Steel Trusses: Definition, Types & Applications

Steel truss definition

Steel fabrication is an industry capable of producing a wealth of different structural elements and details, with the ability to connect several different objects together to create a structural object. One of the most popular (and easiest) objects like this is called a truss – a number of interconnected structural elements that form a triangulated system of sorts.

The single biggest use case for trusses is to create a roof support system by using a multitude of interconnected trusses. Other potential use cases for trusses are all about internal load support – such as suspended ceilings and other services. Trusses are rather popular in the construction field, since they are both relatively light and also capable of supporting massive weight loads.

The most obvious example of how useful trusses can be is the creation of various buildings with extensive roof spans – hangars, airport terminals, auditoriums, stadium roofs, and so on. Trusses can both carry extremely heavy loads and make the structure itself more stable, which makes them an obvious choice for the majority of similar construction projects.

Steel truss types

While the basic truss is an extremely simple construction element, it can also consist of far more than just three elements in the form of a triangle – and that construction element would still be called a truss. There are plenty of different truss types out there, and they can differ in shape, purpose and even specific use case. Here are some of the more popular examples of truss types:

• Warren truss – one of the few truss types that is called in the same way it is shaped, as the letter “W”. It is a specific truss type that has a lot of diagonal members that are alternatively in compression and in tension, with the ability to add more members to provide more stability to the truss itself. Used for extremely large buildings from 20 to 100 meters wide.
• Pratt truss – another truss type that represents a letter in the alphabet (this one is also often called the “N truss” due to its shape. It can be used for the same building types as the Warren truss – large structures with dozens of meters between opposite walls – but the location of members inside of a truss is different (resembles a never-ending letter N, or the mirrored version of that letter).
• Fink truss – a truss type that is mostly used for regular houses and not massive structures, a Fink truss requires relatively little steel to produce and creates a short-span high-pitched roof with a number of shorter elements along with a few of the longer ones that act as the baseline. There are many different variations of a Fink truss depending on the shorter element placements.
• North light truss – a truss type that can be often noticed with industrial buildings, when one side of the truss is far longer than the other one, and only the shorter (and steeper) part of the truss has any form of glazing in it. This allows for a severe reduction in solar gain, offering more natural light in the daylight time (however, the exact potential gains and losses should always be calculated for each building individually). North light trusses allow for the reduction of carbon emission, but may increase the demand for space heating in certain circumstances.
• Sawtooth truss – a variation of North light truss that is used in multi-bay buildings, offering more frequent repetition of the same truss shape. The purpose of this truss is similar to its original form – to reduce the solar gain and provide more natural light.

Of course, this list is not complete – there are far more truss types that are somewhat less popular, such as the Bowstring truss, the Lenticular truss, the Vierendeel truss, and so on.

Benefits and shortcomings of steel trusses

Like with almost any other steel structural element in this industry, steel trusses have all the benefits of steel as a material – recyclability, prefabrication, a great strength-to-weight ratio, resistance to insect plagues and mold, extremely long life span and allows for the creation of structures structures for nearly all of the possible use cases, from residential to industrial.

They also have the shortcomings of that same material – relatively low resistance to corrosion, inability to retain heat for a long time (which is extremely important for residential structures in colder times of the year), and so on.

That being said, this kind of classification with different types is not the only one that exists for steel trusses. There is a second classification that is far easier and mostly focuses on the shape of the truss as a singular structural element. There are only three types of trusses in this classification – simple, planar and space frame.

A simple truss is the most basic combination of elements in the form of a triangle, with no extensions or additional elements. A planar truss describes most of the types above – multiple different steel elements connected to each other with a specific pattern in mind (letter “N”, letter “W”, etc.), every truss type like that is also considered a planar truss. A space frame truss is the most complicated one out of the three, since this truss implies the placement of truss elements in three dimensions, and not within the same planar surface (hence the “planar” truss in the previous type).

Truss elements can also be shaped in several different ways depending on a number of factors – how easy it is to connect different elements to each other, how high is the overall weight of a structure this truss is supporting and, of course, how aesthetically pleasing it is. Possible cross section variations include:

• Tee sections;
• Back-to-back channels;
• Rolled sections;
• Hollow square sections, and more.

Conclusion

Steel trusses are both massively useful and have a lot of different variations of themselves depending on a number of factors. We went over the definition of a steel truss, as well as multiple truss types and use cases, offering a lot of information about how trusses are classified, what are their benefits and shortcomings. With this many different truss types, it is easy to find one truss type that would be able to complement your project in the best way possible.