Structural Assemblies

Structural Bolt Assemblies for Australian Steel Construction

Structural bolt assemblies are pre-matched bolt, nut, and washer kits engineered for structural steel construction — providing the tensile strength, surface treatment, and dimensional consistency that load-bearing connections demand. For Australian structural steelwork, building construction, and industrial fabrication, structural bolt assemblies compliant with AS/NZS 1252 are the specified fastener for connections where bolted joint failure could cause structural collapse. AIMS Industrial supplies structural bolt assemblies from Hobson and approved fastener brands.

What's in a structural bolt assembly

A complete structural bolt assembly comprises three matched components:

• The bolt — typically Class 8.8 or 10.9 high-tensile steel
• The nut — matching grade nut (Class 8 or 10) sized to develop full bolt tensile strength
• The washer(s) — flat washers and (where applicable) load-indicating washers

All three components are matched as a set — substituting components from different sources defeats the engineered performance.

The structural bolt grades we stock

• Class 8.8 (Grade 8.8) — the standard structural grade; tensile strength 800 MPa minimum
• Class 10.9 (Grade 10.9) — higher-strength structural grade; tensile strength 1000 MPa minimum
• Galvanised structural bolts — hot-dip galvanised for outdoor and corrosive environments
• Self-colour (untreated) structural bolts — for indoor applications where corrosion isn't a concern

Where structural bolt assemblies earn their place

• Steel building construction — beam-to-beam, beam-to-column, and column-to-base connections
• Bridge construction — primary structural connections in steel bridges
• Industrial steelwork — heavy industrial buildings, equipment frames, conveyor structures
• Pre-engineered building systems — bolted moment frames and rigid-frame connections
• Structural steel repairs and modifications — adding members or modifying existing structural connections

Compliance — AS/NZS 1252 and AS 4100

Australian structural bolt assemblies must comply with AS/NZS 1252 (the manufacturing standard for high-strength bolts, nuts, and washers for structural engineering). Structural steel design and construction is governed by AS 4100. Together, these standards specify bolt grades, washer requirements, surface treatments, and inspection criteria for structural connections. Don't substitute non-AS/NZS 1252 fasteners in structural applications — building approvals and insurance typically require certified compliance.

Sizing

Structural bolt assemblies come in metric sizes M12 through M36 in standard-length and short-thread variations. The bolt length must extend through the connection plus a small projection beyond the nut for thread engagement verification. Each project's structural drawings specify the required bolt size, grade, and length for each connection — refer to the engineering drawings rather than substituting from general stock.

Tensioning — turn-of-nut and torque

Structural connections require specific bolt tension — typically achieved through torque control or turn-of-nut methods. Turn-of-nut is more reliable: tighten to a snug fit, then turn the nut a specified additional amount (typically 1/3 to 1/2 turn depending on bolt diameter and length). Torque control is faster but more variable. Load-indicating washers (DTI washers) provide visual confirmation of correct tension and are increasingly specified for critical connections.

Brands stocked at AIMS

Hobson covers the structural bolt assembly range across Class 8.8 and 10.9 grades in galvanised and self-colour finishes. Bremick stocks complementary structural fasteners. For specific OEM-pattern bolts, large-quantity orders, or specialty grades, sourcing through our distribution channels covers most requirements.

Companion ranges at AIMS

Structural bolt assemblies sit alongside our broader heavy-duty fastener range — see structural hex nuts, structural washers, safety washers, and threadlockers for related products.

Need help speccing structural bolt assemblies for a specific project or compliance audit? contact our team — we'll match by grade, size, finish, and AS/NZS 1252 requirements.