Direct Answer
A transfer beam carries the reactions of columns or walls above it, delivering very large concentrated loads to fewer columns below. This creates heavy shear, large moment, and significant deflection under load. Fabrication differences: section sizes are larger (often a deep plate girder rather than a rolled W-shape), camber requirements are precise and large, and connection plates at load points are heavily loaded and require special inspection.
Full Explanation
Transfer girder characteristics: (1) Section — often a fabricated plate girder (W40 to W54+ or custom built-up) because the required depth and flange width may not be available in rolled form. (2) Camber — transfer girders can have 2–4" of camber for large spans with heavy column loads; verify camber with the structural engineer and confirm your cambering capability. (3) Bearing stiffeners — required at every concentrated load point (column reaction, wall reaction) to prevent web crippling. These are heavily welded and often require UT inspection. (4) Web shear — web is often thick (3/4" to 1.5") and may be stiffened at close intervals. (5) Connection interfaces — columns above bear on large cap plates welded to the transfer girder top flange; exact elevation and flatness of cap plates is critical.
What This Means for Your Shop
Transfer girders are typically the most critical structural elements in a building — if the transfer girder fails, the structure above it fails. Your QC should treat them accordingly: 100% dimensional inspection, NDT on all key welds, and dedicated piece mark tracking through fabrication.
Common Mistakes
Cambering a transfer girder based on preliminary BOM data and then discovering the final design changed the loading. Always verify the final camber requirement from the IFC structural drawing before applying camber.
Recommended Process
Flag all transfer girders at project kickoff. Give them dedicated piece mark tracking and hold points. Verify camber requirement from IFC drawings. Schedule NDT for bearing stiffener welds before primer application.