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I claim:
1. A roll beam girder system for bridges comprising:
a) a keystone section, including:
i) a top section having a wedge shape defined at each end of the section;
ii) a bottom section including a pair of key locks attached to the top
section, the key locks having a triangular shape and defining an angled
notch at their junction with said top section; and wherein:
iii) the top section of said keystone section extends beyond said key
locks, whereby said keystone section has a pair of projecting ends;
b) a pair of end sections, each end section having a top section and a
bottom section, each end section having a first end and a second end, the
first end of the end section being adapted for connection with an end
support, the second end having an angled notch supplementary to the wedge
shaped end of the top section of said keystone section and a wedge shaped
end on the bottom section of the end section at an angle supplementary to
the angled notch of said keystone section, the bottom sections of the
second ends projecting beyond the end of the top sections of the second
ends in order to support the ends of said keystone section and being
slightly cambered in order to impart a slight degree of curvature to said
roll beam girder; and
c) wherein said keystone section is disposed between said pair of end
sections, the projecting ends of the top section of said keystone section
resting upon and being fastened to the projecting bottom sections of said
end sections at each end of said keystone section.
2. The roll beam girder system for bridges according to claim 1, wherein:
a) the top section of said keystone section comprises a rolled steel beam
having a top flange, a bottom flange, and a web integral with and disposed
between the top flange and the bottom flange, being I-shaped in cross
section, having its ends cut transversely to its longitudinal axis and at
an angle, and having an end plate fixedly attached at each end, the end
plate and the bottom flange defining a wedge shape;
b) the bottom section of said keystone section comprises said pair of key
locks, each key lock being a triangular section cut from a rolled steel
beam, having a bottom flange and having an end plate fixedly attached to
the key lock, the end plate of said key lock being at an angle and
defining a notch adapted to interlock with the wedge shaped end of the
bottom section of said second end, the bottom flange of said key lock
sloping from the end plate of the key lock to the bottom flange of said
top section, terminating a distance from the midpoint of the longitudinal
axis of said keystone section;
c) the top section and the bottom section of said end sections each
comprise a rolled steel beam having a top flange, a bottom flange, and a
web integral with a vertically disposed between the top flange and the
bottom flange, said beams having an I-shaped cross section, the top
section and the bottom sections of said end sections being stacked
vertically and being retained in vertical alignment by a plurality of tie
rods and fixedly connected by welding the bottom flange of the top section
to the top flange of the bottom section;
d) the projecting ends of the top section of said keystone section are
fastened to the projecting ends of the bottom section of said sections by
a plurality of high strength bolts extending through the bottom flange of
the top section of said keystone section and the top flange of the bottom
section of said end sections; and
e) the top sections of said end sections are about two-thirds of the height
of said end sections, the height being measured from the top flange of the
top section to the bottom flange of the bottom section of said end
sections.
3. The roll beam girder system for bridges according to claim 2, wherein:
a) the end plate and the bottom flange of the top section of said keystone
section define a 45.degree. angle; and
b) the wedge shaped end of the bottom section of the end sections define a
45.degree. angle relative to the top flange of the bottom section of said
end sections.
4. A single span roll beam bridge, comprising:
a) a plurality of end supports disposed at both ends of the span;
b) a plurality of roll beam girders according to claim 1, the girders being
supported by said plurality of end supports;
c) a plurality of reinforced concrete planks extending transversely across
said girders and being fixedly attached to the top of said girders; and
wherein:
d) the bridge has a slight curvature at the center of its longitudinal
axis, whereby the bending moments are fixed and the stresses are
transferred to the end supports.
5. The single span roll beam bridge according to claim 4, further
comprising a layer of concrete on top of said planks in order to form a
smooth roadway surface on said bridge.
6. The single span roll beam bridge according to claim 4, wherein:
a) said roll beam girders are prefabricated in sections and transported to
the bridge site; and
b) said reinforced concrete planks are precast and transported to the
bridge site.
7. A compression splice for joining two girders, comprising:
a) a first girder having a top section and a bottom section, wherein:
i) the top section has a wedge shaped end;
ii) the bottom section has a notch defined therein at the same end of the
girder as the wedge shaped end of the top section;
iii) the top section extends beyond the bottom section, whereby said first
girder has a projecting end;
b) a second girder having a top section and a bottom section, wherein:
i) the top section of said second girder has a notch defined at an end
thereof adapted for interlocking with the wedge shaped end of the top
section of said first girder;
ii) the bottom section of said second girder has a wedge shaped end at the
same end of said second girder as the notch defined in the top section of
said second girder, the wedge shaped end of the bottom section of said
second girder being adapted for interlocking with the notch defined in the
bottom section of said first girder;
iii) the bottom section of said second girder extends beyond the top
section of said second girder, whereby said second girder has a projecting
end; and wherein:
c) the projecting end of said first girder rests upon and is supported by
the projecting end of said second girder, said projecting end of said
first girder being fastened to the projecting end of said second girder.
8. The compression splice according to claim 7, wherein:
a) the top section of said first girder is a rolled steel beam having a top
flange, a bottom flange, and an integral vertical web disposed between
said top flange and said bottom flange, said beam having an I-shaped cross
section;
b) the bottom section of said first girder is made from triangular key
locks cut from a rolled steel beam;
c) the top section and the bottom section of said second girder each
comprise a rolled steel beam having a top flange, a bottom flange, and a
web integral with and vertically disposed between said top flange and said
bottom flange, the top section and the bottom section of said second
girder each having an I-shaped cross section, said top section and said
bottom section being stacked vertically and vertically aligned, said top
section and said bottom section being fastened together; and
d) the projecting end of the top section of said first girder is fastened
to the projecting end of said second girder by a plurality of high
strength bolts extending through the bottom flange of the top section of
said first girder and the top flange of the bottom section of said second
girder.
9. The compression splice according to claim 7, wherein said first girder
and said second girder are plate girders. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to girder systems for bridges, and
particularly to a roll beam bridge. It includes a method of forming
compression splices for steel beams, a system of girders for the frame of
the bridge using rolled beams, and a bed of reinforced concrete planks.
2. Description of the Related Art
Bridges may be broadly classified as fixed or moveable. Fixed bridges may
be further classified as beam, arch and suspension. While all bridges must
carry the full weight of the bridge and the traffic on their foundation,
it is significant to note that arch bridges are in compression and thrust
outward on their end supports or bearings, while suspension bridges are in
tension and apply a continual pull on their end supports.
While there are several types of fixed, beam bridges, for purposes of
understanding the present invention in terms of the related art, it is
useful to note that beam bridges include types known as rolled beam, plate
girder, box girder and continuous. Rolled beam bridges use steel girders
rolled as a single, integral unit at the mill in various shapes, such as
I-beam, H-beam, T-beam, etc. Roll beam bridges generally are useful for
short spans of 50 to 150 feet. Plate girder bridges employ steel girders
joined to make different shapes by welding or by bolts or rivets. An
I-beam, for example, may be constructed from three plates, a top flange,
bottom flange, and web, often using angles to construct the girder. Plate
girders generally are capable of having greater stiffness than rolled
beams and permit longer spans. Box girders are constructed from four
plates welded together into a box shape, and have been used for spans from
100 ft to 850 ft. Continuous bridges are supported at three or more
points, and are capable of resisting bending moments and shear at all
sections throughout their length.
An additional consideration includes the material used to construct the
beams. Modern bridges are generally constructed from steel or concrete.
Bridges made of reinforced concrete were either arch bridges, slab bridges
of quite short span, generally consisting of a reinforced concrete slab
extending from end support to end support, or deck girder bridges having a
concrete slab integral with concrete girders. The development of
prestressed concrete has led to increased use of concrete in bridge
construction. Prestressing involves stretching the steel reinforcement
bars or wires before or during casting of the concrete to increase the
compressive strength of the concrete, saving about one-fourth the volume
of concrete and about three-fourths the weight of reinforcing steel.
Prestressed concrete can be used in spans up to 600 feet, and longer spans
are possible with cable support.
The present invention relates to a single span rolled beam bridge of about
60 feet to 150 feet in length using steel girders of the rolled beam
variety. Currently rolled beam girders are custom made, in lengths of 120
feet or more. Such construction methods require special permits for
transportation of the beams to the bridge site. Once erected, contractors
must lay out concrete forms between the beams, which requires that the
workers be supported by cables, construction of sufficient foundations for
safety equipment, and other safety measures which alone add about 90 days
to construction time, as well as hazards to health and safety. The present
invention allows prefabricated construction of the beams from roll beam
girders in sections which may be transported to the job site without
special permits, and flooring made from precast reinforce concrete planks.
A novel method of making a compression splice between the steel girders
permits such a construction technique. The construction of the sections
and the splice permit the moments to be fixed and borne by the end
supports. The prior art does not disclose a similar method of bridge or
girder construction.
U.S. Pat. No. 811,257, issued Jan. 30, 1906 to Joseph B. Strauss, discloses
a concrete or concrete and steel bridge having hollow concrete forms for
beam girders and hollow concrete forms for transverse joists, connected by
steel bars and loops, the hollow forms being erected to form a frame and
filled with concrete to form a concrete bridge using prefabricated forms.
U.S. Pat. No. 1,688,128, issued Oct. 16, 1928 to Ernest Moccetti,
discloses reinforced concrete girders having webbed structures in which
the concrete in not continuously reinforced, but has main tensile
reinforcements in zones of the greatest tension and special tension
reinforcements in the webs for lighter weight, greater internal strength
and smaller bulk.
U.S. Pat. No. 2,336,622, issued Dec. 14, 1943 to Robert G. LeTourneau,
teaches the use of trapezoidal box beam girders with joists extending into
a supported by the beams, supporting a solid metal flooring. U.S. Pat. No.
3,365,852, issued Jan. 30, 1968 to Ronald J. Pitillo, shows structural
framing units made by cutting a triangular piece from the web of an
I-beam, cutting the I-beam longitudinally with cutting torches, and
rejoining the beam in the shape of trusses, etc., using the triangle to
support the joints. Pitillo shows the construction of specialty trusses
and roof beams, but no method suitable to the construction of bridge
beams, and particular not to end sections and keystone sections having
multiple beams cut in specific ratios of web beam sizes and at specific
angles and joined by bolts through the flanges to form a splice.
U.S. Pat. No. 3,425,076, issued Feb. 4, 1969 to Ulrich Finsterwalder, shows
a method for joining the spans of a highway bridge between two
cantilevered spans using resilient tensioning members rigidly connected to
adjoining sections composed of tendons piercing concrete joists and
covered by the road surface. U.S. Pat. No. 4,042,991, issued Aug. 23, 1977
to Macy, et al., describes a portable load carrying structure,
particularly for use in the Arctic to span breaks in the ice, consisting
of I-beams, preferably made of aluminum, hinged together in parallel so
they fold for compact storage and transport.
U.S. Pat. No. 5,526,544, issued Jun. 18, 1996 to Wiedeck, et al., shows a
bridge having a flat base body and at least one roadway surface pivotally
connected to the base body where the roadway surface may be pivoted above
the base body to form a bridge. German Patent No. 1,939,737, published
Feb. 18, 1971, teaches a method of building a prestressed concrete bridge
which uses an orthotropic concrete slab roadway.
Soviet Invention Certificate No. 1,474,201, published Apr. 23, 1989,
describes a method of building a bridge with a "zero bending moment" using
alternating sections composed of two parts, including two end span
sections with beams having a reinforced concrete top and metal bottom, and
a center section with a metal top and reinforced concrete bottom with an
orthotropic roadway in which the metal parts of the beams are placed under
tension by tension members at the end supports and the junctions of the
end sections with the center section, and in which the concrete is in
compression. The bride is a continuous bridge.
None of the above inventions and patents, taken either singularly or in
combination, is seen to describe the instant invention as claimed. Thus a
roll beam girder system for bridges solving the aforementioned problems is
desired.
SUMMARY OF THE INVENTION
The roll beam girder system for bridges has beams constructed from two end
sections and a keystone center section. The two end sections have a top
roll beam welded to a bottom roll beam, the top beam comprising about
two-thirds of the total height of this section, the top beam being shorter
than the bottom beam at the end joining the keystone section, the
projecting end of the bottom beam having a slight camber. The keystone
section has a top girder and triangular bottom key sections. The end
sections and the keystone section have mating 45.degree. ends, with the
ends of the top beam of the keystone section resting on the top of the
projecting end of the bottom beam of the end section, a compression splice
being formed by a row of nine bolts through the flanges on either side of
the web of the mating end section and keystone section beams. Because of
the slight camber of the projecting end of the end section and the nature
of the compression splice, the bending moments are fixed, there is a
slight curvature at the keystone section, and the load is borne by the end
supports. Precast reinforced concrete planks may be welded transversely
between the beams to form the floor of the bridge, which may optionally be
smoothed with a two inch layer of concrete to form the roadway. The beams
are supported by end supports. In this manner a roll beam bridge having a
single span from 60 feet to 150 feet may be constructed.
The roll beam girder system for bridges has the advantage that the two end
sections and the keystone sections may be preassembled in the shop and
transported to the job site. Since no section is greater than about 60
feet in length, no special permits are required for transportation of the
beam sections. The roll beam girders further permit the use of precast
concrete planks, avoiding the safety hazards, costs, and time delays
occasioned by the necessity of forming and setting concrete flooring on
the bridge site.
The compression splice may be modified for use with a plate girder as a
useful alternative to a traditional friction splice. This is accomplished
by resting the projecting end of one plate girder on top of the projecting
end of second plate girder, each of the projecting ends being one-half the
height of each girder, their ends having mating 45.degree. surfaces, the
splice being secured by two rows of nine bolts each through the flanges of
the overlapping projecting ends.
Accordingly, it is a principal object of the invention to provide a roll
beam girder system for bridges which permits construction of a single span
roll beam bridge in which the bending moments are fixed and the load is in
compression on the end supports due to a slight curvature of the beams.
It is another object of the invention to reduce safety hazards, costs, and
delays in the construction of beam bridges by providing a roll beam girder
system in which precast reinforced concrete planks may be welded to the
rolled steel beams.
It is a further object of the invention to reduce delays in construction
due to the necessity of obtaining special transportation permits for
oversized beams by providing a roll beam girder which is prefabricated in
three sections, each of which may be transported separately to the bridge
site without the necessity of special transportation permits, and
assembled on site.
Still another object of the invention is to provide an improved compression
splice as a method for joining steel beams to form beams for use in bridge
construction.
It is an object of the invention to provide improved elements and
arrangements thereof for the purposes described which is inexpensive,
dependable and fully effective in accomplishing its intended purposes.
These and other objects of the present invention will become readily
apparent upon further review of the following specification and drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an largely diagrammatic perspective environmental view of a roll
beam girder system for bridges according to the present invention showing
a roll beam bridge under construction.
FIG. 2 is a partial sectional view of an end support for the roll beam
girder system according to the present invention with the concrete
abutment partially cut away.
FIG. 3 is a lateral view of the roll beam girder system according to the
present invention.
FIG. 4 is a lateral view showing the keystone section of the roll beam
girder system according to the present invention.
FIG. 5 is a lateral view of an end section of the roll beam girder system
according to the present invention.
FIG. 6 is a perspective view of a compression splice of the roll beam
girder system according to the present invention.
FIG. 7 is a cross section along the line 7--7 of FIG. 5.
FIG. 8 is a cross section along the line 8--8 of FIG. 6.
FIG. 9 is a lateral view showing the manner of making a compression splice
for plate girders according to the present invention.
Similar reference characters denote corresponding features consistently
throughout the attached drawings.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is a roll beam girder system for bridges which
provides a novel frame for building a beam bridge using girders made from
rolled steel beams. FIG. 1 shows an environmental perspective view of a
roll beam bridge 10 using the roll beam girder system according to the
present invention. The bridge 10 is a single span bridge supported by
concrete and steel abutments serving as end supports 12 for the roll beam
girder system. The figure shows concrete planks 80 being laid transversely
across the flanges of the beams 20. As shown, the concrete planks 80 may
be lifted by a crane for positioning on the beams 20.
The end supports 12 or abutments are shown more particularly in FIG. 2.
Each support includes a girder saddle 14 having a side centered on and
welded to a steel piling 16 supported vertically by the ground. The girder
saddle 14 is essentially two short beam sections abutted at a 90.degree.
angle to form a butt joint and welded together to support an end of the
beam 20. The saddle 14 supports the bottom of the beam 20 horizontally and
an end of the beam 20 vertically. There may be one or more shims 17
disposed between the saddle 14 and the end of the beam 20. The saddle 14
is also supported by a steel batter piling 18 supported by the ground and
mounted at an angle to oppose any forces driving against the support 12
laterally. The end support 12 is enclosed in a concrete housing 19.
The roll beam girder system is shown more particularly in FIGS. 3 through
8. As shown in FIG. 3, a beam 20 constructed according to the roll beam
girder system of the present invention includes a keystone section 30 in
the center and two end sections 50. The keystone section 30 is shown more
particularly in FIG. 4, and comprises a top section 31 and a bottom
section 33. The top section 31 is a rolled steel I-beam having a top
flange 32 disposed horizontally, a bottom flange 34 disposed parallel to
the top flange 32, and a web 36 disposed vertically between flanges 32 and
34. At either end of the keystone section 30, the beam is cut transversely
to the longitudinal axis and at an angle and a flat cover plate or end
plate 38 is welded to the end of the beam. The flat end plates 38,
typically 3/4" plate, and preferably form an angle of 45.degree. with the
bottom flange 34.
The bottom section 33 is composed of a pair of triangular key locks 40
fixedly attached to the bottom flange 34. Each of the key locks 40 has a
bottom flange 42 and an end plate 44, typically 3/4" plate. The end plates
44 preferably form an angle of 45.degree. with the bottom flange 34 of the
keystone 30 beam. The bottom flange 42 of the key lock 40 slopes from one
end of its end plate 44 to the bottom flange 34 of the keystone section
30, terminating some distance short of the midpoint of the longitudinal
axis of the keystone 30.
The length of the keystone section 30 is about one-third the length of the
span of the bridge 10, the span being between about 60 feet and 150 feet.
The key locks 40 are generally disposed so that the distance from the
junction of the key lock end plate 44 with the bottom flange 34 of the
keystone 30 to the nearest end of the bottom flange 34 is at a distance
equal to the length the bottom flange 42 of the key lock 40 projects onto
the bottom flange of the keystone 30. Typically this distance is about ten
feet. The effect of this disposition is to leave a portion of the keystone
beam 30 projecting beyond the key lock 40.
The end sections 50 are shown more particularly in FIG. 5. The end sections
50 are composed of a top section 52 and a bottom section 54. As shown most
clearly in FIG. 7, the top section 52 and the bottom section 54 are two
I-beams stacked vertically, disposed so that the bottom flange 56 of the
top section rests on the top flange 58 of the bottom section 58. During
assembly the top section 52 and the bottom section 54 are held in vertical
alignment by tie rods 60 extending through the flanges of both beams on
either side of the webs, and are joined by welding 62 the seams formed by
the junction of the bottom flange 56 of the top section 52 and the top
flange 58 of the bottom section 54.
The top section 52 of the end section 50 measures about two-thirds of the
height of the end section 50 measured from the top flange 64 of the top
section 52 to the bottom flange 66 of the bottom section. At one end the
end section has a rectangular end plate 68, typically a 3/4" plate,
extending the height of the end section 50 and having a width equal to the
length of the flanges 56, 58, 64, and 66 welded on to form an interface
with the girder saddle 14 of the end support 12. At the other end of the
end section 50 the top section 52 is cut transversely to its longitudinal
axis and at an angle supplementary to the angle at the end of the top
section 31 of the keystone section 30, and a 3/4" end plate 70 is welded
on. Preferably, the angle between the end plate 70 and the top flange 64
of the top section 52 is about 45.degree..
At this same end, the bottom section 54 of the end section 50 projects
beyond the end plate 70 of the top section 52 so that the top flange 58 of
the bottom section 54 extends beyond the junction of the end plate 70 for
a distance substantially equal to the distance the bottom flange 34 of the
keystone 30 projects beyond its junction with the end plate 44 of the key
40. At this end the bottom section is cut transversely to its longitudinal
axis and at an angle supplementary to the angle formed by the junction of
the key lock 40 with the top section 31 of the keystone section 30 and an
end plate 72 is welded on. Preferably, the angle between the end plate 72
and the top flange 58 of the bottom section is substantially 45.degree..
The I-beam of the top section 52 of the end section has substantially the
same dimensions in cross section as the dimensions of the I-beam of the
keystone section in cross section. The triangular key locks 40 may be made
from length of the same I-beam as the bottom section 54 of the end section
50. It will be seen from this construction the ends top section 31 of the
keystone section 30 define a wedge shape adapted to interlock with notches
defined by the ends of the top section 52 of the end sections 50, and the
ends of the bottom sections 54 of the end sections 50 define a wedge shape
which interlocks with notches defined by the key locks 40 of the keystone
section 30, with a length of the top section 31 of the keystone 30 resting
upon and compressing the bottom section 54 of the end sections 50 between
the interlocking wedges.
The end sections 50 are so constructed that there is a slight degree of
curvature or camber in the bottom section 54 such that there is a gap of
between two and three inches between the end of the top flange 58 of the
bottom section 54 and the plane 74 extending between the junction of the
top section 52 and the bottom section 54 of the end section 50. Normally,
when a load is placed in an I-beam, the top flange is in compression, the
bottom in tension, and the web resists the shear stresses. The degree of
curvature or camber is small enough that the bridge 10 is not classified
as an arch bridge, but it is large enough the transfer the stresses from
the load of the bridge 10 to the end supports 12. Hence the positive
bending moment is balanced to some extent by the negative moment resulting
from the horizontal thrust of the end supports 12.
The manner of splicing the keystone section 30 to the end sections 50 is a
novel compression splice, shown more particularly in FIGS. 6 and 8. The
bottom flange 34 of the keystone 30 rests on the top flange 58 of the
bottom section 54 of the end section 50 with end plate 70 abutting end
plate 38 and end plate 72 abutting end plate 44. The keystone 30 is
fastened to the end section 50 by two rows of nine bolts 76 each, 3/4"
diameter high strength bolts placed about 12" center to center, one row on
either side of web 36.
The end sections 50 are assembled as units in the shop, as is the keystone
section 30. The maximum length of any one section is sixty feet. This
method of construction permits the frame of the bridge 10 to be
prefabricated and transported to the site of the bridge 10 without the
necessity for obtaining special transportation permits for long loads
required for integral beams. The keystone 30 is assembled to the end
sections 50 at the bridge 10 site.
Once the roll beam girders 20 are in place, precast reinforced concrete
planks 80 are welded to the top flanges 52 and 32 of the end sections 50
and the keystone section 30. The planks 80 may have angles 82 which are
field welded to the reinforcing steel of the planks 80 and directly to the
top flanges of the girder 20, or to shims 84 which are stitch welded to
the top flanges of the girder 20, as shown in FIG. 2. The remainder of the
space between the concrete planks 80 and the top of the girders 20 may be
filled with an appropriate filler. The concrete planks 80 may serve as the
roadway, or preferably as a flooring on which a two inch layer of concrete
is poured to smooth the surface. The advantage of using precast reinforced
concrete planks 80 is that the planks may be prefabricated in the shop,
leaving only installation at the site, avoiding the safety hazards and
additional time and expense associated with pouring concrete forms at the
site of the bridge 10. Guard rails or side abutments (not shown) of
conventional construction may be attached along the sides of the roadway.
The method of making a compression splice in the roll beam girder system
may be adapted for use with plate girders as shown in FIG. 9, as an
alternative to the usual friction splice. A female extension 100 is joined
at one end to a first plate girder 105 by a conventional web shop butt
weld 119, and a male extension 110 is joined at one end to a second plate
girder 115, also by a conventional web shop butt weld 120. The extensions
100 and 110 each have the same cross-sectional shape and dimensions as the
first plate girder 105 and the second plate girder 115.
The other end of the female extension 100 is cut and has end plates 104,
106, and 107 joined to the cut edges perpendicularly its web 102 in such a
manner that end plate 104 extends from the top flange 101 of the extension
100 to the midline of its web 102 and forms an angle of 45.degree.
relative to top flange 101, end plate 106 extends horizontally from end
plate 104, projecting outward along the horizontal midline for a distance
of approximately ten feet:, and end plate 107 extends from the end of end
plate 106 to the bottom flange 103 of the extension, forming an angle of
135.degree. relative to bottom flange 103.
The other end of the male extension 110 is cut and joined to end plates
114, 116, and 117 perpendicularly to its web 112 so that end plate 114
forms an angle of 135.degree. relative to its top flange 111 and extends
from the top flange 111 to the midline of the web 112, end plate 116
extends horizontally inward from the end of end plate 114 along the
midline of the web 112, and end plate 117 extends from the end of end
plate 116 to the bottom flange 113 of extension 110 and forms an angle of
45.degree. relative to bottom flange 113.
It will be seen that this construction results in a structure in which the
projecting end of male extension 110 rests on top of the projecting end of
female extension 100, each of the projecting ends being one-half the
height of each girder 105 and 115, the ends of the extensions 100 and 110
having wedge shaped mating 45.degree. surfaces. The splice is secured by
two rows of nine high strength bolts 125 each through the flanges 106 and
116 of the overlapping projecting ends. Thus, this compression splice
presents an alternative method of joining plate girders.
It is to be understood that the present invention is not limited to the
embodiments described above, but encompasses any and all embodiments
within the scope of the following claims. It will be particularly
understood that although FIG. 1 shows a single pair of roadway beams 20,
the bridge 10 may comprise multiple parallel beams 20 to extend the width
of the roadway. It will be further understood that the end supports 12 of
the bridge 10 may have cross bracing between the foot of the pilings 16
and the adjacent end supports 12.
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