U.S. patent application number 10/529954 was filed with the patent office on 2006-08-17 for composite beam.
This patent application is currently assigned to UNIVERSITY OF WESTERN SYDNEY. Invention is credited to Mark Patrick.
Application Number | 20060179750 10/529954 |
Document ID | / |
Family ID | 28047536 |
Filed Date | 2006-08-17 |
United States Patent
Application |
20060179750 |
Kind Code |
A1 |
Patrick; Mark |
August 17, 2006 |
Composite beam
Abstract
A composite beam is disclosed. The beam includes a beam (5), a
solid slab or a composite slab (29) positioned on and supported by
the beam, the solid slab and the composite slab including a slab
section and a plurality of concrete ribs (21) extending from the
slab section. The beam also includes at least one shear connector
(15) positioned in at least one of the concrete ribs and connecting
the solid slab or the composite slab to the beam. The beam also
includes a reinforcing component (19) embedded in at least one
concrete rib that includes an embedded shear connector or
connectors. The reinforcing component is in the form of a mesh that
includes line wires (41) and cross wires (43) that are connected
together at the intersections of the wires.
Inventors: |
Patrick; Mark; (New South
Wales, AU) |
Correspondence
Address: |
THE WEBB LAW FIRM, P.C.
700 KOPPERS BUILDING
436 SEVENTH AVENUE
PITTSBURGH
PA
15219
US
|
Assignee: |
UNIVERSITY OF WESTERN
SYDNEY
Second Avenue
Kingswood
AU
2747
|
Family ID: |
28047536 |
Appl. No.: |
10/529954 |
Filed: |
October 2, 2003 |
PCT Filed: |
October 2, 2003 |
PCT NO: |
PCT/AU03/01300 |
371 Date: |
February 28, 2006 |
Current U.S.
Class: |
52/309.16 |
Current CPC
Class: |
E04B 5/40 20130101; E04C
3/293 20130101; E04C 3/294 20130101 |
Class at
Publication: |
052/309.16 |
International
Class: |
E04C 1/00 20060101
E04C001/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 2, 2002 |
AU |
2002951787 |
Claims
1. A composite beam which includes: (a) a beam; (b) a solid slab or
a composite slab positioned on and supported by the beam, the solid
slab and the composite slab including a slab section and a
plurality of concrete ribs extending from the slab section; (c) at
least one shear connector positioned in at least one of the
concrete ribs and connecting the solid slab or the composite slab
to the beam; and (d) a reinforcing component embedded in at least
one concrete rib that includes a said embedded shear connector or
connectors, the reinforcing component being in the form of a mesh
that includes line wires and cross wires that are connected
together at the intersections of the wires.
2. The composite beam defined in claim 1 wherein the mesh is
positioned so that the line wires extend in the longitudinal
direction of the concrete rib, ie in the longitudinal direction of
the beam.
3. The composite beam defined in claim 1 wherein the mesh is
positioned in the concrete rib between 25% and 75% of the height of
the concrete rib.
4. The composite beam defined in claim 1 wherein, in a situation in
which the composite beam includes a composite slab rather than a
solid slab, the composite slab includes profiled metal sheeting
having a plurality of metal pans separated by metal ribs and
concrete cast on the profiled sheeting, whereby the metal pans and
the metal ribs define an outer surface of the concrete rib.
5. The composite beam defined in claim 4 wherein the mesh is
positioned in the concrete rib below the level of tops of adjacent
metal ribs of the profiled sheeting.
6. The composite beam defined in claim 5 wherein the mesh is
positioned in the concrete rib between 25% and 75% of the height of
the adjacent metal ribs.
7. The composite beam defined in claim 1 wherein the mesh extends
across the width of the concrete rib at the position of the mesh in
the concrete rib.
8. The composite beam defined in claim 1 wherein the reinforcing
component is a flat sheet of welded wire mesh that includes a
rectangular array of parallel line wires and cross wires welded
together at the intersections of the wires.
9. The composite beam defined in claim 1 wherein the reinforcing
component is mesh formed from line wires and cross wires that are
welded together at wire intersections and has line wires that have
a zig-zag shape along at least part of the length of the line
wires.
10. The composite beam defined in claim 1 wherein the reinforcing
component further includes a plurality of additional reinforcing
elements that extend transverse to the lines wires of the mesh and
have one or more than one section out of the plane of the mesh.
11. The composite beam defined in claim 10 wherein the additional
reinforcing elements is cranked handlebar-shaped.
12. The composite beam defined in claim 10 wherein the section or
sections of each additional reinforcing element that is out of the
plane of the mesh extends from the concrete rib into the slab
section of the solid slab on the composite slab.
13. The composite beam defined in claim 1 wherein there are a
plurality of shear connectors in the form of headed studs.
14. The composite beam defined in claim 1 wherein there is a
plurality of shear connectors and a minimum spacing between the
shear connectors along the length of the beam of at least 5 times
the diameter of the shear connectors.
15. The composite beam defined in claim 1 wherein there is a
plurality of shear connectors and the spacing between the shear
connectors along the length of the beam is no more than 7.5 times
the height of the shear connectors above the top of the concrete
ribs.
16. (canceled)
17. A composite beam which includes: (a) a beam; (b) a solid slab
or a composite slab positioned on and supported by the beam, the
solid slab and the composite slab including a slab section and a
plurality of concrete ribs extending from the slab section; (c) at
least one shear connector positioned in at least one of the
concrete ribs and connecting the solid slab or the composite slab
to the beam; and (d) a reinforcing component embedded in at least
one concrete rib that includes a said embedded shear connector or
connectors, the reinforcing component being in the form of a mesh
that includes line wires and cross wires that are connected
together at the intersections of the wires, the mesh being
positioned so that the line wires extend in the longitudinal
direction of the concrete rib, ie in the longitudinal direction of
the beam, and the mesh being positioned in the concrete rib between
25% and 75% of the height of the concrete rib.
Description
[0001] The present invention relates to composite beams for the
construction industry.
[0002] The term "composite beam" is understood herein to mean: (i)
a beam, preferably formed from steel, and (ii) a solid slab or a
composite slab; that are interconnected by shear connection to act
together to resist action effects as a single structural
member.
[0003] The term "shear connection" is understood herein to mean an
interconnection between a beam and a solid slab or a composite slab
of a composite beam which enables the two components to act
together as a single structural member under the action effect of
bending which causes longitudinal shear forces to develop.
[0004] In conventional composite beams, typically, the shear
connection includes shear connectors, slab concrete, and transverse
reinforcement.
[0005] The term "shear connector" is understood herein to mean a
mechanical device attached to a beam (typically to a top flange of
the beam) which forms part of the shear connection.
[0006] The present invention relates particularly, although by no
means exclusively, to composite beams of the type which include:
[0007] (a) a horizontal beam (typically steel) supported at each
end; [0008] (b) a composite slab that is positioned on and
supported by the beam and includes: [0009] (i) profiled metal
(typically steel) sheeting having a plurality of pans separated by
ribs, the profiled sheeting being positioned in relation to the
beam so that the ribs are parallel to the longitudinal axis of the
beam or the ribs and the longitudinal axis of the beam describe an
acute angle of less than or equal to 15.degree.; [0010] (ii)
concrete cast on the sheeting, with the cast concrete including
concrete ribs defined by the pans and sides of adjacent ribs; and
[0011] (iii) reinforcement embedded in the cast concrete; and
[0012] (c) a plurality of shear connectors, typically in the form
of headed studs, embedded in the cast concrete and welded to the
beam thereby to connect the composite slab to the beam.
[0013] The present invention is concerned with overcoming a major
problem that occurs with composite beams of the type described
above that include conventional welded stud shear connectors and
profiled steel decking having open metal ribs. The problem is a
complex type of longitudinal shear failure involving lateral rib
punch-through failure that has been studied by the applicant in
research work that has been carried out by the applicant. The
problem of lateral rib punch-through is not confined to this
particular type of composite beam.
[0014] An object of the present invention is to provide a composite
beam with improved resistance to longitudinal shear failure
involving lateral rib punch-through.
[0015] According to the present invention there is provided a
composite beam which includes: [0016] (a) a beam; [0017] (b) a
solid slab or a composite slab positioned on and supported by the
beam, the solid slab and the composite slab including a slab
section and a plurality of concrete ribs extending from the slab
section; [0018] (c) at least one shear connector positioned in at
least one of the concrete ribs and connecting the solid slab or the
composite slab to the beam; and [0019] (d) a reinforcing component
embedded in at least one concrete rib that includes embedded shear
connector or connectors, the reinforcing component being in the
form of a mesh that includes line wires and cross wires that are
connected together at the intersections of the wires.
[0020] The applicant has found that the reinforcing component
described in sub-paragraph (d) above improves dramatically the
resistance to lateral rib punch-through failure of the composite
beam.
[0021] Preferably the concrete ribs are parallel to the
longitudinal axis of the beam or the concrete ribs and the
longitudinal axis of the beam describe an acute angle of less than
or equal to 15.degree..
[0022] It is preferred that the mesh be positioned so that the line
wires extend in the longitudinal direction of the concrete rib, ie
in the longitudinal direction of the beam.
[0023] With this arrangement, the purpose of the cross wires is to
take tension forces and balance transverse components of shear
connector reactive forces that develop in the base region of the
shear connector or connectors.
[0024] The research work carried out by the applicant indicates
that lateral rib punch-through failure of the beam would not be
prevented without these cross wires.
[0025] One purpose of the line wires is to anchor the cross wires
so that the cross wires can take tension forces.
[0026] Another purpose of the line wires is to balance the
longitudinal components of shear connector reactive forces that
develop in the base region of the shear connector or
connectors.
[0027] It is preferred that the mesh be positioned in the concrete
rib between 25% and 75% of the height of the concrete rib.
[0028] In a situation in which the composite beam includes a
composite slab rather than a solid slab, preferably the composite
slab includes profiled metal sheeting having a plurality of metal
pans separated by metal ribs and concrete cast on the profiled
sheeting. With this arrangement the metal pans and the sides of the
metal ribs define the outer surfaces of the concrete ribs.
[0029] Preferably the mesh is positioned in the concrete rib below
the level of the tops of adjacent ribs of the profiled
sheeting.
[0030] It is preferred that the mesh be positioned in the concrete
rib between 25% and 75% of the height of the adjacent metal
ribs.
[0031] It is preferred that the mesh extend across the width of the
concrete rib at the position of the mesh in the concrete rib.
[0032] It is preferred that the reinforcing component further
includes a plurality of additional reinforcing elements that extend
transverse to the line wires of the mesh and have one or more than
one section out of the plane of the mesh.
[0033] It is preferred that the additional reinforcing elements be
cranked handlebar-shaped elements.
[0034] It is preferred that the section or sections of each
additional reinforcing element that is out of the plane of the mesh
extend from the concrete rib into the slab section of the solid
slab on the composite slab.
[0035] It is preferred that the beam be a steel beam.
[0036] It is preferred that the profiled metal sheeting be profiled
steel sheeting.
[0037] It is preferred that the beam be supported at each end.
[0038] The beam may be supported also at one or more locations
along the length of the beam.
[0039] The beam may be an internal beam or an edge beam.
[0040] It is preferred that there be a plurality of shear
connectors.
[0041] It is preferred that the shear connectors be headed
studs.
[0042] The shear connectors may be of any other suitable form such
as a structural bolts or channels or shot-fired connectors.
[0043] The shear connectors may be arranged in a straight line
along the length of the beam or may be in a staggered arrangement
along the length with successive shear connectors positioned
transversely to the preceding connector.
[0044] There may be more than one shear connector at each location
along the length of the beam. For example, the shear connectors may
be arranged in pairs along the length of the beam.
[0045] It is preferred that there be a minimum spacing between the
shear connectors along the length of the beam of at least 5 times
the diameter of the shear connectors.
[0046] It is preferred that the spacing between the shear
connectors along the length of the beam be no more than 7.5 times
the height of the shear connectors above the top of the concrete
ribs. This maximum spacing avoids having to use a reinforcing
component of the type described in Australian patent application
69998/01 in the name of the applicant in the composite beam.
[0047] In a situation in which the composite beam includes a
composite slab rather than a solid slab and the composite slab
includes profiled metal sheeting, the top of the concrete ribs is
taken to be the top of the adjacent metal ribs.
[0048] In one arrangement it is preferred that the reinforcing
component be a flat sheet of welded wire mesh that includes a
rectangular array of parallel line wires and cross wires welded
together at the intersections of the wires.
[0049] The present invention is not limited to the arrangement
described in the preceding paragraph and extends, by way of
example, to mesh formed from line wires and cross wires that are
welded together at wire intersections and has line wires that have
a zig-zag shape along at least part of the length of the line
wires.
[0050] The present invention is described further by way of example
with reference to the accompanying drawings of which:
[0051] FIG. 1 is a perspective view which illustrates, in
simplified form, an embodiment of a composite beam (without a layer
of concrete that forms part of the beam) in accordance with the
present invention;
[0052] FIG. 2 is an end elevation of the composite beam shown in
FIG. 1 (with the layer of concrete illustrated in the Figure) in
the direction of the arrow A in FIG. 1;
[0053] FIG. 3 is a perspective view of the reinforcing component of
the embodiment of the composite beam in accordance with the present
invention that is shown in FIGS. 1 and 2;
[0054] FIG. 4 is a graph of connector shear force versus
longitudinal slip produced in research work carried out by the
applicant on a composite beam in accordance with the present
invention of the general type shown in FIGS. 1 to 3;
[0055] FIG. 5 is an end elevation similar to that of FIG. 2
illustrating a specific form of the embodiment of the composite
beam shown in FIGS. 1 to 3; and
[0056] FIG. 6 is an end elevation similar to that of FIGS. 2 and 5
illustrating another embodiment of a composite beam in accordance
with the present invention.
[0057] The embodiment of the composite beam 3 in accordance with
the present invention that is shown in FIGS. 1 to 3 is in a
simplified form to illustrate the composite beam 3 more
clearly.
[0058] With reference to FIGS. 1 and 2, the composite beam 3
includes: [0059] (a) a horizontally extending hot-rolled or
fabricated steel beam 5 which is supported at each end and at at
least one location along the length of the beam so that the beam
extends across multiple spans between the beam end supports; [0060]
(b) a composite slab including: [0061] (i) profiled steel sheeting
7 in contact with a top flange 9 of the steel beam 5, the sheeting
7 including a plurality of parallel steel ribs 11 separated by pans
13 and positioned so that the steel ribs 11 extend in a direction
that is parallel to the longitudinal axis of the beam 5; and [0062]
(ii) a layer 29 of concrete cast on the sheeting 7 and having an
upper surface 31 (shown in FIG. 2 only), whereby the metal pans and
the angled sides of the steel ribs define outer surfaces of
concrete ribs 21 and the remainder of the concrete layer 29 defines
a slab section of the composite slab; [0063] (c) a plurality of
pairs of shear connectors 15 in the form of headed studs that
extend through the particular concrete rib 21 shown in FIGS. 1 and
2 that is positioned on the beam 5 and are welded to the top flange
9 of the beam 5 at spaced intervals along the length of the beam 5;
and [0064] (d) a reinforcing component generally identified by the
numeral 19 embedded in the concrete slab in the concrete rib 21 in
which the shear connectors 15 are positioned for preventing lateral
rib punch-through failure of the composite beam 3.
[0065] The beam 5, the shear connectors 15, and the composite slab
may be of any suitable dimensions and construction. Typically, the
shear connectors 15 are spaced longitudinally apart by 100-300 mm
and transversely apart by 60-100 mm. Typically, the composite slab
has a thickness of at least 120 mm.
[0066] In addition, whilst the profiled steel sheeting 7 shown in
FIGS. 1 and 2 has a trapezoidal profile, the sheeting 7 may be
dovetail or of any other suitable shape with open steel ribs.
[0067] The reinforcing component 19 shown in FIGS. 1 to 3 is in the
form of a steel mesh that is formed from line wires 41 and cross
wires 45 that are welded together at the intersections of the wires
to form a generally rectangular array.
[0068] The line wires 41 and the cross wires 45 may be the same or
different diameters, depending on the circumstances.
[0069] The mesh is positioned so that the line wires 41 extend in
the longitudinal direction of the concrete ribs 21 and the
cross-wires 45 extend transversely to the concrete ribs 21.
[0070] In addition, the mesh is positioned within the concrete rib
21 so that it is below the top of the concrete ribs 21, ie below
the tops of adjacent steel ribs 11, and more particularly in the
embodiment shown in FIGS. 1 to 3 is approximately midway between
the base of the pan 13 and the tops of the adjacent ribs 11.
[0071] As is indicated above, the applicant has carried out
research work on a portion of a composite beam of the type shown in
FIGS. 1 to 3 on an experimental push-out rig of the applicant.
[0072] FIG. 4 is a graph of connector shear force versus
longitudinal slip produced in the research work. The applicant
determined in comparative test work that the use of the reinforcing
component 19 produced a 64% increase in the strength of the shear
connector of the composite beam and also an increase in ductility
of the composite beam.
[0073] FIG. 5 illustrates a specific form of the embodiment of the
composite beam shown in FIGS. 1 to 3 designed by the applicant for
a specific application.
[0074] FIG. 5 indicates specific dimensions of the composite beam
and specific design information for the beam.
[0075] It is noted that design of the embodiment of the composite
beam shown in FIGS. 1 to 3 constructed using grade 500 steel can be
based on the information in Table 1 below. TABLE-US-00001 Stud
Longitudinal Cross Wire Cross Wire Line Wire Line Wire Spacing
s.sub.c Diameter Spacing Diameter Spacing (mm) (mm) (mm) (mm) (mm)
.ltoreq.150 9.5 75 7.6 150 >150 9.5 150 7.6 150
[0076] FIG. 6 illustrates another embodiment of a composite beam 3
in accordance with the invention.
[0077] The composite beam 3 has the same basic components as the
embodiment of the composite beam shown in FIGS. 1 to 3 and 5 and
the same reference numerals are used to describe the same
components.
[0078] The reinforcing component 19 also includes a plurality of
spaced apart additional reinforcing elements 51.
[0079] The additional reinforcing elements 51 are in the form of
cranked handlebar-shaped bars that are tied to the cross wires 45
and extend from the rib 21 into the adjoining section of the slab
section of the concrete layer 29 to prevent delamination of the
slab at ultimate load.
[0080] FIG. 6 illustrates a specific form of the embodiment
designed for a specific application.
[0081] In any given situation the number of handlebars can be
determined having regard to factors such as the compressive
strength grade of the concrete and the longitudinal spacing of the
shear connectors.
[0082] Many modifications may be made to the preferred embodiments
of the present invention as described above without departing from
the spirit and scope of the present invention.
[0083] By way of example, whilst the embodiment of the composite
beam shown in FIGS. 1-3 include pairs of shear connectors 15 along
the length of the beams 5, the present invention is not limited to
this arrangement and extends to any suitable arrangements such as
arrangements in which there are single rather than pairs of shear
connectors. Such alternative arrangements are shown in FIGS. 5 and
6.
[0084] Furthermore, whilst the embodiments are arrangements in
which the concrete ribs 21 are parallel to the longitudinal axis of
the beam 5, the present invention is not so limited and extends to
arrangements in which the concrete ribs 21 and the longitudinal
axis describe an acute angle of 15.degree. or less.
[0085] Furthermore, whilst the embodiments are arrangements which
include a composite slab, the present invention is not so limited
and extends to arrangements which include solid concrete slabs.
[0086] Furthermore, whilst the embodiments are arrangements which
include a concrete rib in which the shear connectors 15 are
embedded that is defined by a pan 13 and adjacent steel ribs 11 of
a single profiled steel sheet, the present invention is not so
limited and extends to arrangements in which concrete ribs
containing embedded shear connectors are defined by edge pans and
ribs of adjacent split profiled steel sheets.
[0087] Furthermore, whilst the embodiment shown in FIG. 6 describes
that the cranked handlebar-shaped bars are tied to the cross wires
45, the present invention is not so limited and extends to
arrangements in which the additional reinforcing elements 51 are an
integrally formed part of the reinforcing component 19.
* * * * *