Note: Descriptions are shown in the official language in which they were submitted.
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STRUCTURALLY INTEGRATED ACCESSIBLE FLOOR SYSTEM
BACKGROUND OF THE INVENTION
Technical Field
The present invention relates to floor structures in which space below the
floor is
accessible, and more specifically to an accessible floor structure that is
structurally
integrated with the associated building structure.
Description of the Related Art
The increase in the use of computers, communication devices, and other
electronic
hardware has placed new demands on building designers. Users desire a large
number
of outlets for access to electrical power and communication signals, and they
need the
ability to change the location of such outlets on a regular, sometimes
frequent basis.
Power and data outlets have been located in, or under, a floor, typically in
removable floor
sections elevated above the original floor by supports. Two typical types of
elevated floors
are the pedestal floor and the low-profile floor.
The pedestal access floor has pedestals that consist of metal rods with a base
plate at one end and a supporting plate on the other that supports removable
horizontal
panels, thus forming a raised floor structure. The metal rods are height
adjustable and
rest on a conventional solid floor deck. The solid floor deck may be made of
wood,
concrete, or a combination of metal deck and a concrete topping slab. The rods
are
arranged in a grid, typically square. The rods and plates support removable
floor sections.
The height of the rods is typically about 12 to 18 inches and can be adjusted
to a
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desired height prior to installing the floor sections. Electrical power and
data
cables are laid between the solid floor deck and the underside of the floor
sections. The cables penetrate the floor sections at a desired location to
suit
the user's needs. The penetrations may consist only of openings for cables, or
may be junction boxes, similar to common electrical wall outlets. The
penetrations may accommodate power wires, or signal cables such as cable
television, speaker wire, computer networks, etc. In some designs, the space
between the floor deck and the elevated floor sections is configured to enable
the distribution of conditioned air through grilles and/or registers located
in
selected floor sections. A flooring system of the type described above is
disclosed in U.S. Patent 3,396,501, issued to D.L. Tate on August 13, 1968.
There is a labor premium involved in having to locate and install
the foregoing pedestal system. The pedestals must be braced to meet seismic
code, further increasing labor and material costs. Moreover, the pedestals
increase ceiling height requirements, and ultimately the height of the
building,
especially if the building has many stories, which increases the area of the
exterior envelope, thereby increasing not only construction costs but also
operating costs due to heat loss. If the pedestal access floor is only used in
parts of a building, ramps or structural accommodations must be made for the
changes in floor elevation. As users re-route electrical cables below the
access
floor, the pedestals may present an impediment in pulling cables to a new
location. The access floor also represents another step in the construction
schedule. The acoustical properties of this system are poor. The floor panels
are usually relatively thin, and transmit sound both horizontally and
vertically.
A second type of elevated floor is a low-profile design, which may
be roughly 2% inches to 4 inches high. This design does not use pedestals to
raise and support the floor sections, but rather relies on "feet" at the
corners of
the sections to create the space above the solid floor deck and below the
underside of the panel. The panels, with low "feet," rest directly on the
floor
deck. This low-profile design is less costly than the pedestal floor, but
still
impacts the cost of a traditionally designed floor in a building because it
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requires the use of a solid floor deck. The problem of elevation changes
between the existing conventional floor and accessible floor also remains. It
may also increase the floor-to-floor height of a multi-story building, albeit
less
than a traditional pedestal floor.
There are also disadvantages to the low-profile floor compared to
the pedestal floor. The space below the low-profile sections is not deep
enough to be used to supply air. The resulting floor is not as stable, in
either
the horizontal or vertical dimension, as the pedestal access floor described
above. Since the sections are not fastened to the floor deck, they can move
when cable is being pulled and re-routed. In general, the smaller distance
between the solid floor deck and the surface of the floor sections decreases
the
flexibility of the low-profile floor. Both types require an underlying solid
floor
deck for support, and to provide structural stability to the overall building
structure.
In addition, the acoustical characteristics of both common types of
elevated floors are typically very poor. They tend to transmit noise to a
degree
that makes them impractical for use in many environments.
Another type of accessible floor is disclosed in U.S. Patent
3,583,121, issued to D.L. Tate on June 8, 1971. This system includes two
layers of bar joists laid one on top of the other at right angles thereto.
Panels
laid over the upper layer may be configured to be removable, to provide access
to space underneath. One disadvantage of this system is the height of the two
layers of joists and the added height this imparts to a building.
Additionally, the
joists must be laid at least as closely together as the width of the panels.
The
resulting weight and depth of the system is too great to be practical except
where particularly heavy loads are imposed on the floor. Also, the joists have
to be welded at each intersection greatly increasing field labor costs.
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BRIEF SUMMARY
In accordance with an embodiment, a floor assembly for a
building is provided, the floor assembly having a plurality of primary
structural
building members, a plurality of spaced-apart secondary structural building
members spanning the primary building members, a support grid on the top
surfaces of and rigidly coupled to the secondary building members, and a
plurality of panels mounted on the support grid to form the floor, with each
of
the panels individually removable from the support grid to provide access to
the
space beneath.
According to another embodiment, a prefabricated grid section is
provided, configured to receive a plurality of removable floor panels on an
upper surface. The grid section is configured to be rigidly coupled between
adjacent framing members of a building and to support a selected floor load.
The grid section also has sufficient strength and rigidity to be moved into
position and coupled to the framing members of the building as a single
preassembled unit. According to an embodiment, the grid section is sized to be
transported to a location of the building as an assembled unit.
According to an embodiment, a plurality of prefabricated grid
sections are rigidly coupled to each other and to framing members of the
building to comprise a structurally integrated floor. According to an
embodiment, the floor is configured to function as a building diaphragm.
According to an embodiment, a subfloor deck is provided, that is
coupled below an accessible floor and that includes area that is substantially
unobstructed by structural elements of the floor. According to an embodiment,
the subfloor deck is configured to function as a building diaphragm.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)
Figure 1 shows an isometric view of a section of the floor system
formed in accordance with one embodiment.
Figure 2 shows a detail of a structural support grid element of a
floor system formed in accordance with another embodiment.
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Figure 3 is a cross-sectional view taken along line 111-111 of a
portion of the floor system of Figure 1.
Figure 4 is a cross-sectional illustration of an alternative
embodiment of the floor system of Figure 3 taken along line IV-IV.
Figure 5 is a plan view of a floor system according to another
embodiment.
Figure 6 is a plan view of a floor system according to an
alternative embodiment.
Figure 7 is an isometric view of a further embodiment of a floor
system.
Figure 8 is an isometric view of a floor system illustrating an
alternative embodiment.
Figure 9 is a partially exploded view of a flooring system
according to another embodiment.
Figure 10 is a more detailed view of the system of the
embodiment of Figure 9.
Figure 11 shows a detailed view of a feature of the embodiment
of Figure 9.
Figure 12 is a cross sectional view of the portion of Figure 10
indicated at lines XII-XII.
Figure 13 is a partial cut-away plan view of the system of Figure
9.
Figure 14 is a cross sectional view of the portion of Figure 9
indicated at lines XIV-XIV.
Figure 15 is a cross sectional view of the portion of Figure 9
indicated at lines XV-XV.
Figures 16 and 17 are isometric views of floor systems according
to respective embodiments.
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DETAILED DESCRIPTION OF THE INVENTION
The structural elements of a building comprise the columns,
girders, beams, trusses, joists, braced frames, moment resistant frames,
vertical and lateral resisting elements, and other framing members that are
designed to carry portions of the dead or live load and lateral forces, and
that
are essential to the stability of the building. The term framing member is
used
in the specification and claims to refer to vertical and horizontal structural
elements that comprise portions of the frame of a building.
According to various embodiments, structurally integrated
accessible floor systems are provided. Such systems provide access to space
beneath the floor surface, typically by the use of removable panels. They are
configured to be integrated with the structural frame of a building in a
manner
similar to a conventional floor, and in some embodiments serve to transmit
lateral forces as well as acting as load bearing surfaces. They differ
significantly from conventional accessible floor systems in that they are not
configured to be supported by a solid floor deck, with or without pedestals. A
prior art accessible floor that is configured to be supported below by a
separate
floor surface is not a structurally integrated system, nor is it capable of
integration with a building structure, as the term is used herein.
According to a first embodiment, a structurally integrated
accessible floor system, hereinafter referred to as the floor system, is
designated generally as 100, and is shown isometrically in Figure 1.
Primary framing members 102 are provided, which are integral
parts of metal frame type buildings. Secondary framing members, such as
joists 104 are connected to the primary framing members 102, typically by
welding or riveting, although fasteners of various kinds, which are well known
in
the art, can be used. According to one embodiment of the invention, a
structural support grid 106 is then formed, bearing on the secondary framing
members 104. The grid 106 is configured to receive removable floor panels
108 in the openings 110 formed by the grid 106.
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The grid 106 is configured to span across the secondary framing
members 104 such that a plurality of floor panels 108 are supported by the
grid
between each secondary framing member 104, without the need for support by
a secondary framing member for each floor panel 108. For example, the grid
106 is shown in Figure 1 spanning across a distance D between two secondary
framing members 104 while supporting the width of three panels 108 in that
same distance. This is in contrast to conventional removable flooring systems,
in which each removable panel is generally supported by a grid having a leg,
post, or pedestal at each corner of each panel.
The removable floor panels 108 are of a uniform size to allow
interchangeability, and they may be provided with terminals or hookups 112 for
electrical power and communication access, and with vents or registers 114 for
ventilation.
For the sake of convenience and clarity, one type of power
terminal 112 is shown in Figure 1. However, it will be obvious to those
skilled
in the art that a wide variety of terminals may be used, including standard
110
volt sockets, coaxial cable terminals, fiber optical connections, heavy duty
power terminals, T2 connectors, etc. A user may further choose to provide an
opening in the panel to enable the passage of cable without the use of a
terminal. These and other options are considered to be within the scope of the
invention.
By the same token, a wide variety of means to transmit air and
gas may be used in place of the vent 114, including compressed air hookups,
vacuum lines, fans, directionally adjustable vents, filters, emergency gas
evacuation systems, compressed oxygen, 002, propane, nitrogen, etc.
Figure 1 also shows optional panels 116 attached to metal
channels 118, which are in turn affixed to the underside of the secondary
framing members. These panels 116 are ideally constructed of material that
resists fire, thus forming a fire block. The panels 116 isolate one story of a
building from the next, establishing fire protection, which may be required by
many building codes. The panels 116 attached to the underside of the
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secondary framing members enclose the space between the secondary
framing members. This enclosed space may be employed as a plenum for
HVAC. This can result in a financial savings, because ductwork is reduced or
eliminated. Partitions may be used within this space to permit discreet
sections
of the floor system to pressurize for use as a plenum.
Referring next to Figure 2, shown therein is a section of one
embodiment of the structural support grid 106. According to this embodiment,
the structural support grid comprises L-shaped rail members 202 affixed in
back-to-back relationship to T-shaped joint nodes 200 to form supports for the
removable floor panels. The nodes and rail members are standardized to
permit interchangeability.
It is to be understood that the rail members may have many
different cross-sectional shapes and node configurations. For example, some
alternative cross-sectional shapes include channel, "T", and square.
Figure 3 shows the floor system 100 in cross-section taken along
lines 111-111 in Figure 1. The removable floor panel 108 has a plurality of
layers,
including a top layer 300, which is configured according to the requirements
of
the particular application and may have a carpeted surface or a tile surface.
Alternatively, the top surface 326 may be formed using chemically resistive
materials for use in a lab or other caustic environments. The top layer 300
and
a bottom layer 306 are designed to provide structural stiffness to the panel
108
and are configured according to the structural and weight bearing requirements
of the particular application. Fire retardant layers 304 may also be
structural
and are composed of fire resistant materials such as gypsum, or other
appropriate material, and serve to inhibit the passage of fire from one side
of
the panel 108 to the other. An insulation layer 302 provides thermal and
acoustic insulation, and may be slightly oversized to provide a friction fit
in the
grid.
It will be understood that the composition of the removable floor
panels will vary according to the requirements of a particular application and
will in part be dictated by the anticipated environment, the required load
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carrying capacity, the desired appearance, the anticipated degree of noise
control, local building and fire codes, and other factors.
Although the removable floor panels 108 bear against the
structural support grid 106, panel fasteners 310 may be used to positively
attach the panels 108 to the structural support grid 106. In the embodiment
shown in Figure 3, the panel fasteners 310 comprise threaded fasteners that
pass from a lower surface of the structural support grid 106 into an opening
in a
lower surface of the removable panel 108 via an opening 311 in the rail
member 202 of the structural support grid 106. The opening 311 is oversized in
relation to the threaded fastener 310 to enable adjustment in the position of
the
removable panel 108 relative to the structural support grid 106. The threads
of
the threaded fastener 310 engage the removable panel and a hexagonal head
of the fastener 310 bears against the lower surface 324 of the support grid
106,
drawing the removable panel tight against the structural support grid 106.
Thus, in this embodiment access to the panel fasteners 310 is from beneath
the structural support grid 106.
According to one embodiment, the structural support grid 106 is
welded or otherwise rigidly fastened to the secondary framing members 104.
According to another embodiment, a leveling unit 308 is provided to control a
vertical distance 320 between the structural support grid 106 and the
secondary framing members 104. Figure 3 shows one of a plurality of similar
units that comprise the leveling system, which functions as described below.
As shown in figure 3, the leveling unit 308 includes a threaded rod
312 attached to a support plate 314 that bears against or is welded to an
upper
surface 322 of the secondary framing member 104. The threaded rod 312
passes through a lift plate 316 via an opening in the lift plate 316, with the
lift
plate 316 bearing upward against the lower surface 324 of the structural
support grid 106. The rod 312 is slideably received in an opening 307 formed
in the grid 106. A pair of jam nuts 318 on the threaded rod supports the lift
plate 316. The position of the jam nuts 318 on the threaded rod determines the
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distance 320 between the upper surface 322 of the secondary framing member
104 and the lower surface 324 of the structural support grid 106.
By adjusting each of the plurality of units of the leveling system,
the bearing surface 326 of the floor system 100 can be leveled, even if the
upper surfaces 322 of the secondary framing members are not level.
In another embodiment of the invention, leveling devices that are
functionally similar to the leveling unit 308 described above may be employed
between an upper surface 120 (shown in figure 1) of the primary framing
members 102 and the part of the secondary framing members 104 that bears
against the primary framing members. By adjusting the vertical distance
between the primary and secondary framing members, the level of the
structural support grid 106 can be controlled. Alternatively, shims 105 can be
used to level the secondary framing members. Once leveled, the secondary
framing members 104, the shims, 105, and the primary framing members 102
can be welded together to form a rigid connection.
Other methods of controlling the vertical distance (not shown)
between the primary and secondary framing members 102, 104, or between
the structural support grid 106 and the secondary framing members 104 will be
obvious to those skilled in the art. These methods include the use of wedges,
threaded devices that are accessed from above the floor system, automatic or
remotely adjustable devices, etc., all of which are deemed to be within the
scope of the invention.
Figure 4 is a cross-sectional view of a floor system 100, taken
along line IV-IV, and shows an alternative embodiment of the removable panel
108. In this embodiment, a flexible gasket 400 is affixed to the top edge 412
of
each panel 108, 109. The gaskets 400 of adjoining panels 108, 109 press
against each other, providing a seal between the removable panels 108, 109.
The seal may be employed to prevent spills from leaking through the floor
system. In applications where spills of caustic or dangerous fluids might be
anticipated, the composition of the gasket 400 is chosen to be resistant to
the
particular classes of substances in use. Multiple or interlocking gaskets may
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also be employed to provide a more secure seal. Alternatively, a single gasket
may be wedged between the adjoining panels 108, 109 after they are installed
on the structural support grid 106. The gasket 400 may also be used in
applications where it is desirable to control the movement of air or other
gasses
from one side of the floor system to the other.
Figure 4 also shows an alternative embodiment of the panel
fasteners. Here, the panel fastener 410 is accessed with a tool (not shown)
that is inserted from above the surface of the floor system into the center of
the
joint node 200. The panel fastener 410 is rotated approximately 45 . Fastener
blades 408 rotate from positions in slots (not shown) in the joint node 200
into
slots in the corners of the removable panels 406, locking them in place.
Other locking devices and systems will be evident to those skilled
in the art and are considered to be within the scope of the invention. Such
devices include those employing cam-type fasteners, devices that are
accessible from the surface of the removable floor panels, devices that latch
automatically when the removable floor panels are emplaced, etc.
Depending upon the height and local requirements, some
buildings include devices or methods of construction that provide earthquake
resistance. In conventional construction methods a solid floor deck functions
as a diaphragm, which is resistant to dimensional stresses. As will be
discussed later, elements of a structurally integrated floor system can,
according to various embodiments, function as a diaphragm.
According to one embodiment, and as illustrated in Figure 5, the
structural support grid 106 is attached orthogonally, relative to the primary
102
and secondary 104 framing members. Diagonal stays 422 are employed to
brace and provide the requisite stability to the structure. The stays 422 are
attached directly to the columns 424 of a building and pass underneath the
floor structure 420.
Figure 6 shows floor structure 440 according to an alternative
embodiment, in which the structural support grid 106 is oriented diagonally,
relative to the primary 102 and secondary 104 framing members. In this
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embodiment, the structural support grid 106 itself forms the diagonal bracing
that reinforces the building structure.
In a further embodiment, as shown in Figure 7, repositionable
walls 452 are employed as part of the structurally integrated accessible floor
system 450. These repositionable walls can comprise floor to ceiling room
dividers that are assembled on site, as shown in Figure 7, or prefabricated
and
installed as individual units, or alternatively they may be prefabricated
cubicle
dividers of the type common in office environments. The repositionable walls
452 are affixed directly to the structural support grid 104. Partial floor
panels
108a may be cut to the necessary size at the site, using conventional methods,
or may be manufactured in common dimensions. By affixing the walls 452 to
the grid 106 and employing partial floor panels, acoustical isolation is
enhanced
and the structural stability of the walls 452 is improved.
Electrical components in the walls 452, such as light switches,
thermostats, power connections etc, can be wired directly through the bottom
of
the walls via harnesses (not shown) connected to cables and connectors
underneath the floor panels 108. This is a significant advantage, especially
in
the case of cubicle dividers, over the methods currently in use, because
conventional cubicle dividers must bring power into open areas and may
involve complex interconnections between the dividers, and power drops from
ceilings. Other methods include the use of wireless technology for switches
and
controls. Such technology has the advantage that it doesn't require any wiring
connections in the walls.
Figure 8 illustrates an alternative embodiment 460 of the
invention in which structural support rails 462 are employed. The rails 462
span
the secondary framing members 104 and support the removable floor panels
108 on two sides. The floor panels 108 of this embodiment are configured to
have sufficient rigidity to span the space between the structural support
rails
462 without the additional support of cross rails or bracing.
Another embodiment of the invention is described with reference
to Figures 9-15. A floor system 900 is shown in Figure 9 as part of a building
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structure. The system 900 includes a prefabricated floor section 902 having a
first plurality of support rails 904. Each of the support rails 904 includes a
pair
of spaced-apart angle members running the full length of the section 902.
Cross-support rails 906 are positioned at regular intervals between the
support
rails 904, each adjacent pair of support rails 904 and cross-support rails 906
forming an opening configured to receive a removable floor panel 908 therein.
The prefabricated floor section 902 is configured to span
secondary framing members 909 of the structure. Connectors 910 are affixed
to an upper surface of the secondary framing members 909 in a regularly
spaced relationship, corresponding to the spacing of the support rails 904 of
the prefabricated section 902. The connectors 910 may be affixed to the upper
surface of the secondary framing member 909 by any appropriate method,
including welding, bolting, etc. Figure 10 shows each connector 910 as
comprising a pair of angle sections in a spaced-apart relationship. It will be
understood that the connector 910 may be formed from a single T-shaped
member or some other structure that provides the necessary spacing and
support for the support rail 904. The spaced-apart angle members 905 of each
support rail 904 engage the connector 910 to provide positive contact between
the prefabricated section 902 and the secondary framing member 909. Before
being attached to the connectors, the vertical position of each support rail
can
be adjusted so as to level the floor section 902 relative to the framing
members
909. The support rails 904 are affixed to the connectors 910 by a known
method such as welding or bolting. Alternatively, some of the support rails
904
of the prefabricated section 902 may be affixed to their respective connectors
910, while others of the support rails 904 may be allowed to rest directly on
the
connector 910 without being positively affixed thereto, or to extend over the
framing members without making any contact with the respective support rails
904. The connectors 910 may be preaffixed to the secondary framing member
909 prior to erection of the structure. For example, the secondary support
member 909 may have the connectors 910 affixed thereto at a fabricating plant
prior to shipment to a construction site.
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Spacers 922 are positioned and affixed between the spaced apart
angle members 905 of each of the support rails 904. The spacers 922 maintain
the spaced apart relationship of the angle members 905 in the embodiment
shown, the spacer is illustrated as a section of square rod positioned between
the angle members 905. Figures 10- 12 show the spacers 922 having
threaded holes passing therethrough, and positioned in locations
corresponding to the positions of the cross rails 906.
The prefabricated section 902 includes subfloor rails 912 affixed
to the underside of the prefabricated section 902 at right angles to the
support
rails 904. In the embodiment shown in Figures 9-15, the subfloor rails 912
comprise spaced-apart angle members 917 similar to those of the support rails
904, with square spacers 915 affixed between the angle members 917. The
subfloor rails 912 run the entire width of the prefabricated section 902, and
are
positioned such, that the subfloor rails 912 of adjoining prefabricated
sections
902 meet in an end-to-end configuration. Splice plates 914 affixed between
subfloor rails 912 of adjoining sections 902 join the subfloor rails of
adjoining
sections 902 together. By aligning and joining subfloor rails 912 of adjacent
sections 902 together, correct positioning and spacing of adjacent
prefabricated
sections 902 is assured. Secondary cross rails 916 are positioned in a spaced
apart relationship between adjacent sections 902 in positions corresponding to
the cross rails 906 of the prefabricated floor sections 902 to provide support
for
removable floor panels 908 to be placed between adjacent prefabricated
panels 902.
Gaskets 924 of resilient or semi-resilient material are positioned
between the floor panels 908. The gaskets 924 may be configured to improve
the sound dampening characteristics of the floor system 900. The gaskets 924
may also be configured to provide a seal between adjacent floor panels 908,
configured to prevent the passage of liquids or gasses therethrough. They may
be formed from material that is heat or fire resistant, to provide improved
fire
protection. In Figure 10, the gasket 924 may be seen to have a modified T-
shape in cross-section, with a lower portion sized and configured to fit
snugly
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between the spaced apart angle members 905 of the support rails 904, and the
cross rails 906. The gaskets further include flanges extending to the sides
and
configured to receive the upper portions 911 of the floor panels 908 thereon.
An upwardly extending portion of the gasket 924 rises between two adjacent
floor panels 908 to terminate at a height approximately flush with an upper
surface of the floor panels.
As disclosed in previous embodiments of the invention, the
removable floor panel 908 includes an upper portion 911 having dimensions
that are greater than a lower portion 913, such that, when a floor panel 908
is
appropriately positioned between support rails 904 on two sides and cross
rails
906 on two sides, the lower portion 913 of the floor panel 908 lies between
the
upright portions of the support rails 904 and cross rails 906, while the upper
portion 911 of the panel 908 extends over the support rails 904 and cross
rails
906. Typically, the floor panels 908 are configured to rest on the flanges of
the
gaskets 924, with the upper surface of the support and cross rails 904, 906
bearing the weight of the panels 908 and any load thereon. Such an
arrangement ensures a good seal between the panel 908 and the flange 924.
The lower portion 913 of the panels may comprise insulation and fire retardant
material. The lower portion 913 of the floor panels 908 may be sized and
configured to have a very snug fit in the space between the rails 904, 906 to
provide maximum sound and temperature insulation and fire protection.
Other embodiments may include floor panels configured to bear
against lower portions of the support and cross rails, or may even be
configured to fit entirely between the support and cross rails, with no part
of the
panel extending over the rails.
As shown in Figures 10 through 12, the floor panels 908 are
affixed in position by threaded fasteners 918 that engage threads in the
opening 930 of the spacer 922 of the support rails 904. The floor panel 908
includes a fastener recess 919 at each corner thereof. The fastener recess
919 defines a shoulder 928, against which a head of the threaded fastener 918
bears to maintain the floor panel 908 in position. A fastener 918 is provided
at
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each corner of the floor panel 908, and each fastener 918 bears against the
shoulders 928 of four adjoining removable panels 908. A fastener recess cap
920 is configured to fit in the fastener recesses 919 of four adjoining floor
panels 908, and to cover the respective fastener 918.
As shown in Figures 10, 14, and 15, the floor system 900 includes
deck support rails 934, running generally parallel to the subfloor rails 912,
and
the secondary framing member 909. The deck support rails 934 include
threaded spacers 938, similar to the spacers 922 of the support rails 904.
Threaded rods 926 engage the threaded spacers 915 of the subfloor rails 912
at a first end and the threaded spacers 938 of the deck support rails 934 at a
second end, supporting the deck support rails 934 a selected distance beneath
the section 902. Decking 932, such as, for example, corrugated decking of a
type commonly used in commercial construction to support concrete flooring, is
placed between deck support rails 934 to form a continuous subfloor deck 933.
The deck 933 provides a barrier between floors, preventing passage of fluids
and gasses, as well as objects dropped from above. It can also be used for
ducting or as part of a plenum enclosure for HVAC.
Suspended ceilings, lighting fixtures, fire control sprinklers, and
other utilities for the space beneath the floor system 900 of Figures 9-15,
such
as for a lower story of the structure, can be hung from or affixed to the
corrugated decking 932 or to the deck support rails 934. Fire resistant
paneling
such as gypsum board can also be affixed to the underside of the corrugated
decking 936 the deck support rails 934.
In manufacturing and assembling the floor system 900, much of
the system can be prefabricated and assembled prior to assembly in a
structure. For example, the floor section 902 shown in Figure 9 is an 8
foot by 8 foot prefabricated section, having 2 foot by 2 foot floor panels 908
installed therein. The prefabricated floor section 902 may include temporary
panels, which can be left in place until completion of construction at which
time
the temporary panels 908 are replaced with finished panels. Use of temporary
floor panels prevents damage to the finished panels during construction, and
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allows construction workers, painters, and finishers to work in floored spaces
without the requirement of providing protection for finished flooring. When
the
temporary panels are removed, they can be reused in subsequent projects,
thus providing additional savings to the manufacturer or contractor.
In assembling such a floor system, the secondary framing
members 909 are provided with the connectors 910 pre-attached. Each
section is lifted into place by a hoist or crane, and lowered onto the
connectors
910. Because of the configuration of the connectors 910 and the support rails
904, the floor section 902 is provided with positive positioning in the X-
axis.
As shown in Figure 9, each connector 910 provides positioning
for a support rail 904 from each of two adjoining panels 902 in an end-to-end
configuration. By drawing the support rails 904 of a section 902 tightly
against
the ends of the support rails 904 of a previously installed section 902,
positive
positioning in the Y-axis is assured. After the section 902 is correctly
positioned in the X- and Y-axes, the section is leveled through the use of
shims
or jacks, to bring the section into correct position in the Z-axis. When the
section is correctly positioned in the Z-axis, the support rails 904 of the
section
902 are affixed to the connectors 910, to lock them permanently in position.
This may be achieved by any of several known methods, including welding in
place, the use of bolts or rivets passing through the support rails 904 and
the
connectors 910, or any other acceptable method of attachment.
Next, splice plates 914 are affixed in position between subfloor
rails 912 of adjoining sections 902, secondary cross rails 916 are then
positioned and affixed to adjoining sections 902, and removable floor panels
908 are placed in the spaces created thereby, between adjoining sections 902.
Threaded fasteners 918 and fastener recess caps 920 are installed as
necessary to secure the removable floor panels 908. From underneath the
floor panels 902, threaded rods 926 are affixed to the threaded spacers 915 of
the subfloor rails 912, and to the threaded spacers 938 of the deck support
rails
934. Decking 932 is then laid between the deck support rails 934 to form the
continuous subfloor deck 933 and enclose a space under the floor system 900.
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The decking 932 can be affixed to the support rails 934 by any appropriate
means, including adhesives, rivets, welding, threaded fasteners, and snap-in
connections.
Referring to Figure 15, a single-sided support rail 934a is coupled
to a primary framing member 935 of the building, by welding or some other
acceptable means, and serves to support a periphery of the decking 932 and
couple the subfloor deck to the framing member. With the subfloor deck 933
attached around its perimeter to the building frame, the subfloor deck can be
configured to function as a building diaphragm.
The total height H of the floor system 900 (see Figure 14) above
the surface of the secondary framing members is selected to be approximately
equal to the height or thickness of a conventional steel and concrete floor of
the
type commonly used in hi-rise construction. In some cases a structure may
include a combination of conventional flooring with the structurally-
integrated
flooring according to the principles of the invention. Because the heights are
substantially equal, there is no requirement for ramps or height adjustment at
transitions from one flooring to the other.
While the embodiment of the invention described with reference
to Figures 9-15 is shown having particular selected dimensions, the dimensions
of the sections 902, the spacing of the rails 904, 906, 912, 916, and 934, the
dimensions of the panels 908, and other dimensions and parameters of the
system are selectable according to the requirements of a given application, or
preferences of the user.
Turning now to Figure 16, a structurally integrated accessible
floor system 800 is illustrated, according to another embodiment. Axes X, Y,
and Z are labeled to simplify description of the illustrated embodiment, but
such
designations are not to be construed as limiting the scope of the claims. The
system 800 comprises a plurality of grid members 802 lying parallel to the Y-
axis and extending between primary framing members 804 of a building.
Subfloor rails 806 extend transverse to the grid members 802 and are affixed
to
bottom surfaces of the grid members 802 to form rigid grid sections 808.
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Connectors 810 are affixed, typically by welds or bolts, at intervals to upper
surfaces of the primary framing members 804. First ends 812 of at least two of
the grid members 802 of each grid section 808 are received in corresponding
connectors 810 on a first of the primary framing members 804 and second
ends 814 of the at least two grid members 802 of each grid section 808 are
received in corresponding connectors 810 on a second of the primary framing
members 804. Each connector 810 is configured to receive a first end 812 of a
grid member 802 of one grid section 808 and a second end 814 of a grid
member 802 of an adjacent grid section 808.
Floor panels 816 are positioned to extend between adjacent grid
members 802 and to abut with each other so as to form a continuous floor
surface. Apertures 818 are provided in each corner of each panel 816, and
corresponding apertures 820 are provided in the upper surfaces of the grid
members 802. Fasteners 822 are provided and configured to traverse the
apertures 818 of the panels 816 and to engage the corresponding apertures
820 of the grid members 802 to securely attach each panel to the rigid grid
section 808.
A subfloor deck 830 extends beneath the grid section 808, and
comprises hanging fasteners 824, deck support rails 826, and decking material
828. The hanging fasteners 824 are coupled to respective grid members 802
and hang below the grid section 808. The deck support rails 826 are coupled
to the hanging fasteners 824 and are thereby supported below the grid section
808, and the decking 828 is in turn supported by the deck support rails 826
and
forms the surface of the subfloor deck 830.
According to an embodiment, the grid sections 808 of a building,
including grid members 802 and subfloor rails 806, are prefabricated and then
installed in the building during construction. The connectors 810 are attached
to the primary framing members 804, either prior to delivery of the steel to
the
building site, or during assembly. The grid sections 808 are lowered onto the
framing members 804 until the ends of the grid members 802 engage the
connectors 810. The connectors 810 are configured to limit movement of the
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grid members 802 in the X-axis while permitting movement in the Z-axis.
During installation, each grid section 808 is adjusted vertically until it is
substantially level, then welded or otherwise affixed to the respective
connectors 810 so that the grid section is rigidly held in a level position.
As
shown in Figure 16, the grid section 808 is configured to have sufficient
strength and rigidity that fewer than all of the grid members 802 need be
coupled to the primary framing members 804 by connectors 810. In
embodiments where this is the case, the ends 812, 814 of the grid members
that are not so coupled are be spaced above the framing members. When a
grid section 808 is installed adjacent to another in the Y-axis, with a
framing
member 804 between, each connector 810 is coupled to a first end 812 of a
grid member 802 of one of the sections and to a second end 814 of a grid
member of the adjacent section, thereby coupling the respective grid sections
808 to the framing member 804 and to each other. The ends 812, 814 of the
grid members 802 that are not received by connectors 810 are joined to each
other by appropriate means, such as, for example, butt-welds, gusset plates,
etc.
As grid sections 808 are installed adjacent to each other in the X-
axis, ends of the respective subfloor rails 806 are positioned very close to,
or
touching each other. After a grid section 808 is attached to framing members
804, ends of subfloor rails 806 of adjacent grid sections 808 are welded or
otherwise rigidly coupled to each other. According to an embodiment, subfloor
rail connectors 832 are slid over the ends of each of the subfloor rails 806
of an
installed section 808 before installing a grid section 808 that lies adjacent.
The
adjacent grid section 808 is then installed as described above, which results
in
the respective subfloor rails 806 of the adjacent grid sections lying with
their
ends actually or nearly touching. The subfloor rail connectors 832 are then
slid
back halfway across the joint between rails 806 and welded in place to rigidly
couple the two sections 808 together. Where a grid section 808 is positioned
adjacent to a framing member that lies parallel to the Y-axis, the
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ends of the subfloor rails 806 can be coupled to that framing member, by any
appropriate means.
Grid sections 808 that are rigidly coupled together and to primary
framing members to become components of a rigid floor grid that is
structurally
integrated with the associated building, and that is able, not only to support
vertical loads, but also to transmit lateral forces, and thus can function as
a
diaphragm of the building.
After the grid sections 808 of a floor are installed, the hanging
fasteners 812, deck support rails 826, and subfloor decking 828 are installed.
The hanging fasteners 812 can be coupled to the grid members 802 by any
appropriate means. For example, threaded nuts can be welded to the
undersides of grid members 802 and the hanging fasteners 812 provided with
threads to engage the nuts. Likewise, the deck support rails 826 can be
coupled to the hanging fasteners 812 by any appropriate means. Once the
deck support rails 826 are in place, the decking 828 is laid across the deck
support rails and fastened down by any appropriate means, which can include,
for example, welds, adhesives, and mechanical fasteners. The spacing of the
hanging fasteners 812 and deck support rails 826 is much greater than the
dimensions of the individual floor panels 816, resulting in a subfloor surface
that is largely unobstructed by structural elements. In the embodiment of
Figure 16, only one hanging fastener is coupled to each grid section 808. This
is in contrast to typical pedestal-type accessible floor systems in which a
pedestal is positioned at each corner of each floor panel. The subfloor deck
830 is preferably sized to extend beneath the entire floor, and can be coupled
around its perimeter to framing members of the building, in a manner similar
to
that shown in Figure 15, in order to function as a building diaphragm.
Panels 816 are installed, with fasteners 822 traversing apertures
818 in the panels and engaging corresponding apertures 820 in the grid
members 802. As described in more detail with respect to other embodiments,
the panels 816 can be configured to accommodate any specific requirements,
including air registers, electrical connectors, etc. Additionally, gaskets can
be
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provided for sound and vibration dampening. Such gaskets can be separate
components or integrated with each panel 816, as shown, for example, in the
embodiment of Figure 4.
In the embodiment shown in Figure 16, the grid members 802
and subfloor rails 806 are lengths of rectangular steel tubing, and the panels
816 are configured to be coupled to the upper surfaces of the grid members
and to contact each other to form a continuous floor surface. Accordingly, the
panels 816 are sized, at least in one dimension, to be about equal to the
center-to-center spacing of the grid members 802. According to other
embodiments, the panels 816 are sized and shaped to fit partially or
completely
between the grid members 802. Additionally, as previously described and
illustrated with reference to other embodiments, the grid members can include
flanges extending from and running along each grid member to support a lower
surface of the floor panels.
In the embodiment shown in Figure 16, the primary framing
members 804 of the building lie parallel to the X-axis on eight-foot centers.
Each floor section 808 is eight feet on a side, comprising four eight-foot
grid
members 802 and two eight-foot subfloor rails 806. The grid members 802
extend parallel to the Y-axis between adjacent primary framing members 804
on two-foot centers. The subfloor rails 806 lie parallel to the X-axis and are
centered along the X-axis across the four grid members and are coupled
thereto in positions, on the Y-axis, such that when the floor section 808 is
correctly positioned, each subfloor rail lies parallel to and about one foot
from a
center of one of the primary framing members 804. The floor panels 816 are
typically two feet on a side, and have sufficient stiffness and strength to
span
the distance between adjacent grid members 802 while supporting the
maximum rated load for a given building floor.
According to various embodiments, the dimensions, load-bearing
capacity, and spacing of the individual components of a grid section 808, as
well as the overall dimensions of the floor sections, are selected to meet the
requirements of the intended application. Such considerations are within the
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abilities of one of ordinary skill in the art. The maximum dimensions of the
floor
sections are preferably selected to permit the floor sections to be assembled
offsite and transported to the building site. For example, the U.S. Department
of Transportation currently imposes a width limit of 102 inches and a length
of
48 feet to semi-trailers on interstate highways, although wider or longer
loads
can be hauled with special permits. A grid section having dimensions of eight
feet (96 inches) on a side fits comfortably on a 102 inch flatbed semi-
trailer,
with six sections fitting lengthwise. Four 8 foot by 12 foot sections would
also
fit in the same space. A primary consideration in selecting the length of the
sections is installation, inasmuch as each section is lifted into place by
crane,
and longer sections will require more elaborate lifting harnesses and require
more time per unit to move into place. Of course, in jurisdictions where
trailer
size limits vary, the dimensions of grid sections transported by trailer can
also
be varied accordingly. Furthermore, where grid sections are transported by
other means, such as, for example, by water or rail, the dimensions of the
grid
sections can be selected to make economic use of such transportation.
The length of the hanging fasteners 824 is chosen so as to
support the subfloor deck 830 in a selected position relative to the primary
framing members 804. According to one embodiment, the subfloor deck 830 is
positioned below the primary framing members 804 a distance sufficient to
permit passage of utilities such as cables, pipes, and ducts that may be
required to extend beneath the framing members. According to other
embodiments, the subfloor deck 830 is positioned close against the bottom
surfaces of the primary framing members 804, or between the primary framing
members. In these embodiments, the utilities are configured to extend over the
framing members 804 below the panels 816 and between the grid members
802.
When a row of floor panels 816 extending parallel to the Y-axis
between two adjacent grid members 802 are removed, a large opening of
about two feet by about six feet is exposed, defined by two grid members 802
on the sides and by two subfloor rails 806 on the ends. This affords a
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significantly larger working space than the typical two feet by two feet
available
with prior art accessible floor systems. Additionally, the space between the
grid
members 802 and the subfloor deck 830, and between the primary framing
members 804, is completely unobstructed. It is therefore far simpler, in
comparison to traditional accessible floor systems, to service and move
materials in the subfloor space. In embodiments where utilities extend over
the
primary framing members 804, the subfloor rails 806 can be spaced further
from the framing members to provide additional working space near the framing
members.
Turning now to Figure 17, a portion of a structurally integrated
floor system 500 is shown, according to another embodiment. The floor system
500 includes a plurality of grid sections 504 coupled to each other and to
framing members 502 of the building, with a plurality of removable floor
panels
512 positioned on the grid sections to form a continuous floor surface. Each
grid section 504 includes a plurality of grid members 506 lying spaced-apart
and parallel to a first axis, and a pair of subfloor rails 508 lying parallel
to a
second axis, rigidly coupled to lower surfaces of the grid members and holding
them in position relative to each other. Cross members 510 are coupled by
clips 528 to extend between adjacent pairs of grid members 506 at evenly
spaced intervals.
Each grid member 506 comprises a pair of beams 514 coupled
together with spacers 516 between them to maintain a gap 518, and a plate
520 is coupled to an upper surface of the grid member. The beams 514 are,
preferably, cold-formed steel, and are made from heavy gauge sheet metal.
The plate 520 is steel and has a thickness, preferably, of about 1/8 inch to
1/4
inch. Each of a first plurality of holes 522 in the plate 520 receives a
respective
sheet metal screw to attach the plate to the beams 514. Each of a second
plurality of holes 524 in the plate 520 is threaded to receive a fastener, via
a
respective hole 526 in a floor panel 512, to couple the floor panels 512 to
the
grid member 506, permitting repeated removal and replacement of the floor
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panels. Mounting apertures 540 are provided at each end of the grid members
506, traversing both beams 514 of each grid member.
The beams 514 are shown as having a "C" profile, which is a
commonly available profile. However, any profile having the necessary
structural characteristics for a given application can be employed. The
selection of the appropriate profile is a design consideration that depends on
factors such as required load bearing capacity, spanning distance, appearance,
compatibility with other building systems, availability, etc., and is within
the
abilities of one of ordinary skill in the art.
In addition to providing a thickness of steel in which threaded
apertures 524 are provided to receive the fasteners by which the floor panels
512 are removably coupled to the grid members 506, plates 520 serve to
distribute loads to prevent or minimize deformation of the beams 514 that
might
result from heavy and concentrated point loads on the floor surface. According
to one embodiment in which such load distribution is not required, the plates
520 are omitted, and thread inserts such as are known in the art are affixed
to
the top surfaces of the beams 514 to receive the floor panel fasteners.
Each subfloor rail 508 comprises a pair of angle members 532
that are coupled together in a spaced-apart relationship. The grid members
506 are rigidly coupled to the subfloor rails 508 by any of a number of
acceptable methods, including screws, bolts, welds, adhesive, etc. The
subfloor rails 508 of adjacent pairs of grid sections 504 abut end-to-end, and
are coupled by connector plates 534 that are received between the angle
members 532 of the subfloor rails 508 and extend from one subfloor rail to an
abutting subfloor rail.
Connectors 536, each having a plurality of mounting slots 538,
are coupled to the upper surface of the framing members 502. They are
preferably welded to the framing members, but can be attached by any
appropriate method of attachment. The connectors 536 are configured to be
received in the gap 518 between the beams 514 of respective grid members
506 during installation of the grid sections 504. The grid members 506 are
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coupled to the connectors by bolts that extend through the mounting apertures
540 of each grid member 506 and the corresponding mounting slots 538 of the
respective connectors 536. Before the bolts are tightened, the elevation of
the
grid members can be adjusted to level the grid section 504.
Floor panels 512 are mounted to the grid section via threaded
fasteners that extend through apertures 526 and engage the threaded holes
524 in the plate 520. Gaskets 530, having, for example, an inverted "T" shape,
lie along top surfaces of the grid members 506 and cross members 510, and
receive edges of the floor panels thereon, with a portion extending into
spaces
between adjacent pairs of floor panels.
The cross members 510 serve primarily to provide a sealing
surface for the gaskets 530, and so are coupled to the grid members 506 at a
height that places a top surface of each cross member flush with top surfaces
of the plates 520. This provides coplanar surfaces of the cross members 510
and grid members 506 on which the gaskets 530 can be positioned so that the
gaskets can provide an adequate seal between the floor panels and the top of
the grid section. The cross members 510 are shown as being made from short
pieces of cold-formed steel having the same profile as the beams 514 of the
grid members 506. While this arrangement may provide some economic
advantages to the manufacturer, it is not essential. Provided the cross
members 510 present planar upper surfaces to receive the gaskets 530, they
can have any shape and be formed of any material that otherwise meet the
strength and rigidity requirements of a given application, and can be omitted
entirely in some embodiments.
In the embodiment shown in Figure 17, the floor panels 512 are
about two feet by two feet, and the grid section 504 is about eight feet in
the x
dimension by about twelve feet in the y dimension, which is a convenient size
to be transported by standard flatbed semi-trailer, although the scope of the
invention is not limited to these dimensions. Selecting appropriate dimensions
for floor panels, grid sections, and other components is a matter of design
choice for a given application. A number of factors may influence the
selection,
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including freight costs and dimension constraints, material supply, weight,
preferred units of measure, compatibility with other systems in a building,
local
codes, etc.
While not shown in Figure 17, the floor 500 can be provided with
a subfloor deck as described with reference to other embodiments. Hanging
fasteners for the subfloor deck can be coupled to grid members 506 or to the
subfloor rails 532. As with other disclosed embodiments, a complete floor
structure formed by a number of grid sections can be configured to act as a
diaphragm of the building structure into which it is integrated. Likewise, a
subfloor deck can also be configured to function as a diaphragm.
According to an embodiment, a fixture is provided that is
configured to receive components of a grid section 504 and hold them in their
correct relative positions so that an assembler can engage appropriate
fasteners to couple the elements, for preassembly of the grid sections, prior
to
transporting them to a building site to be installed in a building. The
assembly
fixture is preferably positioned at a height that is convenient to assemblers
working on a grid section, and may be configured to be adjustable in height to
accommodate different stages of the assembly. The assembly fixture includes
fixture beams that are rigidly held in a parallel and spaced-apart
relationship at
a distance that corresponds to the spacing of the framing members of the
building in which the grid sections 504 are to be installed. Upper surfaces of
the fixture beams lie in a common plane, within appropriate tolerances for the
given application. Assembly connectors are provided that are coupled to the
upper surfaces of the fixture beams, which are spaced in correspondence with
the spacing of the connectors 536 to which the finished grid section 504 will
be
coupled when installed in the building. Supports are also provided that are
configured to receive the subfloor rails 508 and to hold them in the
appropriate
position to be attached to the grid members 506.
During assembly, the beams 514 of the grid members 506 are
positioned on the assembly fixture and temporarily coupled to the assembly
connectors. Preferably, marks or stops are provide on the assembly fixture so
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that assemblers can correctly position the beams 514 without separately
measuring the relative position of each beam. The subfloor rails 508 are also
positioned on the assembly fixture. The assembly fixture can also be provided
with clamps or supports arranged to hold the beams 514 and rails 508 in
position during assembly. With at least the major components held in position
by the assembly fixture, an assembler fastens them together to form a grid
section 504. In some cases, smaller components, such as the spacers 516, for
example, can be positioned by hand during assembly, especially where precise
positioning is not essential. In other cases, such as with the cross members
510, in which the positioning is more critical, sub-fixtures can be provided
to
assist in positioning and attaching the elements. For example, according to an
embodiment, once an assembler has coupled together the grid members 506
and subfloor rails 508 of a grid section 504, a sub-fixture configured to hang
between a pair of grid members 506 is positioned. The sub-fixture is provided
with one or more slots sized to receive cross members 510 and hold them
correctly positioned relative to the grid members, so they can be easily
attached. The sub-fixture is also provided with stops or marks that are
positioned for alignment with the ends of the grid members 506, and other
stops that are positioned for alignment with previously attached cross members
510 so that the cross members of a grid section 504 can be accurately
positioned and attached without requiring measurement by the assembler.
In the embodiment of Figure 17, the subfloor rails 508 are
disclosed as each comprising a pair of angle members 532 coupled together in
a spaced-apart relationship. Subfloor rails 508 can be positioned on the
assembly fixture as preassembled subassemblies that are subsequently
attached to the grid members 506. Alternatively, the assembly fixture can be
configured to receive and hold each angle member 532 so that the angle
members can be coupled together to form the subfloor rails 508 during the
same process in which the subfloor rails are coupled to the grid members 506.
Likewise, other components can be positioned as preassembled
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subassemblies or can be assembled on the assembly fixture while the grid
section 504 is assembled.
The components of the grid section 504 can be largely assembled
with self-drilling sheet metal screws such as are well known in the art,
although
any appropriate fastener or process can be employed to couple the
components, including rivets, screws, nuts and bolts, welds or spot welds,
adhesives, etc.
According to one embodiment, the plates 520 are affixed to the
respective grid members 506 by only two or three fasteners. Then, once the
grid section is integrated into the structure of a building with other grid
sections,
installers can loosen the two or three screws holding the plates to the grid
members before attaching all of the floor panels 512 to the plates 520 via the
threaded apertures 524. With the screws loosened, the lateral positions of
each of the plates 520 of each grid section 504 can be adjusted slightly, in
order to make small corrections so that all of the floor panels will fit
properly.
Once a sufficient number of the floor panels are firmly attached, the
installer
can retighten the loosened screws and place additional screws in the remaining
apertures 522 to securely attach the plates 520 to the beams 514.
According to another embodiment, the plates 520 are laid on the
upper surfaces of the grid members 506 and the floor panels 512 are laid over
the plates and fastened thereto. The assembly of plates and floor panels is
then attached to the grid section 504 by a few screws, e.g., one screw in each
corner of the grid assembly, which is sufficient to hold the plates and floor
panels in place while being transported to the building site. After the grid
section 504 is attached to the framing members 502, the screws holding the
plates to the grid section are loosened or removed, and floor panels 512 that
bridge between adjacent grid sections are fastened to the pates 520 of the
respective sections. Any minor position adjustments necessary to bring all the
floor panels 512 into correct alignment are made, after which each of the
plates
520 is securely fastened to the respective grid member 506.
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According to a further embodiment, one or two large panels are
fastened, instead of the floor panels 512, to the plates 520 during initial
assembly of the grid sections 504. Each of the large panels is provided with a
plurality of holes in positions that correspond to respective ones of the
holes
526 in the floor panels 512 and the threaded holes 524 in the plates 520, so
that when the large panels are fastened to the plates, the plates are held in
the
correct positions relative to each other. The large panels are also provided
with
oversized holes in positions that correspond to the holes 522 in the plates,
which are provided for fastening the plates to the grid members 506. After the
large panels are attached to the plates 520, the assembly of panels and plates
is positioned on the grid section 504 and temporarily attached with a small
number of screws, as previously described.
During final assembly of the floor sections 504 to form the floor
system 500 in the building, additional floor panels 512 or temporary panels
are
attached as described above to bridge between the sections, and final position
adjustments are made. The plates 520 are then securely attached to the grid
members 506 via the oversized holes in the large panels. By providing the
oversized holes in the large panels, the plates 520 can be fully secured to
the
grid members 506 without the necessity of removing panels to access the holes
522 in the plates to place fasteners. The large panels can be removed and
returned to the fabricators for use on additional grid sections, or they can
remain in place during finish work on the building to provide a surface on
which
construction workers can stand and move around, and that does not require
special protection from common construction site hazards, such as spills or
dropped objects. When the building interior is largely finished, the large
panels
can be removed and reused, and replaced with floor panels 512.
The connectors 536 can be coupled to the framing members 502
at the building site, or prior to transporting the framing members to the
site.
According to an embodiment, a positioning fixture is provided that includes
slots sized and located to receive connectors 536 at the correct spacing. The
fixture is temporarily placed over a framing member 502. An operator places
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connectors 536 in each of the slots, then moves along the framing member and
welds each connector to the framing member. The fixture is then removed
from the framing member 502, leaving the connectors 536 correctly positioned
and attached. If the connectors 536 are to be installed after the framing
members of a building are assembled, the fixture can also be provided with an
element that aligns with or is coupled to a previously attached connector 536
on another framing member, in order to ensure that when the grid sections are
installed, they will fit and interconnect correctly.
The grid sections 504 of the floor system 500 are transported to a
building site as preassembled units.
As discussed elsewhere with regard to various embodiments,
preassembly of the grid sections provides some important benefits.
Additionally, embodiments that employ cold-formed steel components, as
described, for example, with reference to Figure 17, provide additional
advantages and benefits. These benefits include high strength to weight
ratios,
fast assembly, and reduced manufacturing and transportation costs. Finally,
because of the forming processes employed, cold-formed components can be
made to much closer tolerances with respect to their dimensions. Traditional
steel I-beams and other framing members that are formed in a foundry at very
high temperature can deform as they cool, resulting in final dimensions that
cannot be held to very close tolerances without additional working and
expense. In contrast, cold-formed framing members can be formed to very
high dimensional tolerances, meaning that there is less rejection or rework of
components during assembly of the grid sections and during installation of the
grid sections into a building structure.
In a conventional building, a typical prior art elevated floor system
is installed on top of an existing floor. The elevated floor occupies a space
above the floor, and is not part of the building structure. The accessible
vertical
space provided by such an elevated floor is that space between the panels that
form the surface of the elevated floor and the upper surface of the solid
floor
deck. In the structurally integrated accessible floor system of the
embodiments
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of the invention described herein, the solid floor deck is not needed. The
removable panels provide access to the space beneath the grid and between
the individual secondary framing members. In prior floor structures, this
space
is inaccessible and wasted. Because the structural support grid of the present
invention spans the secondary framing members, the space beneath is
unobstructed, providing simplified access for pulling cables and laying
conduit,
ducting, and pipe.
Building codes in most jurisdictions require that building
structures have some degree of resistance or tolerance to earthquake motions,
the degree of which may depend on the dimensions of the building and the risk
of seismic activity in the particular region. Building structures resist the
lateral
forces of an earthquake ¨ as well as those exerted by high winds on building
faces ¨ by transmitting the lateral forces from upper stories to the ground.
The
structural elements for transmission of such forces define a building's "load
path," and include vertical and horizontal elements that are rigidly coupled
together. Vertical elements can include, for example, shear walls, moment
frames, and braced frames. Horizontal elements can include one or more
diaphragms and the foundation of a building. A diaphragm is a structure that
transmits and distributes lateral loads from vertical elements above it in the
building to elements below, where the loads are eventually transmitted to the
ground via the building foundation. Typically, the floors of a building are
engineered to function as diaphragms, while the vertical-load bearing framing
members are assembled so as to form moment frames and braced frames to
transmit the lateral forces downward toward the foundation. The structural
principles described above are very well known in the art.
Structural engineers use the terms rigid, semi-rigid, and flexible to
classify the behavior of a diaphragm. In particular, the terms refer to the
degree to which a diaphragm will deflect out of the horizontal plane in
response
to a lateral force, relative to the vertical deflection of the vertical
elements in
response to the same force. Thus, a diaphragm having a given degree of
stiffness can be classified as rigid, semi-rigid, or flexible, depending on
the
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stiffness of the vertical elements to which it is attached. However, such
considerations are beyond the scope of the present disclosure. Accordingly,
where these terms are used in the disclosure and claims, unless used to modify
the term diaphragm, they are not to be construed as referring to the
particular
classification of a structurally integrated floor or portion thereof, even
though a
physical embodiment of that floor may be configured to function as a
diaphragm, and if so will certainly be subject to such classification.
For the purposes of the present disclosure, the term rigid is to be
construed as referring to the stiffness of the element indicated, and if used
with
reference to a coupling or connection, it refers to the stiffness of the
coupled
elements relative to the stiffness of the coupling. For example, if two
elements
are described as being rigidly coupled together, the joint at which they are
coupled is no more flexible than the material of the elements. A weld can be
considered a rigid coupling because relative movement of elements that are
welded is substantially limited by the flexibility of the elements, and can
only be
exceeded by removing or destroying the weld. This is in contrast to a flexible
coupling, in which the joint is more flexible than the elements coupled,
permitting some degree of relative movement beyond what would be possible if
the elements and joint were all formed in a single piece.
Prior art pedestal based accessible floor systems cannot function
as diaphragms for several reasons. First, they are not generally connected to
the structure of the building in a way that allows them to receive or transmit
lateral forces. Second, their grid elements are not typically coupled rigidly
to
each other, but instead are clipped or slotted in some fashion to each other
and
the supporting pedestals. This permits relatively simple on-site assembly, and
gives them the flexibility necessary to be adjusted and leveled at each
pedestal, but because of the lack of rigid connection, does not provide a
reliable load path to transmit forces. Finally, because they are intended to
be
supported by a rigid floor deck that itself acts as a diaphragm, they are not
engineered with such a function in mind.
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As noted above with respect to the secondary framing members
104 of Figure 1 and the connectors 910 of Figure 9 and 810 of Figure 16, the
floor system of many of the embodiments can be rigidly coupled to framing
members of the building, and can thus provide the load path necessary to
transmit lateral forces to and from the floor system, which thus acts as a
diaphragm for the building. In some embodiments, where the floor panels are
configured to be fastened to the support grid, the installed floor panels
enhance
the lateral strength of the floor system and contribute to the diaphragm
function
of the system.
According to other embodiments, in which the floor system is
provided with a subfloor deck, such as that described above with reference to
Figures 10 and 14-16, for example, the subfloor deck can also be configured to
function as a diaphragm.
The costs of a structurally integrated floor system according to the
principles disclosed herein are significantly mitigated by several factors. A
conventional structural floor is not required, and the floor system is
essentially
the same height as a conventional structural floor, obviating the need for
ramps
in areas where conventional floors adjoin the floor system. The floor is
installed
during building construction, saving the added labor of installing an elevated
floor after completion of the building. Especially where the floor is
installed as
prefabricated sections, installation time and labor is less than that of a
conventional floor of a building. Additionally, assembly of the sections is
done
in a factory environment, which is easier and faster than on-site assembly,
and
permits higher quality control, which in turn results in more accurate and
consistent spacing of the components, and less reworking. Because the floor
system does not add height per story to the final building structure, there is
a
savings in building materials, and a savings in operating costs over those of
a
building with the same number of stories using accessible floors according to
the prior art. Where building codes impose height limits on new construction,
it
may be possible to build more stories within the limits because of the
reduction
of height per story. Also, because the space under the floor system is
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substantially unencumbered by pedestals, feet, or other support devices, the
floor system has improved flexibility and changeability. Pulling cable, laying
conduit and pipe, and installing ducting are all simplified. The labor costs
and
down time costs are reduced during changeovers. This floor system also
allows the incorporation of, and relocation of, egress lighting in the floor
system, as a part of the gasket systems, or the vertices of the panels, for
example. The gaskets can also be provided with perforations to allow the
passage of gas through the gaskets.
An additional cost savings over conventional construction
methods is realized by the reduction in structural weight provided by the
implementation of an embodiment of the invention. Flooring manufactured
according to the principles of the invention can have a per square foot weight
of
less than half that of conventional high-rise flooring. Such a weight savings
can
exceed 20 to 30 pounds per square foot, without reducing the weight bearing
capacity of the floor. This savings translates to a reduction in the costs of
bringing construction materials to a construction site, the costs of
assembling a
structure, the mass and cost of materials required to support a structure, and
finally, affords the architect structural options that were heretofore
unavailable
due to the weight of the structure.
Advantages of the use of a sub floor space as a plenum for HVAC
have been known previously. However, because of the inaccessibility of that
space in conventionally constructed buildings, or the cost of conventional
removable flooring systems, the associated effort and expense of employing
sub floor spaces as plenums have outweighed the benefits, in most cases.
With the implementation of the principles of the invention, the costs are much
reduced. Sub floor spaces can be easily partitioned such that large areas of a
floor have pressurized, conditioned air, to be accessed as desired.
Accordingly, ventilation can be inexpensively modified to suit varying needs
and preferences, simply by exchanging floor panels with panels having the
desired configuration. By the same token, return plenums having negative
CA 02762775 2016-11-15
pressure can also be configured inexpensively. The need for expensive air
ducting and
channeling can thereby be significantly reduced or eliminated.
The abstract of the present disclosure is provided as a brief outline of some
of the
principles of the invention according to one embodiment, and is not intended
as a
complete or definitive description of any embodiment thereof, nor should it be
relied upon
to define terms used in the specification or claims. The abstract does not
limit the scope
of the claims.
Terms that refer to relative position or orientation, such as top, bottom,
upper,
lower, horizontal, vertical, etc., are used with reference to elements as they
would be
situated when correctly positioned in a completed structure, according to
their function.
References to ordinal axes in the drawings and specification, i.e., X-axis, Y-
axis,
and Z-axis, are to assist in clearly describing the embodiments, and do not
limit the claims.
Generic references to axes in the claims, e.g., first and second axes, do not
necessarily
correspond to particular ones of the ordinal axes, unless specifically recited
as such.
Ordinal numbers, e.g., first, second, third, etc., are used in the
specification and
claims for the purpose of clearly distinguishing between elements or features
thereof.
Unless explicitly stated, the use of such numbers does not suggest any other
relationship,
e.g., order of operation or relative position of such elements. Furthermore,
ordinal
numbers used in the claims have no specific correspondence to those used in
the
specification that refer to elements of disclosed embodiments on which those
claims may
read.
Elements of the various embodiments described above can be combined, and
further modifications can be made, to provide further embodiments without
deviating from
the spirit and scope of the invention. Aspects of the
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embodiments can be modified, if necessary to employ concepts of the various
patents, applications and publications to provide yet further embodiments.
These and other changes can be made to the embodiments in
light of the above-detailed description. In general, in the following claims,
the
terms used should not be construed to limit the claims to the specific
embodiments disclosed in the specification, but should be construed to include
all possible embodiments along with the full scope of equivalents to which
such
claims are entitled. Accordingly, the invention is not limited except as by
the
appended claims.
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