Direct Answer
WUF-W is a prequalified seismic moment connection per AISC 358 Chapter 8 where the beam flanges are connected to the column with CJP groove welds and the beam web is welded to a shear plate (bolted to the column) using fillet welds. Unlike older pre-Northridge connections, WUF-W uses a welded web (not bolted) to improve connection ductility and eliminate bolt-hole stress concentrations under seismic loading.
Full Explanation
The Northridge earthquake (1994) revealed that many pre-Northridge bolted-flange-welded-web (BFWW) connections fractured in a brittle manner. Post-Northridge research produced prequalified connections including WUF-W, RBS, and extended end plate that provide improved ductility. WUF-W requires: CJP flange welds with backing bar removal and root-pass NDT, welded shear plate with continuous fillet welds to the column, specific weld access hole geometry per AISC 358, and D1.8-compliant welding procedures. It is used in SMF and IMF systems.
What This Means for Your Shop
WUF-W connections require the full seismic welding infrastructure: D1.8 WPS, Demand Critical weld qualification, backing bar removal, UT inspection of CJP welds, and careful weld access hole preparation per AISC 358. Bid these connections at a significant premium over standard moment connections.
Common Mistakes
Using the same WPS for WUF-W CJP welds as for standard CJP welds. D1.8 has additional requirements for heat input control, electrode type (low hydrogen), and interpass temperature that don't apply to standard D1.1 work.
Recommended Process
Before welding any WUF-W connection, confirm: weld access hole geometry matches AISC 358 (radius, tangency requirement), backing bars are tack-welded correctly, weld sequence (web plate first, then flanges), and UT inspection is scheduled for after flange welding.