Moment frames in seismic zones live or die by their beam-column connections. When those connections are prequalified under AISC 358, the paperwork chain — WPS, PQR, CMTR, filler cert — has to be tighter than a standard structural job. CWIs who treat an AISC 358 job like a plain D1.1 job regularly get surprised at the first special inspection walk-through.

What AISC 358 Is and Is Not

AISC 358, Prequalified Connections for Special and Intermediate Steel Moment Frames for Seismic Applications, is a companion document to AISC 341 (Seismic Provisions for Structural Steel Buildings). It gives designers and contractors a menu of connection types — Reduced Beam Section (RBS), Welded Unreinforced Flange–Welded Web (WUF-W), Bolted Flange Plate (BFP), Double-Tee (2T), and others — that are considered prequalified for seismic moment frames without requiring a full connection test under AISC 341 Appendix S.

"Prequalified connection" is not the same as "prequalified WPS." The connection geometry is prequalified; the welding procedure still requires full AWS D1.1 compliance and, in most cases, the additional filler metal toughness documentation required by AISC 341.

The Three-Document Stack

For any demand-critical weld in an AISC 358 connection, three documents govern simultaneously:

AWS D1.1:2025 sets the WPS format, essential variable rules (Table 6.6), welder qualification, and acceptance criteria.

AISC 341 (current edition) adds:

  • Filler metal CVN toughness requirement: minimum 20 ft-lb at −20°F, documented on the CMTR or manufacturer's certification.
  • Weld access hole geometry: AWS D1.1 standard holes are permitted only when the EOR approves the standard configuration; many seismic connections specify the "improved" access hole profile from AISC 358 Section 6.10.

AISC 358 further constrains:

  • Connection-specific permitted processes (some connections restrict the filler metal classification list).
  • Required inspections at each connection type — RBS connections, for example, require the flange groove welds to be UT-examined per AWS D1.1 Clause 9.

Failing to reference all three documents when writing the WPS often produces a technically valid D1.1 WPS that still fails the project submittal review.

RBS Connection WPS Constraints

The Reduced Beam Section (RBS) is the most common AISC 358 connection in new construction. The critical welds are:

  • Beam flange to column flange CJP groove welds — demand-critical, full UT required.
  • Beam web to column shear plate weld — connected, but typically not demand-critical.

For the CJP flange welds, the WPS must document:

  1. Filler metal classification and CVN data — the CMTR for each heat/lot must show CVN values at −20°F. Do not rely on the electrode classification alone; the classification does not guarantee CVN at that temperature unless the electrode designation includes it (e.g., E71T-1C-H8 with certified CVN supplement). Keep the CMTRs in the job file alongside the WPS.
  2. Preheat per Table 6.6 — for A992 or A572-50 columns, preheat is typically 150–225°F depending on thickness and carbon equivalent. AISC 358 does not override Table 6.6 preheat; it defers to D1.1.
  3. Backing bar plan — steel backing is commonly left in place on bottom-flange groove welds. If steel backing is used, the WPS must note that, and the EOR should confirm this per AISC 358 Section 5.5 (some editions require removal for certain configuration types).
  4. Weld access hole geometry — document the access hole profile (standard vs. improved) directly on the WPS or in an attached joint sketch.
  5. Pass sequence and interpass temperature — for thick column flanges (>1.5 in.), interpass temperature maximum under AISC 358 and D1.1 is typically 550°F. Document this limit on the WPS.

Rule library based on AWS D1.1:2025; verify against your governing edition.

WUF-W Connection Requirements

The Welded Unreinforced Flange–Welded Web (WUF-W) differs from RBS in that the beam flanges are full-section at the column face, and the web is welded (not just bolted). This geometry:

  • Produces higher moment at the face of the column than an RBS.
  • Requires both flange CJP welds AND the web-to-column plate fillet welds to be considered demand-critical under many project specifications, though AISC 358 designates only the flange welds as such.
  • Puts greater constraint on the backing bar removal requirement — confirm the project spec and the EOR's position in writing before fabrication.

WUF-W WPS development should explicitly identify which welds are demand-critical and which are ordinary structural, because the filler metal toughness documentation and special inspection requirements differ between the two categories.

CVN Filler Metal Documentation in Practice

The biggest source of submittal rejections on seismic moment frame work is missing or inadequate filler metal CVN documentation. Here is what to have in hand before the first arc is struck:

  1. Mill Certificate (CMTR) for the filler metal lot — not just the classification test report from the electrode manufacturer's catalog. The CMTR is heat/lot-specific and shows the actual tested CVN values for that production run.
  2. Cross-reference to Table 6.6 — confirm the filler classification is on the permitted list for the process and base metal group (Table 6.6 row 4 in AWS D1.1:2025 dropped A5.36 designators without –D or –G suffixes for GMAW/FCAW — verify the electrode you spec'd is still on the list).
  3. Storage documentation — low-hydrogen electrodes used on demand-critical welds should be baked and stored per the manufacturer's instructions, and the oven logs retained. Moisture in the flux is the direct cause of diffusible hydrogen cracking in high-restraint beam-column connections.

Submittal Package for AISC 358 Jobs

A complete WPS submittal for an AISC 358 moment frame job typically includes:

  • WPS (AWS Annex M format or equivalent), one per process/position combination
  • Applicable PQRs — or prequalified WPS documentation per D1.1 Clause 5 if process and joint fall within prequalified limits
  • Filler metal CMTR showing CVN at −20°F for each demand-critical filler metal lot
  • Welder qualification records (WPQs) for all positions used
  • Weld access hole geometry sketch (AISC 358 Section 6.10 profile or standard, as specified by EOR)
  • Weld inspection plan identifying demand-critical welds and associated UT examination scope

The special inspector assigned to the project will verify this package before work begins. Gaps in the filler metal documentation are the most common cause of stop-work notices on seismic moment frame structural packages.

Connecting WPS Management to Production

Large seismic frame jobs involve dozens of beam-column connections, often with multiple column and beam sizes that cross WPS qualification boundaries. A WPS library that maps each connection type — flange thickness, process, position — to a specific approved WPS prevents the field from improvising. For shops managing multiple concurrent seismic projects, software that links each weld joint to its governing WPS and the corresponding welder qualifications reduces the risk of a welder running a connection with a WPS they are not qualified on.

See WPS vs PQR vs WPQ explained for the foundational document relationships, CVN supplementary essential variables for AWS D1.1:2025 Table 6.8 CVN triggers, demand-critical weld filler metal selection for electrode choices, and AISC 341 WPS requirements for the broader seismic framework. When your WPS library needs to track these across projects, /pricing covers what the platform manages for you.