What is a Truss?
- In Architecture and Structural Engineering, a truss is a structure comprising one or more triangular units constructed with straight slender members whose ends are connected at joints referred to as nodes.
- External forces and reactions to those forces are considered to act only at the nodes and result in forces in the members which are either tensile or compressive forces.
- Moments (torsional forces) are explicitly excluded because, and only because, all the joints in a truss are treated as revolutes.
In this article, we are going to discuss the various types of roof trusses in wood and steel and their uses in various kinds of construction.
Different types of Wooden and Steel Roof Trusses:
- King Post Truss
- Queen Post Truss
- Howe Truss
- Pratt Truss
- Fan Truss
- North Light Roof Truss
- Quadrangular Roof Truss
Trusses for large span constructions
King Post Truss
- King Post Truss is a wooden truss.
- It can also be built of combination of wood and steel.
- It can be used for spans upto 8m.
Queen Post Truss
- Queen Post Truss is also a wooden truss.
- It can be used for spans upto 10m.
Howe Truss
- It is made of combination of wood and steel.
- The vertical members or tension members are made of steel.
- It can be used for spans from 6-30m.
Pratt Truss
- Pratt Truss is made of steel.
- These are less economical than the Fink Trusses.
- Vertical members are tension and diagonal members are compression.
- Fink Trusses are very economical form of roof trusses.
- It can be used for spans from 6-10m.
Fan Truss
- It is made of steel.
- Fan trusses are form of Fink roof truss.
- In Fan Trusses, top chords are divided into small lengths in order to provide supports for purlins which would not come at joints in Fink trusses.
- It can be used for spans from 10-15m.
North Light Roof Truss
- When the floor span exceeds 15m, it is generally more economical to change from a simple truss arrangement to one employing wide span lattice girders which support trusses at right angles.
- In order to light up the space satisfactorily, roof lighting has to replace or supplement, side lighting provision must also be made for ventilation form the roof.
- One of the oldest and economical methods of covering large areas is the North Light and Lattice girder.
- This roof consists of a series of trusses fixed to girders. The short vertical side of the truss is glazed so that when the roof is used in the Northern Hemisphere, the glazed portion faces North for the best light.
- It can be used for spans from 20-30m.
- Used for industrial buildings, drawing rooms etc.
Quadrangular roof Trusses
- These trusses are used for large spans such as railway sheds and Auditoriums.
Large Span Trusses
does anyone knows the figure of combined howe and pratt truss? A roof truss..
Warren Truss is similar to the combination of Howe and Pratt Truss. Maybe that is what you are looking for.
Hai Benzu, Gud day
Could u help me 4 my project? i need to design a roof truss for a span of 25m*13m, plz lemme knw which type f truss is 2 b used and design considerations if any
Thank you 🙂
the queen truss shown above are not according to the concept used in books but seems like scissors truss,why?……if it’s right, please rectify it.
Hello Nawin,
This is a typical queen’s truss. This is not a scissor’s truss and does not resemble a scissor’s truss in anyway. Scissor’s truss resembles an inverted V-shaped arch.
Hi….
Plz advice me whether 10m-12m cantilever span is possible in steel structures? On support of 2 or 3 columns
And plz also give ur expert opinion on shoe foundation. wat is this? and where we can use it?
hello, i want the design of roof truss for small indoor stadium with 2 badminton court having the span of 20.5meter, it is around 8meter above the ground level.
so can you tell which type of truss is to be and design procedure
tell me including the asthetic look which would be better eigther flat or curvedor any other type of truss
Hello:
We are in need of Warren type of steel truss. Can you design one. Please let me know your charges.
Thank you.
Ravi
Useful write up.
Want to know the truss type for clear span of 110 Feet with the spacing interval of 20 feet. kindly suggest the details to proceed.
Hi Benzu ,i doing project on design of Indutrial trusses by post tentioning method for 12 m span which type of truss suitable for 12m span?
You should research on Tubular roof trusses as well as North light roof trusses.
Hi BenzuJK,
do you have minimum distances between the individual members of Quadrangular roof Truss? or better the whole specs for this? thanks.
Engr. del Rosario
Can a dual angle truss spanning 36 ft and a support wall at 18 ft (mid point) with a ong side of 3.5-4 pitch. The long side is 27 feet and 9 feet on the short side. Can this truss be built with 2 x 4s?
Hi this is zahir I need to know the design of cascalted steel structure .in these structures m.s plates of diffrent depths.n thk are
used .how can I design those please help
it is good for the basic and the advance concept. But please tell the in which condition the fink truss is used instead of hoew truss? because the span criteria of both truss 6-30m.
And my second question is that please tell me that in north light truss what is the wind load criteria is mentain?
sir,
can u help me find what type of steel truss design we use in 20×15 meter car terminal.
thank you
Can u provide me a truss design for 15m span. For a ms sheet roof hall 15mx18m size
Hello Amit,
Here’s the link to our architecture and engineering design services. You might want to consider contacting through it.
http://www.designservices.civilprojectsonline.com
Cheers 🙂
i want to design a ware house of height 32 feet. the column height will be 24 feet and truss rise will be 8 feet. i am using pratt type truss.span of truss is 20 metre. I want to tube section please suggest me the nominal bore for the tube section.
I am building a W braced post and beam pavilion with the north wall 20′ high and the south wall 10′ high with a span of 15′. It will hold about 1,000 pounds of solar panels.
I would like to make a quadrangle roof. Any suggestions of what dimensions of lumber to use for the 15′ span and how deep the truss needs to be?
Thanks
design of MS Angular truss on roof of house
what type of steel truss s ideal for an auditorium span is 28m and spacing is 4.5 m
the truss is in kerala INDIA
I don’t have professional experience in steel structures. I mainly do RCC structural design.