When an earthquake occurs, ground acceleration can increase the horizontal loadings on storage systems by a factor of 10 or more. Rack frames and beams respond by swaying to and fro, and the total mass within the racks – the stored pallets – begins to move in relation to the ground, creating inertial cross-aisle (transverse) and down-aisle (longitudinal) forces within the rack structure.
While some rack suppliers make use of vertical and horizontal bracing to stabilise the rack in the longitudinal direction, this can be problematic since the bracing is prone to damage when putting away and retrieving pallets, possibly reducing its effectiveness under load.
Colby avoids the use of down-aisle bracing at the rear of rack frames whenever possible, preferring instead to opt for the use of “standard” racking uprights and beams, increasing in size as necessary to accommodate the seismic loads.
Colby also uses chemical anchors and special seismic baseplates, designed to behave in a predictable manner in the presence of uplift forces, along with heavy-duty cross bracing, super-strong 4-tang beam connectors, and a full range of rack damage protection designed to eliminate day-to-day damage which can weaken the structure.
It is important buyers know what they are paying for when purchasing storage systems. Storage systems may all look similar, but their performance can vary significantly. The flood of cheap, imported and often look-a-like racks into Australia and New Zealand means that storage system buyers should insist on detailed manufacturing specifications and any necessary certification to ensure they are actually getting what they pay for, and that it is fit for purpose.