Pre-engineered industrial shed design — 60 m clear span.

Project overview

A Darwin-based industrial fabricator engaged ASTCAD for the structural design of a new 60 m clear-span workshop housing two 12.5-tonne overhead cranes and a 6 m mezzanine office. The site is within cyclonic Region D, requiring full importance-level 2 wind design with corner cladding pressure coefficients.

The challenge

The client needed the largest practical clear span for crane operation, plus a mezzanine that didn’t interfere with the crane runway, all within a tight footprint constrained by existing site services. Region D wind loading and the requirement for the structure to remain in service immediately after a cyclonic event drove the design.

Our approach

• Tapered portal frame design optimised for 60 m clear span with internal mezzanine columns
• Crane runway beam design for two 12.5 t cranes per AS 1418.18
• Wind loading per AS/NZS 1170.2 Region D — wind speed Vu = 88 m/s
• Connection design to AS/NZS 5131 CC3 (high consequence of failure)
• Mezzanine and stair design to AS 1657 with edge protection

Deliverables

• Structural drawings — portal frames, purlins, girts, bracing
• Crane runway beam shop drawings with connection details
• Mezzanine framing plans and stair details
• Engineering certifications for council and building surveyor sign-off
• Tekla model and material take-off for fabrication tender

Outcome

The PEB was fabricated and erected in 16 weeks — ahead of programme. The Tekla model went straight into the fabricator’s CNC line, eliminating shop-floor mark-out. The structure has weathered two cyclonic events since commissioning, with no damage or repair required.

How we approach PEB shed design in cyclonic regions

PEB shed design for Darwin means Region C cyclonic wind loading drives every decision. We design portal frames to AS 4100 with wind loads from AS/NZS 1170.2 applied properly — internal pressure coefficients for the dominant-opening cases that sheds routinely present, not the benign assumptions that fail in a cyclone. Connection design, purlin and girt selection, and cladding fastener schedules all follow the wind classification through, and tie-down design carries the uplift to footings sized for it. The optimisation work happens inside those constraints: tapered members, sensible bay spacing and repetition that keeps fabrication economical.

Shed engineering deliverables

The package includes frame analysis and member design documentation, fabrication drawings for the portal frames and bracing, purlin, girt and cladding schedules, footing design coordinated with the geotechnical conditions, and certification documentation for building approval in the relevant jurisdiction. For shed builders we can align the deliverables with your standard product range so engineering per sale becomes a repeatable process rather than a bespoke exercise.

We engineer sheds and PEB structures across all Australian wind regions, from residential shedding to industrial warehousing — including the cyclonic-region work that many southern engineering offices decline. Fixed-fee packages are available for shed builders with recurring volume.

Shed builders operating across wind regions face a documentation problem as much as an engineering one: the same product sold in Brisbane and Darwin needs different engineering, and keeping the variants straight per sale is where errors creep in. We structure shed engineering as a documented product matrix — spans, bays, heights and wind classifications — so each sale maps to a pre-engineered configuration with certification ready to lodge. It turns per-sale engineering from a bottleneck into paperwork.