Four-storey steel frame with red reduced-beam-section moment frames and yellow chevron braces

Solution · Steel for high-seismic regions

Steel structures built for earthquake country

Special moment frames, braced frames and eccentrically braced frames fabricated for high-seismic regions – capacity-designed details, demand-critical welds, controlled materials and full traceability, to AISC 341, EN 1998, NZS 3404 and the codes of your market.

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SDC D–F
US seismic design categories: DCM · DCH
Eurocode 8 ductility classes: 100 %
UT of CJP demand-critical welds: EXC3 · CC3
Certified fabrication

Seismic moment connection in a steel frame

Ductility is fabricated, not just designed

In a strong earthquake a steel building survives because selected elements – beam hinges, braces or links – yield again and again while the rest of the frame stays elastic. Whether that happens depends as much on the fabricator as on the engineer: on the right steel with the right toughness, on weld access holes cut to the specified geometry, backing bars removed and back-gouged, protected zones left untouched and every critical weld tested.

World Steel fabricates seismic force-resisting systems for projects in seismically active markets. We work to the engineer of record's drawings and the project specification, apply the fabrication and quality requirements of AISC 341 and AWS D1.8, EN 1998 and EN 1090-2 or NZS 3404 and AS/NZS 5131, and deliver a quality dossier that supports the owner's quality assurance and special inspection.

Seismic systems

Seismic force-resisting systems we fabricate

Each system dissipates energy in a different element – our shop process is set up for the critical details of each one.

R = 8 · q up to 5αu/α1

Special moment frames (SMF)

Open bays and maximum architectural freedom. Plastic hinges form in reduced beam sections (RBS) or other prequalified connections; column panel zones get continuity and doubler plates.

R = 6

Special concentric braced frames (SCBF)

Stiff and economical. Braces yield in tension and buckle in compression; gusset plates are detailed for brace end rotation and the expected brace strength.

R = 8

Eccentrically braced frames (EBF)

Stiffness of a braced frame with the ductility of a moment frame – a short, fully stiffened link yields in shear while braces and columns stay elastic.

AISC 358

Prequalified moment connections

RBS, welded unreinforced flange (WUF-W), bolted end plates and bolted flange plates – fabricated with demand-critical CJP welds and documented protected zones.

Applications

Where seismic steel matters

Offices & mixed use

Moment-frame perimeters and braced cores in mid-rise buildings.

Hospitals & schools

Essential and high-occupancy buildings with higher importance factors.

Industrial plants

Process structures, pipe racks and equipment supports to industrial seismic codes.

Mining & energy

Conveyor galleries, transfer towers and plant buildings in the Andes and Pacific Rim.

Warehouses & logistics

High-bay buildings and racks where seismic mass is large.

Airports & transport

Long-span roofs, terminals and pedestrian bridges in seismic zones.

Normes et conformité

Seismic codes by market

The engineer of record selects the system and code; we fabricate and document to it. Key references:

United States

ASCE 7Seismic design categories; AISC 341 governs SFRS in SDC D, E and F (and where R > 3)
AISC 341Seismic provisions for structural steel buildings
AISC 358Prequalified connections for SMF and IMF
AWS D1.8Structural welding code – seismic supplement
AWS D1.1Structural welding code – steel

Material: Expected yield Ry: A992 and A572 Gr 50 = 1.1, A36 = 1.5; Fy ≤ 50 ksi for most yielding members
Demand-critical welds: Filler metal with CVN ≥ 20 ft·lbf at 0 °F (classification) and ≥ 40 ft·lbf at 70 °F (heat-input testing)
Bolts: Pretensioned high-strength bolts, faying surfaces at least Class A
Inspection: AISC 341 Chapter J QC / QA; IBC Chapter 17 special inspection

Toutes les normes United States →

New Zealand / Australia

NZS 1170.5Earthquake actions – New Zealand
NZS 3404Steel structures – ductility categories (fully, limited, nominally ductile, elastic)
AS 1170.4Earthquake actions in Australia – earthquake design categories
AS 4100Steel structures – Section 13 earthquake design
AS/NZS 5131 Certifié WSCFabrication and erection – construction category CC3 typical for seismic frames

Welding: AS/NZS 1554.1 SP category for critical welds, with the NDT the designer specifies
NZ market: Many NZ clients require a fabricator certified under the SFC scheme – confirm per project

Toutes les normes Australia & New Zealand →

Europe

EN 1998-1Design of structures for earthquake resistance – Section 6 steel buildings
EN 1993-1-8Design of joints
EN 1090-2 Certifié WSCExecution – EXC3 commonly specified for dissipative structures
EN ISO 3834-2Comprehensive welding quality requirements

Ductility classes: DCL (q ≤ 1.5 recommended), DCM and DCH
Overstrength: γov = 1.25 recommended; actual fy,max ≤ 1.1 γov fy for dissipative zones
Conformity: CE marking – World Steel FPC certificate 2797 CPR 827443 (EXC3)

Toutes les normes Europe →

Other seismic markets

NCh 433 / NCh 2369Chile – buildings and industrial structures
E.030Peru – earthquake-resistant design
NSCP 2015Philippines – national structural code
SNI 1726 / SNI 7860Indonesia – seismic actions and steel seismic provisions
TBDY 2018Turkey – building earthquake code
TCVN 9386Vietnam – design of structures for earthquake resistance

World Steel does not hold AISC Certified Fabricator status – US projects are fabricated to the project's AISC 341 / AWS D1.8 requirements with third-party special inspection as required by IBC Chapter 17.

Synthèse fournie à titre indicatif – le cahier des charges du projet, l'édition du code adoptée et l'autorité compétente prévalent.

Ingénierie

Capacity design: protect everything except the fuse

Every seismic system has a deliberate weak link. In a moment frame it is the beam hinge, in a braced frame the brace, in an EBF the link. Columns, connections and gussets are designed for the expected strength of that fuse – Ry·Fy, not the nominal yield.

That is why we control material grades and mill certificates, avoid uncontrolled substitutions with stronger steel, and identify yielding members on the drawings, in the shop and on the delivery documents.

Ingénierie

The details that decide performance

Reduced beam sections are CNC-cut to the a, b, c geometry of AISC 358 and ground smooth. Weld access holes follow the specified profile; bottom-flange backing is removed, back-gouged and reinforced with a fillet weld; weld tabs are removed and ends ground.

Protected zones are marked on shop drawings and on the steel – no shear studs, shot pins, welded attachments or erection aids there. Complete-joint-penetration welds are ultrasonically tested and recorded.

Ingénierie

A quality chain built for seismic work

Welding procedures are qualified for the toughness the project requires, welders are qualified for the joints they make, and each demand-critical weld is traceable to welder, procedure, consumable and NDT report.

Our welding quality system is certified to EN ISO 3834-2; our fabrication certificates EN 1090 EXC3 and AS/NZS 5131 CC3 cover the highest execution classes normally specified for seismic frames.

Spécifications

What we supply

Moment frames: Columns with continuity and doubler plates, RBS or end-plate beams, column splices, base plates
Braced frames: HSS or wide-flange braces, gusset plates with clearance for rotation, chevron beams, collector and chord members
EBF links: Links with full-depth stiffeners, link-to-column connections, lateral bracing at link ends
BRBF: Frames and gussets fabricated by World Steel; buckling-restrained braces supplied by qualified specialist manufacturers
Materials: ASTM A992 / A572 Gr 50, EN 10025 S355 J2/K2, AS/NZS 3679 / 3678 Gr 350 L0 – with 3.1 certificates and CVN where specified
Documentation: WPS / PQR, welder records, UT / MT reports, protected-zone marking, material traceability, QC records for the owner's QA

Processus

How we deliver seismic steel

1
Specification review
Code, system, SDC or ductility class, toughness, NDT and inspection requirements.
2
Shop drawings
RBS geometry, access holes, protected zones and demand-critical welds identified.
3
Procedures & materials
Seismic WPS / PQR, consumables and steel with the required properties.
4
Fabrication
CNC cutting, controlled welding, back-gouging and grinding of critical details.
5
Testing
UT of CJP welds, MT where required, dimensional checks and trial fit-up.
6
Dossier & delivery
Traceable QC records for special inspection, marked and sequenced deliveries.

Certification indépendante

Certified for high execution classes

EN 1090 EXC3 · CEBSI Group The Netherlands B.V. – Notified Body 27972797 CPR 827443

AS/NZS 5131 CC3BSI Group Australia & New Zealand (Benchmark Product Certification)BMP 827566

IAS AC472International Accreditation Service (IAS)MB-268

FAQ

Questions fréquentes

Which seismic systems can World Steel fabricate?

Special, intermediate and ordinary moment frames, special and ordinary concentric braced frames, eccentrically braced frames and the steel frames of buckling-restrained braced frames – to AISC 341, EN 1998, NZS 3404 / AS 4100 or the code in your specification.

Is World Steel an AISC Certified Fabricator?

No. World Steel holds EN 1090 EXC3, AS/NZS 5131 CC3, EN ISO 3834-2, and IAS AC472 certification. For US projects we fabricate to the AISC 341 and AWS D1.8 requirements of the project specification, with quality assurance and special inspection as required by IBC Chapter 17 and the building official.

What is a demand-critical weld?

A weld identified by AISC 341 whose failure would compromise the seismic system – for example the complete-joint-penetration beam-flange-to-column welds of a moment frame. They require filler metal with specified toughness, qualified procedures and, typically, 100 % ultrasonic testing.

What is a protected zone?

The region of a member that is expected to yield, such as the reduced beam section of an SMF beam or an EBF link. Welded attachments, shear studs, shot pins and other discontinuities are not allowed there; we mark these zones on drawings and on the steel.

Can you supply buckling-restrained braces?

BRB cores and casings are proprietary products qualified by testing. We fabricate the frames, gussets and connections and coordinate the braces from a qualified specialist manufacturer named or approved by the engineer of record.

Do you supply industrial structures in Chile and Peru?

Yes. Mining and industrial structures are fabricated to the owner's specification and the applicable seismic codes such as NCh 2369 in Chile and E.030 in Peru, with the fabrication and NDT requirements of the project.

Building in a high-seismic region?

Send us the drawings, the seismic system and the specification – we return a fabrication review, a quality plan and a delivered price.

Discuss your seismic project +84 902 881 833

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Steel structures built for earthquake country

Ductility is fabricated, not just designed