A rebar shop is a crane building with a very heavy floor
Rebar fabrication is simple in principle: bar arrives in bundles, is cut to length, bent to shape, bundled again and lifted onto a truck. Every one of those steps puts a specific demand on the building.
Everything moves by crane
Bar bundles are long, heavy and awkward. They are handled by overhead crane or by gantry, and that single fact determines the structure: a crane runway, columns designed for the crane's vertical and lateral loads, and a clear height above the hook path.
The crane rail level is the number to settle first. It has to clear the tallest stack of bundles on the floor, the machines, and the load being carried below the hook. Setting it from the building height backwards produces a crane that cannot lift over the stack it was bought for.
The floor is loaded in points, not areas
Bar bundles concentrate a large mass on a small contact area, and the machines — shears, benders, straighteners — sit on feet with anchor bolts and transmit vibration into the slab.
A slab designed for a general industrial floor load will not do. What is needed is a slab designed for the actual bundle weights and the machine footprints, with a surface that resists abrasion from dragged steel.
Where the shop also stores scrap and offcuts, the loads get worse and the floor gets less accessible. Scrap handling is part of the layout, not a corner.
Long material sets the building length, not the width
A rebar shop is long because bar comes in long lengths and the cutting table has to feed without reversing. The building proportions follow the material, which is the opposite of a warehouse where the pallet racking sets the grid.
That has a structural consequence: a long, narrow building has a large thermal movement along its length and needs either expansion joints or a frame designed for the movement.
The interface with the site is a truck and a crane
Finished bundles are loaded onto flatbeds or trailers. Loading can be by the same overhead crane through a door, by a separate gantry outside, or by a mobile crane in the yard.
Which one it is determines the door size, the apron and whether the building needs a cantilevered loading bay. A shop that loads through a door it discovered late in design ends up with a crane that cannot reach the truck.
What I want before drawings
- The crane capacity, span and rail level, and whether it is overhead or gantry.
- The bundle weights and the stack heights on the floor.
- The machine schedule with footprints and foundation requirements.
- The bar lengths handled and the resulting building length.
- The loading method and the truck sizes.
- The wind speed for the site in km/h from the applicable local code, not a round number.
Rebar shops are usually built quickly because they serve a project that is already running. That makes the crane rail level and the slab the two numbers worth arguing about early, since both are expensive to change.
Written by Johnny Joe, who advises owners and project managers in Africa and South America on steel buildings. If this decision is live on a project, send the layout and the constraint that worries you and I will tell you what it changes.
Related: where the crane rail goes · a workshop laid out around vehicles · height set by lifting · a floor added inside a shed
