Design a warehouse with an overhead crane

Factories and logistics buildings often have an overhead travelling crane running the length of the building. The crane adds heavy, concentrated and moving loads that change the whole design: the columns get a bracket and a large eccentric load, the runway beams carry wheel loads, and the frame must resist the sideways surge of the crab. The Warehouse with crane template sets all of this up for you.

#How the crane loads the building

An overhead crane is a bridge spanning the building on wheels, with a crab (the hoist trolley) running across it. Its loads travel like this:

• The lifted load, the crab and the bridge weight reach the wheels. When the crab is near one rail, that rail gets most of the load.
• The wheels load the crane runway beams, which span between frames on brackets fixed to the columns.
• The brackets put the runway reaction into the columns off their axis, so the columns carry both a large axial force and a moment from the eccentricity.
• Braking and acceleration of the crab cause surge — a horizontal force across the building at rail level, which the frame resists in bending.

#What the template puts on the model

For a crane capacity Q, Struxt3D takes the crab as 0.2 Q and the bridge as 0.6 Q. The crane stands in the middle bay with the crab at the near rail, and applies at mid-bay of each runway:

• Near rail: 0.9 × (Q + crab) + bridge / 2 downwards.
• Far rail: 0.1 × (Q + crab) + bridge / 2 downwards.
• Surge: 10 % of (Q + crab), shared by the two rails, across the building.

For the default 100 kN crane that is 138 kN on the near rail, 42 kN on the far rail and 6 kN of surge on each. These loads are part of the Live load case.

#Step 1 — Pick the template

1. In the gallery choose Industrial › Warehouse with crane.
2. The default is a 24 m span, eight 6 m bays, 10 m to the eaves, with a 100 kN crane at 7 m. Bases are fixed — crane buildings need the extra sway stiffness.

#Step 2 — Set the size

Parameter	Section	Default	Range
Span	Span	24 m	12–36 m
Bays	Plan	8	3–15
Frame spacing	Plan	6 m	5–10 m
Eaves height	Height	10 m	6–16 m
Crane rail height	Crane	7 m	4–13 m
Crane capacity	Crane	100 kN	20–500 kN
Roof pitch	More options	6°	3–20°

The rail is kept at least 1 m below the eaves. The brackets project 0.75 m inside the columns, and each runway beam spans one bay.

#Step 3 — Materials and sections

1. Choose the Design code and steel Grade.
2. Sections: Columns, Rafters, Purlins, Crane runway (the runway beams and brackets) and Bracing.
3. Keep Size members for me on — but note the brackets share the runway group, so they are sized together.

#Step 4 — Supports and loads

1. Leave Bases fixed. Switch on Pad footings — crane columns produce large base moments, so the footings will be bigger than in a plain shed.
2. Set the roof Finishes and services load and the Wind speed.
3. Use Show on the model › Live to see the crane wheel loads on the runway in the middle bay.

#Step 5 — Analyse

Press Run analysis (F5) and check, for the Live case and the envelope:

1. Moment in the columns at bracket level — the bracket eccentricity creates a step in the column moment there.
2. Displacement: the horizontal movement of the columns at rail level. Crane operation needs tight limits — a common rule is height to the rail / 400 or less, and limits on the change in rail spacing.
3. Vertical deflection of the loaded runway beams — rule of thumb span / 600 to span / 1000 for crane runways.
4. Axial: the near-rail columns carry the most.

#Step 6 — Design

1. Press Run design (F6). Columns, rafters, runways and bracing are checked and sized; connections (base plates, end plates, fin plates, gussets) are designed.
2. Show Utilization: the columns in the crane bay and the loaded runway usually govern.
3. Open the member report of the worst column for the full check at the governing combination.

#Typical problems and fixes

• Runway beams pass strength but deflect too much. Raise the runway section. Remember the default deflection check is span/250 under D + L; crane runways need stricter limits — tighten it in Design settings… (Deflection span /).
• Columns very heavy. The bracket moment and surge govern. Fixed bases, a lower rail, or a stepped column (in a real project) help.
• Only the middle frames are critical. That is where the crane stands. Move or copy the crane point loads to other bays to check the end frames and bracing.

#Rules of thumb

• Runway beam depth ≈ span / 10 to span / 12 for heavy cranes, span / 15 for light ones.
• Bracket eccentricity: keep it small — every 100 mm adds a column moment of 0.1 × wheel reaction.
• Crane columns are typically 1.5–2× heavier than plain portal columns of the same height.