Are all welds in an eccentrically braced frame demand-critical?

No. Only welds in connections where fracture could compromise the lateral load path carry that designation. In an EBF, the link-to-column CJP groove welds are demand-critical. Welds connecting braces to gussets outside the link or floor beam attachments are typically not, though the engineer of record makes the final determination for each connection.

What CVN toughness is required for demand-critical filler metals in EBF link connections?

AWS D1.8 requires filler metals for demand-critical welds to meet a minimum Charpy V-notch toughness of 20 ft-lbf [27 J] at −20°F [−29°C], verified by the filler metal manufacturer's classification testing. The project specification may impose stricter CVN requirements. AISC 341-22 also requires that the filler metal's minimum specified tensile strength equal or exceed that of the base metal.

Can a prequalified AWS D1.1:2025 WPS be used for an EBF link-to-column weld?

Yes, if the WPS also satisfies AWS D1.8 requirements. Prequalified joint geometries and processes under AWS D1.1:2025 Clause 5 are still acceptable for demand-critical welds as long as the filler metal meets CVN requirements, the heat input stays within AWS D1.8 limits, and the WPS explicitly designates the weld as demand-critical. The WPS package must reference both D1.1 and D1.8.

What is the EBF protected zone, and how does it affect weld repair?

AISC 341-22 defines a protected zone within the link — the energy-dissipating segment of the EBF beam — where attachments, notches, and welded connections are restricted to avoid initiating fracture in the yielding region. Weld repairs inside the protected zone require explicit approval from the engineer of record and must follow AWS D1.8 requirements. Production tack welds and strongbacks inside the protected zone are generally not permitted without EOR approval.

EBF Link Beam Welds: AWS D1.8 and AISC 341-22 Requirements

EBF link-to-column CJP welds are demand-critical. Here's what AWS D1.8 and AISC 341-22 add to your D1.1 WPS — filler metal CVN, heat input, and protected zone rules.

Eccentrically braced frames (EBF) are one of the most efficient seismic lateral systems for mid-rise and high-rise steel structures. The EBF derives its ductility from a deliberately short segment of beam — the link — that yields in shear or bending before the columns, braces, or beam segments outside the link are stressed. That strategy puts enormous demand on the welds connecting the link to adjacent framing, particularly the link-to-column joint.

If you are fabricating or inspecting an EBF, your AWS D1.1:2025 WPS is necessary but not sufficient. AWS D1.8 and AISC 341-22 add requirements that govern filler metal toughness, heat input limits, inspection frequency, and a restricted zone inside the link where welding is controlled or prohibited. Shops that treat EBF welds as standard moment frame work miss these overlays — and auditors catching it mid-project can force weld removal and requalification.

How the EBF link works and why the welds matter

In an EBF, one or both ends of a beam connect to a brace at an eccentricity. The segment between the brace connections — or between the brace connection and the column — is the link. Under design-level seismic loading, the link yields first, absorbing and dissipating energy through inelastic deformation. The remainder of the frame — columns, braces, beam segments outside the link — is designed to remain elastic.

Short links (link length-to-depth ratio below a threshold defined in AISC 341-22) yield primarily in shear. Longer links develop flexural yielding. Both types demand that the link complete multiple cycles of plastic deformation without fracturing. The welds at the link boundaries — particularly the link-to-column CJP groove welds — must remain intact while the link deforms repeatedly at strains far beyond yield.

This is a different regime than static or wind-loading connections. A weld that passes standard AWS D1.1 acceptance criteria for monotonic tension may not survive the cyclic demand of a design-level earthquake. That is the engineering basis for the additional requirements in AWS D1.8 and AISC 341-22.

Demand-critical designation and what it triggers

AISC 341-22 defines demand-critical welds as those in connections where fracture of the weld would lead to significant degradation in the strength and stiffness of the seismic force-resisting system. For EBF, the link-to-column CJP groove weld meets this definition in most configurations. The engineer of record identifies demand-critical welds on the structural drawings; CWIs should confirm the designation is transferred to the WPS and traveler before production begins.

The demand-critical designation activates requirements from two documents that stack on top of AWS D1.1:2025:

AWS D1.8 imposes restrictions on filler metal toughness, heat input, preheat and interpass temperature, and NDE coverage. It does not replace D1.1 qualification — it supplements it. The WPS must reference both standards.

AISC 341-22 specifies base metal requirements (A992, A572 Gr. 50, or other approved grades), filler metal compatibility, and the protected zone restrictions described below.

For a thorough overview of how D1.8 overlays standard D1.1 WPS qualification, see AWS D1.8 Seismic Supplement: WPS for Demand-Critical Welds. For the broader AISC 341 welding framework across all seismic systems, see AISC 341 Seismic Provisions: WPS and PQR Requirements.

Filler metal selection for link-to-column CJP welds

Demand-critical filler metals must meet both classification-level and lot-level requirements:

Classification CVN: The filler metal's AWS classification must include a minimum CVN toughness designation that demonstrates 20 ft-lbf [27 J] at −20°F [−29°C] or colder. For E70-class electrodes, this means the electrode must be tested and classified with a temperature designator proving toughness at −20°F. Not all E71T-1 or E7018 electrodes within the same class carry that CVN designation — the specific electrode must.

Lot certification: AWS D1.8 requires that filler metals for demand-critical welds be certified by heat and lot number, with CVN test results provided for that specific lot. The filler metal used in production must match the lot on the certification. This means purchasing and receiving controls at the fab shop level: filler metals cannot be pooled from multiple heats or interchanged between certified and uncertified stock.

Tensile strength: AISC 341-22 requires the filler metal's minimum specified tensile strength to meet or exceed the base metal's minimum. For A992 wide-flange material (Fy = 50 ksi min., Fu = 65 ksi min.), an E70-class filler metal is generally acceptable, but verify against current AISC 341-22 Table A3.1 or the project specification.

The weld WPS must list the specific filler metal classification, manufacturer, and lot or heat requirement. If a lot runs out mid-project and a new lot is substituted, the new lot certificate must be reviewed before production resumes. This is one of the most common compliance gaps on EBF projects.

Heat input and interpass temperature limits

AWS D1.8 imposes maximum heat input and maximum interpass temperature limits on demand-critical welds. These limits protect the heat-affected zone microstructure and weld metal toughness — excessive heat input during CJP groove welding of link-to-column connections can coarsen grain structure and reduce the CVN toughness that the filler metal classification tested.

The WPS must state maximum heat input in kJ/in (or kJ/mm) calculated from the actual welding parameters. The formula is the same as AWS D1.1:2025 for heat input purposes, but the ceiling may be tighter than you would otherwise choose for productivity. Review the current edition of AWS D1.8 for the applicable limits, as they vary by process and joint configuration.

Interpass temperature must be monitored and documented for demand-critical welds. The WPS should state the maximum interpass limit, and the production parameter log must record the measured interpass temperature at each pass or at defined intervals. See CVN Supplementary Essential Variables: AWS D1.1 Table 6.8 for the context on how interpass temperature interacts with toughness qualification under D1.1, and note that D1.8 imposes its own interpass ceiling independent of the D1.1 supplementary essential variable framework.

Rule library based on AWS D1.1:2025; verify against your governing edition (the AHJ or contract may specify 2020 or earlier).

Protected zone: what welding is prohibited inside the link

AISC 341-22 establishes a protected zone within the link — the beam segment bounded by the link length — where the following are restricted or prohibited:

Welded attachments not part of the structural design (shear studs, decking anchors, coping details)
Arc strikes, gouges, or notches from temporary attachments
Tack welds for strongbacks, alignment fixtures, or erection aids, unless specifically approved by the engineer of record and documented in a WPS

The protected zone boundary should be marked on the structural drawings and transferred to the shop traveler. CWIs inspecting EBF link assemblies must verify that no unauthorized welding occurred inside this zone. If tack welds were placed and then removed, the removal scars must be ground smooth and inspected visually and by magnetic particle testing before the assembly ships.

For contrast, this is stricter than what AWS D1.1:2025 Clause 7 requires for stud welding in general structural applications. The seismic protected zone has no analog in standard structural work, and inspectors unfamiliar with AISC 341 sometimes miss it entirely on first-time EBF projects.

NDE requirements for EBF link welds

Demand-critical CJP groove welds require 100 percent nondestructive examination. AWS D1.8 mandates UT or RT of all demand-critical groove welds — spot inspection rates applicable to standard structural work under AWS D1.1:2025 do not apply here.

UT should be performed using procedures qualified under AWS D1.1:2025 Annex K (or ASME requirements per the project specification). The reference inspection level and acceptance criteria follow AWS D1.8 rather than the standard D1.1 Table 9.20 UT acceptance table — verify which criteria govern with the project specification before running examinations.

Weld access holes at the link-to-column connection (if required by the connection detail) must also be examined by UT or MT/PT for lamellar tears or laminations that could propagate during seismic loading.

WPS and documentation checklist for EBF link connections

Before the first arc on a link-to-column weld, verify:

WPS references both AWS D1.1:2025 and AWS D1.8
Joint geometry matches the structural drawing and the prequalified or tested detail
Filler metal is lot-certified with CVN results meeting D1.8 demand-critical requirements
WPS states maximum heat input and maximum interpass temperature
WPS designates the weld as demand-critical
Preheat procedure matches the base metal carbon equivalent and thickness
NDE plan specifies 100% UT or RT for all demand-critical groove welds
Protected zone boundaries are marked and communicated to welders and inspectors
Production parameter log format is ready to capture heat input, interpass temperature, and lot number for each weld

Shops with a structured WPS library and audit-ready documentation system have a significant advantage here. EBF projects involve multiple weld categories — standard structural, demand-critical, and sometimes prequalified moment connections — and the paper trail for each must be kept distinct from first article through final inspection.

Common gaps CWIs find on EBF projects

The three most frequent deficiencies on EBF link weld packages:

Filler metal lot interchanged without certification review. A box of electrodes from a different heat runs out, a new box is opened, and no one checks whether the new lot certificate shows CVN compliance. The inspector finds the lot mismatch during traceability review.

Heat input not calculated and recorded. Welders set parameters within the WPS range but nobody converts amps, volts, and travel speed to heat input kJ/in for the production log. AWS D1.8 compliance requires the calculation, not just that the parameters are within the WPS range.

Protected zone unmarked on shop traveler. The structural drawing shows the protected zone, but the shop traveler used by welders and inspectors during fabrication does not transfer that boundary. Erection aids get tacked inside the link, removal is incomplete, and the assembly fails MT before shipment.

For a structured approach to catching documentation gaps before an auditor does, the Common WPS Deficiencies Found in Third-Party Audits article outlines the most frequent findings across both standard structural and seismic work.