U.S. patent application number 10/167477 was filed with the patent office on 2003-12-18 for take-up devices for use in building structure.
Invention is credited to Gignac, Marcel, Hobbs, Brian, Shahnazarian, George.
Application Number | 20030230032 10/167477 |
Document ID | / |
Family ID | 29732200 |
Filed Date | 2003-12-18 |
United States Patent
Application |
20030230032 |
Kind Code |
A1 |
Shahnazarian, George ; et
al. |
December 18, 2003 |
Take-up devices for use in building structure
Abstract
A take up device for a building structure, e.g. holdown for
securing the building structure to a foundation, has a housing
secured by fasteners to the building structure, the housing
defining a cylindrical chamber containing a piston and fluid, with
a piston rod projecting from the housing. The piston rod is
connected to a foundation anchor, and a fluid passage interconnects
portions of the cylindrical chamber at opposite sides of the
piston. The fluid passage is provided with a one-way valve, which
allows the housing to move upwardly relative to the piston, to
maintain the tightness of the connection to the anchor bolt, but
resists opposite movement of the housing.
Inventors: |
Shahnazarian, George; (North
Burnaby, CA) ; Gignac, Marcel; (Chilliwack, CA)
; Hobbs, Brian; (Burnaby, CA) |
Correspondence
Address: |
LONG AND CAMERON
SUITE 1401 - 1166 ALBERNI STREET
VANCOUVER
BC
V6E 3Z3
CA
|
Family ID: |
29732200 |
Appl. No.: |
10/167477 |
Filed: |
June 13, 2002 |
Current U.S.
Class: |
52/167.3 ;
52/223.13; 52/295; 52/585.1 |
Current CPC
Class: |
Y02A 50/00 20180101;
E04B 2001/2688 20130101; E04H 9/14 20130101; E04B 2001/268
20130101; Y02A 50/14 20180101 |
Class at
Publication: |
52/167.3 ;
52/295; 52/223.13; 52/585.1 |
International
Class: |
E04B 001/98 |
Claims
We claim:
1. A take up device, comprising: a housing; said housing defining
the cylindrical chamber within said housing and said cylindrical
chamber having a cylindrical wall; a piston within said cylindrical
chamber, said piston having a piston rod projecting from said
housing; and a fluid within said chamber; a one-way valve which is
deflectable by pressure of the fluid to prevent displacement of
said piston and said piston rod in a first axial direction along
said cylindrical chamber toward said anchor and resisting
displacement of said piston and said piston rod in an opposite
axial direction along said cylindrical chamber; fasteners for
securing said housing to a building structure; and an anchor for
securing said take up device to a building foundation; and a
connector between said anchor and said piston rod.
2. A take up device as claimed in claim 1, including a fluid
passage interconnecting portions of said cylindrical chamber at
opposite sides of said piston.
3. A take up device has claimed in claim 1, wherein said fluid
passage extends through said piston.
4. A take up device as claimed in claim 2, wherein said fluid
passage extends within said housing and outwardly of said
piston.
5. A take up device has claimed in claim 2, wherein said fluid
passage extends exteriorly of said housing.
6. A take up device as claimed in claim 1, wherein said one-way
valve comprises an annular seal of elastomeric material extending
around said piston.
7. A take up device as claimed in claim 6, wherein said annular
seal has a cross-sectional shape having a first limb thereof in
sealing contact with said piston and a second limb thereof in
sealing contact with said cylindrical wall.
8. A take up device as claimed in claim 7, wherein said
cross-sectional shape of said O-ring has an intermediate portion
abutting said piston and interconnecting said first and second
limbs.
9. A take up device as claimed in claim 7, wherein said
cross-sectional shape of said annular seal has third and fourth
limbs extending oppositely from said first and second limbs, said
third limb sealingly contacting said piston and said fourth limb
being in sealing contact with said cylinder wall and abutting said
piston.
10. A take up device as claimed in claim 6, wherein said piston has
an annular surface and a peripheral projection forming an annular
shoulder on said piston and a frustoconical surface portion
converging from said annular surface, said O-ring normally
extending around said annular surface in abutment with said
peripheral surface and being displaceable from said annular surface
to said frustoconical surface by the fluid on displacement of said
piston and said piston in said first direction relative to said
housing.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to take up devices for use in
building structures and is useful in particular, but not
exclusively, holdowns for reinforcing building structures against
seismic vibrations and hurricane damage.
[0003] 2. Description of the Related Art
[0004] Holdowns are used in wood frame building structures in order
to secure the structures to their concrete foundations. For this
purpose, conventional holdowns are made of sheet metal and are
secured by nails, bolts and other fasteners to the wooden
components of the building structure and by anchor bolts to the
concrete foundations of the buildings.
[0005] It is found, in practice, that nuts securing the holdowns to
the anchor bolts tend to become loose, after a period of time, as a
consequence of wood shrinkage due to drying and, also, due to
vibration of the building structure caused by seismic activity.
BRIEF SUMMARY OF THE INVENTION
[0006] It is, therefore, an object of the present invention to
provide a novel and improved take up device for building structures
which will counteract such loosening of the securing nuts.
[0007] According to the present invention, there is provided a take
up device which comprises a housing secured by fasteners to a
building structure, the housing defining a cylindrical chamber
containing a piston and a fluid, i.e. a liquid or a gas, with a
piston rod projecting from one or both ends of the housing. One end
of the piston rod is connected to a foundation anchor, and a fluid
passage interconnects portions of the cylindrical chamber at
opposite sides of the piston. The fluid passage is provided with a
one-way valve.
[0008] In use, the one-way valve allows the housing to move in one
direction, i.e. toward the anchor member, relative to the piston in
order to maintain a tight connection between the housing and the
anchor. This tightening movement counteracts any compression of the
wooden components of the building structure. However, the one-way
valve counteracts flow of the fluid in the opposite direction
through the fluid passage so as to prevent loosening of this
connection.
[0009] The present take up device may be used as a holdown or part
of a holdown, e.g. for securing a building structure to a
foundation, or as a take up device between e.g. horizontally or
vertically adjacent building components.
[0010] In a preferred embodiment of the invention, the fluid
passage is formed by a clearance between the piston and the wall of
the cylindrical chamber, and the one-way valve comprises an annular
seal between the piston and the cylinder wall.
[0011] To allow the present device to act as a dampener, e.g. for
dampening seismic vibrations of the building structure, a further
fluid flow passage may be provided, e.g. through the piston or
bypassing the piston, to allow relaxation of the connection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] The invention will be more readily understood from the
following description of preferred embodiments thereof given, by
way of example, with reference to the accompanying drawings, in
which:--
[0013] FIG. 1 shows an exploded view, in perspective, of a holdown
according to a first embodiment of the present invention;
[0014] FIG. 2 shows a view in perspective of components of the
holdown of FIG. 1;
[0015] FIG. 3 shows a view in perspective of a piston and an
annular seal forming parts of the holdown of FIG. 1;
[0016] FIG. 3A shows a view taken it in cross-section through the
annular seal of FIG. 3 along the line 3A-3A of FIG. 3;
[0017] FIGS. 4 and 4A show views corresponding to those of FIGS. 3
and 3A, but of a modified annular seal;
[0018] FIGS. 5 and 5A show views in vertical cross-section through
a housing, a piston and a one-way valve forming components of the
holdown of FIG. 1;
[0019] FIGS. 6 and 7 show views corresponding to that of FIG. 5 but
illustrating modifications of the holdown components of FIG. 5;
[0020] FIG. 8 shows a view in perspective of the holdown of FIG. 1
in an assembled condition;
[0021] FIGS. 9 and 9A show views corresponding to that of FIG. 8,
but illustrating modifications of the holdown of FIG. 8;
[0022] FIG. 10 shows a broken-away view, in perspective, of another
modification of the holdown of FIG. 1;
[0023] FIGS. 11 and 12 shows views in perspective of two further
modifications of the holdown of FIG. 1, in a partly exploded
condition;
[0024] FIGS. 13 and 14 show, respectively, a view in perspective of
the holdown of FIG. 1 with added components and a broken-away view
in side elevation of an application of that holdown;
[0025] FIGS. 15 through 22 show views corresponding to those of the
FIGS. 13 and 14, but illustrating different applications of the
holdown according to the present invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0026] As shown in FIG. 1, a holdown indicated generally by
reference numeral 10 has a housing 12 provided with a housing cover
14, which is secured to the housing 12 by screws 15.
[0027] A piston 16 on a piston rod 18 is located in a cylindrical
chamber 20 (FIG. 5) in the housing. 12. The cylindrical chamber 20
is closed at one end by the housing cover 14 and, at its opposite
end, by a wall 22 of the housing. The housing cover 14 has a
cylindrical recess accommodating a bushing 24, and the wall 22 has
a cylindrical recess accommodating a bushing 26. The piston rod 18
extends in opposite directions from the piston 16 through the
bushings 24 and 26, and has opposite threaded ends 28 and 30.
[0028] The outer diameter of the piston 16 is less than the inner
diameter of the cylindrical chamber 20, so that a clearance 31
(FIGS. 5 and 5A) is provided between the periphery of the piston 16
and the cylindrical wall of the cylindrical chamber 20. An annular
seal 32 extends around the periphery of the piston 16 and provides
a seal between the piston 16 and the wall of the cylindrical
chamber 20, as described in greater detail below. More
particularly, and as shown in FIG. 3A, the annular seal 32 has a
U-shaped cross-section comprising limbs 34 and 35 connected by an
intermediate portion 36. The limb 34, which is the outermost limb,
is normally in sealing contact with the cylindrical wall of the
cylindrical chamber 20, and the inner limb 35 is in sealing contact
with the piston 16.
[0029] FIGS. 4 and 4A show a modified O-ring 38, which has first
and second limbs 39 and 40, extending toward one side of the O-ring
38, which are in sealing contact with the cylindrical wall and the
piston 16, respectively, and third and fourth limbs 42 and 43
extending oppositely from the limbs 39 and 40, and sealingly
contacting the cylinder wall. The O-ring 38 of FIGS. 4 and 4A is
used instead of the O-ring 32 on the piston 16, as shown in FIG. 6
and described in greater detail below.
[0030] As can be seen in FIG. 5, the piston 16 has an annular
intermediate surface 46, which is cylindrical, between an annular
peripheral projection 48, forming a shoulder on the piston 16, and
a frustoconical surface 50, which tapers convergently from the
annular intermediate surface 46. The modified annular seal 38, as
shown, in FIG. 6, extends around the annular intermediate surface
46, with its limbs 39 and 43 in sealing contact with the annular
intermediate surface 46.
[0031] Referring again to FIG. 1 of the accompanying drawings, the
holdown 10 is provided with inlet openings 52 and 54 which are
provided with threaded plugs 55 and through which a fluid is
introduced into the cylindrical chamber 20 at opposite sides of the
piston 16. The opening 52 is provided in the housing 12, and
communicates directly with the cylindrical chamber 20, while the
opening 54 is provided in the housing cover 14 and communicates
with the cylindrical chamber 20 through an axial passage 56 in the
housing cover 14.
[0032] In operation of the holdown 10, as it has so far been
described, the piston is able to move along the cylinder 20 toward
the housing cover 14, e.g. in response to shrinkage of the wooden
building components secured by the holdown 10 as described below,
so that the housing 12 is able to move relative to the piston 16
toward the end 30 of the piston rod 18. When this occurs, the
pressure of the fluid in the portion of the cylindrical chamber 20
between the piston and the housing cover 14 causes some of the
fluid to flow through the clearance 31 between the piston 16 and
the wall of the cylindrical chamber 20, thereby causing the annular
seal 32 to be dislodged from the annular intermediate surface 46 to
the frustoconical surface 50, as shown in FIG. 5A. When this
occurs, the annular seal 32 no longer provides a seal between the
piston 16 and the wall of the cylindrical chamber 20.
[0033] When, however, the piston 16 is urged in the opposite
direction, i.e. toward the end wall 22 of the housing 12, the fluid
in the portion of the cylindrical chamber 20 between the piston 16
and the wall 22 of the housing presses the annular seal 32 back
onto the annular intermediate surface 46 and into sealing contact
with the piston 16 and the wall of the cylindrical chamber 20.
Consequently, the displacement of the piston 16 in this direction
is counteracted by the pressure of the fluid between the piston 16
and the housing wall 22.
[0034] Therefore, the annular seal 32 serves as a one-way valve,
which allows the piston 16 to be displaced in one direction
relative to the housing 20 but which counteracts, or even prevents,
displacement of the housing 12 in the opposite direction relative
to the housing 20.
[0035] The piston 16 is also formed with a further annular
peripheral projection 52, toward which the frustoconical surface 50
tapers. This further annular peripheral projection 52 serves to
retain the annular seal 32 on the piston 16 when the seal is
displaced, as described above, from the annular intermediate
surface 46 to the frustoconical surface 50.
[0036] FIG. 6 shows a modification of the piston 16, which is
indicated by reference numeral 60. The piston 60 differs from the
piston 16 in that the piston 60, which is otherwise the identical
to the piston 16, is formed with a boring 62 extending through the
piston 60, parallel to the longitudinal axis of the piston rod 18.
This boring 62 provides a further fluid flow passage
interconnecting the portions of the cylindrical chamber 20 at
opposite sides of the piston 16, and allows a restricted flow of
the fluid past the piston 16. In this embodiment of the present
invention, the annular seal 32 is replaced by the annular seal
38.
[0037] By this means, the piston 16 is enabled to move gradually
toward the housing wall 22. Consequently, when this modified piston
60 is substituted for the piston 16 in the holdown 10, the latter
acts as a dampener.
[0038] FIG. 7 illustrates a further modified piston, indicated by
reference numeral 64, which is identical to the piston 60 of FIG. 6
except that the piston 64 is additionally provided with a flow
control screw 66, in the form of a grub screw, which can be screwed
into a correspondingly threaded opening 68 in the piston 64. When
thus inserted into the piston 64, the flow control screw 66 can be
adjusted so as to obstruct, to a greater or lesser extent, the
cross-sectional area of the boring 62 and, thus, so as to
adjustably restrict the flow of fluid through this further flow
passage and, thereby, to control the damping effect of the piston
64.
[0039] FIG. 8 shows a view in perspective of the holdown 10 of FIG.
1 in an assembled condition.
[0040] FIG. 9 shows a view corresponding to that of FIG. 8 but
illustrating a modification of the holdowns of FIGS. 6 and 7,
indicated generally by reference numeral 10A, in which the piston
16 is provided, i.e. the piston lacks the further flow passage
formed by the boring 62 in the piston 60 or 64, but in which the
opposite sides of the piston 16 are instead interconnected by a
further flow passage extending through a tube 70 at the exterior of
the housing. The tube 70 is provided with a check valve 69
controlling flow through the tube 70.
[0041] FIG. 9A shows the holdown of FIG. 9 modified by the
provision of an adjustment screw 71, which can be screwed into the
check valve 69 to a greater or lesser extent in order to
correspondingly adjust the flow through the tube 70.
[0042] FIGS. 10 to 12 show further modifications 10B, 10C and 10D
of the holdown 10, in which flow passages within the housings of
the modified holdowns interconnect the portions of the cylindrical
chambers at opposite sides of the pistons.
[0043] In FIG. 10, an auxiliary chamber 72 communicates through
openings 74 and 76 with opposite sides of the piston.
[0044] In FIG. 11, a modified piston rod 16C projects downwardly
from the holdown 10C but does not project upwardly through a cover
14C of a housing 12C. A spring (not shown) is provided between the
piston 16C and the housing 12C. An auxiliary chamber 78,
corresponding to the chamber 72 of FIG. 10, interconnects opposite
sides of piston 16C.
[0045] The holdown 10D of FIG. 12 is similar to the holdown 10C
except that, as shown in FIG. 12, the upper end 28 of the piston
rod 18 projects through housing cover 14D.
[0046] FIG. 13 shows the holdown 10 mounted on a pair of parallel
elongate support blocks 100, which are provided with
through-openings 102 for receiving fasteners, for example screws
(not shown). In FIG. 14, the holdown 10 of FIG. 13, together with
its support blocks 100, is shown mounted on the top of a building
structure indicated generally by reference numeral 104 at the top
of the building structure 105. The fasteners (not shown) extend
through the support blocks 100 so to secure the holdown 10 to the
top of a plate 104. The piston rod 18 thus extends vertically, and
its lower threaded end 30 is connected through a plurality of
connecting rods 106 and couplings 108 to an anchor bolt 110, which
is secured in a concrete foundation 112.
[0047] Two further holdowns 10 are shown in FIG. 14, which are
interconnected between two of the couplers 108 and plates 109 on
joists 111 at intermediate floors of the building structure 105.
However, these two further holdowns 10 may be omitted if not
required.
[0048] FIG. 15 shows the holdown 10 secured to one face of a
vertical metal plate 112, formed with bolt holes 113, with a
support block 114, which is fixed to the plate 112, underlying the
housing 12 of the holdown 10. A plurality of such holdowns 10, each
provided with a respective vertical plate 112, can then be bolted
to vertical studs 116 of building structure, as shown in FIG. 16,
and connected between the uppermost holdown 10, which is similar to
that of FIG. 13, and the anchor bolt 110.
[0049] FIG. 17 shows the holdown 10 secured to a pair of a vertical
metal plates 120. As shown in FIG. 18, these vertical plates can
then be secured by nuts 122 and bolts 123 between a pair of studs
124, with the bolts 123 extending through bolt holes 126 in the
plates 120 and through the studs 124, the holdown 10 being
connected between the anchor bolt 110 and the lower end 30 of the
piston rod 18 by one of the couplers 108. The upper end 28 of the
piston rod 18 is connected by a further coupler 108 and connecting
rod 106 to an overlying holdown (not shown).
[0050] FIG. 19 shows the holdown 10 mounted on a conventional sheet
metal holdown indicated generally by reference numeral 130. The
holdown 130 is secured to a pair of studs 132 by a pair of bolts
134, each provided with a nut 136 and a washer 138 (FIG. 20). The
holdown 10 is mounted on an intermediate portion 140 of the holdown
130 extending between opposite sidewalls 142 and is connected by
coupler 108 to the anchor bolt 110.
[0051] FIG. 21 shows a further arrangement of the holdown 10, which
in this case is mounted between a pair of identical elongate
rectangular plates 150, to which the housing 12 of the holdown 10
is attached by welding or otherwise. The plates 150 are formed with
circular openings 152, which are connected through tubes 154 welded
or otherwise attached to the plates 150.
[0052] As shown in FIG. 22, the holdown 10 together with the plates
150 are located between a pair of wooden studs 156, with bolts 158
extending through the studs 156 and through the tubes 154 and
secured by nuts 160. The holdown 10 is again connected through
coupler 108 to the anchor bolt 110.
[0053] The fluid provided in the holdowns according to the present
invention may be hydraulic fluid or any suitable inert gas.
[0054] As will be apparent to those skilled in the art, various
modifications may be made in the above described invention within
the scope and spirit of the accompanying claims.
* * * * *