Without base plates (sometimes called foot plates), industrial steel pallet racks would slide or fall over in the event of an impact. This design feature, located at the bottom of every rack column, provides a surface for anchor bolts to grip when drilled into the floor. Critical to the structural integrity of the rack, they create a connection surface for the anchor bolts. Anchor bolts, in turn, secure the pallet rack columns to the floor.
ANSI MH16.1’s Requirements for Base Plate Design
As required by ANSI MH16.1: Specification for the Design, Testing and Utilization of Industrial Steel Storage Racks, the design and engineering of these key rack components ensures they resist the forces experienced at the base of a column. In addition to the downward forces generated by the weight of the stored loads, a rack’s stability is also susceptible to uplift forces caused by a forklift collision or to seismic forces caused by an earthquake or wind forces. Column base plates and anchors work together to keep the racking structure in an upright position. This reduces the risk of a collapse and improves the safety of personnel working in the area.
Provided there is a proper connection to the column, base plates accept these concentrated forces and distribute them uniformly over their bearing surface. ANSI MHI16.1’s section on “Column Base Plates” discusses the requirements for racks installed on concrete floors in more detail. It includes the calculations required of the rack manufacturer to determine the thickness and dimension of the plates.
These calculations must account for the downward vertical load, uplift and axial load (plus bending) in order to determine a large enough bearing area. Further, ANSI MHI16.1’s section on “Anchor Bolts” requires the rack engineer to calculate and specify the length and number of anchors used to secure each base plate to the floor.
Installation Site Affects Sizing
Depending on the requirements of the installation site, base plates can range in size from 3 x 5 x 0.125 inches up to 12 x 12 x 0.75 inches or larger for tall systems in seismic zones. It is incumbent upon the rack manufacturer or professional rack engineer to detail the quantity, brand and size of the anchor bolts.
The rack engineer will also specify how many holes each base plate should have. However, most base plates include extra holes to accommodate obstructions in the floor, such as reinforcement. Additionally, columns being anchored near floor expansion joints require special attention.
Learn More About Base Plates
Have more questions about safe rack design? Additional information can be found in RMI’s publication, “Considerations for the Planning and Use of Industrial Steel Storage Racks.”
