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Types Of Truss Bridges

Updated on October 22, 2011

Truss bridges are probably one of the oldest and the most common types of bridges in the world. Basically a truss bridge is composed of truss which is straight lined structure made up of small triangular units.

The elements used in the making of the truss bridge are connected through compression stress, tension or sometimes all of these factors.

On the basis of designs and the elements used for the making of the bridge, the truss bridges are classified into following types:

Allan Truss Bridge

The Allan truss bridge is named after Percy Allan, a famous Australian architect and engineer who designed the bridge.

Allan Truss Bridge
Allan Truss Bridge

His design consists of vertical and diagonal arrangements of trusses which are were originally composed of steel.

Today many of the bridges based on Percy Allan’s design are composed of iron bark or even timber to reduce the cost.

The Hampden Bridge in New South Wales Australia was the first bridge to be built on Percy Allan’s design.

Howe Truss Design
Howe Truss Design

Howe Truss Bridge

Howe truss bridge is a basic design of truss bridges based on which many engineers gave modified designs for many other famous truss bridges of the world.

It has a simple design which consists of diagonal and vertical trusses. The diagonal trusses move upwards and slope towards the centre of the bridge. The vertical members of the truss are in tension while the members of the diagonal truss are in compression.

This bridge was first designed by William Howe in 1840. Jay Bridge in New York and Sandy creek covered bridge in Jefferson County, Missouri are to bridges based on Howe’s design.

A Pratt Truss Bridge
A Pratt Truss Bridge

Pratt Truss Bridge

The design of the Pratt truss is bridge is the opposite of the Howe Truss Bridge. Although they too like the Howe truss have vertical and diagonal members, the major difference between the two is that in the Pratt Truss Bridge the Diagonal slope down towards the centre.

This bridge was invented by Thomas and Caleb Pratt in1844. Originally this bridge was built with iron but not wood is also used in its making. This bridge can be extended up to 250 feet therefore it is commonly used as a railway bridge.

A Bailey Bridge
A Bailey Bridge

Bailey Bridge

The Bailey bridge is basically built for the military purposes.

It built at the extension of 60m and can bear the weight of heavy loaded ranks.

The design of these bridges is simple and may only consist of trusses stacked vertically.

The construction of the bridge does not require heavy machinery or tools for its construction.

A modern Bowstring Arch Truss
A modern Bowstring Arch Truss

K Truss Bridge

The K truss bridges have a complex and a complicated design and are believed to the hardest bridges to build.

As the name suggests the shape of the bridge is in the form of the letter K. The members are oriented in a way that the vertical and the oblique members are shaped in letter K in each panel.

Bowstring Arch Truss

The bowstring Arch truss or the Tied Arch Bridge was designed in 1840 by Squire Whipple. The bridge is composed of Thrust Arches which transform their vertical load along the arc of the arch.

At the ends of the arc, the thrust arches are resolved into two components a vertical and a horizontal thrust.

The vertical thrust is usually equal to the weight and load of the bridge section while the horizontal typically is taken down to the ground. If the arch is bowstring the horizontal thrust is taken to the opposite side of the arch by a chord.

The load which is faced vertically by the thrust arches are usually transferred along the path of the arc.

King Post Truss Design
King Post Truss Design
Lattice Truss Bridges
Lattice Truss Bridges

King Post Truss

The king post truss which is also known as the ‘crown post’ truss bridge is probably the simplest type of truss bridges.

It simply consists of a single vertical support on which two angled trusses lean to.

It is also the oldest or most probably the first kind of truss bridges ever made. They were common during the medieval times.

Lattice Truss Bridges

Lattice truss bridges are another type of simple truss bridges which are comparatively easier to construct than the other types of bridges.

They are usually built of iron, steel or wood and are common in small towns and cities.

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    • john000 profile image

      John R Wilsdon 6 years ago from Superior, Arizona

      I enjoyed reading about the different truss bridges. When I taught junior high technology, I had a unit on bridge building and all students were required to build a truss model. This brought back good memories. Good hub.

    • hassam profile image
      Author

      hassam 6 years ago from Pakistan

      Thanks! :)

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      Student 6 years ago

      very helpful. Doing science fair project on this and need different types of trusses

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      John 6 years ago

      do you know what type of truss bridge is the strongest? I need to know for a straw bridge design project. Thanks :D

    • profile image

      Shayne Liddell 5 years ago

      Omg!! thank you!!! I have to find 8 different type of bridges for my homework and you just made my homework so much easier!

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      Abraham Ahumada 5 years ago

      that kid has the same teacher i do but in a different class, and you also made it alote easier for me thanks

    • profile image

      mobi 5 years ago

      Good information

    • profile image

      rere 5 years ago

      THIS HELPED ME A lot WITH MY TRUSS BRIDGE PROJECT

    • profile image

      karim 5 years ago

      Thanks, great help!

    • profile image

      Henita 5 years ago

      So cool

    • profile image

      Elham 5 years ago

      Awesome!

    • profile image

      Jennifer 5 years ago

      Nice!

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      Julia 5 years ago

      Very helpful! now i don't have to ask my teacher & he wont look at me like i'm a freak because i didn't try.

    • profile image

      Cesar 5 years ago

      Hi Hassam! i like to follow you. & you're Pakistanian mustache.

    • profile image

      Kevin 5 years ago

      You're cute!

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      hi 5 years ago

      thankyou hub pages

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      Blackwatch 38 5 years ago

      What's the strongest kind of truss bridges for popsicle stick bridges

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      Joe kinglet (fake name(-;) 5 years ago

      This helped

    • melingoed profile image

      melingoed 5 years ago from Newcastle Emlyn

      Interesting read. I remember bridge making competitions at school using plastic straws and pins

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