U.S. patent number 3,779,660 [Application Number 05/213,684] was granted by the patent office on 1973-12-18 for expansion joint seal.
This patent grant is currently assigned to Construction Specialties, Inc.. Invention is credited to Frank L. McGeary, Patrick L. Zampetti.
United States Patent |
3,779,660 |
McGeary , et al. |
December 18, 1973 |
EXPANSION JOINT SEAL
Abstract
An expansion joint seal for bridging and sealing an expansion
space between structural members comprises a pair of elongated
frame members, each of which is adapted to be secured rigidly to
one of the structural members on either side of the joint, an
elongated substantially rigid bridge member extending lengthwise of
the joint and spanning the expansion space between the structural
members, the lateral edges of the bridge member being spaced from
the edges of the frame members, and a seal member of elastomeric
material received between the bridge member and the edges of the
respective frame members. The frame members and bridge member
include companion surfaces disposed in substantially horizontal
planes so that the frame members support the bridge member but are
able to move toward and away from each other and relative to the
bridge member. Generally C-shaped cavities are provided at, first,
a portion of each frame member adjacent and above the horizontal
supporting surface and, second, portions adjacent the lateral edges
of the bridge member, the respective cavities of the frame members
and bridge member facing each other across the space above the
horizontal surfaces of the frame members. The elastomeric material
extends into and is therefore captured and sealed within the
C-shaped cavity on each frame member and on the bridge member. The
inherent resiliency of the elastomeric material tends to hold the
bridge member centered between the frame members and distends in
accordance with relative movements of the frame members. A bond
breaker medium is provided between the seal members and all
underlying substantially horizontal surfaces of the frame member
and bridge member and prevents any bonding between the seal members
and such surfaces.
Inventors: |
McGeary; Frank L. (Scotch
Plains, NJ), Zampetti; Patrick L. (Cranford, NJ) |
Assignee: |
Construction Specialties, Inc.
(Cranford, NJ)
|
Family
ID: |
22796090 |
Appl.
No.: |
05/213,684 |
Filed: |
December 29, 1971 |
Current U.S.
Class: |
404/69 |
Current CPC
Class: |
F16L
25/0027 (20130101); E04B 1/6804 (20130101) |
Current International
Class: |
E04B
1/68 (20060101); F16L 25/00 (20060101); E01c
011/04 () |
Field of
Search: |
;94/18,18.2 ;52/395,396
;14/16 ;404/47,69,67 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Frazier; Roy D.
Assistant Examiner: Holko; Thomas J.
Claims
We claim:
1. An expansion joint seal for bridging and sealing an expansion
space between structural members comprising a pair of elongated
frame members, each of which is arranged to be secured rigidly to
one of the structural members adjacent the space and to extend
along the length of said members, each frame member being of
uniform cross-section along its length and including in
cross-section a portion defining a cavity having an opening facing
generally inwardly toward the expansion space, the interior of the
cavity having a greater cross-sectional dimension than the
dimension across said opening, and each frame member including a
base portion adjacent the cavity portion, the base portions of the
members having surfaces that are substantially coplanar when the
members are installed at the joint, and each frame member further
including in cross-section a generally "C"-shaped slot located
along a marginal portion thereof remote from the expansion space; a
substantially impermeable fluid membrane of flexible material
disposed adjacent each frame member, each membrane having a portion
received in said slot; a resilient retainer member received in the
slot to hold the membrane in place; a substantially rigid elongated
bridge member extending lengthwise of the joint, spanning the
expansion space, having surfaces engaging the said coplanar
surfaces of the frame members for relative sliding movement and
having in cross-section a portion along each longer side edge
defining a cavity that faces generally outward from the space and
is generally opposite the cavity in a respective frame member, the
side edges of the bridge member being spaced from the outer
extremities, relative to the expansion space, of said frame
membersurfaces and providing a zone between the bridge member and
each frame member for substantial sliding movement of the bridge
member relative to the frame members; and a unitary body of an
elastomeric material received in each said zone and in the cavities
of the respective frame and the bridge members, each said body
filling said zone and being bonded and sealed to the cavities but
being free of any substantial bond to said coplanar surface of the
frame member.
2. An expansion joint seal according to claim 1 and further
comprising a bond breaker medium between said coplanar surfaces and
the respective body of elastomeric material to prevent the
formation of a bond between the said coplanar surfaces and the body
of elastomeric material.
3. An expansion joint seal according to claim 1 wherein the
cavities are generally C-shaped in cross-section and provide a
mechanical interlock with the body of elastomeric material received
therein.
4. An expansion joint seal according to claim 1 and further
comprising at least one retainer acting between the frame members
and the bridge member for resiliently retaining the said surfaces
of those members in engagement while affording relative sliding
movement.
5. An expansion joint seal according to claim 1 wherein the
elastomeric material received in each zone reacts to any lateral
deformation of the material in the opposite zone causing movement
of the bridge member and resists said deformation thus tending to
hold the bridge member in a substantially centered position between
the frame members.
6. An expansion joint seal for bridging and sealing an expansion
space between structural members comprising a pair of elongated
frame members, each of which is arranged to be secured rigidly to
one of the structural members adjacent the space and to extend
along the length of said members, each frame member being of
uniform cross-section along its length and including in
cross-section a portion defining a cavity having an opening facing
generally inwardly toward the expansion space, the interior of the
cavity having a greater cross-sectional dimension than the
dimension across said opening, and each frame member including a
base portion adjacent the cavity portion, the base portions of the
members having surfaces that are substantially coplanar when the
members are installed at the joint, and each frame member further
including a first part that includes the cavity portion and base
portion, and a separate second part to support the first part and
arranged to be secured to the structural member; a substantially
rigid elongated bridge member extending lengthwise of the joint,
spanning the expansion space, having surfaces engaging the said
coplanar surfaces of the frame members for relative sliding
movement and having in cross-section a portion along each longer
side edge defining a cavity that faces generally outward from the
space and is generally opposite the cavity in a respective frame
member, the side edges of the bridge member being spaced from the
outer extremities, relative to the expansion space, of said frame
member surfaces and providing a zone between the bridge member and
each frame member for substantial sliding movement of the bridge
member relative to the frame members; a unitary body of an
elastomeric material received in each said zone and in the cavities
of the respective frame and the bridge members, each said body
filling said zone and being bonded and sealed to the cavities but
being free of any substantial bond to said coplanar surface of the
frame member; and means positioned for access for detachably
securing the first part of the frame member to the second part
thereof such that an assembly that includes at least the first
parts of the frame members, the bodies of elastomeric material and
the bridge member is readily removable from and replaceable in the
joint as a unit.
Description
BACKGROUND OF THE INVENTION
This invention relates to expansion joint seals for bridging and
sealing an elongated expansion space between adjacent horizontal
members of a building structure.
It is common practice in the construction of large buildings to
provide expansion spaces between portions of the structure that
allow for relative expansion and contraction of such portions or
for other forms of relative movement between the portions, such as
deflection due to wind load or other loading conditions. In
general, such expansion spaces are located at extremities of
structural units of a building and are constituted by parallel,
spaced-apart structural members of two adjacent units. Inasmuch as
expansion spaces may in some instances be located at places other
than between structural members ("structural" in the sense of
providing primary load carrying ability in the structure), the term
structural members are used herein is used in its broadest sense as
applying to any members in a building structure and, therefore,
includes not only structural beams, but floor panels, roof panels
and similar building elements.
Many forms of covers or bridges for filling the space between
adjacent structural members at an expansion joint have been
proposed and used heretofore. Some forms of closures for expansion
joints in building construction provide only limited load carrying
ability and are intended primarily simply to fill the space for
esthetic or utility reasons other than load carrying. For example,
some joints are caulked or filled with a material that renders the
joint air and water tight.
Although a joint according to the present invention may be used in
almost any expansion space for the relatively limited purpose of
sealing the space, the expansion joint seal, according to the
present invention, is intended primarily for load-carrying uses. In
general, load-carrying types of expansion joint seals or bridges
include a bridge member extending across the joint and supported on
frame members secured to the structural members on either side of
the expansion space so that loads imposed on the bridge member are
carried across the joint and into the building members on either
side of the expansion space.
Applicant's assignee has for some years manufactured and sold
several forms of expansion joint covers or seals including some
types that provide substantial load-carrying ability by virtue of
including a substantially rigid bridge member extending across the
joint. One such form of expansion joint seal and cover is described
in U.S. Pat. No. 3,394,639 granted July 30, 1968, entitled
Expansion Joint, and owned by applicant's assignee. The expansion
joint described in that patent comprises frame members secured to
the building members on either side of the expansion space, a
bridge member spanning the space between and supported on
horizontal surfaces of the frame members, and preformed elastomeric
members received in spaces in between side flanges formed on the
respective frame members and the side edges of the bridge member.
The preformed elastomeric members are compressed in the spaces so
that they expand upon movement of the structural members away from
each other, and they are constructed so that they are readily
compressed upon movement of the structural members toward each
other.
Although the expansion joint bridge of U.S. Pat. No. 3,394,639 has
proved very successful in service, occasional problems have arisen
insofar as providing an effective water seal. It is possible for
fine particles of dirt to work down between the elastomeric sealing
members and provide enough of a gap at the interfaces between the
sealing members and the other members of the joint to allow water
leakage. While the problem has generally been negligible or
non-existent when such joints are used in interior or covered areas
of a building structure, the absence of a positive seal in the
joint construction can be a significant problem when the joint is
used in open or exposed areas, such as in a roof, or in other areas
where there may be substantial exposure to dirt and water, for
example, in a parking garage.
SUMMARY OF THE INVENTION
There is provided, in accordance with the present invention, an
improved expansion joint seal of the type used to bridge and seal
an expansion space between structural members. The expansion joint
seal of the invention includes a load-carrying bridge member
extending across the joint and highly effective seal members of an
expandable elastomeric material that are bonded and captured within
cavities formed in the respective members and insure a durable and
tight seal at the joint.
More particularly, an expansion joint seal, according to the
invention, comprises a pair of elongated frame members, each of
which is arranged to be secured rigidly to one of the structural
members adjacent the expansion space and extends lengthwise of the
structural members. Each frame member is of uniform cross-section
along its length and includes, in cross-section, a top marginal
portion formed with a cavity that has an opening facing generally
inwardly toward the expansion space, the interior of the cavity
having, in cross-section, a greater dimension than the
cross-sectional dimension across the opening. Each frame member
also has a horizontal base portion adjacent the cavity portion, the
base portions of the frame members having surfaces that are
substantially co-planar when the members are installed in the
joint. A substantially rigid, elongated bridge member extends
lengthwise of the joint and across the expansion space and has
surfaces that engage and are supported by the horizontal surfaces
of the frame members. The lateral edges of the bridge member are
spaced from the edge of each horizontal surface of the respective
frame members so that relative sliding movement of the frame
members toward and away from each other and relative to the bridge
member is afforded. The side edges of the bridge member are also
formed with cavities, the cavities facing generally outwardly from
the space and being located generally opposite the cavities in the
respective frame members. A unitary body of an elastic material is
received in each space between the cavity portion of the frame
member and the cavity portion of the bridge member, each body of
elastomeric material filling the space and being received, and
bonded and sealed, within the cavities firmly to be interconnected
between the frame member and the bridge member and provide a highly
effective water and dirt seal at the joint. The elastomeric
material, nonetheless, distorts in shape and dimension upon
relative movement of the frame members to accommodate such
movement.
The seal members are preferably formed in situ by pouring an
appropriate elastomeric material in liquid or semi-liquid form into
the spaces between the edges of the bridge members and the edges of
the frame members. The in-place formation of the sealing members
affords an essentially permanent bonding of the sealing members to
the bridge member and to the frame members.
An important feature of the invention is the provision of a bond
breaker medium between substantially all horizontal surfaces of the
frame members and the bridge member in zones thereof occupied by
the elastomeric material. The bond breaker medium may be a
flexible, thin strip of a material that is non-adherent to either
the material of the frame member or the elastomeric material or
both or a fluid coating of a material that inhibits bond formation
between the elastomeric material and the material of the frame
member and is provided between all generally horizontal interfaces
between the elastomeric material, on the one hand, and the frame
and bridge members, on the other hand. The inhibition of a bond at
the horizontal interfaces ensures distortion of the elastomeric
sealing members relatively uniformly throughout their cross-section
without the inhibiting effect of a bond between the elastomeric
members and the other components of the seal of the joint structure
at such horizontal interfaces.
As a further preferred feature of providing a highly effective
water seal at the expansion joint, each frame member of the joint
seal has a slot that receives an edge portion of a
liquid-impermeable membrane that is built into the building
structure. The membrane is held in place in the slot by a
compressible retainer band extending continuously along the slot
and captured within the slot so that it clamps and seals the
membrane continuously along the edge of the frame member and
ensures against leakage between the structural member and the frame
member, since the frame member is sealed to the membrane and blocks
the passage of any water trapped at the membrane.
The expansion joint seal of the invention provides important
advantages. For one thing, it provides a load-carrying ability by
virtue of a rigid bridge member extending between and supported by
the frame members, thus making the joint particularly suitable for
buildings in which substantial loads will be imposed in areas
across the joints. For example, the expansion joint seal is
particularly useful for parking garages in which automobiles and
other traffic will traverse the joint and will carry dirt and water
over the joint. The sealing characteristics of the joint, insofar
as it provides sealed and bonded elastomeric members and may also
include the uniting of the joint frame with a membrane, make the
joint also highly useful in exposed areas of a building, such as a
roof. The bodies of elastomeric material mechanically unite the
bridge member with the frame members to provide a unitary bridge
structure extending across the joint between the frame members. The
inherent elastomeric properties of the elastomeric material,
coupled with substantially free movement of the bridge member
relative to the frame members, provide a self-centering effect in
that the bridge member will tend to occupy a center position at the
joint; the greater the tendency of the bridge member to be located
off center, relative to the two frame members, the greater is the
tendency for centering, because the inherent elastomeric properties
of the elastomeric seal members will result in an unequal force
application by one of the other bodies of elastomeric material in
the joint when the bridge member is off center, and this force
imbalance will tend to shift the bridge member to a centered
position. For example, when the structural members, and therefore
the frame members, are more widely spaced than the neutral or
normal position, both seal members are stretched and under tension.
If the bridge member is not centered, the tension forces generated
by the body of elastomeric material that is more greatly stretched
will tend to pull the bridge member to the center position and
balance the force distribution between the two elastomeric members.
In addition to maintaining a balance of forces between the two
elastomeric members, which will prevent either one from being
overstressed in use, the balancing of forces and the centering
effect on the bridge member assists in retaining the bridge member
in proper supported relation on the frame members.
Inasmuch as the bridge member and the bodies of elastomeric
material and the frame members tend to form a unit, by reason of
the in situ formation of the bodies of elastomeric material, it is
advantageous to construct the frame members in two parts, one part
of which includes the cavities that receive the elastomeric bodies
and the horizontal surfaces supporting the bridge member, and the
other part being separate and permanently installed in the
structural system. The first parts are appropriately secured to the
permanent parts in a manner that permits them to be readily removed
so that the entire bridge member and seal member assembly can be
removed from the expansion space to permit access to the space.
DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention and of the advantages
it provides, reference may be made to the following description of
an exemplary embodiment, taken in conjunction with the accompanying
drawing, which is an end view in cross-section taken at a
representative point along the length of the embodiment and
substantially perpendicular to the plane of the floor of the
structure, portions of the structural members associated with the
joint also being shown.
DESCRIPTION OF AN EXEMPLARY EMBODIMENT
In the drawing, the reference numeral 10 designates an expansion
space between opposed faces 12 and 14 of an elongated expansion
joint between a pair of spaced-apart structural members 16 and 18.
In the embodiment, the structural members are represented as
reinforced concrete beams, but it will be understood by those
skilled in the art that various members may be located on either
side of an expansion space and that the embodiment and other forms
of an expansion joint seal, in accordance with the invention, may
be used in various structural environments.
The embodiment comprises a pair of elongated frame members 20L and
20R appropriately secured to the respective structural members 16
and 18 and extending lengthwise of the joint 10. Inasmuch as the
frame members 20L and 20R are identical, only one needs to be
described. Each frame member 20L or 20R is composed of two parts, a
detachable part 22 and a permanently installed part 24, both parts
being elongated members of uniform cross-section. Advantageously,
they are extrusions from aluminum, brass or the like. The
permanently installed part 24 includes, in cross-section, a body
portion 26 formed with longitudinally spaced apart tapped holes 28
for receiving fasteners 30 by which the removable part 22 is
secured to the permanent part 24. The permanent part 24 further
includes, in cross-section, a laterally outwardly extending flange
portion 32 through which fasteners 33 are inserted at appropriate
spacing lengthwise of the joint to secure the permanent part 24 to
the structural member 16 or 18. Although the fastener in the
embodiment is a bolt and expansion anchor, other forms of
fasteners, such as concrete anchors in concrete construction and
various types of interconnection in other forms of structure, may
be provided.
The permanent member 24 further includes, in cross-section, a
vertical flange 34 that extends up to essentially finished floor
grade and provides a grade level by which a final floor layer can
be brought to proper level with the joint seal. The flange 34 also
provides a companion engaging surface for the outermost extremity
of the removable frame member part 22.
Frequently, a building structure in which the expansion joint is
used will have a water and vapor seal membrane 36 associated with
it. To ensure a tight seal at the intersection between the
structural member and the joint seal, the edge of the membrane 36
is brought up to the frame and secured to it by inserting the edge
in a generally C-shaped slot 38 and anchoring it in place in the
slot by inserting a locking rod 40 of a resilient elastomeric
material. The elastomeric rod form of lock 40 not only mechanically
secures the membrane in place to the frame member but ensures a
good seal between the membrane and the frame member to prevent
possible leakage from occurring at the intersection between the
expansion joint seal structure and the adjacent portion of the
building structure.
The removable part 22 of the frame includes a base portion 42 that
presents a substantially horizontal surface of a width, in a
direction transverse to the length of the joint, sufficient to
provide for the desired amount of relative movement of the building
structures. A pair of continuous parallel, spaced-apart legs 44 and
46 depend from the underside of the portion 42 and are supported on
shims 47 (or directly on the surface of the structural member).
Alternatively, the bottoms of the legs 44 and 46 may rest on a
flange (not shown) extending inwardly from the base of the body
portion 26 of the permanent part 24 of the frame to or near to the
inner edge of the structural member 16 or 18. The inner end,
relative to the expansion space, of the base portion 42 is formed
with a small depending rib 48 and an overhanging lip 50 that define
a small continuous slot that receives the upper end of a leg of a
W-shaped spring 54 that holds a bridge member 56 down in place on
the frame members 20L and 20R.
The removable part 22 of each frame further includes a body portion
60 that is formed, in cross-section, with a generally C-shaped,
inwardly opening cavity 62. The dimension of the inside of the
cavity is greater than the opening of the cavity so that a seal
member 64 of an elastomeric material that is poured in place in the
joint is received in the C-shaped cavity and is mechanically
anchored and adhesively united and sealed within the cavity. The
screws 30 by which the removable member 22 is secured to the
permanent member 24 of each frame member extend through holes
drilled and countersunk through the body portion 60 at appropriate
spacing.
The two-part construction of each frame member is a preferred
feature; a single frame member cna readily be provided of generally
similar format. Moreover, various specific configurations for the
frame member are, of course, possible and will be readily apparent
to those skilled in the art.
The space across the expansion joint 10 between the frame members
is bridged by a bridge member 56 that extends the entire length of
the frame members and is dimensioned and shaped appropriately to be
supported by the frame members and to carry vertical loads imposed
upon it across the joint and into the frame members and thence into
the structural members on either side of the joint. In this regard,
the width of the bridge member 56 is such that at the position of
greatest separation between the innermost edges of the frame
members, which condition will obtain, of course, when the
structural members of the building are at their widest separation,
the bridge member remains supported by the base portions 42 of the
frame members. In the embodiment, the outer-most edges of the
bridge member 56 are formed with outwardly projecting flange
portions 61 that are part of the surface by which the bridge member
is supported on the base portions 42 of the respective frame
members. Each flange 61 may be of substantially greater width than
shown to accommodate greater movements between the structural
members. Similarly, the lateral dimensions of the horizontal
surfaces of the frame members can be somewhat larger than the
dimensions illustrated in the drawings.
Each side edge of the bridge member 56 is formed with a generally
C-shaped cavity 63 which is shaped and dimensioned similarly to the
corresponding cavities 62 in the frame member parts 22. The body 64
of elastomeric material extends into the cavities 63 to unite the
bodies of elastomeric material by a mechanical interlock and by
adhesion.
More particularly, the seal members 64 are formed of an elastomeric
material that is poured in place with the members preassembled in
the position they will occupy in the joint, as installed in the
building, when the expansion space is at a neutral configuration,
that is, at the nominal neutral design width of the expansion space
10. Various elastomeric materials, particularly various synthetic
rubbers or other elastomeric polymers, may be used for the sealing
members 64. Very good results are obtained with two-part
polyurethane compounds. Although the sealing member 64 may be
poured in the field on the job, it is advantageous, because of the
advantages of providing controlled conditions and maintaining
cleanliness in the joint parts, to factory-pour the seal members
64.
It is evident that the shape of the cavities 62 of the frame
members and the cavities 63 of the bridge member provide a
mechanical interlock between the sealing members. Advantageously,
however, it is also desirable to provide an adhesive bonding
between the seal members and the cavities, and various elastomeric
materials having good bonding properties with aluminum or other
metals from which the frame member and bridge member may be formed
are available. Various known primer materials may be applied to the
portions of the frame member and bridge member to enhance the
bonds.
It is also evident that the sealing material would form a bond with
the horizontal surface presented by the base portion 42 of each
frame member and the essentially horizontal surface 58 of the
outwardly projecting flange 61 of the bridge member 56. Inasmuch as
such a bond would tend to impede a uniform distortion of the
sealing material and might tend to create stress concentrations and
possible failure conditions in the sealing material, it is an
important feature of the invention to provide a "bond breaker"
medium at any potential interface between the seal member 64 and
all horizontal or substantially horizontal surfaces of the bridge
member and the frame member. Various forms of bond breaker medium,
such as strips of flexible film material that are non-adherent to
either the seal member or the frame or bridge members, or a coating
of a release agent, such as a silicone release liquid, may be used.
In the embodiment, the bond breaker medium is a strip 70 of a
lightly adhesive tape having a silicone-treated backing, the
adhesive side of the tape being applied to the flange 58 of the
bridge member 56 and to the base portion 42 prior to pouring the
sealing member 64. The tape offers the advantages of staying in
place and ensuring against leakage during the pouring
operation.
The bridge member is held in place on the frame members by a series
of longitudinally spaced-apart W-shaped leaf-type springs 54
secured by bolts 72 to the bridge member. The center apex of the
W-spring receives an elongated threaded fastener 74 that has lugs
76 projecting out through slots in the spring so that the fastener
74 is securely held on the spring 54, and the upper ends of the
outermost free legs of the spring 54 are captured in the slots at
the innermost ends of the frame members 22. The screw 72 is
inserted through the bridge member 56 and tightened to draw the
apex of the spring upwardly and hold the bridge member down on the
frame members. The W-configuration of the springs affords relative
inward and outward movement of the frame members.
In use, the structural members and frame members move toward and
away from each other as the structural members 16 and 18 of the
building move toward and away from each other. Upon relative inward
movement of the frame members, the sealing members 64 are
compressed and will distort to accommodate such compression. Should
one or the other of the sealing members 64 tend to be compressed to
a greater extent that the other, a correspondingly greater force
resisting compression will be developed and will tend to shift the
bridge member laterally toward the more lightly compressed sealing
member. A similar effect occurs as the structural members move
farther apart and place the sealing members in tension. Thus, the
sealing members tend to hold the bridge member in centered relation
between the frame members.
The mechanical interlocks between the sealing members and the
respective frame members and the bridge member provide effective
liquid and dirt seals between the several members at the joint.
Such seals are further enhanced by providing an adhesive bond. Thus
the joint provides highly effective sealing of the expansion
space.
The expansion joint seals of the invention may be constructed in
appropriate lengths or sections, and the sections united or joined
at butt joints or corners. Usually, the adjacent ends of two
sections are spaced apart to allow expansion and contraction
lengthwise of the sections. The space can be filled and sealed by
installing a bridging strip immediately under the endmost portions
of the bridge members of adjacent sections, such bridging strips
being supported on the laterally innermost ends of the frame
members. The same elastomeric material as used for the sealing
member 64 in the main expansion joint seals can be poured in place
in the gap between the ends of butted or corner-to-corner sections.
Accordingly, a butt or corner-to-corner joint between two sections
of the expansion joint seals provides for longitudinal relative
expansion and contraction of the joint structure, for
load-carrying, and for effective sealing.
It is apparent that by removing the screws by which the bridge
member is held down on the frame members, the bridge member can be
removed by pulling it upwardly. However, this would result in
destruction of the seal members. Accordingly, it is preferable to
remove the screws by which the removable parts of the frame members
are secured to the permanent parts. This permits the entire joint
assembly, except for the permanent frame members, to be removed for
access to the joint. This is entirely an optional feature but
offers the significant advantage of permitting the joint cover to
be removed and replaced, should it be necessary to do so, without
destruction.
In the embodiment, there are two sealing members 64, one on either
side of the bridge member 56, and the top surface of the bridge
member is at finished surface level. It will be apparent to those
skilled in the art, however, that the bridge member may be recessed
below the finished surface and that the sealing material may carry
entirely across the top of the joint and over the bridge member. In
such a case, a bond breaker is provided entirely across the span
underneath all horizontal or substantially horizontal surfaces of
the seal member.
The embodiment of the invention described above is intended to be
merely exemplary, and those skilled in the art will be able to make
numerous variations and modifications of it without departing from
the spirit and scope of the invention. All such variations and
modifications are intended to be included within the scope of the
invention, as defined in the appended claims.
* * * * *