U.S. patent application number 10/543015 was filed with the patent office on 2007-01-04 for structural decking system.
This patent application is currently assigned to UNIVERSITY OF WESTERN SYDNEY. Invention is credited to Ross Grey, Graeme McGregor, Mark Patrick.
Application Number | 20070000197 10/543015 |
Document ID | / |
Family ID | 30004999 |
Filed Date | 2007-01-04 |
United States Patent
Application |
20070000197 |
Kind Code |
A1 |
Patrick; Mark ; et
al. |
January 4, 2007 |
Structural decking system
Abstract
A main decking panel for a structural decking system that
includes a plurality of the main decking panels is disclosed. The
main decking panel includes a base component that includes a
central pan (7) and lap joints (9) on each side of the pan to
enable adjacent main decking panels to be positioned side by side
in overlapping relationship. The main decking panel also includes a
strengthening component in the form of an inverted channel member
secured to the base component. The channel member includes two
oppoesd side walls (11) formed from web components and a top (13)
formed from a chord component. The web and top chord components are
manufactured as separate components and thereafter assembled
together to form the channel member.
Inventors: |
Patrick; Mark; (SPRINGWOOD,
AU) ; Grey; Ross; (Beecfroft, AU) ; McGregor;
Graeme; (Burradoo, AU) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
UNIVERSITY OF WESTERN
SYDNEY
SECOND STREET
KINGSWOOD, NEW SOUTH WALES
AU
2747
|
Family ID: |
30004999 |
Appl. No.: |
10/543015 |
Filed: |
January 23, 2004 |
PCT Filed: |
January 23, 2004 |
PCT NO: |
PCT/AU04/00084 |
371 Date: |
May 9, 2006 |
Current U.S.
Class: |
52/335 ; 52/414;
52/434 |
Current CPC
Class: |
E04C 3/293 20130101;
E04C 2003/0439 20130101; E04B 5/40 20130101; E04B 5/29 20130101;
E04C 2003/0469 20130101; E04C 2003/0413 20130101 |
Class at
Publication: |
052/335 ;
052/434; 052/414 |
International
Class: |
E04B 1/16 20060101
E04B001/16; E04B 2/00 20060101 E04B002/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 23, 2003 |
AU |
2003900295 |
Claims
1. A main decking panel for a structural decking system that
includes a plurality of the main decking panels, with the main
decking panel including: (a) a base component that includes a
central pan and lap joints on each side of the pan to enable
adjacent main decking panels to be positioned side by side in
overlapping relationship; and (b) a strengthening component in the
form of an inverted channel member secured to the base component,
with the channel member including two opposed side walls formed
from web components and a top formed from a chord component, and
with the web and top chord components being manufactured as
separate components and thereafter assembled together to form the
channel member.
2. The main decking panel defined in claim 1 wherein the central
pan includes at least one longitudinal stiffener.
3. The main decking panel defined in claim 2 wherein the web
components are secured to the base component at locations between
the longitudinal stiffener or stiffeners and the lap joints.
4. The main decking panel defined in claim 3 wherein the web
components butt against the longitudinal stiffener or stiffeners
and/or the lap joints.
5. The main decking panel defined in claim 1 wherein the lap joints
are formed so that a successive decking panel can be positioned in
side by side overlapping relationship with another decking panel by
pressing the lap joint of the successive decking panel downwardly
over the lap joint of the other decking panel.
6. The main decking panel defined in claim 1 wherein the
strengthening component is secured to the base component at a
plurality of discrete connection locations along the length of the
channel member.
7. The main decking panel defined in claim 6 wherein the
strengthening component is secured to the base component at the
plurality of discrete connection locations by deformed sections of
the components at the locations that interlock the components
together.
8. The main decking panel defined in claim 7 wherein the deformed
sections are button shaped.
9. The main decking panel defined in claim 7 wherein the deformed
sections are formed by holding the components together and pressing
the deformed sections, such as buttons, from one side of the
components.
10. The main decking panel defined in claim 1 wherein the web
components and the top chord components are assembled together by
securing the components together at a plurality of discrete
connection locations along the lengths of the components.
11. The main decking panel defined in claim 10 wherein the web
components and the top chord components are secured together at the
plurality of discrete connection locations by deformed sections of
the components at the locations that interlock the components
together.
12. The main decking panel defined in claim 11 wherein the deformed
sections are button shaped.
13. The main decking panel defined in claim 10 wherein the deformed
sections are formed by holding the components together and pressing
the deformed sections from one side of the components.
14. The main decking panel defined in claim 1 wherein the web
components include flanges and the web and top chord components are
secured together at the flanges.
15. The main decking panel defined in claim 1 wherein the top chord
component includes one or more than one longitudinal stiffener.
16. The main decking panel defined in claim 15 wherein the
stiffener or stiffeners extend along the length of the top chord
component.
17. The main decking panel defined in claim 1 wherein the top chord
component includes down-turned sides.
18. The main decking panel defined in claim 1 wherein the web
components include corrugations.
19. The main decking panel defined in claim 18 wherein the
corrugations are vertical corrugations.
20. The main decking panel defined in claim 1 wherein web
components include openings to allow concrete to flow into the
channel member.
21. A structural decking system formed from a plurality of the main
decking panel defined in claim 1 positioned side by side with the
lap joints in overlapping relationship.
22. The structural decking system defined in claim 21 includes one
or more than one infill decking panel that is positioned between
two main decking panels, with the infill decking panel including
lap joints on each side of the pan that are in overlapping
relationship with the lap joints of adjacent main decking
panels.
23. A composite slab that includes the structural decking system
defined in claim 21 and a layer of hardened concrete on the
structural decking system.
Description
TECHNICAL FIELD
[0001] The present invention relates to structural decking systems
and to composite slabs that include the systems.
[0002] The present invention also relates to a method of
manufacturing structural decking systems.
[0003] The present invention relates particularly to structural
decking systems for constructing composite slabs.
[0004] A major, although not the only, end use application of such
structural decking systems is in the construction of composite
slabs that form floors in buildings (which term includes car
parks).
[0005] Another, although not the only other, end use application of
such structural decking systems is in the construction of composite
slabs that form vertical wall panels.
BACKGROUND ART
(a) Conventional Composite Slab Construction
[0006] Structural steel decking can serve a dual function when used
in the construction of composite steel/concrete floor slabs and
beams. The decking can act as structural formwork by supporting
building materials and personnel before the concrete hardens. In
addition, after reinforcing steel (bars and/or mesh) has been laid,
and concrete has been poured on top of the decking, and the
concrete has reached sufficient compressive strength, the decking
can act as main reinforcement by interacting with the concrete.
When the decking acts as main reinforcement it will continue to do
so for the remainder of the life of the building.
[0007] All of the types of steel decking described in this section
interact with the hardened concrete to take advantage of composite
action.
[0008] The cellular panel described in Australian patent
application 12620/70 in the name of H. L. Burn et al is a one-way
load-carrying panel that falls outside this description.
(b) Existing Steel Decking Profiles
[0009] Conventional structural steel decking is roll-formed from
flat steel strip into long panels of uniform cross-section. Decks
are principally distinguished by differences in their
cross-sectional shape or profile. The profiles used in the world
today are very varied, e.g. trapezoidal decks with "open ribs" (see
Fig. 1(a)) versus decks with "closed ribs" (see Fig. 1(b)), but
they all have one factor in common: the nominal thickness of the
sheeting is constant around the profile perimeter.
[0010] Also, roll-forming machines are only designed to roll steel
sheeting up to a certain maximum thickness, e.g. 1.2-1.6 mm. This
significantly restricts the maximum flexural stiffness and ultimate
strength of a deck with a set geometry. This in turn can severely
impact on the minimum overall depth of the steel decking that can
be used to achieve a certain span, which itself can significantly
affect the minimum overall depth of the composite slab.
[0011] Conventional roll-forming machines are only used to
manufacture one profile of steel decking. The nominal dimensions of
the geometric features that define the profile, e.g. the overall
depth, cannot be significantly varied.
[0012] Therefore, if a greater spanning or load-carrying capability
is required and the profile must be changed, then new roll-forming
sets must be built.
[0013] Therefore, with demand growing in the world today for
decking to be used in a variety of applications, major decking
manufacturers are beginning to produce a suite of decks from flat
steel strip, with each deck requiring different roll-forming
sets.
[0014] The suite of decks includes some very deep decks (greater
than 200 mm) that are used in the construction of composite slabs
having a thin coverage (typically, 50 mm) of concrete over the tops
of the ribs and therefore exhibit one-way action.
[0015] Flat steel strip used to roll-form any given deck is one
steel grade. Therefore, the steel in all of the parts of a
roll-formed deck (flanges and webs) has the same yield stress.
[0016] The coating on flat steel strip can be varied to some degree
between the top and bottom surfaces. For example, it can be
galvanised on both surfaces but pre-painted on the side that will
form the soffit exposed to the air. Alternatively, the steel can be
uncoated on both sides, which is done in benign environments to
reduce the cost.
[0017] Some decking manufacturers modify the decks they produce
once the decks have been roll-formed. This is done to improve their
functionality or structural performance. Important aspects of
structural performance are flexural stiffness and ultimate
strength. Flexural stiffness affects the magnitude of vertical
deflections, in particular under the weight of wet concrete, which
often control in design. The moment capacity and shear capacity of
critical regions affects ultimate strength, which can also control
in design.
[0018] Two types of modified decks are discussed below.
(i) "Cellular" decks that are made by welding a flat sheet of steel
across the entire base of each decking panel (see Fig. 1(c)).
[0019] This arrangement creates closed cells for the passage of
sensitive building services, in particular electrical cabling for
computers, thus giving rise to so-called "electrified floors".
[0020] Attaching the flat sheets to the decking panel also
increases the load-carrying capacity and flexural stiffness of the
original deck, provided the connection between the sheet and the
deck is sufficiently strong. Therefore, this functional improvement
can also improve the structural performance of the deck when it
acts as formwork.
[0021] Importantly, for example as is disclosed in Canadian patent
704842 in the name of H.H. Robertson Company, the decking element
fixed to the top of the flat base sheet may be incomplete, with the
base sheet incorporating side lap joints. This also led the
inventors of the patent to adopt the unusual option of welding the
W decking without the lap joints upside-down to the underside of
the same decking with lap joints, thus forming a closed multi-cell
box deck. Similar decks are shown in Canadian patent 692135 in the
name of Inland Steel Products Company.
[0022] Japanese patent 11-192613 in the name of NKK Corporation
shows a form of cellular deck which includes a series of openings
in the webs of the trapezoidal ribs to accommodate transverse
reinforcing bars. It is not clear from the patent the way the
cellular deck is manufactured. In any case, the trapezoidal rib of
the panel is formed as one part and would therefore be of uniform
thickness like conventional decking. It could be that these
trapezoidal ribs (which could also be referred to as inverted
troughs) are individually welded to a flat plate to form an
inverted form of the cellular panel described in Burn's Australian
patent application 12620/70. The transverse reinforcing bars appear
to clip into the holes in the web sides, and most likely act as
shear keys in the final composite slab once the concrete has
hardened, noting that the concrete would fill the decking ribs and
encapsulate the bars. Another arrangement shown in the Japanese
patent application appears to comprise transverse reinforcing bars
welded to the tops of the trapezoidal ribs, presumably again to
promote composite action between the decking and the concrete.
(ii) The structural performance of a closed-rib decking produced in
Australia (Stramit's Condeck HP) has recently been improved by
screwing a continuous rib to the side of the lap joint when it acts
as formwork (see Fig. 1(d)).
[0023] This attachment is located on the top face of the decking
and is cast in the concrete and can potentially increase or
decrease the longitudinal slip resistance of the plain deck,
depending upon its design and the strength of its connection to the
rib.
[0024] However, in accordance with the manufacturer's
recommendations, the attachment is only connected to the steel
decking by three small screws placed through the rib sides (one at
the end support, one at mid-span, and one at the accessory end
within the internal span), and by two small screws or shot-fired
pins through the base of the accessory and into the steel beams at
the ends of the span being strengthened. Therefore, interaction
between the sheeting and the accessory is very limited. The
manufacturer discounts any improvement to the flexural stiffness of
the steel decking on account of the accessory. The moment
capacities of peak moment regions are assumed to increase, but the
increases claimed again only reflect a low level of longitudinal
shear connection between the decking and the accessory. Another
major disadvantage with this invention is that the accessory must
be fitted when the sheeting is in its final position in the
building. The manufacturer discounts any effect that the accessory
might have on the longitudinal slip resistance of the deck, which
could be an unsafe conclusion.
[0025] The description of the modified decks in items (i) and (ii)
above is not to be taken as an admission of the common general
knowledge in Australia.
DISCLOSURE OF INVENTION
[0026] The present invention is an alternative structural decking
system to the above-described systems.
[0027] According to the present invention there is provided a main
decking panel for a structural decking system that includes a
plurality of the main decking panels, with the main decking panel
including:
(a) a base component that includes a central pan and lap joints on
each side of the pan to enable adjacent main decking panels to be
positioned side by side in overlapping relationship; and
[0028] (b) a strengthening component in the form of an inverted
channel member secured to the base component, with the channel
member including two opposed side walls formed from web components
and a top formed from a chord component, and with the web and top
chord components being manufactured as separate components and
thereafter assembled together to form the channel member.
[0029] A significant advantage of the present invention is that the
use of separate components that are assembled together makes it
possible to optimise the structural requirements of the components
to the required performance of the components.
[0030] Preferably the central pan includes at least one
longitudinal stiffener.
[0031] Preferably the web components are secured to the base
component at locations between the longitudinal stiffener or
stiffeners and the lap joints.
[0032] Preferably the web components butt against the longitudinal
stiffener or stiffeners and/or the lap joints.
[0033] Preferably the lap joints are formed so that a successive
decking panel can be positioned in side by side overlapping
relationship with another decking panel by pressing the lap joint
of the successive decking panel downwardly over the lap joint of
the other decking panel.
[0034] Preferably the strengthening component is secured to the
base component at a plurality of discrete connection locations
along the length of the channel member.
[0035] Preferably the strengthening component is secured to the
base component at the plurality of discrete connection locations by
deformed sections of the components at the locations that interlock
the components together.
[0036] Preferably the deformed sections are button shaped.
[0037] The deformed sections may be formed by holding the
components together and pressing the deformed sections, such as
buttons, from one side of the components.
[0038] Preferably the web components and the top chord components
are assembled together by securing the components together at a
plurality of discrete connection locations along the lengths of the
components.
[0039] Preferably the web components and the top chord components
are secured together at the plurality of discrete connection
locations by deformed sections of the components at the locations
that interlock the components together.
[0040] Preferably the deformed sections are button shaped.
[0041] The deformed sections may be formed by holding the
components together and pressing the deformed sections from one
side of the components.
[0042] Preferably the web components include flanges and the web
and top chord components are secured together at the flanges.
[0043] Preferably the top chord component includes one or more than
one longitudinal stiffener.
[0044] Preferably the stiffener or stiffeners extend along the
length of the top chord component.
[0045] Preferably the top chord component includes down-turned
sides.
[0046] The longitudinal stiffeners and the down-turned sides of the
top chord component are provided to strengthen the decking panel.
Specifically the longitudinal stiffeners and down-turned sides
stiffen the top chord component to resist buckling due to
longitudinal compression loads.
[0047] Preferably the web components include corrugations.
[0048] Preferably the corrugations are vertical corrugations.
[0049] The corrugations are provided to strengthen the decking
panel. Specifically the corrugations stiffen the web components to
resist vertical and longitudinal shear.
[0050] Preferably the web components include openings to allow
concrete to flow into the channel member.
[0051] The decking panel may include a plurality of parallel
strengthening members.
[0052] According to the present invention there is also provided a
structural decking system formed from a plurality of the
above-described main decking panel positioned side by side with the
lap joints in overlapping relationship.
[0053] Preferably the structural decking system includes an infill
decking panel that is positioned between two main decking panels,
with the infill decking panel including lap joints on each side of
the pan that are in overlapping relationship with the lap joints of
adjacent main decking panels.
[0054] According to the present invention there is also provided a
composite slab that includes the above described structural decking
system and a layer of hardened concrete on the structural decking
system.
BEST MODES OF CARRYING OUT THE INVENTION
[0055] The main features of embodiments of the main decking panel
and the structural decking system of the present invention are
described below, by way of example, with reference to FIGS. 2 to
17.
[0056] It is noted that the main decking panels are described as
"hybrid" decking panels in the Figures.
[0057] The structural decking system of the present invention is
based on modules in the form of:
[0058] (a) main decking panels; and
[0059] (b) infill decking panels.
[0060] The main and infill decking panels are typically 2.5-9 m
long.
[0061] FIGS. 6-8 are vertical cross-sections perpendicular to the
lengthwise axis of embodiments of the main decking panel that
includes:
(a) an elongate base component that includes a central pan 7 and
lap joints 9 on each side of the pan to enable adjacent main
decking panels to be positioned side by side in overlapping
relationship; and
[0062] (b) an elongate strengthening component in the form of a
single inverted channel member that is secured to the base
component, with the channel member including two opposed sides 11
formed from web components and a top 13 formed from a chord
component, and with the web and top chord components being
manufactured as separate components and thereafter assembled
together to form the channel member.
[0063] In each of the above-mentioned embodiments the web
components are secured to the base component and the top component
is secured to the web components at discrete locations along the
lengths of the components. In the case of the embodiments shown in
FIGS. 6-8 the connections are in the form of deformed buttons 17
that interlock the components together. The nature of the
connections between the components is discussed further in a later
part of the description.
[0064] Each embodiment of the infill decking panel shown in the
Figures includes a central pan and lap joints on each side of the
pan that are formed to allow the infill decking panel to be
positioned in side by side overlapping relationship with the lap
joints of adjacent main decking panels.
[0065] Two specific embodiments of the infill decking panel 5 are
shown in FIG. 2(d). The Figures show cross sections perpendicular
to the lengthwise axis of the infill decking panels. The lower
embodiment of FIG. 2(d) has a flat pan 21 and lap joints 9 the
upper embodiment has a pan 21 with trapezoidal profile.
[0066] FIGS. 3-5 and 10-11 illustrate a series of different
combinations of main and infill decking panels connected together
in side by side overlapping relationship to form structural decking
systems.
[0067] Preferably the main decking and infill decking panels are
narrow single units (see FIGS. 3 and 4), ie units with a single
strengthening member in the case of the main decking panels.
Typcially, the main decking and infill decking panels are 200-350
mm wide. The present invention is not confined to this arrangement
and extends to arrangements in which there is more than one
strengthening member. The preference for narrow modules is to keep
the weight per unit length down and allow the panels to be used in
long lengths and lifted individually and easily handled on site by
workers.
[0068] Being the main spanning elements, the main decking panels 3
can be used by themselves (see FIGS. 3(a), 4(a) and 10).
[0069] Alternatively, infill decking panels 5 can be fitted between
the main decking panels to improve economy (see FIGS. 3(b), 4(b)
and 11), since they are less costly to manufacture than the main
decking panels, and to provide other benefits such as reducing
weight, etc.
[0070] Using infill panels 5 makes it possible to introduce voids
27 between adjacent main decking panels or to accommodate
longitudinal prestressing cables or reinforcing bars placed low in
a composite slab.
[0071] The main decking panels 3 are preferably placed in position
first to support the infill panels 5, which only span in the
transverse direction perpendicular to the main span.
[0072] The main decking panels 3 are preferably assembled from
purpose-built steel components (see FIGS. 2, 9 and 12).
[0073] The major dimensions (e.g. thickness, width and height) and
the mechanical properties of the steel components can be varied in
production to provide main decking panel designs that are more
economical than the known decking systems described above and which
can satisfy a much wider and more demanding range of design
requirements including achieving very long un-propped spans (e.g.
up to 8-9 metres) and allowing reinforced-concrete floors of
minimum overall depth to be built.
[0074] The different durability requirements of each component can
also be taken into account and the steel coatings can be varied to
improve economy.
[0075] The components of the main decking panels 3 and the infill
panels 5 can be efficiently packaged and transported to distant
assembly sites. This centralises main production, and can save on
transportation costs.
[0076] The web components of the main decking panels 5 can be
purpose-designed to provide high vertical shear capacity, thereby
allowing the decking panels to be pre-cambered during manufacture,
and to accommodate regularly-spaced, large unreinforced or
reinforced openings for multiple purposes including the passage of
transverse steel reinforcing bars and prestressing cables.
[0077] The web components of the main decking panels 3 may include
openings 29 punched along the length of the panel. Typical openings
are shown in FIGS. 14 and 17. This is particularly desirable in
situations when it is necessary to partially or entirely fill
channel members to form a solid concrete slab or to pass transverse
reinforcing bars and cables and/or building services. Two-way
acting concrete slabs can thus be constructed and the resulting
improvements in structural efficiencies compared with one-way
acting slabs can be achieved. For this purpose, the lap joints 9 of
the main decking panels (and the infill decking panels) should
preferably be shallow, e.g. 20-30 mm.
[0078] The openings 29 in the web components of the main decking
panels can be placed close to end supports and still perform
adequately. Typically, the nearer sides of the openings 29 are 2-3
times the height of the web components inboard of the end supports.
In addition, typically, the height of the openings 29 is no more
than 60% of the height of the web components. In addition,
typically, there is at least 15% web material clearance above and
below the openings 29. Computer-controlled punching equipment may
be used to place the openings 29 as required along the length of
the web components.
[0079] The web components of the main decking panels 3 may have
deep vertical corrugations 33 (see FIGS. 7 and 14). Preferably the
corrugations 33 have a pitch of 20-50 mm and a crest-to-valley
height of 3-6 mm. Preferably the corrugations 22 are stamped in the
web components. The corrugations 33 make it possible to achieve a
high level of vertical shear capacity with the thinnest possible
steel sheeting. For easier forming the grade of steel used in the
web can be reduced compared with the other components, which also
has economic benefits. For economy, the steel can be left uncoated
because it is later cast in concrete. This is also a way of
reducing glare from sunlight, which can be a safety problem for
workers on site working with metal coated decks. The height and
spacing of the openings in the webs can be varied along the length
of the main decking panels, e.g. to accommodate the passage of
transverse prestressing cables which normally vary in height above
a slab soffit.
[0080] The web components of the main decking panels 3 are
preferably roll-formed with a camber in their flat plane. This can
be achieved by varying the pitch of the vertical corrugations
slightly between the top and bottom regions of the web components
or by stretching the flanges.
[0081] Separately formed top chord component, web components, and
base component, with the web components having the above-described
camber, can be assembled on a curved bed to produce a permanent
upwards camber in the main decking panel (FIG. 17). This allows
bending strength rather than flexural stiffness to govern design,
which can lead to a significant reduction in the quantity of steel
needed to manufacture the main decking panels for any given
situation. It also means that a flatter soffit can be produced in
the final structure.
[0082] To assist with manufacturing, the web components of the main
decking panels 3 are preferably assembled at the same angle to the
vertical, irrespective of their overall height (see FIGS. 7 and 8).
Preferably the angle is in the range of 60-80.degree., more
preferably 70-80.degree..
[0083] The distance between the web components of the main decking
panels 3 at their connections onto the base component is also
preferably kept constant. Therefore, the longitudinal stiffeners of
the main decking panels vary in width across their tops, becoming
narrower as the longitudinal stiffener height increases.
[0084] The web components of the main decking panels 3 may have
outwardly angled flanges 35 or inwardly angled flanges 37 or
outwardly/inwardly angled flanges. The options are shown for
example in FIGS. 2-8 and 10-12. The options facilitate connection
of the web components to the top chord component and to the base
component.
[0085] There may be situations in which it is necessary to
strengthen the upper flanges 35, 37 of the web components. One such
situation is where the main decking system is subject to long wave
buckles that can lift the top chord component up to 5-10 mm and
straighten the upper flanges of the web components. Suitable
strengthening options include providing crimped stiffeners in the
corners between the flanges and the upstanding web of the web
components.
[0086] The openings 29 in the web components of the main decking
panels (FIGS. 14 and 17) can be partially stamped during
manufacture so that they can be selectively knocked out on the
building site as required.
[0087] By way of example, the openings 27 may be knocked out on
site over internal walls that run perpendicular to the span of the
decking. As a consequence, the decking does not create a void over
the walls, which can otherwise be a problem acoustically or for
fire rating.
[0088] It may also be necessary to locally fill the void with
concrete over the support in this manner if the support is a steel
beam and shear connectors are going to be fitted close to the steel
longitudinal stiffener of the main decking panel, which would
otherwise be weakened by rib punch-through.
[0089] The top chord component of the main decking panels 3 is
preferably purpose-designed to concentrate a large area of cheaper,
uncoated and lower-grade steel than base component near the
upper-most extremity of the steel deck. This is a highly efficient
way of enhancing the moment capacity and flexural stiffness of the
panels, under conditions of either positive or negative
bending.
[0090] The top chord component of the main decking panels 3 is
preferably designed to develop a sufficiently high level of
mechanical resistance with the hardened concrete so that it can act
as effective longitudinal tensile or compressive reinforcement in
the composite slab.
[0091] In part the mechanical resistance develops due to the
discrete connections between the top chord component and the web
components.
[0092] The top chord component may also include lengthwise
extending stiffeners 39 (FIGS. 7, 8, and 10-12) or its sides may be
downwardly turned (FIGS. 6-8 and 10-12) or deformed or punched to
improve the stiffness of the top chord component and therefore the
mechanical resistance without interfering with the integrity of the
connection between the components.
[0093] The top chord component of the main decking panels can be
designed to be compact, i.e. develop its rull potential compressive
capacity without failing prematurely by local buckling. This is
helped by the component being relatively thick compared with normal
steel decking. To be compact it is preferably attached to the web
components of the main decking panel at close centres
longitudinally along the length of the main decking panels.
[0094] Preferably the top chord component of the main decking
panels 3 is relatively wide so that it can form a large surface
area to walk on during construction and provides a wide support for
reinforcing bars laid transversely on top of the component.
[0095] Preferably the top chord component of the main decking
panels 3 is relatively thick compared with normal steel decking and
therefore is much more robust against accidental damage during
handling and on site.
[0096] Whilst it may not always be the case, generally the
thickness of top chord component will be greater than that of the
web components. Typically, the top chord component is up to 3-4
times the thickness of the web chord component.
[0097] The ends of the top chord component of the main decking
panels 3 may be manufactured with additional mechanical features
(e.g. embossments and punched tapered holes) that further enhance
the mechanical resistance developed in these regions, thus
significantly reducing the length of lapping bars required over
support regions in negative bending.
[0098] The top chord component of the main decking panels may be
manufactured with mechanical features (e.g. embossments 41--FIGS.
6-8 and 12) along the length to improve the mechanical interlock
with the hardened concrete.
[0099] The base component of the main decking panels 3 can be
purpose-designed to concentrate a large area of steel and develop a
large longitudinal tensile or compressive force near the lower-most
extremity of the steel deck. This is a highly efficient way of
enhancing the moment capacity and flexural stiffness of the panels,
under conditions of either positive or negative bending.
[0100] Preferably the base component of the main decking panels 3
includes longitudinal stiffeners 45 (preferably 20-30 mm high)--see
FIGS. 6-11.
[0101] The stiffeners 45 in the base component also facilitate
assembly of the main decking panels 3. Specifically, the sections
of the base component between the stiffeners 45 and the lap joints
9 form footprints for the lower flanges 35 of the web
components.
[0102] In addition, preferably the stiffeners 45 in the base
component are formed so that the lower upwardly extending sections
of the web components butt against the stiffeners and this
arrangement contributes to the mechanical interlock of the
components of the main decking panels.
[0103] The base component of the main decking panels can be
roll-formed from the thinnest possible galvanised high-tensile
steel sheeting, e.g. G550, 0.55 mm. The galvanising makes the
soffit of the decking durable, which can also be pre-painted for
additional corrosion resistance or for appearance and
functionality.
[0104] Preferably the base component of the main decking panels 3,
acting in conjunction with the web components and their
connections, is designed to develop a sufficiently high level of
mechanical resistance with the hardened concrete so that it can act
as highly effective longitudinal tensile or compressive
reinforcement in a composite slab.
[0105] The base component of the main decking panels can be
modified slightly to allow the component to be used as an infill
decking panel. FIG. 9 shows such a modified panel that can be used
as an infill panel. The panel shown in FIG. 9 includes embossments
61 and is formed with both lap joints 9 being adapted to be pressed
over lap joints of adjacent side by side positioned main decking
panels.
[0106] The infill decking panels can be purpose-designed to
economically cover a gap between adjacent main decking panels.
[0107] The lap joints 9 of the main and infill decking panels 3, 5
are preferably designed so that the infill decking panels can be
installed from the top once the main decking panels are in their
final position in the building (see FIGS. 5, 10, and 11). This
feature recognises the highly limited longitudinal spanning
capability of the infill decking panels compared with the hybrid
decking panels.
[0108] The infill decking panels are also preferably designed to
develop a sufficiently high level of mechanical resistance with the
hardened concrete so that they can act as effective longitudinal
tensile or compressive reinforcement in the composite slab. In
order to do this the lap joints may be specially designed to grip
concrete and the panels may be embossed (see FIG. 9) or otherwise
formed for this purpose.
[0109] The infill decking panels 5 may take on a variety of shapes,
e.g. flat (possibly including a slight camber) to give a final flat
soffit, or trapezoidal to create a ribbed one-way composite
slab.
[0110] The infill decking panels may also be fitted with internal
voids, such as styrene blocks, to reduce the volume of concrete
(FIG. 3(b)).
[0111] For economy, the panels are preferably roll-formed from the
thinnest possible galvanised high-tensile steel sheeting, e.g.
G550, 0.55 mm. The galvanising makes the soffit of the decking
durable, which can also be pre-painted for additional corrosion
resistance or for appearance and functionality.
[0112] The components of the main decking panels 3 can be assembled
together without using welding, and this is an advantage because it
allows pre-painted and other types of high-quality sheeting
coatings to be used on the exposed soffit of the panels that may
otherwise be damaged during a welding operation.
[0113] Non-welded connection options include glueing, deforming,
clinching (without perforating) and conventional mechanical
fasteners.
[0114] As discussed above, a preferred non-welded connection option
shown in the Figures is in the form of "buttons" 17 (FIGS. 6-8)
pressed from the components at the connection locations.
Specifically, the connections are formed by holding the 2
components together at the connection location and applying a die
to one side of the components and pressing through the components
and deforming the components and pressing a button of the deformed
material from the other side of the components. The end result of
this process is that the components are interlocked at the
connection locations and therefore the connectors can carry
longitudinal and transverse shear forces as required for a given
design.
[0115] The connection together of the components of the main
decking panels 3 provides an important contribution to the
mechanical resistance developed by these panels in the hardened
concrete. Also, the design of the connection between the
components, in particular the frequency of the connections along
the length of the panels, can be varied as required given the
particular load and support conditions that are likely to be
experienced in use of the main decking panels.
[0116] When openings 29 are punched in the web components of the
main decking panels 3, small air breather holes are preferably also
simultaneously punched in the tops of the web components to allow
air to escape from underneath the top chord components when
concrete is poured, thus ensuring that, with adequate vibration of
the concrete, the void formed by the steel longitudinal stiffener
of the main decking panel is effectively filled with concrete thus
allowing a solid slab to be formed.
[0117] The top chord component may also be provided with openings
(not shown).
[0118] The corrugated web components of the main decking panels 3
contribute as longitudinal steel in a composite slab, particularly
when the steel stiffeners of these panels are filled with concrete
and consequently the web components are sandwiched in the concrete
making longitudinal slip very difficult.
[0119] The main and infill decking panels 3,5 can be made to any
length.
[0120] Steel diaphragms 55 (FIG. 13) may be fitted near the ends of
the main decking panels 3 to strengthen the web components against
buckling due to large vertical reactions that occur in these
locations.
[0121] These diaphragms 55 can also act as plugs to the ends of the
channel members of the main decking panels preventing the ingress
of concrete when this is required.
[0122] Either an internal or an external type of steel diaphragm
can be fitted at locations where the main decking panels 3 extend
over temporary or permanent supports, if it is necessary to
strengthen the panels against buckling of the webs due to the large
vertical reaction.
[0123] Intermediate diaphragms or plugs can be fitted at a
designated distance in from the ends of the main decking panels 3,
and the openings in the web components can be punched out over this
distance only. This can be done to enhance the vertical shear
capacity of a composite slab in support regions. It can also be
done to form solid concrete flanges of composite beams when
composite slabs are shear connected to supporting steel or concrete
beams.
[0124] For a similar purpose, the small open lap joint at the
connection between a pair of main decking panels 3 and between a
main decking panel 3 and an infill decking panel 5 can be locally
squashed together or cut away to eliminate the void and therefore
not interfere with the performance of any shear connectors placed
near these joints if composite beams are formed with steel
supporting beams without having a detrimental affect on the
structural behavior of the main panels.
[0125] The infill panels 5 can be holed on site at any location to
accommodate vertical building services. The width of the panels may
be adjusted as necessary to suit the layout of the services.
Purpose-built bridging elements can be used to support any main
decking panels that are weakened by being cut to accommodate
vertical building services or otherwise be temporarily supported
from beneath.
[0126] The main decking panels 3 and infill decking panels 5 can be
pre-assembled in a factory or on the ground at the building site
into wider panels, with any transverse reinforcing bars required
for a given design situation being fitted through openings in the
web components of the main decking panels or being positioned to
sit on or be attached to the top chord components. These panels can
then be lifted into final position, normally by crane. If the
supports are not flat, and possibly even curved into an arch, then
narrow main and infill decking panels, including the transverse
reinforcement, will readily adjust to the shape of the
supports.
[0127] Longitudinal reinforcing bars or post-tensioning cables can
be supported in position so as to be cast in the lower regions of a
composite slab between adjacent steel stiffeners of the main
decking panels.
[0128] If voids formed by the channel members of the main decking
panels are not filled with concrete, then if necessary, alternative
materials can be used to improve thermal reflectivity and
insulation, e.g. mineral fibre, under fire conditions, and/or sound
insulation.
[0129] Typically, the main decking panels 3 and infill decking
panels 5 are used to construct composite slabs. However, they can
readily be used in different combinations and arrangements that
suit the construction of non-composite and composite beam and slab
arrangements, e.g. see FIGS. 15 and 16. In these types of
applications, the openings in the web components are preferably
removed on one side only of the main decking panels.
[0130] The use of galvanised decking materials can cause a high
level of reflection and glare to the installers. This is an
identified safety and occupational health and safety concern on
site. The use of dull (non galvanised) materials in particular for
the wide top chord component and web components of the main decking
panel can greatly enhance safety and worker comfort.
[0131] The use of thin material in the pans of the base component
of the main and infill decking panels 3,5 results in transverse
deflection between the channel members, with the greater this
distance the more pronounced the deflection. The attachment of the
web components of the main decking panels to the base component of
the panels reduces the effective transverse span and hence
deflection and hence minimises this as a design criterion for pan
thickness. The void in the infill decking panels component can also
act in a similar manner, reducing the transverse deflection and
allowing the use of very thin materials.
[0132] Many modifications may be made to the preferred embodiments
of the present invention described above without departing from the
spirit and scope of the invention.
* * * * *