The flat steel plate at the bottom of a rack upright, anchored to the warehouse floor.
Detailed Definition
The rack base plate, also called a footplate, is welded or bolted to the bottom of each column of an upright frame. It spreads the column load over a larger area of the concrete slab and provides holes for anchor bolts. Plate size and thickness are chosen by the rack designer under the RMI specification ANSI MH16.1, based on column load and slab conditions. Taller, heavily loaded, or seismically designed racks often use larger plates with more anchors.
What the base plate does
Each rack column carries the weight of every pallet on the beams above it. Without a base plate, that load would bear on a small steel section and could damage the slab. The plate spreads the load, gives a level bearing surface and lets the column be anchored so it resists sliding and overturning. In seismic regions the base plate and anchors also carry earthquake forces into the floor.
Common problems found in inspections
- Bent or cracked plates, often from forklift impacts at floor level.
- Missing or loose anchors, or anchor holes left empty.
- Excessive shims or improvised packing under the plate.
- Cracked or spalled concrete around the plate.
- Plates that have been replaced with parts from a different manufacturer.
A damaged plate changes how load reaches the floor and should be assessed against the manufacturer's damage limits before the bay is reloaded.
Floor and replacement considerations
The slab must be strong enough for the column loads that the plate delivers, so new or heavier rack may need a slab check. Replacement plates and repair kits should come from the original manufacturer or an engineered repair. Column protectors at aisle ends and corners help prevent repeat damage.
Related Glossary Terms
Frequently Asked Questions
Can a bent rack base plate be straightened in place?
It is not recommended to bend damaged rack parts back. A base plate that is bent, cracked or pulled away from the column has been overstressed, and straightening it does not restore the original strength. Unload the bay, and have the damage assessed against the rack manufacturer's guidance. Repairs normally use manufacturer parts or an engineered repair kit.
Why are some rack base plates bigger than others?
Base plate size depends on the column load, the rack height and the forces the rack must resist. Heavier loads and taller frames send more force to each column, and racks designed for seismic areas must resist sideways forces. Larger plates spread the load over more concrete and allow more anchors. The rack designer sets the plate size; do not swap in a smaller plate from another system.