What are seismic calculations?
Seismic calculations are an engineer’s measurement of the stability of the racking in a seismic event (aka, earthquake). The engineer will give you the maximum capacity of each beam level based on your proposed configuration.
When determining seismic calculations, engineers consider several factors including racking manufacturer, gauge of material, strutting type and placement, type of baseplate, steel chemical composition, beam length, face size, gauge, number of endplate pins, beam placement (how many levels and at what heights from the ground level), how much weight is going on each level, and the thickness of the concrete.
Seismic calculations are separate from but play a part in the capacity of your rack system.
Do I need Seismic Calculations?
Seismic Calculations are almost always a requirement of the permit process. However, this is not something you can do on your own (unless, I suppose, you happen to be a seismic engineer). The good news is, we’re here to help. Our seismic engineers will prepare all the required calculations and documentation required for permitting.
The map shows seismic activity across the United States.
The more seismic activity there is in your state, the higher likelihood that you’ll be required to obtain seismic calculations. If you’re in Oregon, Washington, or California, you definitely need seismic calculations. States in the mid-west with little seismic activity sometimes do not have requirements for seismic calculations.
Seismic Calculations and Rack Configurations
Every different configuration of racking must have the required calculations. Consequently, the cost of pallet rack seismic calculations increases as the number of different configurations increases.
You can keep your costs down by standardizing your racking system. Limit the number of configurations by keeping everything as consistent as possible. Having beams at different elevations, or different heights/depths of frames, or different length or capacity of beams is all counted as separate configuration. Each configuration has to be independently calculated by an engineer. Consequently, the cost of the seismic calculations increases the more configurations you have.
Factors Considered in Seismic Calculations:
When an engineer performs calculations to determine acceptable capacities, he will consider many factors, including:
- Beam spacing & length
- Frame depth & height
- Steel gauge
- Desired capacities
- Seismic activity
- Concrete thickness
- And more
If the engineer determines that your proposed racking is insufficient for your desired capacities, they will indicate what changes would need to be made to the racking. For example, they may specify a heavier gauge frame, or a larger face size beam.
The seismic calculations determine what type and how many anchors you need, as well as what kind of footplates you need.
Seismic Calculation FAQs
Here are some answers to frequently asked questions about seismic calculations:
What is the difference between static load capacity and seismic load capacity?
A static load is the capacity that the manufacturer states it is structurally capable of holding. Therefore, all capacities are per pair of beams. This is what it could hold assuming there are no earthquakes. A seismic load is the capacity that the engineer calculates your particularly racking can hold based on the factors above. This is an important difference!
We commonly get customers to call us and complain because some company sold them pallet rack with a stated capacity of, for example, 5,000lbs per beam level. However, when they went to get permits for it, they found out the the engineer would only rate it for 4,000 lbs. The different is that the manufacturer specifies static load capacity (what it can hold without an earthquake), but the engineer is rating it for seismic capacity (what it can hold during an earthquake).
How much do seismic calculations cost?
The cost of seismic calculations depends on several factors, but the two largest factors are:
- The number of rack configurations — Every different size frame or beam, beam elevations (shelf level), manufacturers, condition, etc. is considered a separate configuration. Typical packages include 2 to 4 configurations, and additional configurations can be added for an extra charge.
- Manufacturer — If the manufacturer of the racking cannot be identified, or if the manufacturer has not had proper testing already performed, then costly stress testing must be done on the racking.
Can I get permits on used pallet racking?
Usually, but it depends. One of the biggest problems with used pallet racking is that it can be difficult to permit it. As we discuss above, seismic calculations are required in most states. A seismic engineer must know the exact size, dimension, gauge, and manufacturer of the pallet racking in order to get the seismic calculations. While the dimensions aren’t hard to figure out, the gauge and manufacturer can be more difficult. You usually do not know the manufacturer of used pallet rack. The seismic engineer may be able to identify the manufacturer from closeup photos. However, if the seismic engineer is unable to identify the manufacturer, then the engineer must perform seismic stress testing on a sample of the used racking. This is very costly, as you have to send samples of the racking to the engineer for testing.
Different Manufacturers of Pallet Racking:
If your used racking is not all exactly the same, it could be from different manufacturers, so you have to send samples of every style of racking. The cost of all the seismic stress testing required to get permits on unknown used pallet rack frequently makes it more expensive than buying new racking. New rack typically already has this seismic stress testing completed.
Contact us for a quote on pallet rack seismic calculations for your warehouse racking project.