Capacity is the amount of weight which can be safely placed onto an upright or a pair of beams in any given situation. Racks are commonly quoted with static load capacities based on the loading values stated in most manufacturer’s literature and are based on non moving situations. Seismic zones indicate the likelihood of the earth moving. The higher the seismic zone, the higher the risk of the earth moving or the higher the risk of an earthquake.

In southern California we are in the most severe seismic zone – zone 4. The capacity of rack drops dramatically in zone 4. An upright which will hold 35,000 pounds in a static non moving environment may hold only 15,000 pounds during a seismic event. You should always ask your dealer for preliminary calculations from a certified, licensed engineer in order to make the proper upright selection.

Other items which are commonly effected by seismic zones are footplates, distance between the holes for anchoring, size of the holes for anchoring, thickness of the footplate, beams, the number of pins required on the beam connectors, Whether you buy your rack from us or another vendor, be sure to ask for engineering prelims based on your address and zip code. We will always offer you prelims when laying out your rack designs.