It is seven in the morning and the building is still cold. The operator picks up the pendant, the bridge starts with its low hum and begins to travel down the runway, twenty-six feet above the floor, with a steel coil hanging from the hook. It will repeat that trip hundreds of times before the shift ends, and thousands of times a year. Every start, every stop and every lift loads two beams nobody looks at: the runway girders.
Get a quoteThe important part first. At Indumor we fabricate the structure that carries an overhead crane: the runway girders with their rail and fastenings, the brackets or dedicated crane columns, the bracing that takes the braking forces and the end stops; in Argentina we erect it as well. The crane — bridge, trolley and hoist — comes from its manufacturer; we build the runway it will travel on for its entire life. Four numbers drive everything else: capacity, span, service class and hook height. And two things are not negotiable: fatigue, because the load comes back every day, and tolerances, because a crane does not forgive a crooked runway. If the building already exists, it is checked to see whether it can take the crane with reinforcement or whether an independent structure makes more sense.
And a fifth one that gets forgotten: will there be a second crane someday? Planning for it today is cheap. Adding it later is not.
An ordinary structure is designed mainly for the maximum load. A runway girder is also designed for the load that repeats: every pass of the crane is a cycle, and in a busy building the cycles add up to enormous numbers over the years. A fatigue crack starts at a small detail — the toe of a weld, a badly terminated stiffener, a hole drilled in the field — and grows slowly, without warning. That is why the weld details of a runway girder are chosen for how they behave in fatigue, not for the shop's convenience.
A runway girder does not fail under the biggest load. It fails under the one that comes back every day.
A runway girder is never reinforced by welding plates onto it without engineering: in a member working in fatigue, a misplaced weld is exactly where the crack starts.
Rail spacing, alignment and runway elevation work in millimeters over tens of meters. A runway out of tolerance eats wheels and rails, makes the crane skew as it travels and multiplies maintenance. The tolerances are set by the crane and structural standards — in the Americas, for example, CMAA and AISC Design Guide 7 — and they are checked with a survey after erection, before the crane goes into service. Rail clips with elastomeric pads allow the alignment to be adjusted without cutting or welding.
It gets checked first. Sometimes the existing structure can take a light crane with local reinforcement; other times an independent structure makes more sense, with its own frames for the crane, asking nothing of the building. We build both. What does not work is deciding by eye: the column that holds up the roof today will not necessarily hold a crane braking above it.
No. The crane — the bridge, the trolley and the hoist — comes from its manufacturer. We build the structure, and we coordinate wheel loads, rail type and end stops with them.
Sometimes, with local reinforcement; other times an independent structure makes more sense, with its own frames for the crane, without touching the building. It is decided after checking the columns, the foundations and the room for the runway.
Rolled, when the span and load allow it and the section is available. Built up, by welding web and flanges, when the crane calls for sections that are not rolled or not available in time.
The columns of a crane building bring down more load, and horizontal forces as well. Base plates, foundations and anchor rods are designed for that from the start.
Send us the crane and building data, and we will tell you whether reinforcement is enough or a dedicated structure makes more sense.
© Indumor 2010–2026 — Industrial steel fabrication, Córdoba, Argentina
