' and 21a'' in their
circular recesses 101 and 102 causes a combination of horizontal
and vertical movement of a threaded anchor hole 103 which receives
the set screw described above for anchoring the vertical rail 25 to
the bracket 21a. Once the desired vertical and horizontal
adjustment is obtained, the ring parts 21a'' and 21a'' can be
locked against further rotation either by drilling dowel holes 104
or milling other anchorage holes or slots 104b spanning the
boundaries of adjacent ring parts 21a', 21a'' and 21a''' and
inserting dowels 104a or anchorage plates 104c into those dowel or
anchorage holes or slots, or by drilling pairs of anchor holes 105
into adjacent ring parts 21a', 21a'' and 21a', and inserting dowel
protrusions 106 of locking elements 107 into those drilled anchor
holes 105. The recesses 101 and 102 are described and illustrated
in FIG. 14b as being circular, but as an alternative they may be
shaped as regular polygons as illustrated in FIG. 14c or toothed
like gear wheels as illustrated in FIG. 14d, so that incremental
angular movement of the ring parts 21a'' and 21a''' is all that is
permitted in order to obtain the desired horizontal and vertical
alignment of the mounting bracket 21a, in which case the dowel
holes or slots 104 or 104b or the anchor holes 105 are unnecessary
because tightening of the holding nut 22 to draw the bracket 21a
firmly against the pattress plate 17 is sufficient to lock the ring
parts 21a'' and 21a''' against further rotation. The outer shape of
the outer ring part 21a''' is shown as rectangular in FIG. 14d
merely to illustrate that any outer shape may be suitable.
Horizontal rails 26 of cold rolled steel section are bolted to
support flanges or projections 27 carried by the vertical rails,
and if desired additional diagonal brace members 28 may be bolted
to the vertical or horizontal rails to complete the frame assembly.
FIG. 14a shows a support flange or projection 29 fitted to the
vertical rail 25 to provide an anchorage for the top of one such
diagonal brace member 28. FIG. 14a also illustrates a one-piece
universal vertical rail 25 as an alternative to the two
back-to-back rails 25 of FIG. 14. The bolts are fully tightened
only after the entire framework has been checked for accurate
positioning in the vertical and horizontal planes, there being
sufficient flexibility in the framework flanged joints to permit
some adjustment before that final tightening. The final nuts to be
tightened are the nuts 22 which may be self-locking nuts or may be
held against loosening in use for example by additional lock nuts
(not shown).
FIG. 15 shows the final support framework against the external wall
of the building. It should be understood, however, that the actual
size and construction of the support framework is chosen to match
and support the actual EWI panels to be hung on the outside of the
building. For example, instead of the vertical and horizontal rails
of FIGS. 14 and 15 which are parallel flange channels (PFCs) of
cold rolled steel section, vertical or horizontal rails of
rectangular hollow section or of some different sectional profile
may be more suited to the final choice of EWI panels to be used;
and the shape of the anchorage bracket 21 of FIGS. 14 and 15 may be
different from that illustrated, to match the size and profile of
those vertical and horizontal rails. In all cases, however, the
anchorage of the support framework to the building will be through
the tie bars 10 which extend through the wall panels and a
substantial distance into the floor/ceiling panels of the building,
providing a significant reinforcement of the building against
disproportionate collapse.
It is important that the support framework is erected precisely,
with extreme care being taken to establish the accuracy of the
vertical and horizontal alignment and the exact spacing apart of
the channels to fit the size of the external structural panels.
Unfortunately it has been shown that in many existing tower block
buildings, especially those of large panel system construction
which use hollow floor/ceiling panels, the layout of the core holes
in the floor/ceiling panels can vary from panel to panel, and even
in the same building the core holes in the floor/ceiling panels may
not be evenly spaced. The result is that when the tie bar anchorage
is complete, the projecting threaded end portions of the tie bars
may not be in a sufficiently consistent array of locations for the
precise alignment of the horizontal and vertical rails of the
support framework which is to be attached to them even when the
adjustment means of FIGS. 14b to 14d are used. In such
circumstances the vertical and horizontal PFC rails of the support
framework may be positioned and adjusted using fixing plates and
locking plates which are drilled on-site to establish accurate
positioning.
For example, for on-site positioning of the horizontal rails of the
support framework, the horizontal rails may be provided with
elongate slots (drilled or milled on-site if necessary to
correspond to the actual positioning of the projecting threaded end
portions of the tie bars) through which the projecting threaded end
portions of the tie bars extend, the size and location of those
elongate slots being sufficient to permit accurate adjustment and
ultimate positioning of the horizontal rails. The horizontal rails,
when positioned accurately, are attached to those projecting
threaded ends of the tie bars by locking plates tightened against
the horizontal rails by nuts threaded onto the tie bar projecting
ends and tightened to a desired torque rating. If desired the
locking plates may be provided with dowel anchors or set screws
which are located in holes drilled on-site into the horizontal
rails, for more secure connection to the horizontal rails after the
nuts have been tightened.
The on-site positioning of the vertical rails, which may extend the
height of one or more floors, of the support framework may be
adjusted and the final positioning established by having vertical
fixing plates positioned behind or on top of the horizontal rails
between the horizontal rails and the external wall of the building.
Each vertical fixing plate is provided with an elongate slot
through which the projecting threaded end of the tie bar passes, so
that the vertical fixing plate can be moved vertically to a desired
precise level. When the nuts threaded onto the projecting ends of
the tie bars are tightened to the desired torque rating, that
clamps the horizontal rails between the fixing plates and the
locking plates and also draws the vertical fixing plates into firm
and secure contact with the outer face of the building and at the
desired adjustment height. The vertical fixing plates project out
above and below the horizontal rails so as to provide projecting
portions to which the vertical rails are bolted.
The vertical rails of the support structure may then be bolted onto
the projecting portions of the vertical fixing plates using bolt
holes pre-drilled into the vertical fixing plates or holes drilled
on-site. Additional vertical fixing plates may if desired be bolted
to the fronts of the vertical rails to connect together vertical
rails above and below the horizontal rails, again using pre-drilled
bolt holes or bolt holes drilled on-site, or a combination of
pre-drilled and on-site drilled holes. Alternatively, the
additional fixing plates may be welded to the fronts of the
vertical rails. The provision of vertical fixing plates both in
front of and behind the horizontal channels means that there is a
very secure connection between the vertical and horizontal rails of
the support framework. The framework may be assembled from the top
down or from the bottom up, or from a mid-section of the
building.
Another use of fixing plates and locking plates to position and
adjust the vertical and horizontal PFC rails of the support
framework would be to proceed as outlined above but with the
elongate slots drilled or milled into the vertical rails and the
horizontal rails bolted to the fixing plates. In such an inversion
of the above described use of fixing plates and locking plates the
fixing plates would be horizontal or vertical fixing plates
projecting out on either side of the vertical rails so as to
provide projecting portions to which the horizontal rails are
bolted. That may create a final support framework in which the
vertical rails are set away from the face of the building by a
small space of perhaps 10 mm, in which case support pads are
preferably at spaced intervals to bridge the gap between the
vertical rails and the face of the building.
Both the horizontal and vertical rails of the support framework are
thus capable of precise and accurate adjustment even though the
projecting threaded ends of the tie bars may be out of alignment
with the external frame, while the fact that the tie bars extend
for some considerable distance through the wall panels and into the
floor/ceiling panels creates the significant reinforcement of the
building against disproportionate collapse.
The external frame should be designed following an intrusive
investigation carried out by a structural engineer or other
suitably qualified person who will carry out tests and will assess
the condition of the building and also the internal floor and the
external wall panels.
Following the completion of this assessment the design of the
internal anchors and floor slab reinforcement can be finalised and
this will include preparing a specification for the size and shape
and layout of the steel members so that the support frame is also a
structural restraint frame that will act to contain and support the
panels that may be masonry or concrete or other construction
material in the event of an internal explosion all according to the
parameters and rules laid down in current legislation.
Steel, aluminium or any other suitable material may be used to form
the frame and for example the cross section shape of the members
may also include for Square (SHS), Rectangular (RHS), Round (CHS),
Parallel Flange Channel (PFC) Unequal or Equal Angle, T Section, Z
section or special formed or extruded section.
Finally External Wall Insulation (EWI) (a non-flammable product
should be specified) is attached to the external support frame in
order to enclose the building in a thick layer of insulation, for
example a 110-150 mm layer of mineral wool slabs may be cut to size
to fit between and over the vertical rails where they may be
fastened to the building before they are covered with a layer of
render, or suitable cladding or rain screening material.
Although exemplary embodiments have been described in the preceding
paragraphs, it should be understood that various modifications may
be made to those embodiments without departing from the scope of
the appended claims. Thus, the breadth and scope of the claims
should not be limited to the above-described exemplary
embodiments.
Any combination of the above-described features in all possible
variations thereof is encompassed by the present disclosure unless
otherwise indicated herein or otherwise clearly contradicted by
context.
Unless the context clearly requires otherwise, throughout the
description and the claims, the words "comprise", "comprising", and
the like, are to be construed in an inclusive as opposed to an
exclusive or exhaustive sense; that is to say, in the sense of
"including, but not limited to".
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