Structural Engineering · Engineering Glossary
A truss is a structural assembly of individual members arranged in a triangulated pattern that together act to span distances greater than a single beam of similar depth could economically achieve. Trusses carry loads primarily through axial tension and compression forces in their members.
Wood roof trusses are manufactured off-site and are the dominant roof framing system for residential and light commercial construction. Steel bar joists are open-web trusses common in industrial, retail, and commercial buildings. The efficiency of trusses comes from triangulation — each panel is a triangle, which is a rigid geometric shape. The top chord carries compression, the bottom chord carries tension, and the webs carry shear as a combination of tension and compression. The engineer must verify that panel point loads align with the truss joints, since out-of-panel loads create bending in the top chord that standard truss designs do not account for. Installing heavy HVAC equipment on a roof framed with light wood trusses requires engineering review.
Apex Grid Engineering maintains this glossary as a resource for architects, contractors, developers, and property owners who encounter unfamiliar engineering terminology on their projects.
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