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BACKGROUND OF THE INVENTION
This invention relates to grids or gratings useful for open or filled
bridge decks, walkways, drain gratings and the like and more particularly,
this invention relates to grids or gratings that are constructed and held
together without welding.
In making prior gratings for bridge decks, whether the deck is open or
filled with concrete, a certain amount of welding is performed to hold or
bind the individual components together. That is, if the grid is used for
open grating or open bridge deck, the main load-bearing members, secondary
load-bearing members and tertiary load-bearing members are welded
together, usually by puddle welding, to hold the members together and give
the deck or grating strength. Even if the grid or deck is to be encased in
concrete, still some welding is required to hold the assembly in a rigid
configuration until the concrete hardens. If only minimal welding is
performed, then the deck or grid work when encased in concrete has a
decreased level of strength. Thus, for peak bridge strength, the various
components of the grating or bridge deck must be fastened together to
perform as a unit.
Various deck or grating systems have been proposed in the art, and the
members comprising the grating deck are welded together. For example, U.S.
Pat. No. 3,260,023 discloses a bridge floor and surfacing component. The
bridge floor comprises parallel bearer bars and cross bars. The cross bars
are pressure welded into the tops of the bearer bars.
U.S. Pat. No. 4,865,586 discloses a method of assembling a steel grid and
concrete deck wherein the primary load-bearing bars are formed with
openings to receive slotted secondary load-bearing bars that are passed
through the primary load-bearing bars. However, the patent discloses that
tack welds are used to temporarily hold the grating in its desired
configuration. A concrete component encases at least the top surface of
the grating base member and secures the elements of the grating base
member together.
U.S. Pat. No. 2,128,753 discloses a steel floor construction having a
series of parallel main bars in spaced relationship. Each of the main bars
is provided with a plurality of rectangular-shaped openings. The openings
are designed to permit the insertion thereon and the positioning of two
cross bars. A third set of bar is placed in slots in the cross bars. After
the members are assembled, the entire construction may be welded together
to maintain the different parts in position.
U.S. Pat. No. 2,190,214 discloses a grating wherein a desired number of
parallel spaced apart main bearer bars with intermediate bearer bars of
less depth are placed between the main bearer bars. The main bearer bars
and intermediate bearer bars are connected at their tops by cross bars
secured thereto by electric pressure welding. Carrier bars which pass
through slots in the main bearer bars are welded to the intermediate
bearer bars. Also, carrier bars are welded to the main bearer bars.
U.S. Pat. No. 2,645,985 discloses an open floor grating having a plurality
of longitudinal primary members, a plurality of transverse secondary
members welded to and extending between the primary members. A plurality
of tertiary members are welded to the secondary members. A rod is inserted
through holes in the webs of the primary members and welded thereto.
U.S. Pat. No. 2,834,267 discloses a grating comprised of a plurality of
spaced parallel main longitudinal bars and a plurality of spaced parallel
lacing bars and tertiary longitudinal bars intermediate the main bars.
Bottom bars are inserted through holes in the webbing of the main bars.
The intersection between the lacing bars and the tertiary bars are welded
and the bottom bar is welded to the webbing of the main bar.
U.S. Pat. No. 4,452,025 discloses a self-interlocking grille consisting of
a plurality of metallic or plastic strips or flats or bars with certain
types of notches and holes disposed along the length of the strip or flats
or bars in a regular interval, which are used together with a plurality of
rods in assembling a variety of interlocking grills.
U.S. Pat. No. 4,780,021 discloses an exodermic deck conversion method for
converting a conventional grid deck to an exodermic deck. Tertiary
load-bearing bars are placed on top of the grating parallel to and between
the primary load-bearing bars. A plurality of shear connectors, such as
vertical studs, are welded or attached to the surface of the grating. It
will be seen from the above that in gratings and bridge decks, usually
some form of welding or cement is used to hold the assembly together.
However, welding gratings or deck structures have the problem that toxic
fumes are released into the atmosphere causing health hazards to the
welders and pollution of the environment. Welding of structures such as
bridge decks results in curling or deforming of the deck as the welds
cool. Thus, the design of the deck is complicated in that the curling or
deforming must be accommodated in the design. Further, welding has the
disadvantage that it is time consuming and often is the rate-determining
step at which decks can be built. Welding also requires that the gratings
or deck assemblies be maintained in jigs prior to starting the welding
process. This is an additional, undesirable step in the process of making
a bridge deck. Further, welds on bridge decks have the problem of cracking
either with use or as the temperature cycles between winter and summer. It
is desirable to rustproof gratings by galvanizing. However, because
galvanizing is destroyed by welding, the welded grating or deck is often
galvanized as a unit. However, this also results in temperature
cyclization and warping of the bridge deck with the result that welds
often break, detrimentally affecting the integrity of the deck.
Thus, it will be seen that there is a great need for an improved bridge
deck or grating which will eliminate these problems and will provide for
an improved deck or grating structure. The present invention provides such
a structure.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved grating.
It is another object of the invention to provide a grating suitable for use
on bridge decks.
It is a further object of the invention to provide an interlocking grating
fastened together without welding.
Still, it is another object of the invention to provide an interlocking
grating which may be used for open bridge decks or may be utilized with a
concrete component that encases at least a top portion of the grating.
Yet, it is a further object of the invention to provide an interlocking
grating for bridge decks and the like employing a primary load-bearing
member and a secondary load-bearing member securely held together without
welding.
And yet, it is an additional object of the invention to provide an
interlocking grating for open or concrete encased bridge decks and the
like employing a primary load-bearing member, a secondary member and a
tertiary load-bearing member held together without welding.
These and other objects will become apparent from the drawings,
specification and claims appended hereto.
In accordance with these objects, there is provided a grating comprising:
(a) a plurality of longitudinally extending primary load bearing members
having a top portion and a bottom portion having a plurality of
spaced-apart slots therein extending downwardly through the top portion,
the slots in each of said primary load bearing members being aligned with
the slots in adjacent primary load bearing members; (b) a plurality of
secondary load bearing members having a top portion, the secondary load
bearing members positioned in the aligned slots in the primary load
bearing members, the secondary load bearing members provided with slots
extending downwardly through the top portion and located between said
primary load bearing members; (c) a plurality of tertiary load bearing
members positioned in the slots in the secondary load bearing members; and
(d) a rod extending through said tertiary load bearing members and said
primary load bearing members locking said tertiary load bearing members in
the slots in said secondary load bearing members and locking said
secondary load bearing members in the slots in said primary load bearing
members to form said grating.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a grating in accordance with the invention
utilizing deep web primary load-bearing members.
FIG. 2 is a perspective view showing the parts of the grating of FIG. 1 in
unassembled relationship.
FIG. 3 is an end view along the primary load-bearing members showing a pan
mounted on upper ribs of the primary load-bearing members to contain wet
concrete.
FIG. 4 is an end view along the primary load-bearing members showing a pan
mounted on lower ribs of the primary load-bearing members to contain wet
concrete.
FIG. 5 is a perspective cutaway view of a grating utilizing a deep web with
concrete encasing the top portion of the grating.
FIG. 6 is a perspective view of a grating utilizing an inverted T-shaped
primary load-bearing member.
FIG. 7 is a perspective view showing the parts of the grating utilizing the
inverted T-shaped web of FIG. 6 in unassembled relationship.
FIG. 8 is an end view along the inverted T-shaped web showing a pan for
containing wet concrete.
FIG. 9 is a perspective cutaway showing the grating of FIG. 6 encased in
concrete.
FIG. 10 is a perspective view of the pan of FIG. 4.
FIG. 11 is an end view of the pan of FIG. 3 showing tabs to lock the pan in
place.
FIG. 12 is an end view of the pan of FIG. 4.
FIG. 13 is a top view showing a top view of a grating having a tertiary
load bearing member having a zigzag configuration.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Referring now to FIG. 1, there is shown a grating in accordance with the
present invention. Grating 2 is comprised of a plurality of primary
load-bearing bars 4, a plurality of transverse secondary bars 6, a
plurality of tertiary bars 8 shown running substantially parallel to the
primary load-bearing bars 4. A rod 10 is shown laced through web 12 of
primary load-bearing bar 4 and tertiary bars 8.
In FIG. 2, the primary load-bearing bars 4, transverse secondary bars 6,
tertiary bars 8 and rod 10 are shown in an unassembled relationship. It
will be seen that primary load-bearing bars 4 have slots 14 cut out to
receive secondary bar 6. Slot 14 should be of a sufficient width to
provide a snug fit for bar 6. Thus, each primary load-bearing bar 4 has a
plurality of slots to receive each secondary load-bearing bar 6. Further,
each secondary load-bearing bar 6 has a plurality of slots 16 that align
with slots 14 in primary load-bearing bar 4 when assembled.
The depth of slots 14 and 16 in primary load-bearing bar 4 and secondary
load-bearing bar 6 is normally about one-half the depth of secondary
load-bearing bar 6 such that edges 18 and 20 when assembled form a planar
surface. It should be understood that slots 14 and 16 may be cut to a
depth to provide a raised edge 18 or 20, if necessary.
Further, it should be understood that slots 14 and 16 may be cut to
accommodate each other. That is, if slot 14 is cut deeper than half of bar
6 then slot 16 may be cut shallower to provide for a planar surface.
Secondary load-bearing bar 6 has a plurality of spaced-apart slots 22 on
edge 20. In the embodiment shown in FIG. 2, two slots 22 are shown on
secondary load-bearing bar 6 between primary load-bearing bar 4. Slots 22
are provided to accommodate tertiary load-bearing bars 8 which in the
embodiment shown in FIG. 2 are mounted substantially parallel to primary
load-bearing bar 4. It should be understood that one tertiary load-bearing
bar 8 may be used between primary load-bearing bars 4. It will be
appreciated that different combinations of bars may be used, all of which
are encompassed within the scope of the invention.
Tertiary load-bearing bars 8 are provided with a plurality of slots 24 for
alignment with slots 22. In assembly, slots 24 line up with slots 22 so as
to provide a planar surface, if necessary. To provide a planar surface,
slots 24 and 22 should have a depth equal to half the depth of tertiary
load-bearing bar 8. However, as explained earlier, if it is desired to
have tertiary load-bearing bar 8 project above edge 20, then slot 22 may
be shallower. Also, as explained earlier, any combination of slot depths
may be used to provide either a planar surface or a ridge or rough surface
for traction. Also, in some cases, the secondary load bearing member may
not be provided with slots 16, provided slot 14 is sufficiently deep to
accept bar 6. Similarly, slots 24 may be eliminated if slots 22 are
sufficiently deep in member 6.
Thus, it will be seen that in assembly, primary load-bearing bars 4 are
first placed or fixed in position and then secondary load-bearing bars 6
are placed across primary load-bearing bars 4 with slots 14 and 16 in
alignment. Thereafter, tertiary load-bearing bars 8 are placed across
secondary load-bearing bars 6 with slots 22 and 24 being aligned.
For purposes of locking the assembly comprised of primary load-bearing bar
4, secondary load-bearing bars 6 and tertiary load-bearing bars 8, an
aperture 30 is provided in primary load-bearing bars 4 between secondary
load-bearing bars 6, the aperture being formed to have an axis
substantially parallel to secondary load-bearing bars 6. Likewise,
tertiary load-bearing bars 8 have apertures 32 formed so as to be in
alignment with apertures 30 of primary load-bearing bars 4. Rod 10 then is
fitted through a first aperture 30 in a first primary load-bearing bar 4,
then through apertures 32 of tertiary load-bearing bar 8 and finally
through a second aperture 30 in second primary load-bearing bar 4. In this
assembly, end 11 of rod 10 may be bent, fitted with a pin or nut to ensure
that it does not move. Thus, after having secured rod 10, primary
load-bearing bars 4, secondary load-bearing bars 6 and tertiary
load-bearing bars 8 are locked together to form a unit grating without the
attendant problems inherent with welding. Further, because of the
additional rod used, the strength of the grating structure is improved
dramatically. It will be appreciated that one rod or more can be used
between each set of secondary load-bearing bars 6. Further, fewer rods can
be used. That is, in the present invention rods 10 can be selectively
placed between secondary load-bearing bars 6. For example, in the present
invention, high strength grating can be obtained when rods 10 are used
between every other set of secondary load-bearing bars 6.
With respect to rod 10, it will be noted that a round bar has been
illustrated. However, any cross-sectional configuration may be used.
In FIG. 1, primary load-bearing bar 4 is shown with a lower flange 34, a
web portion 36, a bulbous portion 38, and a rib 40. However, primary
load-bearing bars 4 can have other cross-sectional configurations that may
be used. In the embodiment shown in FIG. 1, rib 40 and flange 34 provide
for special features as explained herein.
Secondary load-bearing bars 6 can have a depth generally less than the
depth of primary load-bearing bars 4, and tertiary load-bearing bars 8 can
have a depth less than the depth of secondary load-bearing bars 6.
Further, it should be noted that if secondary load-bearing bars 6 are
sufficiently deep, then notch or slots 22 may be of sufficient depth to
accommodate the full depth of the tertiary load-bearing bars 8 without
slots 24 being provided in tertiary load-bearing bars 8. Rod 10 can
provide sufficient resistance to sideways movement of tertiary
load-bearing bars 8.
FIG. 6 illustrates a grating 50 in accordance with the invention having
another configuration for primary load-bearing bars 4. In FIG. 6, like
numbers have been used for like components. Primary load-bearing bars 4
are fabricated out of members that have a T-shaped configuration. Thus,
primary load-bearing bars 4 have a bottom flange 34 and a generally planar
web 36. Further, in FIG. 6, grating 50 is shown having primary
load-bearing bars 4 having a web 36 substantially the same depth as
secondary load-bearing bar 6. Also, tertiary load-bearing bars 8 have a
depth substantially the same depth as the web in primary load-bearing bars
4 and substantially the same as secondary load-bearing bars 6. Primary
load-bearing bars 4, secondary load-bearing bars 6 and tertiary
load-bearing bars 8 can be assembled to provide a planar surface. Rod 10
is shown inserted parallel to secondary load-bearing bars 6 and through
tertiary load-bearing bars 8 and web 36 of primary load-bearing bars 4 to
provide a rigid unit grating by locking tertiary load-bearing bars 8 into
secondary load-bearing bars 6. In the embodiment of the invention shown in
FIG. 6, rods 10 are shown inserted between every other set of secondary
load-bearing bars 6.
FIG. 7 is a perspective view showing the parts of the grating of FIG. 6 in
unassembled relationship. Thus, there is shown primary load-bearing bars 4
having a plurality of slots 14 in alignment to receive secondary
load-bearing bars 6. Secondary load-bearing bars 6 are provided with slots
16 to coincide with slots 14 when the grating is assembled. In addition,
secondary load-bearing bars 6 are provided with a plurality of slots 22 in
alignment as shown in FIG. 7. A plurality of tertiary load-bearing bars 8
are provided to fit into slots 22. Further, tertiary load-bearing bars 8
are provided with a plurality of slots adapted to coincide with slots 22.
The depth of the slots can be as described earlier with respect to the
embodiments described in FIGS. 1 and 2. While the gratings herein are
shown with primary load-bearing bars 4 having a flange 34, it should be
noted that such members may be flange free and all the members can be the
same depth.
In the embodiment illustrated in FIGS. 6 and 7, web 36 is provided with
apertures 30. Also, tertiary load-bearing bars 8 are provided with
apertures 32. Apertures 30 and 32 are located in webs 36 and tertiary
load-bearing bars 8 so that when the bars are assembled into a grating,
apertures 30 and 32 are aligned to receive rods 10 thereby locking the
bars or members in place to provide a grating. The grating may be used in
an open configuration or it may be encased in concrete or it may be
provided with an exodermic deck.
When the grating is used for open decks such as bridge decks, straight
secondary load-bearing bars or straight tertiary load-bearing bars,
particularly parallel to the direction of travel on the bridge deck, can
result in vehicles being swayed back and forth in a direction transverse
to the direction of travel. To avoid or minimize swaying, some of the
bars, particularly the secondary load-bearing bars and/or the tertiary
load-bearing bars are made to form an X-pattern or a zigzag pattern. In
the present invention, either the secondary load-bearing bars or tertiary
load-bearing bars can be formed to provide a zigzag pattern to minimize
vehicle sway in the direction of travel. If tertiary load-bearing bars are
formed to provide a zigzag pattern, then the slots 22 formed in top edges
20 of secondary load-bearing bars can be misaligned to accommodate the
pattern formed in the tertiary load-bearing bars. If it is desired to mate
the bars as noted previously, then the appropriate slots can be cut in the
formed tertiary load-bearing bars. Also, apertures 30 and 32 are formed in
web 36 and in the tertiary load-bearing bars. Aperture 30 in web 36 will
be substantially perpendicular to the web. However, in the patterned
tertiary load-bearing bars, the aperture will be formed entering the bar
at an angle and thus can be more difficult to form. A rod 10 is then
inserted through the aperture in web 36 and through the aperture in the
patterned tertiary load-bearing bars to lock the components of the grating
together to form a unitary grating having a pattern.
The grating employing zigzag tertiary load bearing bars 60 is shown in FIG.
13 which is a top view. Two primary load bearing bars 4 and four secondary
load bearing bars 6 are also shown. Further, in the embodiment shown in
FIG. 13, zigzag tertiary load bearing bars 60 are separated by a straight
tertiary load bearing bar 8. Rods 10 are shown fastening or locking the
grating together. That is, rod 10 is inserted through an aperture in
primary load bearing bar 4, patterned tertiary load bearing bar 60,
straight tertiary load bearing bar 8, patterned tertiary load bearing bar
60 and lastly primary load bearing bar 4. In this embodiment, slots are
cut in the bars to provide a planar surface as explained earlier. In
assembly of this embodiment, the webs of primary load bearing bars 4 are
placed in a parallel and upright position, as shown, then secondary load
bearing bars 6 are placed in matching slots in primary load bearing bars
4. Tertiary load bearing bars 60 are placed in matching slots in secondary
load bearing bars 6. The slots are cut in secondary load bearing bars 6 at
locations denoted by 62 for tertiary load bearing bars 60 and at 64 in
tertiary load bearing bar 8. After rod 10 has been inserted, ends 11 may
be fastened by any suitable means.
When it is desired to encase at least a portion of the grating in concrete,
a pan or sheet member 50 is positioned between primary load-bearing bars 4
as shown in FIG. 3. Pan 50 is formed to extend the length of primary
load-bearing bars 4 and to rest on ribs 40. Thus, pan 50 can be
substantially flat as shown in FIGS. 10 and 11. Further, pan 50 can be
provided with tabs 52 to grip the lower edge of rib 40. This configuration
using tabs 52 locks the pan in place. Thus, the grating can be shipped to
the job site without pans 50 moving or dropping out of the grating. It
should be noted that welding pans 50 in place is undesirable because of
warpage that occurs. The warpage results in uneven thickness of concrete
and also in spaces between the rib and the pan which results in wet
concrete seeping or dripping onto the surfaces below. The assembled
grating in accordance with the invention has a rigid configuration without
substantially any movement of the bars or members. Thus, for example,
because primary load bearing bars do not move or wobble, the pans can be
placed on or inserted between the primary load bearing bars prior to
shipping.
If it is desired to encase substantially the depth of the grating in
concrete, a different shaped pan can be used, as shown in FIGS. 4 and 12.
That is, pan 51 (see FIG. 12) can be provided with beveled edges 54 which
are contoured to fit snugly with flange 34. Pan 51 can be lightly press
fitted between primary load-bearing bars 4 to prevent movement, and
additionally edges of pan 51 in contact with web 36 of primary
load-bearing bars 4 can be serrated to ensure against slippage. The
fitting of pan 51 as noted in FIG. 4 is also aesthetically pleasing when
viewed from below. Instead of shaping pan 51 as shown in FIGS. 4 and 12,
pan 51 can have a flat rectangular shape, preferably with serrated edges
which rest on top of shoulders of flange 34.
FIG. 5 is a schematic showing concrete 56 provided in the upper portion of
the grating.
FIG. 8 is an end view of FIG. 6 showing a pan 58 resting on shoulders of
flange 34. Again, preferably pan 58 is provided with serrated edges to
prevent movement. In FIG. 9, there is shown a cutaway of the grating
described in FIGS. 6, 7 and 8 having concrete provided to encase the
grating.
It should be understood that while the grating of the invention has been
shown encasing a top portion of the grating (FIG. 5) or all of the grating
such as in FIG. 9, the concrete can extend above and below the grating, if
desired. That is, the grating can be substantially encapsulated with
concrete.
For many applications, rod 10 is preferred to be formed from a solid bar
such as a metal bar. However, when the grating in accordance with the
invention is used for floors for buildings such as mall floors or is used
for concrete encased bridge decks, rod 10 may be a hollow member or pipe
connected at the ends so as to form a continuous pipe. Heating liquid can
be passed through the pipe for purposes of heating the building.
While the invention has been described with respect to a grating employing
a three-bar system and a locking rod, the invention contemplates grating
fabricated using two rails such as the primary load bearing bars and
secondary load bearing bars. When the grating is fabricated using two
rails, then locking rod 10 is inserted through both rails in a diagonal
direction.
Further, while the invention has been depicted showing primary load bearing
bars having flanges, the invention contemplates gratings fabricated using
plain bars for all three load-bearing bars; and in certain gratings, the
three bars can have the same dimensions.
The gratings of the invention can be fabricated from metals such as steels,
carbon steel, stainless steels and aluminum alloys or from plastics such
as fiberglass-reinforced plastics.
In the present invention, if steel bars are used, they may be galvanized
prior to assembly or after assembly. If galvanized before assembly, touch
up may have to be used to cover scratches resulting from assembly.
Further, in the present invention, the slots should be dimensioned to
provide for a snug fit to minimize collection of debris such as salts that
cause corrosion, particularly in open gratings.
It will be seen that gratings in accordance with the present invention
overcome the disadvantages of welded gratings referred to earlier.
However, even though welds can be applied to the grating of the present
invention, welding is believed to be more detrimental than advantageous.
While the invention has been described in terms of preferred embodiments,
the claims appended hereto are intended to encompass other embodiments
which fall within the spirit of the invention.
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