U.S. patent application number 11/104536 was filed with the patent office on 2006-12-07 for composite floor system with fully-embedded studs.
Invention is credited to Michael Hatzinikolas.
Application Number | 20060272251 11/104536 |
Document ID | / |
Family ID | 37101478 |
Filed Date | 2006-12-07 |
United States Patent
Application |
20060272251 |
Kind Code |
A1 |
Hatzinikolas; Michael |
December 7, 2006 |
Composite floor system with fully-embedded studs
Abstract
A composite floor system is provided and includes at least one
lower beam, a plurality of projections and a floor slab. The at
least one lower beam is made from a metallic material. The at least
one lower beam has a longitudinal direction. The at least one lower
beam has an upper surface. Each projection has a connection to the
upper surface of the at least one lower beam. Each projection
extends upwards from the upper surface of the at least one lower
beam. Each projection is metallic. The floor slab is made from a
cementitious material. The floor slab is in contact with the upper
surface of the at least one lower beam. Each projection has a first
portion that is embedded in the floor slab. Each projection has a
second portion that includes the connection. The second portion is
spaced from the floor slab in at least a selected longitudinal
direction.
Inventors: |
Hatzinikolas; Michael;
(Edmonton, CA) |
Correspondence
Address: |
BERESKIN AND PARR
40 KING STREET WEST
BOX 401
TORONTO
ON
M5H 3Y2
CA
|
Family ID: |
37101478 |
Appl. No.: |
11/104536 |
Filed: |
April 13, 2005 |
Current U.S.
Class: |
52/340 |
Current CPC
Class: |
E04C 3/294 20130101;
E04C 5/0645 20130101; E04B 5/29 20130101 |
Class at
Publication: |
052/340 |
International
Class: |
E04B 5/18 20060101
E04B005/18 |
Claims
1. A composite floor system, comprising: at least one lower beam
made from a metallic material, wherein the at least one lower beam
has a longitudinal direction, and wherein the at least one lower
beam has an upper surface; a plurality of projections, wherein each
projection has a connection to the upper surface of the at least
one lower beam and wherein each projection extends upwards from the
upper surface of the at least one lower beam, and wherein each
projection is metallic; and a floor slab made from a cementitious
material, wherein the floor slab is in contact with the upper
surface of the at least one lower beam, wherein each projection has
a first portion that is embedded in the floor slab, and wherein
each projection has a second portion that includes the connection,
wherein the second portion is spaced from the floor slab in at
least a selected longitudinal direction.
2. A composite floor system as claimed in claim 1, wherein the
second portion of each projection is spaced from the floor slab in
the selected longitudinal direction by at least a selected
distance.
3. A composite floor system as claimed in claim 2, wherein the
second portion has a selected length and wherein the length of the
second portion and the selected distance in the longitudinal
direction are selected based at least in part on a selected
ductility for the composite floor system.
4. A composite floor system as claimed in claim 1, further
comprising a plurality of spacers, wherein each spacer is
positioned between the second portion of one of the projections and
the floor slab, and wherein each spacer is made from a material
that permits deformation of the projection in at least the selected
longitudinal direction.
5. A composite floor system as claimed in claim 4, wherein the
spacers are made from a polymeric material.
6. A composite floor system as claimed in claim 5, wherein the
spacers are made from a foam rubber.
7. A composite floor system as claimed in claim 4, wherein the
spacers are adhered to the at least one lower beam.
8. A composite floor system as claimed in claim 4, wherein the
spacers are adhered to the projections.
9. A composite floor system as claimed in claim 1, wherein the at
least one lower beam is an I-beam.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to composite floor systems,
and more particularly the invention relates to a composite floor
system with a floor slab positioned on one or more lower beams.
BACKGROUND OF THE INVENTION
[0002] A composite floor system typically consists of a concrete
floor slab positioned on several steel I-beams that extend in
parallel. To act together in resisting loads, shear studs are
typically resistance-welded to the top surface of the I-beams. The
concrete that makes up the floor slab surrounds the shear studs,
such that the entirety of each shear stud is embedded in the
concrete.
[0003] When a vertical load is imposed on the floor system, a
compressive load is developed in the concrete floor slab and a
tensile force is developed in the I-beam. Such a system, however,
typically has relatively low ductility. In general, systems having
relatively lower ductility are less able to absorb energy from
dynamic forces, such as those that occur during earthquakes, than
systems with relatively higher ductility, such as pure steel
structures.
SUMMARY OF THE INVENTION
[0004] In a first aspect, the invention is directed to a composite
floor including at least one lower beam, a plurality of projections
and a floor slab. The at least one lower beam is made from a
metallic material. The at least one lower beam has a longitudinal
direction. The at least one lower beam has an upper surface. Each
projection has a connection to the upper surface of the at least
one lower beam. Each projection extends upwards from the upper
surface of the at least one lower beam. Each projection is
metallic. The floor slab is made from a cementitious material. The
floor slab is in contact with the upper surface of the at least one
lower beam. Each projection has a first portion that is embedded in
the floor slab. Each projection has a second portion that includes
the connection. The second portion is spaced from the floor slab in
at least a selected longitudinal direction.
BRIEF DESCRIPTION OF THE DRAWINGS
[0005] The present invention will now be described by way of
example only with reference to the attached drawings in which:
[0006] FIG. 1 is a sectional side view of a composite floor system
in accordance with an embodiment of the present invention; and
[0007] FIG. 2 is a magnified sectional side view of a portion of
the composite floor system shown in FIG. 1;
[0008] FIG. 3 is a plan view of the composite floor system shown in
FIG. 1;
[0009] FIG. 4 is a sectional side view of the composite floor
system shown FIG. 1, after experiencing deformation due to an
event; and
[0010] FIG. 5 is a perspective view of a portion of the lower beam,
projections and spacer which make up part of the composite floor
system shown in FIG. 1;
[0011] FIG. 6 is a perspective view of a portion of the lower beam
and projections shown in FIG. 1, with an alternative spacer;
[0012] FIG. 7 is a sectional side view of a portion of the lower
beam and projections shown in FIG. 1, with an alternative
configuration for apertures around the projections, to that which
is shown in FIG. 1;
[0013] FIG. 8 is a sectional side view of a portion of the lower
beam and projections shown in FIG. 1, with another alternative
configuration for apertures around the projections, to that which
is shown in FIG. 1; and
[0014] FIG. 9 is a sectional side view of a portion of the lower
beam and projections shown in FIG. 1, with yet another alternative
configuration for apertures around the projections, to that which
is shown in FIG. 1.
DETAILED DESCRIPTION OF THE INVENTION
[0015] Reference is made to FIG. 1, which shows a composite floor
system 10 made in accordance with an embodiment of the present
invention. The composite floor system 10 includes at least one
lower beam 12 and may include a plurality of lower beams 12 (see
FIG. 3) arranged in parallel and spaced at a selected distance from
one another.
[0016] The composite floor system further includes a plurality of
projections 14 which extend upwards from each of the lower beams
12, and further includes a floor slab 16, which is positioned on
the lower beams 12.
[0017] The lower beams 12 may be any suitable type of beam, such
as, for example, I-beams or box beams. The lower beam 12 shown in
FIG. 1 is an I-beam. The lower beam 12 has an upper surface 18,
from which the projections 14 extend upwards. The upper surface 18
is the surface of the lower beam 12 that supports the floor slab
16.
[0018] The lower beam 12 is made from a material that is ductile
and resistant to catastrophic failure when experiencing tensile
forces, such as can occur when the composite floor system 10 is
loaded, and in particular during an earthquake or other event. An
especially suitable material for the lower beam 12 is steel,
however, other materials may be used.
[0019] The relative spacing between adjacent lower beams 12 may be
selected at least in part based on the overall strength
requirements of the floor system 10.
[0020] The projections 14 extend upwards from the upper surface 18
of the lower beam 12. The projections 14 may be positioned in a row
along the longitudinally-extending, vertical-plane centerline,
shown at CLvplong-lb in FIG. 3, of each lower beam 12. The relative
spacing of the projections 14 from one another may be selected at
least in part on the strength requirements of the composite floor
system 10.
[0021] Reference is made to FIG. 2. Each projection 14 has a top 19
and a bottom 20. The projection 14 is joined to the upper surface
18 of the lower beam 12 at a connection 21. From the connection 21,
the projection 14 extends upwards into the floor slab 16 that rests
on the upper surface 18 of the lower beam 12. The connection 21 may
be made by any other suitable means, such as, for example, by
resistance welding the projection 14 to the lower beam 12.
[0022] Around each projection 14 is an aperture 22 in the floor
slab 16. The aperture 22 surrounds the projection 14 such that the
projection 14 is spaced from the aperture wall, shown at 24 in the
longitudinal direction by a distance Dlong. The aperture 22 may be
circular, as shown in FIG. 3, such that the projection 14 is spaced
from the aperture wall 24 by the same distance in all directions
measured in the plane of the floor system 10. Alternatively, the
aperture 22 may be made non-circular. For example, the aperture 22
may be made elliptical such that the distance between the
projection 14 and the aperture wall 24 is relatively greater in the
longitudinal direction (ie. the direction parallel to the
centerline CLvplong-lb, see FIG. 3), and relatively smaller in the
lateral direction.
[0023] The depth of the aperture 22 is selected so that a first
portion 26 of the projection 14 is embedded within the floor slab
16, and a second portion 28 of the projection 14 is surrounded by
the aperture and is therefore spaced from the aperture wall 24. The
depth of the aperture 22 is shown at Dvert. It will be noted that
the depth Dvert is the same as the length of the second portion 28
of the projections 14.
[0024] The projection 14 is made from a ductile material, and the
connection 21 between the projection 14 and the lower beam 12 is a
ductile connection, permitting a selected amount of deformation,
including elastic and/or plastic deformation, prior to experiencing
catastrophic failure. An example of a suitable material for the
projections 14 is steel.
[0025] The projection 14 may be a stud, eg. a threaded rod, or may
be some other member, such as, for example, a bolt.
[0026] The floor slab 16 rests on the upper surfaces 18 of the
lower beams 12. As a result of the embedment of the projections 14
into the floor slab 16, the composite floor system 10 acts under
load as a single, composite structure. The composite floor system
10 has a horizontal-plane centerline CLhp-fs that divides the floor
system 10 into a lower half 30 and an upper half 32. In the absence
of any pre-stressing of the components of the composite floor
system 10, when the floor system 10 is under a bending load the
bottom half 30 is in tension and the top half 32 is in compression.
Preferably, the bottom half 30 of the floor system 10 includes
substantially all of the lower beam 12, and preferably the top half
32 includes substantially all of the floor slab 16.
[0027] A suitable material for the floor slab 16 is a material that
is strong in compression, such as, for example, a cementitious
material. For the purposes of this disclosure, a cementitious
material is any material that is a mixture of aggregate and matrix
material such as, for example, concrete, Portland cement, or the
like, that is known to a person skilled in the art for use in
composite floor systems. Typically, such materials are poured into
a form. They may be poured on site, or alternatively they may be
poured and hardened first and subsequently shipped to the site for
installation. The floor slab 16 has an upper surface 34, which may
be covered with other layers to make up a floor having whatever
physical or aesthetic properties are desired.
[0028] Referring to FIG. 1, when the floor system 10 is under a
bending load, the compressive load on the upper half 32 of the
floor system 10 increases in a direction away from the
horizontal-plane floor system centerline CLhp-fs and towards the
upper surface 34 of the floor slab 16, and simultaneously, the
tensile load on the lower half 30 of the floor system 10 increases
in a direction away from the horizontal-plane floor system
centerline CLhp-fs and towards the lower surface of the lower beam
12, shown at 36. As a result, different forces act on the tops 19
and bottoms 20 of the projections 14. Referring to FIG. 4, the
spacing of the lower (ie. second) portions 28 of the projections 14
from the aperture walls 24 permits the second portions 28 of the
projections 14 to bend in the longitudinal direction while
remaining spaced from the floor slab 16. In this way, their
ductility can be used advantageously so that the floor system 10
can incur loads and absorb energy with a reduced likelihood of
shearing the projections 14 off the lower beam 12. As a result, the
composite floor system 10 can remain in better condition after an
event, such as an earthquake, than a composite floor system that
lacks apertures around the projections. The distance Dlong may be
selected so that the projections 14 can incur a selected amount of
bending in the longitudinal direction. If the distance Dlong is
selected to be sufficiently large, ie. beyond a critical value,
then it is contemplated that the floor slab 16 would remain spaced
in the longitudinal direction from the second portions 28, even at
the maximum load which the composite floor system 10 is designed to
withstand. A person skilled in the art, after having read this
disclosure, would be able to readily calculate the aforementioned
critical value for the distance Dlong.
[0029] There is a relationship between the longitudinal distance
Dlong, the depth Dvert, the shape of the apertures 22 and the
amount of longitudinal bending that can take place in the
projections 14. Increasing the depth Dvert of the aperture 22
increases the lengths of the unembedded portions of the projections
14, ie. the lengths of the second portions 28, which in turn
increases the energy absorption capability of the projections 14.
However, care should be taken so that the embedded (ie. first)
portions 26 of the projections 14 have sufficient length to meet
the strength requirements of the installation.
[0030] In earthquake zones, a floor system may be required to be
sufficiently strong to withstand a particular strength of
earthquake, based on whatever regulations are applicable in the
local jurisdiction. The ductility of the composite floor system 10
is a value that is related to the ability of the composite floor
system 10 to absorb energy, such as the energy that would be
imparted to the floor system during an earthquake. If a floor
system is designed with sufficient ductility the strength of the
floor system required by code can be reduced, because it is
expected that such a floor system would be capable of absorbing a
greater amount of energy than a rigid floor system without
undergoing catastrophic failure in the event of an earthquake. As a
result, the composite floor system 10 can be provided at less cost
than a composite floor system without apertures around the
projections, while still meeting the design requirements
established by such regulations.
[0031] The longitudinal distance Dlong and the depth Dvert may be
selected based at least in part on the overall ductility that is
selected to be provided for the composite floor system 10.
Additionally, or alternatively, the longitudinal distance Dlong and
the depth Dvert may be selected based at least in part on a maximum
selected bending load that the floor system is to withstand.
[0032] While it is preferable that the distance Dlong be equal to
or greater than the aforementioned critical value, any spacing
Dlong in combination with any depth Dvert permit some energy
absorption to take place in the projections 14 and thus, provide
some advantage over a composite floor system that lacks apertures
around the projections.
[0033] The apertures 22 may be formed in the floor slab 16 by any
suitable means. For example, in the case where the floor slab 16 is
made from a material that is poured over the projections 14, a
spacer 38 (see in particular FIG. 5) may be fitted around each
projection 14 so that the material of the floor slab 16 (see FIG.
2) hardens around the spacers 38, thereby forming the apertures 22.
In the embodiment of the floor system 10 shown in FIGS. 1-5, the
spacers 38 would be captured permanently between the floor slab 16
and the lower beam 12. In embodiments such as this, ie. where the
spacers 38 will remain in place after the floor slab 16 hardens,
the spacers 38 may be made from a deformable material that permits
deformation in the projections 14 when the floor system 10 incurs a
bending load. However, in addition to being deformable, the spacers
38 have sufficient strength to retain their shape sufficiently to
form the apertures 22 when the material for the floor slab 16 is
poured.
[0034] The spacers 38 may be made from a synthetic or natural
polymeric material, such as, for example, a foam rubber. In
embodiments where the spacers 38 are foam structures, they may
include a projection aperture 40 (see FIG. 2) for receiving the
projections 14 and a slit 42 (see FIG. 5) permitting the spacers 38
to be easily placed around the projections 14.
[0035] Other configurations for the spacers 38 would alternatively
be suitable. For example, referring to FIG. 6, spacers 43 may be
provided, each comprising a hollow shell 44 that has a projection
aperture 46 to permit the pass-through of a projection 14. The
shell 44 may be made from a suitably strong material to withstand
the load imposed thereon when the material for the floor slab 16
(FIG. 1) is poured. For example, the Shell may be made from a
metallic material, such as steel, or aluminum. The shell 44 may
include a slit 48 and may be made sufficiently flexible and
resilient to permit the shell 44 to be fit around the projection
14.
[0036] Adhesive or some other suitable bonding means may be used to
hold the spacers 38 and 43 in place, so that they do not lift
upwards when the material for the floor slab 16 is poured. For
example, the spacer 38 may be bonded to the projection 14 with
adhesive.
[0037] It is shown in FIG. 2 that the projection 14 is spaced from
the aperture wall 24 by the distance Dlong in both directions
longitudinally. However, it is alternatively possible for the
spacing Dlong to be provided in one longitudinal direction, and for
some lesser spacing, or alternatively no spacing, to be provided in
the other longitudinal direction. The side in which the spacing
Dlong is provided would be selected based on which way the
projection 14 is expected to bend during loading of the floor
system 10. The direction of bending of the projection 14 depends at
least in part on where the beam is expected to be supported in use,
and the magnitudes and positions of any loads that the floor system
10 is being designed to withstand.
[0038] The particular composition of the steel or other ductile
material used for the lower beams 12, connections 21 and
projections 14 will be readily selectable by one skilled in the art
based on the particular requirements of the installation of the
composite floor system 10.
[0039] The apertures 22 formed in the floor slab 16 are shown in
the figures as having walls 24 that extend directly vertically. It
is alternatively possible for the aperture walls 24 to extend
inwardly towards the projections 14 while extending upwards.
Reference is made to FIG. 7, which illustrates a wall 24 that
extends upwards at a selected angle, A, from the horizontal. It is
alternatively possible for the wall to extend at an angle B, from
the horizontal, as shown in FIG. 8. As another alternative, the
wall 24 may have some other shape, such as a curved shape, as shown
in FIG. 9. It will be understood, that the spacers 38 or 43 (FIGS.
5 and 6 respectively) would be provided with selected shapes in
order to form whatever configuration is selected for the wall
24.
[0040] It is possible for the floor slab 16 to be manufactured
prior to installation on the lower beams 12. In such an embodiment,
the apertures 22 may be formed in the floor slab 16 by any suitable
means, and they may remain empty, ie. with no spacer therein, after
the floor slab 16 is installed on the lower beams 12. Suitable
means, such as an adhesive paste could be provided in
projection-receiving apertures in such a floor slab 16, for
receiving the top, (ie. first), portions 26 of the projections 14
and for adhering the floor slab 16 thereto.
[0041] As will be apparent to persons skilled in the art, various
modifications and adaptations of the apparatus described above may
be made without departure from the present invention, the scope of
which is defined in the appended claims.
* * * * *