Crane Loads for Steel Workshops: 5 Inputs to Specify

In short: Before designing a steel workshop with an overhead travelling crane, fix 5 inputs: rated capacity in tonnes, crane span in meters, FEM or ISO duty class, hook height above floor, and maximum wheel load in kN. These values determine runway beam design, column sections, bracing, base plates and foundation reactions. Missing any one can cause costly structural redesign.

Why Must Crane Data Be Fixed Before Workshop Design?

An overhead travelling crane introduces concentrated moving loads into a steel building. Unlike ordinary roof loads, crane forces act directly on runway beams and supporting columns. They also create horizontal forces, vibration and repeated stress cycles.

For a conventional steel workshop without a crane, engineers mainly consider roof dead load, wind load, snow load and building use. Adding a 5 t, 10 t or 20 t overhead crane changes the structural load path. The columns may need stronger sections, the foundations may need larger dimensions, and the building frame may require additional bracing.

Our engineers recommend confirming the crane supplier's preliminary technical data before freezing the building layout. A difference of 20% in wheel load can change the required runway beam, column connection and foundation design.

• Building column spacing and crane runway support positions.
• Runway beam strength, deflection and fatigue resistance.
• Column buckling resistance and combined bending forces.
• Foundation bearing pressure, uplift and anchor bolt forces.
• Building clearance, maintenance access and future crane upgrades.

1. What Crane Capacity Should a Steel Workshop Specify?

Crane capacity is the maximum rated lifting load, normally expressed in tonnes (t). Common industrial workshop capacities include 5 t, 10 t and 20 t. However, the crane's rated capacity is not the same as the maximum vertical load transferred to each runway support.

Engineers must consider the bridge self-weight, trolley and hoist weight, lifted load, dynamic effects and the position of the trolley. The maximum wheel reaction occurs when the trolley approaches a particular end of the crane bridge.

For preliminary planning, consider these typical applications:

• 5 t crane: Suitable for light fabrication, equipment maintenance and general manufacturing. A preliminary building clear height of 6-8 m is common.
• 10 t crane: Used in medium-duty fabrication, machinery assembly and material handling. A 7-10 m clear building height may be appropriate.
• 20 t crane: Suitable for heavy fabrication, steel processing and large equipment handling. An 8-12 m clear height is a reasonable initial planning range.

These are building planning ranges, not mandatory crane dimensions. The actual column size depends on the maximum wheel load, crane geometry, building height, frame spacing, wind conditions and applicable design code.

2. How Does Crane Span Affect Runway Beam and Columns?

Crane span is the horizontal distance between the crane's runway rails, measured in meters. It is normally related to the distance between the supporting workshop columns. A wider span generally increases crane bridge weight and can increase the wheel reactions transferred to the runway beams.

Typical industrial workshop crane spans range from 12-30 m, although specialized applications can exceed this range. The relationship between building span and crane span must be checked during the initial layout.

A 20 m workshop may accommodate a crane with a similar rail-to-rail span, depending on the building arrangement. However, the crane bridge end trucks, rail position and required operating clearances must also be considered.

Wider crane spans can increase:

• Crane bridge dead weight and maximum wheel reactions.
• Runway beam bending moments and deflection.
• Horizontal forces transferred to columns and bracing.
• Column section weight and foundation overturning effects.

Bay spacing is another important parameter. A typical preliminary workshop bay spacing may be 6-9 m. Changing the spacing changes the runway beam support arrangement and the forces transferred into individual columns.

3. Which FEM or ISO Duty Class Is Required?

Duty class describes how frequently and intensively a crane operates. Two cranes with the same 10 t lifting capacity may require different structural arrangements because one operates occasionally while the other handles heavy loads throughout multiple shifts.

FEM crane classifications and ISO classifications should be specified using the actual crane manufacturer's design documentation. ISO 4301-1 defines crane classification through utilization and load spectrum. The ISO A1-A8 classification system should not be confused with the ISO M1-M8 mechanism classification.

For preliminary discussions, the following operating ranges can help identify the likely duty level:

• Light duty: Approximately 1-2 operating hours per day, with relatively low lifting frequency.
• Medium duty: Approximately 3-6 operating hours per day, with regular material handling.
• Heavy duty: Approximately 8-16 operating hours per day, with frequent lifting and higher load utilization.

These operating hours are planning assumptions, not direct replacements for FEM or ISO classifications. Engineers need the actual load spectrum, working cycles and crane classification to calculate fatigue effects.

Higher duty levels can increase fatigue demands on runway beams, welded connections, rail clips and column brackets. Fatigue checks are especially important for workshops with frequent crane travel and repeated heavy lifting.

4. How Does Hook Height Change Workshop Column Design?

Hook height is the vertical distance from the finished workshop floor to the crane hook's highest required operating position. It directly affects the crane runway elevation, building eave height and total structural column length.

For example, a workshop requiring a 6 m hook height cannot simply use a 6 m building eave height. The design must allow for the crane hoist arrangement, trolley height, crane bridge depth, runway beam depth and operating clearances.

In a typical industrial arrangement, the runway rail may be approximately 6-10 m above floor level. The required building eave height could be approximately 8-13 m, depending on crane geometry and roof clearance.

Increasing the hook height by 1 m can increase the column length and wind-exposed area. Taller columns may need larger steel sections or additional lateral restraint. The resulting changes can also affect column base moments, anchor bolts and foundation dimensions.

Before selecting the building height, obtain the crane manufacturer's required maximum hook position, minimum hook approach and overall crane height. These dimensions are more useful than specifying hook height alone.

5. Why Is Maximum Wheel Load Critical for Runway Beam Design?

Maximum wheel load is one of the most important inputs for designing a crane-supported steel workshop. It is the maximum vertical reaction transferred by an individual crane wheel to the runway rail under a defined loading condition. Manufacturers normally provide maximum and minimum wheel loads in kN.

Engineers use these reactions to calculate runway beam bending, shear, local flange stresses, web buckling and vertical deflection. They must also consider horizontal transverse forces from trolley movement and longitudinal forces from crane acceleration and braking.

For preliminary structural coordination, the following ranges illustrate possible planning allowances. They are not manufacturer-certified wheel reactions or final member sizes.

Crane capacity	Typical crane span	Typical duty class	Preliminary runway beam depth	Illustrative column steel weight
5 t	12-18 m	ISO A3-A4	400-600 mm	60-100 kg/m
10 t	15-22 m	ISO A4-A5	500-750 mm	80-130 kg/m
20 t	18-25 m	ISO A5-A6	650-900 mm	110-180 kg/m
20 t	25-30 m	ISO A5-A6	750-1,100 mm	140-220 kg/m

The table provides preliminary budgeting ranges only. Column weights are illustrative estimates for crane-supporting building columns, not calculated section selections. Actual values depend on column height, frame spacing, steel grade, wind loads and connection conditions.

Runway beam depth also depends on wheel spacing, rail arrangement, support conditions and allowable deflection. A 20 t crane with closely spaced wheels can produce a different beam design from a crane with the same capacity but a different bridge configuration.

Foundation design must account for the combined effects of vertical reactions, horizontal forces, column moments and building stability. Depending on the soil bearing capacity and structural arrangement, engineers may need larger isolated footings, combined foundations or reinforced concrete tie beams.

What Technical Information Should the Crane Supplier Provide?

Before finalizing the workshop design, request a technical data sheet and preliminary general arrangement drawing from the crane manufacturer. The information should be detailed enough for the structural engineer to establish the design load cases.

• Rated lifting capacity in tonnes, including any auxiliary hoist capacity.
• Crane span in mm or m, with runway rail centerline dimensions.
• FEM classification or ISO 4301-1 crane duty classification.
• Maximum hook height, minimum hook approach and crane overall height in mm.
• Maximum and minimum wheel loads in kN for each wheel.
• Wheel spacing, number of wheels and wheel diameter in mm.
• Crane bridge and trolley self-weight in kg or kN.
• Horizontal transverse and longitudinal forces in kN.
• Crane travel speed, lifting speed and braking arrangement.
• Applicable dynamic factors, load combinations and fatigue requirements.

Structural design should follow the applicable building and crane standards. Depending on the project location, relevant references may include EN 1991-3 for actions induced by cranes, EN 1993-6 for crane-supporting structures, ISO 4301-1 for crane classification, and the applicable national steel design code. A project using American standards may require AISC 360 and ASCE 7 provisions.

Do not assume that a runway beam designed for one crane can automatically support a replacement crane of the same rated capacity. Different wheel spacing, self-weight, duty classification and braking forces can produce different structural demands.

Quick answers

Can a 10 t overhead crane be installed in an existing steel workshop? Yes, but the columns, runway supports, foundations and connections must be checked against the new crane reactions.

Is crane capacity enough to calculate runway beam size? No. Span, wheel loads, wheel spacing, duty class and horizontal forces are also required.

Can a workshop be upgraded from a 5 t to a 20 t crane later? Not without rechecking the complete supporting structure, including runway beams, columns, bracing and foundations.

Next step: Review our steel structure building solutions, explore our steel structure product range, and learn more about our steel structure engineering and fabrication capabilities before preparing your workshop specifications.