Built-Up Tapered Steel Members for PEB Frames

Built-up tapered members are the columns and rafters at the heart of most pre-engineered frames. Instead of using a rolled section of constant depth, the member is welded from separate flange and web plates, and the web depth changes along its length to follow the forces it carries. Deep sections are used at the knee and other high-moment zones, and shallower sections where the moment is lower.

This approach places material where it does the most work. Flange width and thickness, web depth and web thickness are each chosen by the project engineer, so a frame can be lighter than one made from uniform rolled sections while still meeting the strength and serviceability requirements of the governing code.

World Steel fabricates built-up members from structural plate using automated cutting and welding processes. Web-to-flange welds are typically continuous fillet welds made by submerged arc or similar processes, and end plates, stiffeners and connection plates are added to the shop drawings. Welding procedures, welder qualification and inspection follow the welding code named in the project specification.

Members are marked, primed or coated as specified and shipped ready for bolting. Because each member is made for its position in the building, the erection drawings identify every piece and its location.

Tapered members are used for rigid frame columns and rafters, crane columns, canopy beams, mezzanine beams and special structures where an economical deep section is needed. The same fabrication process also produces prismatic built-up sections when constant depth suits the design better.

For supply-only orders, the buyer should provide the design drawings or member schedule, the material standard and grade, the welding code, inspection requirements and the finish. World Steel then prepares shop drawings for approval before fabrication begins.