Crane Girder Pre-sizing Estimator

Depth H ≈ L/18 to L/14. Deflection scales with L³/I — depth is the cheapest stiffness. Heavy duty pushes toward L/14; light duty can live nearer L/18.

Width B ≈ H/3 to H/2, and at least L/50 for lateral and torsional stability under trolley acceleration and skewing loads.

Plate thickness steps with capacity: webs 6–12 mm, flanges 10–24 mm across the 5–100 t range, refined by local buckling checks (stiffener spacing) in detailed design.

Camber ≈ L/1000 compensates dead-load sag so the trolley doesn't run uphill at midspan. The deflection limit itself depends on your standard — GB/T 3811 uses L/800–L/1000 by duty, CMAA 70 uses L/888.