Steel Workshop Building Prefab Steel Structure Workshop with 1-300 Ton Crane and 30m Span Q355B Steel

A steel structure workshop is a production tool. The crane, the column spacing and the floor loads are fixed by what you make and how you move it; the building follows. We prefabricate the frame, the crane runway, the purlins and the cladding as one package.

Frames are welded H-section in Q355B and bolted on site. Clear spans run from 12 m to 40 m, crane capacity from 1 t to 300 t, and the eave height is set from the hook height you actually need, not from a standard drawing.

We supply a complete steel structure workshop kit: main frame columns and rafters, crane runway beams and brackets, cold-formed C or Z purlins, angle and pipe bracing, roof and wall panels, flashings, gutters and downpipes, doors and windows, high-strength bolts, anchor bolts and the erection drawings.

You supply the foundation, the slab, local transport, unloading, erection labour and the mobile crane used to lift the frame. We issue the anchor bolt setting-out and the frame loads those works depend on.

Capacity, span, hook height and duty class are the four numbers that shape the building. Capacity runs from 1 t to 300 t. Duty runs from A3 for intermittent maintenance lifting to A7 for continuous production duty.

On a steel structure workshop all four have to be known before the foundation is designed, because the crane load reaches the ground through the column and the base plate. A crane added later means new brackets, a heavier column and, in most cases, a new foundation.

Hook height is not eave height. The crane bridge and trolley take 1.2–2.0 m out of the section, and a further 300–500 mm is kept as clearance to the rafter.

Working back from the tallest lift gives the eave height. Most industrial workshops land between 9 and 15 m. A second crane level or a tall process vessel pushes it higher.

A standard bay is 6, 9 or 12 m. Where the line runs across the building, a 24 m or 30 m bay takes the columns off the production floor and lets the line run uninterrupted.

Wider bays are heavier: the rafter deepens and the runway beam spans further. The cheapest frame is not always the cheapest building, because the cost of a column in the middle of a production line is paid every shift.

The runway beam is what separates a crane beam workshop from an ordinary portal frame: a welded H-section carried on a bracket off each column, stiffened at the web. It is governed by fatigue rather than by static strength, which is why the bracket detail and the rail fixing matter more than the section size alone.

Rails are QU70 or QU80 with welded or clipped fixings, set to the track tolerance given by the crane supplier. We confirm the rail level and the wheel base before fabrication.

An industrial slab is commonly 200–300 mm thick with a live load of 5–10 t/m², but machines rarely load a slab uniformly. Presses, compressors and machining centres need isolated foundations, and precision machines need the slab separated from the frame so that traffic vibration does not reach them.

We provide the frame loads and the base plate positions. Machine foundations are designed by your equipment supplier and cast by the local contractor.

A mezzanine at 300–500 kg/m² carries stores, offices or a canteen above the floor without adding to the footprint. Offices inside the building need a fire separation and their own escape route.

Skylight belts, pre-formed ventilation openings, roller shutter or sliding doors, personnel doors and future expansion provisions all cost less when they are drawn into the frame than when they are cut into a finished building.

A workshop generates heat, fume and dust, and a sealed envelope makes it worse. Welding fume is extracted at source. General ventilation is sized at 6–12 air changes per hour, with ridge ventilators and low-level inlets so that make-up air enters where people work.

Where a process gives off heat — furnaces, ovens, large motors — the roof is fitted with powered exhaust, and skylight belts are placed to draw air along the production line rather than across it.

The main frame of a steel structure workshop is welded H-section in Q355B, or Q420D for heavy duty, with cold-formed purlins, angle bracing and bolted site connections. Roof and wall are steel sheet or insulated sandwich panel.

Surface treatment follows the environment: shot blast to Sa2.5, epoxy zinc-rich primer and a polyurethane topcoat inland. For coastal or chemical sites the specification moves to a corrosion resistant workshop build with hot-dip galvanizing and a coating thickness set by the exposure category.

Every steel structure workshop is designed in Tekla, AutoCAD and PKPM. The drawing set includes a general arrangement, the anchor bolt plan, the member schedule with section sizes, the crane runway arrangement and the erection sequence.

Fabrication runs through cutting, drilling, welding, shot blasting and painting, with the typical frame trial-assembled before packing so that bolt holes line up on site. Material certificates, dimensional checks and coating thickness readings are recorded against each batch. Components are packed in bundles by erection sequence and marked, with main frames in 40 ft open-top containers and panels in 40 ft high-cube.

• Crane capacity, span, hook height and duty class
• Building length, width and eave height
• Any column spacing the line requires
• Floor loads and machine foundation positions
• Heat, fume and ventilation requirement
• Mezzanine, internal office or future extension
• Wind, snow and seismic loads at the site
• Execution standard: GB, EN 1993, ASTM or JIS