Which trusses are the three most commonly used types?

The selection of parallel chord truss, pitched chord truss, and bowstring truss as the three most commonly used types reflects their widespread application in various construction scenarios due to their structural efficiency and versatility.

The parallel chord truss is particularly favored in floor framing systems as it provides excellent load distribution and can span large distances without the need for intermediate supports. This design helps optimize space within buildings, making it ideal for commercial and industrial applications.

The pitched chord truss is often utilized in roof systems and other applications where an inclined plane is needed to facilitate drainage or achieve aesthetic qualities. Its design supports the roof while allowing for a greater volume of space underneath, which can be advantageous in creating tall ceilings or open interior layouts.

The bowstring truss combines a curved upper chord and straight lower chord, creating a distinctive shape that is not only aesthetically pleasing but also efficiently handles loads. It is commonly used in large structures like gymnasiums and auditoriums, where the sweeping curve allows for expansive open spaces inside.

Thus, these three types of trusses are chosen for their ability to effectively manage various loading conditions while providing functional and aesthetic benefits in construction.