Direct Answer
A transfer beam (or transfer girder) is a structural member that supports columns or bearing walls from floors above and transfers those loads laterally to a smaller number of support points below — allowing column-free spaces at lower floors. Transfer beams are among the most heavily-loaded members in a building and are typically very deep, very heavy, and fabricated as complex built-up plate girder sections.
Full Explanation
Transfer beams carry the loads from multiple columns above to the supports below, so they can carry thousands of kips of axial plus bending load. They are often fabricated as plate girders (a web plate welded between two flange plates) rather than rolled wide-flange sections, because the required depth and flange size may exceed what is available in rolled sections. Plate girder fabrication is highly labor-intensive: the web-to-flange weld is typically a CJP or large fillet weld running the full length, stiffeners are required at load points and web panel mid-points, and the member may exceed 100 feet in length (requiring field splices).
What This Means for Your Shop
Transfer beam fabrication is specialty work. If your shop has never fabricated a built-up plate girder of this size, engage with a structural steel consultant to review the welding procedure, preheat requirements (for thick plate), distortion control, and handling requirements before committing to the scope.
Common Mistakes
Underestimating the labor in a transfer beam because its tonnage is low relative to the complexity. A 10-ton transfer beam can require more shop hours than 100 tons of standard structural beams.
Recommended Process
Before pricing a transfer beam scope, obtain the plate thicknesses, total length, stiffener count, and connection details. Walk through the welding sequence and preheat requirements with your lead welder. Estimate shop hours bottom-up before applying a $/ton rate.