The invention relates to a bridge with truss structures, in particular a bridge of the
Warren type with a double intersection.
5 In this type of bridge, truss structures are provided on either side of a deck to
support this deck and owing to girders stretched between these truss structures. These
truss structures are configured to withstand the weight of the bridge and the weight of the
loads present on the deck of the bridge.
These truss structures generally comprise an upper beam and a lower beam that
10 work by traction and compression or vice versa, as well as the stiffening members that
extend between these beams. These members are sometimes made from metal profiles
welded to form X-shaped reinforcements, intended to be assembled to the upper and
lower beams on the installation site of the bridge. These X-shaped reinforcements must
be conveyed to this site, most oflen inside containers, such as sea freight containers,
15 within which they take up considerable space, since their shape does not allow them to be
densely juxtaposed. This results in lost space and excess costs during transport, since the
containers cannot be loaded with a quantity of material corresponding to their nominal
maximum transport mass. Furthermore, these X-shaped reinforcements are heavy and
difficult to manipulate both on the packaging site and on the installation site of the bridge.
20 Similar problems may arise with other types of bridges with truss structures.
The invention more particularly aims to resolve these drawbacks by proposing a
new bridge structure with trusses, the assembly and conveyance of which on the site are
facilitated.
To that end, the invention relates to a bridge with truss structures, in particular of
25 the Warren type with a double intersection, this bridge comprising a deck, two truss
structures that each comprise an upper beam, a lower beam and members that extend
between the upper and lower beams while forming the X-shaped reinforcements. This
bridge also comprises girders stretched between the truss structures and that support the
deck. Each truss structure includes several modules that each comprise a segment of the
30 upper beam, a segment of the lower beam and at least one X-shaped reinforcement.
According to the invention, each X-shaped reinforcement is formed by a long member
fixed, at a first end, on the upper beam segment, and, at a second end, on the lower beam
segment, as well as by two short members each fixed, at a first end, on one of the beam
segments, and at a second end, on the long member.
35 Owing to the invention, the X-shaped reinforcement can be formed on the
installation site of the bridge, by fixing both ends of the two short members on the long
2
member, before securing this reinforcement to the lower and upper beams owing to the
two ends of the long member and the first ends of the two short members. Each
reinforcement can be transported to the site in the disassembled state, its long and short -
members being arranged parallel to one another, with a reduced bulk. This makes it
5 possible to load a container with a significant number of reinforcements, with a mass close
to its nominal maximum transport mass.
According to other advantageous, but optional aspects of the invention, such a
bridge with truss structures may incorporate one or more of the following features,
considered in any technically allowable combination:
10 - The beam segments and the members are each formed by a welded
reconstituted beam.
- Each beam segment has a U-shaped section, with a bottom thicker than its
flanks. In this case, the thickness of the bottom of the beam segment is advantageously
comprised between 18 and 30 mm, preferably equal to about 20 mm, while the thickness
15 of the flanks of the beam segment is comprised between 10 and 16 mm, preferably equal
to about 12 mm.
- Each member has an I- or H-shaped section, with a core thinner than its flanks.
In this case, the thickness of the core of the member is advantageously comprised
between 4 and 8 mm, preferably about equal to 8 mm, while the thickness of the flanks of
20 the member is comprised between 10 and 16 mm, preferably equal to about 12 mm.
- The flanks of the beam segment and the flanks of the member have identical
thicknesses.
-The members are assembled to one another and to the beam segments and the
modules are assembled to one another using splice bars bolted on the members and on
25 the beam segments, in particular on side flanks of these members and segments.
- The upper beam works by traction, while the lower beam works by compression,
the upper beam segments of two adjacent modules are assembled by arranging an axial
space between them and the lower beam segments of two adjacent modules are
assembled in contact with one another.
30 - The truss structures may include running modules that each include an upper
beam segment, a lower beam segment and an X-shaped reinforcement, as well as at
least one end module that comprises an upper beam segment, a lower beam segment
and at least one X-shaped reinforcing part, while the length of the end module is smaller
than the length of a running module and the total length of the bridge is a multiple of one
35 third of the length of a running module.
3
The invention will be better understood, and other advantages thereof will appear
more clearly, in light of the following description of one embodiment of a bridge with truss
structures according to its principle, provided solely as an example and done in reference
to the appended drawings, in which:
- figure 1 is an interrupted side view of a bridge according to the invention,
- figure 2 is an interrupted side view of the bridge of figure 1,
- figure 3 is an enlarged sectional view along line Ill-Ill of figure 2,
- figure 4 is an enlarged sectional view along line IV-IV of figure 1,
- figure 5 is a section view using the same scale as figure 4 along line V-V in
figure 1,
- figure 6 is a perspective view of one end of the bridge of figures 1 to 5, and
- figure 7 is a cutaway partial perspective view of the bridge of figures 1 to 6, at a
running part of this bridge.
The bridge 2 shown in the figures extends, along a longitudinal axis X2, between
15 two foundations M shown only in figure 1. Reference L2 denotes the total length of the
bridge 2 measured parallel to the axis X2.
This bridge comprises a deck 4 formed by decking plates 6 supported by beams 8
arranged horizontally and perpendicular to the axis X2 and that are stretched between two
metal truss structures 10 and 12, which in turn are arranged vertically and parallel to the
20 axis X2. In figures 1 and 2, the bridge 2 is shown with a deck 4 that comprises, widthwise,
four decking plates 6, whereas in figures 6 and 7, it is shown in the case where the deck
comprises three decking plates arranged between the sidewalks. This corresponds to
different possible configurations for the bridge 2.
The structures 10 and 12 are symmetrical relative to a vertical plane P2 passing
25 through the axis X2, which is arranged between the structures 10 and 12 and equidistant
therefrom.
The truss structure 10 comprises an upper beam 100 and a lower beam 102, as
well as members that extend between the beams 100 and 102 while forming X-shaped
reinforcements 104. These reinforcements 104 make it possible to stiffen the truss
30 structure 100.
The bridge 2 is therefore a bridge with two truss structures, more particularly a
bridge of the Warren type with a double intersection.
The truss structure 10 is made up of the juxtaposition, along the axis X2, of several
modules, including at least two running modules 106 whereof the length, measured
35 parallel to the axis X2, is denoted L106. In the example, the length L106 is about 9.15 m.
4
A running module 106 of the truss structure 10 is a module identical to several
other modules juxtaposed to form the structure 10 over the majority of its length.
The structure 10 also comprises two end modules 108 and 109, the lengths of
which, measured parallel to the axis X2, are respectively denoted L108 and L109. These
5 L108 L109 lengths respectively have values of about 4.57 m and 1.52 m. The ratios L106 and - are L106
respectively approximately equal to 112 and 116.
Each end module 108 or 109 comprises, on each side, a vertical end upright 108a,
109a, respectively.
The structure 10 is primarily made up of running modules 106.
10 Inasmuch as the desired length L2 for the bridge 2 can be a multiple of the length
L106, the end modules 108 and 109 are optional and the structure 10 can be made up
exclusively of running modules 106, optionally modified to include a vertical end upright.
Owing to the use of running modules 106, the number of which is adapted to the
desired span of the bridge 2 as well as the end modules 108 andlor 109, the total length
15 L2 of the bridge 2 can be a multiple of one third of the length L106 of a running module
106.
Each running module 106 comprises a segment 1060 of the upper beam, a
segment 1062 of the lower beam and three X-shaped reinforcements 104. Only two
reinforcements 104 are shown in position in figure 7, having specified that the third
20 reinforcement 104 is intended to be mounted, along the axis X2, overlapping an adjacent
module, situated on the left or right of the running module 106 in figures 1 and 7. This third
X-shaped reinforcement 104 is shown in the exploded configuration in the lower left part
of figure 7.
Each X-shaped reinforcement 104 is formed by a long member 1066 and two short
25 members 1067 and 1068.
Each long member 1066 comprises a first end 1066A by which it is fixed to the
upper beam segment 1060 and a second end 1066B by which it is fixed to the lower beam
segment 1062. The short member 1067 comprises a first end 1067A by which it is fixed to
the lower beam segment 1062 and a second end 10676 by which it is fixed to the long
30 member 1066. The short member 1068 in turn comprises a first end 1068A by which it is
fixed to the upper beam segment 1060 and a second end 10688 by which it is fixed to the
long member 1066. In practice, the ends 10678 and 1068B are fixed on either side of an
intermediate zone of the long beam 1066, midway between its ends 1066A and 10666.
The fixing of the ends 1066A, 1066B, 1067A and 1068A on the beam segments
35 1060 and 1062 is done using splice bars 1069 that overlap these ends and lugs 1060A
and 1062A respectively arranged on the beam segments 1060 and 1062 to serve as a
5
"starting point" for the members 1066, 1067 and 1068. In practice, orifices 1060C and
1062C are arranged in the lugs 1060A and 1062A and orifices 1066C, 1067C and 1068C
are arranged in the ends 1066A, 1066B, 1067A and 1068A, these orifices being intended
to be aligned with corresponding orifices of one of the splice bars 1069. Bolts with non-
5 rustible heads, of the HRC type, are inserted into these orifices and tightened in position
until their heads break, which causes reliable and lasting immobilization of the ends of the
members 1066, 1067 and 1068 with respect to the beam segments 1060 and 1062.
Likewise, splice bars 1069 are used to secure the ends 10678 and 10688 of the
short members 1067 and 1068 on the intermediate part of the long member 1066, which
10 is provided with other orifices 1066C at this level.
In figure 7, for clarity of the drawing, only some of the splice bars are shown, which
makes it possible to view the passage orifices of the bolts 1060C, 1062C, 1066C, 1067C
and 1068C respectively provided in the beam segments 1060 and 1062 and in the
members 1066 to 1068. Splice bars 1069 are also shown separately, in the bottom part of
15 figure 7, which makes it possible to identify their bolt passage orifices 1069C.
The upper beam segment 1060 is formed by a welded reconstituted beam or
"PRS", that is made by welding steel plates with a U-shaped cross-section more
particularly shown in figure 4. Reference 1060D denotes the bottom of the U-shaped
section of the segment 1060. References 1060E and 1060F also denote the branches of
20 this U-shaped section that constitute the flanks of the beam segment 1060. Weld beads
1061 provide the connection between the parts 1060D, 1060E and 1060F, respectively.
Reference el denotes the thickness of the bottom 1060D and e2 denotes the thickness of
a flank 1060E or 1060F, which is the same. The thickness el is greater than the thickness
e2, which corresponds to the fact that it is the horizontal part of the upper beam 100 that
25 works by traction, more than its flanks. In practice, the thickness e l is comprised between
18 and 30 mm, preferably about 20 mm, while the thickness e2 is comprised between 10
and 16 mm, preferably about 12 mm.
The lower beam segment 1062 is also formed by a PRS made from steel plates,
with a U-shaped cross-section similar to that of the segment 1060.
30 Each member is also formed by a PRS made from steel plates, with an I- or Hshaped
cross-section, as shown in figure 5 for a long member 1066. More specifically
more specifically, this member has a core 1066D and two flanks 1066E and 1066F that
are connected to the core 1066D by weld beads 1063. Reference e3 denotes the
thickness of the core 1066D and e4 denotes the thickness of the flanks 1066E or 1066F,
35 which is the same. The thickness e3 is smaller than the thickness e4, which is preferably
equal to the thickness e2, which makes it possible to align the flanks 1060E and 1066E
6
vertically, as well as the flanks 1060F and 1066F. In practice, the thickness e3 is
comprised between 4 and 8 mm, preferably about 8 mm, while the thickness e4 is
comprised between 10 and 16 mm, preferably about 12 mm. Here again, the distribution
of the thicknesses of the sheets making up the PRS forming the member 1066 is
5 optimized based on the mechanical stresses of these sheets and their interaction with the
component parts of the segments 1060 and 1062. In particular, the core 1066D can be
relatively thin, since it is not stressed very much by the weight of the bridge and loads
present on the deck 4.
The members 1067 and 1068 each have an I-shaped cross-section similar to that
10 of the member 1066 shown in figure 5.
In practice, the orifices 1060C, 1062C, 1066C, 1067C and 1068C are formed in
the flanks 1060E, 1060F, 1066E, 1066F and equivalent of the parts 1060, 1062, 1066,
1067 and 1068, such that the splice bars 1069 can be affixed bearing on the outside of
these flanks.
15 In this respect, it will be noted that the intermediate part of a long member 1066 is
provided, on its flanks, with lugs 1066G comparable to the lugs 1060A and 1062A and in
which certain orifices 1066C are arranged that are intended to receive bolts for
immobilizing splice bars 1069, which also cooperate with the second ends 10678 and
10688 of the short members 1067 and 1068.
20 According to one aspect of the invention that is not shown, splice bars can also be
provided to connect the cores of the members to one another and with intermediate ribs
provided at the lug 1060A and 1062A inside beam segments 1060 and 1062.
Making the beam segments 1060 and 1062 and the members 1066 to 1068 in
PRS form provides great freedom in the design of the modules 106 of the truss structure
25 10. This freedom makes it possible to optimize the quantity of steel consumed to form
each module 106, and therefore the weight and cost of the truss structure 10.
Thus formed, each running module 106 of the truss structure 10 forms a rigid
structure thatcan be assembled with adjacent modules, of the running or end type, using
splice bars, some of which are visible in figures 6 and 7 with references 1071 and 1073.
30 Likewise, the truss structure 12 comprises an upper beam 120, a lower beam 122,
reinforcements 124, running modules 126 and end modules 128 and 129. A running
segment 126 comprises an upper beam segment 1260, a lower beam segment 1262 and
reinforcements 124 formed by long members 1266 and short members 1267 and 1268.
In practice, a running module 126 is identical to a running module 106. Likewise,
35 an end module 128 or 129 is identical to an end module 108 or 109, down to the fact that
straight and bent elements exist.
7
The end modules 108, 109, 128 and 129 each comprise an upper beam segment,
a lower beam segment and at least one reinforcement 104 or 124 or a reinforcing part.
The main difference between an end module 108, 109, 128 or 129 and a running module
106 or 126 is the length of its beam segments, which is smaller than that of the beam
5 segments 1060 and 1062, as explained above.
In order to impart a camber to the bridge 2, it may be provided that the upper beam
segment 1060 of a running module 106 is assembled to the upper beam segments of the
adjacent modules by arranging a nonzero axial space between them, along the axis X2,
greater than 20 mm, this space being defined by the geometry of the splice bars 1071 and
10 1073 used at these upper beam segments. On the contrary, the lower beam segments of
two adjacent modules are assembled in contact with one another or with an axial distance
between them smaller than that used at the upper beam segments, for example about 2 to
4 mm.
When the bridge 2 is conveyed to its installation site, the component elements of a
15 running module 106 to 109 or 126 to 129 can be transported in containers, in particular
sea freight containers, since the maximum length of a piece of such an element is the
maximum length of a beam segment 1060, 1062, 1260 or 1262 of a running element 106
or 126, which is 9.15 meters. Furthermore, the members 1066, 1067, 1068, 1266, 1267,
1268 and equivalents can be arranged parallel to one another inside the container, which
20 allows them to be stored with a high density and avoids filling containers with a load
significantly lower than the nominal weight that they can transport, which would be the
case if the X-shaped reinforcements were formed by rigid and preassembled cross
structures.
Thus, owing to the truss structures 10 and 12, the beam can be conveyed
25 relatively easily to its installation site, while having a relatively low mass per unit length.
This makes it possible to create a bridge 2 that may have a span greater than 90
meters with a mass per unit length of about 2 tons for a bridge with a deck having one
traffic lane. In the case of a bridge with a deck having two traffic lanes, the span of the
bridge may be greater than 60 m.
30 According to possible developments of the deck 4 of the bridge 2, the latter may be
equipped with safety gates 42, as shown in figures 1 to 3, or sidewalks 44 and hand rails
46, as shown in figures 6 and 7. Other developments, not shown, of the deck may be
considered, such as lighting columns. Alternatively, the sidewalks 44 can be arranged
outside the truss structures 10, 12, cantilevered relative to the latter.
35 The invention is described above in the case of a Warren-type bridge with a double
intersection. It is, however, applicable to other types of bridges having truss structures
8
including X-shaped reinforcements, in particular Pratt bridges with a double intersection,
or Parker, Bowstring, Camelback, Pennsylvania or Baltimore bridges.
The embodiment and alternatives considered above may be combined with one
another to create new embodiments

CLAIMS
1.- A bridge (2) with truss structures (10, 12), in particular of the Warren type with
a double intersection, this bridge comprising:
- a deck (4);
- two truss structures (10, 12) that each comprise an upper beam (100, 120), a
lower beam (102, 122) and members (1066-1068, 1266-1268) that extend
between the upper and lower beams while forming X-shaped reinforcements
(104, 124), and
- girders (8) stretched between the truss structures (10, 12) and that support the
deck (4),
each truss structure including several modules (106, 108, 126, 128) that each comprise a
segment (1060, 1260) of the upper beam, a segment (1062, 1262) of the lower beam and
at least one X-shaped reinforcement (104, 124),
15 characterized in that each X-shaped reinforcement (104, 124) is formed by a long member
(1066, 1266) fixed, at a first end (1066A), on the upper beam segment (1060, 1260), and,
at a second end (1066B), on the lower beam segment (1062, 1262), as well as by hnro
short members (1 067, 1068, 1267, 1268) each fixed, at a first end (1 067A, 1068, 1267,
1268), on one of the beam segments (1060, 1062, 1260, 1262), and at a second end
20 (1067B,1068B), on the long member (1066,1266).
2.- The bridge according to claim 1, characterized in that the beam segments
(1060, 1062, 1260, 1262) and the members (1066-1 068, 1266-1268) are each formed by
a welded reconstituted beam (PRS).
3.- The bridge according to claim 2, characterized in that each beam segment
25 (1060, 1062, 1260, 1262) has a U-shaped section, with a bottom (1060D) thicker than its
flanks (1060E, 1060F).
4.- The bridge according to claim 3, characterized in that the thickness (el) of the
bottom (1 060D) of the beam segment (1 060, 1062, 1260, 1262) is comprised between 18
and 30 mm, preferably equal to about 20 mm, while the thickness (e2) of the flanks
30 (1060E, 1060F) of the beam segment is comprised between 10 and 16 mm, preferably
equal to about 12 mm.
5.- The bridge according to one of claims 2 to 4, characterized in that each
member (1066-1068, 1266-1068) has an I- or H-shaped section, with a core (1066D)
thinner than its flanks (1066E, 1066F).
35 6.- The bridge according to claim 5, characterized in that the thickness (e3) of the
core (1066D) of the member (1066-1068, 1266-1268) is advantageously comprised
10
between 4 and 8 mm, preferably equal to about 8 mm, while the thickness (e4) of the
flanks (1066E, 1066F) of the member is compr~sed between 10 and 16 mm, preferably
equal to about 12 mm.
7.- The bridge according to claims 3 and 5, characterized in that the flanks (1060E,
5 1060~o)f the beam segment (1060, 1062, 1260, 1262) and the flanks (1066E, 1066F) of
the member (1066-1068, 1266-1268) have identical thicknesses (e2, e4).
8.- The bridge according to one of the preceding claims, characterized in that the
members (1066-1068, 1266-1268) are assembled to one another and to the beam
segments (1060, 1062, 1260, 1262) and the modules (106-109, 126-129) are assembled
10 to one another using splice bars (1069, 1071, 1073) bolted on the members and on the
beam segments, in particular on side flanks (1060E, 1060F, 1066E, 1066F) of these
members and segments.
9.- The bridge according to one of the preceding claims, characterized in that
- the upper beam (1 00) works by traction,
- the lower beam (102) works by compression,
- the upper beam segments (1060, 1260) of two adjacent modules (106, 108,
109, 126, 128,129) are assembled with a space arranged between them, and
- the lower beam segments (1062, 1262) of two adjacent modules are
assembled in contact with one another.
10.- The bridge according to one of the preceding claims, characterized in that
- the truss structures (10, 12) include running modules (106, 126) that each
comprise a segment (1060, 1260) of the upper beam, a segment (1062, 1262)
of the lower beam and at least one X-shaped reinforcement (104, 124), and at
least one end module (108, 109, 128, 129) that comprises an upper beam
segment, a lower beam segment and at least one X-shaped reinforcing par?,
- the length (L108, L109) of the end module is smaller than the length (L106) of
a running module (106),
- the total length (L2) of the bridge is a multiple of one third of the length of a
running module.