Bridge whose load-bearing superstructure is composed of a truss
Truss bridge
![A truss bridge operated by Southern Pacific Railroad in Contra Costa County, California converted to pedestrian use and pipeline support](//upload.wikimedia.org/wikipedia/commons/thumb/c/c5/RRTrussBridgeSideView.jpg/240px-RRTrussBridgeSideView.jpg) |
Ancestor
| Beam bridge
[
citation needed
]
|
---|
Related
| None
|
---|
Descendant
| Cantilever bridge
,
truss arch bridge
,
transporter bridge
,
lattice bridge
[
citation needed
]
|
---|
Carries
| Pedestrians
,
pipelines
,
automobiles
,
trucks
,
light rail
,
heavy rail
|
---|
Span range
| Short to medium ? not very long unless it is continuous
|
---|
Material
| Timber
,
iron
,
steel
,
reinforced concrete
,
prestressed concrete
|
---|
Movable
| May be movable ? see
movable bridge
|
---|
Design effort
| Medium
|
---|
Falsework
required
| Depends upon length, materials, and degree of prefabrication
|
---|
A
truss bridge
is a
bridge
whose load-bearing
superstructure
is composed of a
truss
, a structure of connected elements, usually forming triangular units. The connected elements, typically straight, may be stressed from
tension
,
compression
, or sometimes both in response to dynamic loads. There are several types of truss bridges, including some with simple designs that were among the first bridges designed in the 19th and early 20th centuries. A truss bridge is economical to construct primarily because it uses materials efficiently.
Design
[
edit
]
The components of a typical truss bridge
[1]
The nature of a
truss
allows the
analysis
of its structure using a few assumptions and the application of
Newton's laws of motion
according to the branch of
physics
known as
statics
. For purposes of analysis, trusses are assumed to be pin jointed where the straight components meet, meaning that taken alone, every joint on the structure is functionally considered to be a flexible joint as opposed to a rigid joint with the strength to maintain its shape, and the resulting shape and strength of the structure are only maintained by the interlocking of the components. This assumption means that members of the truss (chords, verticals, and diagonals) will act only in tension or compression. A more complex analysis is required where rigid joints impose significant
bending
loads upon the elements, as in a
Vierendeel truss
.
In the bridge illustrated in the
infobox
at the top, vertical members are in tension, lower horizontal members in tension,
shear
, and bending, outer diagonal and top members are in compression, while the inner diagonals are in tension. The central vertical member stabilizes the upper compression member, preventing it from
buckling
. If the top member is sufficiently stiff then this vertical element may be eliminated. If the lower chord (a horizontal member of a truss) is sufficiently resistant to bending and shear, the outer vertical elements may be eliminated, but with additional strength added to other members in compensation. The ability to distribute the forces in various ways has led to a large variety of truss bridge types. Some types may be more advantageous when the wood is employed for compression elements while other types may be easier to erect in particular site conditions, or when the balance between labor, machinery, and material costs has certain favorable proportions.
The inclusion of the elements shown is largely an engineering decision based upon economics, being a balance between the costs of raw materials, off-site fabrication, component transportation, on-site erection, the availability of machinery, and the cost of labor. In other cases, the appearance of the structure may take on greater importance and so influence the design decisions beyond mere matters of economics. Modern materials such as
prestressed concrete
and fabrication methods, such as automated
welding
, and the changing price of steel relative to that of labor have significantly influenced the design of modern bridges.
Model bridges
[
edit
]
A pure truss can be represented as a pin-jointed structure, one where the only forces on the truss members are tension or compression, not bending. This is used in the teaching of statics, by the building of
model bridges from spaghetti
. Spaghetti is brittle and although it can carry a modest tension force, it breaks easily if bent. A model spaghetti bridge thus demonstrates the use of a truss structure to produce a usefully strong complete structure from individually weak elements.
United States
[
edit
]
In the
United States
, because wood was in abundance, early truss bridges would typically use carefully fitted timbers for members taking compression and iron rods for
tension members
, usually constructed as a
covered bridge
to protect the structure. In 1820, a simple form of truss,
Town's lattice truss
, was patented, and had the advantage of requiring neither high labor skills nor much metal. Few iron truss bridges were built in the United States before 1850.
Truss bridges became a common type of bridge built from the 1870s through the 1930s. Examples of these bridges still remain across the US, but their numbers are dropping rapidly as they are demolished and replaced with new structures. As metal slowly started to replace timber,
wrought iron
bridges in the US started being built on a large scale in the 1870s. Bowstring truss bridges were a common truss design during this time, with their arched top chords. Companies like the
Massillon Bridge Company
of
Massillon, Ohio
, and the
King Bridge Company
of
Cleveland
, became well-known, as they marketed their designs to cities and townships.
The bowstring truss design fell out of favor due to a lack of durability, and gave way to the Pratt truss design, which was stronger. Again, the bridge companies marketed their designs, with the Wrought Iron Bridge Company in the lead. As the 1880s and 1890s progressed,
steel
began to replace wrought iron as the preferred material. Other truss designs were used during this time, including the camel-back. By the 1910s, many states developed standard plan truss bridges, including steel Warren
pony
truss bridges.
In the 1920s and 1930s,
Pennsylvania
and several states continued to build steel truss bridges, using massive steel through-truss bridges for long spans. Other states, such as
Michigan
, used standard plan concrete girder and beam bridges, and only a limited number of truss bridges were built.
Roadbed types
[
edit
]
The truss may carry its
roadbed
on top, in the middle, or at the bottom of the truss. Bridges with the roadbed at the top or the bottom are the most common as this allows both the top and bottom to be stiffened, forming a
box truss
. When the roadbed is atop the truss, it is a deck truss; an example of this was the
I-35W Mississippi River bridge
. When the truss members are both above and below the roadbed it is called a through truss; an example of this is the
Pulaski Skyway
, and where the sides extend above the roadbed but are not connected, a pony truss or
half-through
truss.
Sometimes both the upper and lower chords support roadbeds, forming a
double-decked truss
. This can be used to separate rail from road traffic or to separate the two directions of road traffic.
Since through truss bridges have supports located over the bridge deck, they are susceptible to being hit by
overheight loads
when used on highways. The
I-5 Skagit River bridge collapsed
after such a strike; before the collapse, similar incidents had been common and had necessitated frequent repairs.
[2]
Gallery
[
edit
]
-
Pratt
through truss
of the former
Seaboard Air Line Railway
, located near
Willow, Florida
; abandoned since the mid-1980s
-
Deck truss
railroad bridge over the
Erie Canal
in
Lockport, New York
-
The four span through truss
General Hertzog Bridge
over the
Orange River
at
Aliwal North
carries vehicular traffic
-
The through truss Skagit River bridge on Interstate 5
collapsed
after an overhead support was hit by a passing truck
-
-
Pony truss
bridge of reinforced concrete
-
Sky Gate Bridge R at
Kansai International Airport
,
Osaka
, Japan, is the longest double-decked truss bridge in the world. It carries three lanes of automobile traffic on top and two of rail below over nine truss spans.
-
Railroad Truss bridge over Trinity River near
Goodrich, Texas
-
The
Hart Bridge
spanning the
St. Johns River
in
Jacksonville, Florida
, is a continuous, cantilevered truss bridge which combines a suspended road deck on the 332-metre (1,088 ft) main span and through truss decks on the adjacent approach spans
-
-
Chevelon Creek Warren Pony Truss Bridge,Chevelon Creek, Navajo County Arizona built 1913
-
Side view of the iron truss railway bridge over
Mura River
in
Mursko Sredi??e
,
Croatia
-
Railroad Truss Drawbridge across Buffalo Bayou?Houston
Multiple spans
[
edit
]
Truss bridges consisting of more than one
span
may be either a
continuous truss
or a series of simple trusses. In the simple truss design, each span is supported only at the ends and is fully independent of any adjacent spans. Each span must fully support the weight of any vehicles traveling over it (the
live load
).
In contrast, a continuous truss functions as a single rigid structure over multiple supports. This means that the live load on one span is partially supported by the other spans, and consequently it is possible to use less material in the truss.
[3]
: 168
Continuous truss bridges were not very common before the mid-20th century because they are
statically indeterminate
, which makes them difficult to design without the
use of computers
.
A multi-span truss bridge may also be constructed using
cantilever
spans, which are supported at only one end rather than both ends like other types of trusses. Unlike a continuous truss, a cantilever truss does not need to be connected rigidly, or indeed at all, at the center.
[3]
: 169?170
Many cantilever bridges, like the
Quebec Bridge
shown below, have two cantilever spans supporting a simple truss in the center. The bridge would remain standing if the simple truss section were removed.
Truss types used in bridges
[
edit
]
Bridges are the most widely known examples of truss use. There are many types,
[4]
some of them dating back hundreds of years. Below are some of the more common designs.
Allan truss
[
edit
]
An Allan truss
The
Allan truss
, designed by
Percy Allan
, is partly based on the
Howe truss
. The first Allan truss was completed on 13 August 1894 over Glennies Creek at Camberwell, New South Wales and the last Allan truss bridge was built over Mill Creek near
Wisemans Ferry
in 1929.
[5]
[6]
Completed in March 1895, the
Tharwa Bridge
located at
Tharwa, Australian Capital Territory
, was the second Allan truss bridge to be built, the oldest surviving bridge in the
Australian Capital Territory
and the oldest, longest continuously used Allan truss bridge.
[7]
[8]
[9]
Completed in November 1895, the
Hampden Bridge
in
Wagga Wagga, New South Wales
, Australia, the first of the Allan truss bridges with overhead bracing, was originally designed as a steel bridge but was constructed with timber to reduce cost.
[10]
In his design, Allan used Australian
ironbark
for its strength.
[11]
A similar bridge also designed by Percy Allen is the
Victoria Bridge
on Prince Street,
Picton, New South Wales
. Also constructed of ironbark, the bridge is still in use today for pedestrian and light traffic.
[12]
Bailey truss
[
edit
]
Bailey truss over the
Meurthe River
in France
The
Bailey truss
was designed by the British in 1940?1941 for military uses during World War II. A short selection of prefabricated modular components could be easily and speedily combined on land in various configurations to adapt to the needs at the site and allow rapid deployment of completed trusses. In the image, note the use of pairs of doubled trusses to adapt to the span and load requirements. In other applications the trusses may be stacked vertically, and doubled as necessary.
Baltimore truss
[
edit
]
The
Baltimore truss
is a subclass of the Pratt truss. A Baltimore truss has additional bracing in the lower section of the truss to prevent buckling in the compression members and to control deflection. It is mainly used for rail bridges, showing off a simple and very strong design. In the Pratt truss the intersection of the verticals and the lower horizontal tension members are used to anchor the supports for the short-span girders under the tracks (among other things). With the Baltimore truss, there are almost twice as many points for this to happen because the short verticals will also be used to anchor the supports. Thus the short-span girders can be made lighter because their span is shorter. A good example of the Baltimore truss is the
Amtrak Old Saybrook ? Old Lyme Bridge
in
Connecticut
, United States.
Bollman truss
[
edit
]
A Bollman truss in
Savage, Maryland
; built in 1869, it was moved to Savage in 1887 and has been in continuous use since as a pedestrian bridge.
39°8′5.42″N
76°49′30.33″W
/
39.1348389°N 76.8250917°W
/
39.1348389; -76.8250917
The
Bollman Truss Railroad Bridge
at
Savage, Maryland
, United States is the only surviving example of a revolutionary design in the history of American bridge engineering. The type was named after its inventor,
Wendel Bollman
, a self-educated
Baltimore
engineer. It was the first successful all-metal bridge design (patented in 1852) to be adopted and consistently used on a railroad. The design employs
wrought iron
tension members and
cast iron
compression members. The use of multiple independent tension elements reduces the likelihood of catastrophic failure. The structure was also easy to assemble.
Wells Creek Bollman Bridge
is the only other bridge designed by Wendel Bollman still in existence, but it is a Warren truss configuration.
Bowstring truss
[
edit
]
Bowstring truss
A bowstring truss bridge, in
London, Ontario
, Canada
The
bowstring truss
bridge was patented in 1841
[13]
by
Squire Whipple
.
[14]
While similar in appearance to a
tied-arch bridge
, a bowstring truss has diagonal load-bearing members: these diagonals result in a structure that more closely matches a
Parker truss
or
Pratt truss
than a
true arch
.
Brown truss
[
edit
]
Brown truss
In the
Brown truss
all vertical elements are under tension, with exception of the end posts. This type of truss is particularly suited for timber structures that use iron rods as tension members.
Brunel truss
[
edit
]
See
Lenticular truss
below.
Burr arch truss
[
edit
]
Baumgardener's Covered Bridge
, a
Burr Arch Truss
in
Lancaster County, Pennsylvania
This combines an arch with a truss to form a structure both strong and rigid.
Cantilever truss
[
edit
]
Forth Bridge
, crossing the
Firth of Forth
in eastern Scotland
Most trusses have the lower chord under tension and the upper chord under compression. In a
cantilever truss
the situation is reversed, at least over a portion of the span. The typical cantilever truss bridge is a "balanced cantilever", which enables the construction to proceed outward from a central vertical spar in each direction. Usually these are built in pairs until the outer sections may be anchored to footings. A central gap, if present, can then be filled by lifting a conventional truss into place or by building it in place using a "traveling support". In another method of construction, one outboard half of each balanced truss is built upon temporary falsework. When the outboard halves are completed and anchored the inboard halves may then be constructed and the center section completed as described above.
Fink truss
[
edit
]
A
Fink truss
(half span and cross section)
The
Fink truss
was designed by
Albert Fink
of Germany in 1854. This type of bridge was popular with the
Baltimore and Ohio Railroad
. The
Appomattox High Bridge
on the
Norfolk and Western Railway
included 21 Fink deck truss spans from 1869 until their replacement in 1886.
There are also
inverted Fink truss
bridges such as the
Moody Pedestrian Bridge
in Austin, Texas.
Howe truss
[
edit
]
A
Howe truss
with diagonals under compression under balanced loading
The
Howe truss
, patented in 1840 by
Massachusetts
millwright
William Howe
, includes vertical members and diagonals that slope up towards the center, the opposite of the
Pratt truss
.
[15]
In contrast to the Pratt truss, the diagonal web members are in compression and the vertical web members are in tension. Few of these bridges remain standing. Examples include
Jay Bridge
in
Jay, New York
;
McConnell's Mill Covered Bridge
in
Slippery Rock Township, Lawrence County, Pennsylvania
;
Sandy Creek Covered Bridge
in
Jefferson County, Missouri
; and
Westham Island Bridge
in
Delta, British Columbia
, Canada.
K-truss
[
edit
]
K-truss
The
I-895
K-truss in
Baltimore
The
K-truss
is named after the
K
formed in each panel by the vertical member and two oblique members. Examples include the Sudbrucke rail bridge over the River Rhine, Mainz, Germany,
[16]
the bridge on I-895 (Baltimore Harbor Tunnel Thruway) in Baltimore, Maryland, the
Long?Allen Bridge
in
Morgan City, Louisiana
(Morgan City Bridge) with three 600-foot-long spans, and the Wax Lake Outlet bridge in
Calumet, Louisiana
[17]
Kingpost truss
[
edit
]
King post truss
One of the simplest truss styles to implement, the
king post
consists of two angled supports leaning into a common vertical support.
Lattice truss (Town's lattice truss)
[
edit
]
Lattice, or Warren quadrangular truss illustrated
Runcorn Railway Bridge
, a lattice truss
This type of bridge uses a substantial number of lightweight elements, easing the task of construction. Truss elements are usually of wood, iron, or steel.
Lenticular truss
[
edit
]
Aiken Street Bridge in
Lowell, Massachusetts
, built in 1883 by
Berlin Iron Bridge Co.
, is the longest lenticular truss bridge in the United States with five spans, and the second-oldest lenticular truss bridge in
Massachusetts
.
[18]
Royal Albert Bridge
under construction in 1859
A
lenticular truss
bridge includes a lens-shape truss, with trusses between an upper chord functioning as an arch that curves up and then down to end points, and a lower chord (functioning as a suspension cable) that curves down and then up to meet at the same end points.
[19]
Where the arches extend above and below the roadbed, it is called a
lenticular pony truss bridge
. The
Pauli truss
bridge is a specific variant of the lenticular truss, but the terms are not interchangeable.
[19]
One type of lenticular truss consists of arcuate upper compression chords and lower
eyebar
chain tension links.
Brunel
's
Royal Albert Bridge
over the
River Tamar
between
Devon
and
Cornwall
uses a single tubular upper chord. As the horizontal tension and compression forces are balanced these horizontal forces are not transferred to the supporting pylons (as is the case with most arch types). This in turn enables the truss to be fabricated on the ground and then to be raised by jacking as supporting masonry pylons are constructed. This truss has been used in the construction of a stadium,
[20]
with the upper chords of parallel trusses supporting a roof that may be rolled back. The
Smithfield Street Bridge
in
Pittsburgh, Pennsylvania
, is another example of this type.
The old Großhesselohe bridge before 1905, designed by Friedrich von Pauli
An example of a lenticular pony truss bridge that uses regular spans of iron is the
Turn-of-River Bridge
designed and manufactured by the
Berlin Iron Bridge Co.
The Pauli truss is a variant of the lenticular truss, "with the top chord carefully shaped so that it has a constant force along the entire length of the truss."
[19]
It is named after
Friedrich Augustus von Pauli
[
de
]
, whose 1857 railway bridge (the
Großhesseloher Brucke
[
de
]
) spanned the
Isar
near
Munich
. (
See also
Grosshesselohe Isartal station
.) The term Pauli truss is not interchangeable with the term lenticular truss and, according to Thomas Boothby, the casual use of the term has clouded the literature.
[19]
Long truss
[
edit
]
HAER
diagram of a Long truss
The
Long truss
was designed by Stephen H. Long in 1830. The design resembles a
Howe truss
, but is entirely made of wood instead of a combination of wood and metal.
[21]
The longest surviving example is the
Eldean Covered Bridge
north of
Troy, Ohio
, spanning 224 feet (68 m).
[22]
One of the earliest examples is the
Old Blenheim Bridge
, which with a span of 210 feet (64 m) and a total length of 232 feet (71 m) long was the second-longest covered bridge in the United States, until its destruction from flooding in 2011.
The Busching bridge, often erroneously used as an example of a Long truss, is an example of a Howe truss, as the verticals are metal rods.
[23]
Parker (camelback) truss
[
edit
]
Woolsey Bridge
, a Parker camelback truss
A
Parker truss
bridge is a Pratt truss design with a polygonal upper chord. A "camelback" is a subset of the Parker type, where the upper chord consists of exactly five segments. An example of a Parker truss is the
Traffic Bridge
in
Saskatoon
, Canada. An example of a camelback truss is the
Woolsey Bridge
near
Woolsey, Arkansas
.
Partridge truss
[
edit
]
Partridge truss design
Designed and patented in 1872 by
Reuben Partridge
, after local bridge designs proved ineffective against road traffic and heavy rains.
[24]
It became the standard for
covered bridges
built in central Ohio in the late 1800s and early 1900s.
Pegram truss
[
edit
]
Pegram truss
The
Pegram truss
is a hybrid between the Warren and Parker trusses where the upper chords are all of equal length and the lower chords are longer than the corresponding upper chord. Because of the difference in upper and lower chord length, each panel is not square. The members which would be vertical in a Parker truss vary from near vertical in the center of the span to diagonal near each end, similar to a Warren truss.
George H. Pegram
, while the chief engineer of Edge Moor Iron Company in
Wilmington, Delaware
, patented this truss design in 1885.
[25]
The Pegram truss consists of a Parker type design with the vertical posts leaning towards the center at an angle between 60 and 75°. The variable post angle and constant chord length allowed steel in existing bridges to be recycled into a new span using the Pegram truss design. This design also facilitated reassembly and permitted a bridge to be adjusted to fit different span lengths. There are twelve known remaining Pegram span bridges in the United States with seven in
Idaho
, two in
Kansas
, and one each in
California
,
Washington
, and
Utah
.
[
citation needed
]
Pennsylvania (Petit) truss
[
edit
]
The
Fair Oaks Bridge
is an example of Pennsylvania Petit truss bridge.
The
Pennsylvania (Petit) truss
is a variation on the
Pratt truss
.
[
citation needed
]
The Pratt truss includes braced diagonal members in all panels; the Pennsylvania truss adds to this design half-length struts or ties in the top, bottom, or both parts of the panels. It is named after the
Pennsylvania Railroad
, which pioneered this design. It was once used for hundreds of bridges in the United States, but fell out of favor in the 1930s and very few examples of this design remain.
[26]
Examples of this truss type include the
Lower Trenton Bridge
in
Trenton, New Jersey
, the
Fort Wayne Street Bridge
in
Goshen, Indiana
, the
Schell Bridge
in
Northfield, Massachusetts
, the
Inclined Plane Bridge
in
Johnstown, Pennsylvania
, the
Easton?Phillipsburg Toll Bridge
in
Easton, Pennsylvania
, the
Connecticut River Bridge
in
Brattleboro, Vermont
, the
Metropolis Bridge
in
Metropolis, Illinois
, and the
Healdsburg Memorial Bridge
in
Healdsburg, California
.
Post truss
[
edit
]
A Post truss
A
Post truss
is a hybrid between a Warren truss and a double-intersection Pratt truss. Invented in 1863 by Simeon S. Post, it is occasionally referred to as a
Post patent truss
although he never received a patent for it.
[27]
The
Ponakin Bridge
and the
Bell Ford Bridge
are two examples of this truss.
Pratt truss
[
edit
]
A Pratt truss
Gatton Railway Bridge showing the Pratt truss design
Macleay River Railway Bridge
, a Pratt truss design at Kempsey in NSW, Australia
A
Pratt truss
includes vertical members and diagonals that slope down towards the center, the opposite of the
Howe truss
.
[15]
The interior diagonals are under tension under balanced loading and vertical elements under compression. If pure tension elements (such as
eyebars
) are used in the diagonals, then crossing elements may be needed near the center to accept concentrated live loads as they traverse the span. It can be subdivided, creating Y- and K-shaped patterns. The Pratt truss was invented in 1844 by
Thomas
and Caleb Pratt.
[28]
[29]
This truss is practical for use with spans up to 250 feet (76 m) and was a common configuration for railroad bridges as truss bridges moved from wood to metal. They are
statically determinate
bridges, which lend themselves well to long spans. They were common in the United States between 1844 and the early 20th century.
[29]
Examples of Pratt truss bridges are the
Governor's Bridge
in
Maryland
;
[29]
the
Hayden RR Bridge
in
Springfield, Oregon
, built in 1882; the
Dearborn River High Bridge
near Augusta, Montana, built in 1897; and the
Fair Oaks Bridge
in
Fair Oaks, California
, built 1907?09.
The
Scenic Bridge
near
Tarkio, Montana
, is an example of a Pratt deck truss bridge, where the roadway is on top of the truss.
Queenpost truss
[
edit
]
A
Queen post
truss
The
queenpost truss
, sometimes called "queen post" or queenspost, is similar to a king post truss in that the outer supports are angled towards the center of the structure. The primary difference is the horizontal extension at the center which relies on
beam
action to provide mechanical stability. This truss style is only suitable for relatively short spans.
[30]
Smith truss
[
edit
]
Smith truss
The
Smith truss
, patented by Robert W Smith on July 16, 1867,
[31]
has mostly diagonal criss-crossed supports. Smith's company used many variations of this pattern in the wooden covered bridges it built.
While most all of the bridges built in the 19th century in the
Jackson County, Ohio
, area used the Smith truss design, the
Johnson Road Covered Bridge
is the last known surviving example in the state.
[32]
Thacher truss
[
edit
]
A Thacher truss bridge
The
Thacher truss
[33]
combines some of the characteristics of a
Pratt truss
with diagonals under tension and of a
Howe truss
with diagonals under compression, which is rare.
Truss arch
[
edit
]
Truss arch bridge
A
truss arch
may contain all horizontal forces within the arch itself, or alternatively may be either a thrust arch consisting of a truss, or of two arcuate sections pinned at the apex. The latter form is common when the bridge is constructed as
cantilever
segments from each side as in the
Navajo Bridge
.
Vierendeel truss
[
edit
]
A
Vierendeel bridge
The
Vierendeel truss
, unlike common pin-jointed trusses, imposes significant bending forces upon its members?but this in turn allows the elimination of many diagonal elements. It is a structure where the members are not triangulated but form rectangular openings, and is a frame with fixed joints that are capable of transferring and resisting bending moments. While rare as a bridge type due to higher costs compared to a triangulated truss, it is commonly employed in modern building construction as it allows the resolution of gross shear forces against the frame elements while retaining rectangular openings between columns. This is advantageous both in allowing flexibility in the use of the building space and freedom in selection of the building's outer
curtain wall
, which affects both interior and exterior styling aspects.
Waddell truss
[
edit
]
Waddell "A" truss bridge, assembled in 1898
Patented 1894 (
U.S. patent 529,220
); its simplicity eases erection at the site. It was intended to be used as a railroad bridge.
One example was the
Waddell "A" Truss Bridge
in
Parkville, Missouri
.
Warren truss
[
edit
]
A
Warren truss
The
Warren truss
was patented in 1848 by
James Warren
and Willoughby Theobald Monzani, and consists of longitudinal members joined only by angled cross-members, forming alternately inverted
equilateral triangle
-shaped spaces along its length, ensuring that no individual
strut
, beam, or
tie
is subject to bending or torsional straining forces, but only to tension or compression. Loads on the diagonals alternate between compression and tension approaching the center, with no vertical elements, while elements near the center must support both tension and compression in response to live loads. This configuration combines strength with economy of materials and can therefore be relatively light. The girders being of equal length, it is ideal for use in prefabricated modular bridges. It is an improvement over the Neville truss which uses a spacing configuration of
isosceles triangles
.
Whipple truss
[
edit
]
Bridge L-158
, a double-intersection Whipple rail truss over the
Muscoot Reservoir
in
Golden's Bridge, New York
A
Whipple truss
, named after its inventor
Squire Whipple
, is usually considered a subclass of the Pratt truss because the diagonal members are designed to work in tension. The main characteristic of a Whipple truss is that the tension members are elongated, usually thin, and at a shallow angle, and cross two or more bays (rectangular sections defined by the vertical members).
Wichert truss
[
edit
]
Homestead Grays Bridge
over the
Monongahela River
in
Pittsburgh
The
Wichert truss
is a modified type of
continuous truss
which is
statically determinate
and helps avoid some of the other shortcomings of continuous trusses.
[34]
It was patented in 1930 by
Pittsburgh
-based civil engineer Edward Martin Wichert (1883?1955).
[35]
[36]
The defining feature of this truss type is a hinged
kite-shaped
section above each intermediate support.
[
citation needed
]
Only about ten Wichert truss bridges were ever built, mostly in Pennsylvania and Maryland. Of these, one of the best known is the
Homestead Grays Bridge
in Pittsburgh.
[37]
Truss bridge video
[
edit
]
Driving across a truss bridge: The video shows the roadway perspective of a through truss bridge over the
Willamette River
in
Harrisburg, Oregon
. The bridge features three simply supported Parker Truss spans.
References
[
edit
]
- ^
Science and Industry
Archived
2017-02-15 at the
Wayback Machine
, Members of a Truss Bridge by Benj. F. La Rue, Home Study Magazine, Published by the Colliery Engineer Company, Vol 3, No. 2, March 1898, pages 67-68.
- ^
"Temporary Skagit River bridge may be open in weeks"
.
King 5 television
. May 26, 2013. Archived from
the original
on June 7, 2013
. Retrieved
March 27,
2013
.
- ^
a
b
Adams, Charles Kendall, ed. (1909). "Bridges".
Universal Cyclopædia and Atlas
. New York: D. Appleton and Company. pp. 161?174
. Retrieved
September 1,
2022
.
- ^
Kirsanov, M. (2019).
Planar Trusses: Schemes and Formulas
. GB: Cambridge Scholars Publishing. p. 206.
ISBN
978-1-5275-3531-2
.
- ^
"Timber Truss Bridges"
(PDF)
.
McMillan Britton & Kell Pty Limited
. Roads and Traffic Authority. December 1998.
Archived
(PDF)
from the original on 19 March 2011
. Retrieved
23 November
2010
.
- ^
"Tharwa Bridge Conservation Management Plan"
(PDF)
.
Philip Leeson Architects
. Roads ACT. 5 March 2009. pp. 42, 45.
Archived
(PDF)
from the original on 21 February 2011
. Retrieved
23 November
2010
.
- ^
"1307.8 ? Australian Capital Territory in Focus, 2007"
.
Australian Bureau of Statistics
. 27 November 2007.
Archived
from the original on 14 October 2012
. Retrieved
23 November
2010
.
- ^
"Tharwa Bridge"
.
Engineers Australia
. Canberra's Engineering Heritage. Archived from
the original
on 2011-02-19
. Retrieved
23 November
2010
.
- ^
"July 2010 Newsletter | Engineers Australia"
.
www.engineersaustralia.org.au
.
Archived
from the original on 2021-10-01
. Retrieved
2021-03-24
.
- ^
"Minutes of State Heritage Register Committee meeting"
(PDF)
.
State Heritage Register Committee
. Heritage Council of New South Wales. 5 November 2008. p. 5. Archived from
the original
(PDF)
on 17 March 2011
. Retrieved
23 November
2010
.
- ^
"Hampden Bridge, Wagga Wagga, NSW"
. Timber Building in Australia. Archived from
the original
on 2013-05-12
. Retrieved
2008-06-05
.
- ^
Google-maps "-34.180255,150.610654" clearly shows bridge with traffic
- ^
U.S. patent 2,064
- ^
Gardner, Denis P. (2008).
Wood, Concrete, Stone, Steel: Minnesota's Historic Bridges
. Minneapolis: University of Minnesota Press. p. 51.
ISBN
978-0-8166-4666-1
.
- ^
a
b
Matsuo Bridge Company,
Bridge Types ? Truss
Archived
2006-09-05 at the
Wayback Machine
, accessed September 2007
- ^
Panoramio
- Reviewed 2020-03-23
- ^
Historic Context for Louisiana Bridges
Archived
2020-12-24 at the
Wayback Machine
- Retrieved 2020-03-23 (section 3, pp 71)
- ^
"Aiken Street Bridge: Ouellette Bridge"
.
HistoricBridges.org
. 2018.
Archived
from the original on 9 July 2018
. Retrieved
9 July
2018
.
- ^
a
b
c
d
Boothby, Thomas (2020).
"Designing American Lenticular Truss Bridges 1878?1900"
. History Cooperative.
Archived
from the original on 5 November 2020
. Retrieved
5 March
2020
.
- ^
"Arizona Cardinals Stadium"
. Archived from
the original
on 2007-11-03
. Retrieved
2008-04-28
.
- ^
"CoveredBridgeSite, Long truss"
.
Archived
from the original on 2018-05-02
. Retrieved
2008-10-20
.
- ^
Eldean Covered Bridge ? Troy, Ohio ? Covered Bridges on
Archived
2012-10-18 at the
Wayback Machine
. Waymarking.com. Retrieved on 2013-07-23.
- ^
"Busching Bridge"
. CLR Inc. Construction and Transportation. Archived from
the original
on August 20, 2011
. Retrieved
June 25,
2012
.
- ^
Kennedy, Willella Shearer. "Heritage: Being Little Stories of Union County".
Union County Historical Society
, Printed by The Marysville Journal Tribune. 1963. Pg. 48.
- ^
US 314262
, Pegram, George H., "Truss for Roofs and Bridges", published 10-24-1881, issued 03-24-1885
- ^
National Register of Historic Places Registration Form
Archived
2013-01-15 at the
Wayback Machine
for
Healdsburg Memorial Bridge
, California State Park System, accessed 2011-12-26.
- ^
Jackson, Donald C. (1995).
Great American Bridges and Dams
. New York: John Wiley & Sons. p.
92
.
ISBN
978-0-471-14385-7
.
- ^
Thomas and Caleb Pratt,
US patent 3523
in European Patent Office database
- ^
a
b
c
Maryland Historical Trust Property Number PG-74B-1 & AA-85I
(PDF)
, Maryland Inventory of Historic Bridges,
archived
(PDF)
from the original on 26 December 2013
, retrieved
5 January
2013
- ^
Covered Bridge's Truss Types
Archived
2006-09-04 at the
Wayback Machine
- ^
"R.W. Smith Truss Patent 66,900"
.
United States Patent Office
. United States of America. July 16, 1867.
Archived
from the original on 11 November 2018
. Retrieved
10 November
2018
.
- ^
Lorrie K. Owen, ed. (1999).
Ohio Historic Places Dictionary, Volume 2
. Somerset Publishers, Inc. p. 794.
ISBN
9781878592705
.
Archived
from the original on 2020-06-14
. Retrieved
2020-01-05
.
- ^
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.
Library of Congress
.
Archived
from the original on 2020-12-13
. Retrieved
2021-02-04
.
- ^
Steinman, D. B. (1932).
The Wichert Truss
. New York: D. Van Nostrand Company, Inc
. Retrieved
August 29,
2022
.
- ^
"The Wichert Truss".
Historic Highway Bridges in Maryland: 1631-1960, Historic Context Report
(PDF)
. Maryland Department of Transportation State Highway Administration. 1995
. Retrieved
August 27,
2022
.
- ^
"E. M. Wichert Services Set For Tomorrow"
.
Pittsburgh Post-Gazette
. March 23, 1955
. Retrieved
August 29,
2022
– via Newspapers.com.
- ^
Wilson, Helen; Wilson, Todd (November 2017).
"From Browns to Grays: Evolution of the Homestead Grays Bridge"
(PDF)
.
Historic Bridge Bulletin
.
4
(3): 5?9
. Retrieved
August 27,
2022
.
External links
[
edit
]
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Structural types
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Lists of bridges by type
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Lists of bridges by size
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Additional lists
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Related
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