TRUSSES
(Railway Bridges)
TRUS
S
◇ A truss is a structure composed of members
connected together to form a rigid framework.
Members are the load-carrying components of a
structure. In most trusses, members are arranged in
interconnected triangles.
◇ Today trusses are often used in the roofs of buildings
and stadiums, in towers, construction cranes, and
many similar structures and machines.
◇ truss members carry load primarily in tension and
compression. Because trusses are very strong for
their weight.
◇ In general, trusses are used to:
◇ Achieve long spans.
◇ Minimize the weight of a structure.
◇ Reduced deflection.
◇ Support heavy loads.
REASONS OF ADOPTING
TRUSS DESIGN IN RAILWAY
BRIDGES
◇ In this triangular unit design minimal materials
are required to built the structure in an efficient
manner.
◇ This structure can withstand tension,
compression and heavy dynamic loads.
◇ Truss design bridges can be built across long
spans without much compromise on their
strength.
◇ It can be installed quickly.
HISTORY OF TRUSS
BRIDGE
◇ In 1820, Ithiel Town’s lattice truss design
became the first patented truss bridge design.
It required little metal to build, which made it
easy to construct.
◇ Before the truss bridge was designed, the
main types of bridges were arch and beam
bridges.
◇ Most of the construction of beam was wood
before we go into metal like steel.
◇ Meanwhile arch bridges were mainly of built
out of stone and brick.
◇ The earliest form of truss bridges were built
out of metal although many claim wood.
CONSTRUCTION
Truss is a formation produced by triangular components, in accordance
with the truss bridge drawing and coupled at joints known as nodes. The
triangular unit forming the truss are slim and straight in form. The truss
bridges consist of a grouping of triangles that are manufactured from
straight and steel bars, according to the truss bridge designs. The solid
arms of the triangles extended from the pier sides. The diagonal steel tube
projects from the bottom and top of each pier, and assist in holding the
arms in the correct position. Trusses are organized as a straight elements
that are connects at the ends by hinges to develop a secure arrangement.
MATERIALS USED IN THE
CONSTRUCTION OF TRUSS
◇ Steel
◇ Reinforced Concrete
◇ Pre – stresses concrete
◇ Stone and asphalt
◇ Iron
◇ Timber
◇ Aluminum
TRUSS BRIDGE
CONNECTIONS
The pieces of the framework of a truss bridge are held together by
connections. Most connections on historic bridges are either riveted
or pinned.
PINNED CONNECTIONS - Pinned connections RIVETED CONNECTIONS – Riveted connections
can be identified by the bolt-like object called a are identified by a “gusset plate” which diagonal
pin going through the loops of the members. and vertical members are riveted to, and no pin is
They tend to show up on bridges from the first present. These connections tend to shop up in the
half of the truss bridge era . second half of the truss bridge era.
PARTS OF TRUSS
ISOMETRIC VIEW OF
TRUSS
ELEVATION OF TRUSS
TYPES OF TRUSSES
Pratt Truss
Baltimore Truss
Bollman truss
Deck Truss
Half – through Truss
Bowstring Arch Truss
Whipple Truss
PRATT TRUSS
The Pratt truss bridge is bridge whose super structure is made of
truss this type of truss bridge is built with vertical and diagonal
members that go down towards the center.
The two men responsible for this type of truss bridge is Caleb
Pratt and his son Thomas Pratt. The bridge was designed in 1844
in Maryland, at first it was of wood and iron diagonal roads but
they changed it entirely to iron.
The Pratt truss bridge presented a cheaper and stronger version
of a truss bridge entirely using iron.
GATTON RAILWAY BRIDGE
BALTIMORE TRUSS
The Baltimore truss is a modified version of the Pratt truss.
The difference between the Pratt truss bridge and the
Baltimore truss bridge is the extra diagonal beams located
on the lower half of the truss to help support against
buckling from compression and to help control deflection.
WELLLAND CANAL BRIDGE, ONTARIO, CANADA
BOLLMAN TRUSS
Bollman truss, is a very distinctive design that features diagonals that span
varying lengths from top to bottom chord. Most diagonals originate from the
end post. As such, one might imagine how the diagonals function in a manner
similar to a cable-stayed bridge. In the truss, all compression members on the
bridge (top chord, end post, and verticals) are made of cast iron. All tension
members (diagonals, bottom chord) are made of wrought iron. The
connection of the diagonals to the top of the end post is enclosed in a
protective wooden enclosure. Bollman's design was the first metal truss
bridge design to be used in any notable quantity by the railroads, and is thus
significant in the development of the metal truss bridge.
BOLLMAN TRUSS RAILROAD BRIDGE AT SAVAGE, MARYLAND
DECK TRUSS
A deck truss is a type of bridge on which the road deck lies
above the structural parts. Deck truss is also known as
“Upside down Bridge”. Bridges with a deck truss design
were first built in the middle 1800’s. They were used for
railroad crossings because the design was strong enough
to carry heavy iron, steam engine trains. It was rumored
that it limits the size of a boat. Safer for taller trains.
LAMONE VII BRIDGE, ITALY
TRUSS
A ‘half-through’ bridge configuration provides a solution for small
and medium span bridges where the depth available between the
trafficked surface (top of rails for a railway bridge) and the
clearance level beneath the bridge is too shallow to accommodate
the structural elements spanning across the bridge supports.
This means that a half-through bridge is in the form of a ‘trough’, i.e.
it has a square U-shaped form. Half – through truss bridge is also
called pony truss bridge.
SKEW RAILWAY BRIDGE
BOWSTRING ARCH
TRUSS
A bowstring truss is a structural device commonly used in
bridge-building and, less often, in industrial architecture.
Used to span wide, column-free spaces, it consists of an
arched beam (the bow) joined at each end by a straight
beam (the string), with diagonal support beams joining
the two. This bridge was patented in 1840 by S.
Whipple.
NEWARK DYLE RAIL BRIDGE
WHIPPLE TRUSS
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).
GOLDEN’S BRIDGE, NEW YORK
SOME OTHER TYPES OF
TRUSSES
ADVANTAGES AND
DISADVANTAGES OF TRUSS
BRIDGE
ADVANTAGES DISADVANTAGES
Economic to build Complicated design
Very strong Maintenance
Road placement Waste of materials
Built in difficult places Very Heavy
CONCLUSION
Truss bridges are a type of bridge design that uses
multiple triangles to support very heavy loads.
They are widely used and re most common with
road traffic bridges due to their heavy load
capabilities. Along with the triangular
formations, joints and other forms of
enforcement are used to further increase the
bridge’s strengths.
REFERENCES https://usbridge.com
https://www.britannica.com/technology/truss-bridge
https://www.slideshare.net/kaiumbhai/truss-bridge-final-presentation
https://www.slideshare.net/yvonnewowlife/truss-bridge-report
https://www.slideshare.net/rajdutt1111/project-report-on-truss-bridge
Made by (group 1) –
MEET BOGHARA
RIYA DARJI
SUHANI JOSHI
RIDDHI KARANGIYA
GARGI KOUL
THANKYOU
