Note: Descriptions are shown in the official language in which they were submitted.
CA 02592710 2007-07-20
COMPOSITE ENERGY ABSORBING STRUCTURE
FIELD OF THE INVENTION
[001] The present invention relates to an energy absorbing structure which is
constructed to transfer horizontal forces from floor slabs to shear wall
panels to permit
buildings to withstand earthquakes and other forces exerted on them.
BACKGROUND OF THE INVENTION
[002] Earthquakes exert lateral and vertical forces on a building, and
fabricating a
structure that tivill withstand these random, often sudden forces is a complex
task. When
designing an earthquake-resistant building, engineers can choose various
structural
components, such as shear walls, braced frames, moment resisting frames,
diaphragms
and horizontal trusses. These building elements impart earthquake resistant
structures
with the ability to resist and sometimes to absorb and dissipate seismically
induced
motion through a combination of means, including damping means which absorbs
energy and decreases the amplitude of oscillations of a vibrating structure
and inelastic
defoi-mation means which can withstand considerable inelastic deformation. The
structural elements can be used alone or in combination to achieve the
necessary
sti-ength and energy absorption and dissipation.
[003] Shear walls at-e an example of a structural element used in earthquake
resistance structures. A shear wall is a vertical element in a building
lateral load
resisting system that transfers horizontal forces vertically downward from a
diaphragm
-ibove to a diapliragm or a foundation below. Thus, horizontal wind or seismic
forces
are collected at floor or roof diaphragm levels and transferred to the
building foundation
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by the strength and rigidity of the shear walls. In a lateral load resisting
system,
concrete floor slabs often act as diaphragms, and thus the connection between
the floor
slabs and the shear wall panels is critical for effective transference of
lateral forces. In
this regard, the stronger the connection between the shear wall panels and the
floor
slabs, the more effective the entire lateral load resisting system will be in
transferring
lateral loads to the foundation.
[004] Accordingly, there is a need for a means to provide a strong connection
between floor slabs and shear wall panels in a building lateral load resisting
system to
improve the effectiveness of the system in transferring lateral loads to the
building
foundation.
StIMMARY OF THE INVENTION
[005] According to the present invention, a shear wall panel partially
embedded in a
floor slab transfers horizontal forces from the floor slab to the shear wall
or from one
floor slab to an adjacent floor slab. Specifically, a composite energy
absorbing structure
according to an exemplary embodiment of the present invention includes a shear
wall
panel having at least one horizontally-disposed structural member at least
partially
embedded in a floor slab such that horizontal forces exerted on the floor slab
are
transferred to the shear wall panel through the structural member.
[006] In at least one embodiment, the structural member includes two or more
bars
each having an angle shape in cross section and each having a vertical leg and
a
horizontal leg.
[007] The invention also encompasses a method of forming a composite structure
in
a building, including forming a shear wall panel having a structural member,
and at least
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partially embedding the structural member in a floor slab, such that
horizontal forces
exerted on the floor slab are transferred to the shear wall panel through the
structural
member.
[0081 These and other features of this invention are described in, or are
apparent
from, the following detailed description of various exemplary embodiments of
this
invention
BRIEF DESCRIPTION OF THE DRAWINGS
[009] Various exemPlary embodiments of this invention will be described in
detail,
with reference to the following figures, wherein:
[010] FIG. 1 illustrates a shear wall according to an exemplary embodiment of
the
present invention;
[011] FIG. 2 illustrates a shear wall according to another exemplary
embodiment of
the prescnt invention;
[012] FIG. 3 is a cross-sectional view along the line A-A shown in FIG. 1; and
[013] FIG. 4 is a perspective view showing the shear wall of FIG. 1 including
a
structural member imbedded in a floor slab.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[014] The various exemplary embodiments of the present invention are directed
to a
shear wall that imparts buildings with the ability to withstand forces caused
by, for
example, earthquakes. The shear wall includes multiple shear wall panels, each
including, as a component, a structural member, that transfers horizontal
forces exerted
on floor slabs, in which the structural member is at least partially embedded,
to the shear
wall panel. It should be appreciated that the various concepts of the present
invention
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are not necessarily limited to earthquake resistant structures, but are also
applicable to
structures that are designed to withstand forces generated by any other
factor, such as,
for example, explosions or high winds. It should also be appreciated that the
present
invention is not limited to the particular shear wall structures expressly
illustrated herein
and that other shear wall structures may be used.
[015] FIG. 1 shows a shear wall panel, generally designated by reference
number 10,
according to an exemplary embodiment of the present invention. The shear wall
panel
may be one of many such panels that make up one shear wall of a building. The
shear wall panel 10 is composed of a generally rectangular shaped frame
including two
vertically disposed frame members 12 and two horizontally disposed structural
members
14. An opening 16 is defined by the frame members 12 and structural members 14
within the shear wall panel 10. The frame members 12 and structural members 14
may
be attached to each other by any suitable means, such as, for example, pin
joints,
welding, bolts or connector elements 18.
[016] The shear wall panel also includes shear transfer means which can take
any
useful form. FIG. 1 shows the shear transfer means as diagonal braces 20.
Another type
of shear transfer means may include a shear panel or a suitable energy
absorber such as
shown in FIG. 2 and described in co-pending U.S. Patent Application Serial No.
10/941,159, incorporated herein by reference. Specifically, referring to FIG.
2, the
energy absorber, generally designated by reference number 21, includes a
ductile
member 22 and four braces 24. The braces 24 support the ductile member 22 at
substantially the center of the opening 16. The ductile member 22 is formed of
a ductil_e
material, such as, for example, steel or aluminum. One of the ends of the
braces 24 are
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connected to the ductile member 22 by any suitable fastening elements, such
as, for
example, adjustable nuts 26. The opposite ends of the braces 24 are attached
to
i-espective corners of the connector elements 18 by, for example, pin joints,
welding or
bolts. The number of braces 24 is not limited to four and any number of braces
24 can
be used in the various exemplary embodiments of the invention. In the present
embodiment of the invention, the braces 24 are tension rods, but can also be
any other
suitably rigid structural supports for the ductile element 22. Further, the
ductile member
22 need not be ring-shaped, as shown in FIG. 2, but could have other shapes as
would be
understood by workers skilled in the art.
10171 Structural members 14 can take any useful form, for example angles or I-
beams. As best seen in FIG_ 3, which is a cross-sectional view along the line
A-A in FIG.
l, the structural members 14 may each include two metal bars, generally
designated by
reference numbers 26, 28. Such structural members are disclosed in U.S. Patent
No.
4,592,184, incorporated herein by reference. Each of the bars 26, 28 have an
angle
shape and include a vertical leg 30 and a horizontal leg 32. The horizontal
leg 32 of the
bar 26 extends in the opposite direction from that in which the horizontal leg
32 of the
bar 28 extends. The height of the vertical legs 30 of the bars 26, 28 are
preferably the
same, although in other embodiments the heights may be different. The vertical
legs 30
of the two bai=s 26, 28 are spaced apart by the width of the connector
elements 18.
Concrete engaging means 34 such as, for example, protrusions or slots are
preferably
formed at spaced intervals along the length of the vertical legs 30. It should
be
appreciated that the bars 26, 28 ma_y have any other suitable shape.
[018) As best shown in FIG. 4, a shear wall panel 10 is incorporated into a
building
CA 02592710 2007-07-20
structure by forming the concrete floor slab 36 in intimate contact with shear
wall panel
10. In this regard, concrete may be poured such that the structural member 14
is at least
partially, but preferably completely, embedded in the floor slab 36. The floor
slab 36
may form a component of a flooring system, such as the flooring system
disclosed in U.S.
Patent No. 4,592,184. The shear wall panel 10 may also extend upwards into an
upper
floor, such that the upper structural member 14 may also be embedded in a
floor slab 36
of an upper flooring system. Many such shear wall panels are embedded in the
floor
slabs of a building to form the entire building structure.
[019] By placing the floor slabs 36 in intimate contact with the structural
members
14, any horizontal forces exerted on the floor slabs 36 will be transferred to
the shear
wall 10 through the structural members 14 and/or from one floor slab to a
neighboring
floor slab. The deformed structural members 14 enable the floor slabs 36 to
more
effectively act as diaphragms in transferring energy to the shear wall 10 or
to a
neighboring floor slab 36.
10201 While this invention has been described in conjunction with the
exemplary
embodiments outlined above, it is evident that many alternatives,
modifications and
variations will be apparent to those skilled in the art. Accordingly, the
exemplary
embodiments of the invention, as set forth above, are intended to be
illustrative, not
limiting. Various changes may be made without departing from the spirit and
scope of
the invention.
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