What is Beam Deflection

Beam deflection is a common occurrence in pallet rack systems with hefty loads. Below, you will find a practical beam deflection formula to help calculate maximum deflection and determine if your deflection is within the acceptable range. Keep reading to learn more and visit our pallet rack guide for more info on pallet racking. 

Beam deflection is the bowing or bending of a beam under heavy capacities. Although it sounds dangerous (and most certainly can be), there is actually a normal and acceptable range for deflection. Our beam deflection formula helps calculate if your beam’s deflection is within the normal range. 

For cantilever racking, deflection occurs when the load is placed at the end of a cantilever arm, causing the arm to bend away from the upright column. For typical pallet rack systems, excessive deflection occurs when there is a point load or when loads are too heavy for the pallet rack system. 

Again, beam deflection is a natural occurrence and some beam deflection is standard. 

Beam deflection

Beam Deflection Formula

This beam deflection formula is simple and easy to apply to your pallet rack systems. The diagram below illustrates the beam deflection formula process. To calculate the deflection and determine if your beams are in the normal range, you first need to determine what amount of deflection is acceptable for your pallet rack beams. 

How to Calculate Beam Deflection

Follow these four steps to specify the permissible deflection range for your beam and to calculate your beam’s current deflection: 

  • Step 1: Measure the length of your beam
  • Step 2: Divide the beam length by 180 to determine the allowable deflection
  • Step 3: Measure from the floor to the beam at both the end and center of the beam
  • Step 4: Subtract end measurement from center measurement to determine the current deflection
Beam deflection formula

Watch: Beam Deflection Formula in Action

For a visual guide, watch this short video in which Pete Brandon demonstrates how to calculate beam deflection using the beam deflection formula:

How to Combat Beam Deflection

Wire Decks

Wire decks, specifically waterfall wire decks that wrap over the edge of the beam, create a sturdy flat surface for pallets and products to sit on. They help to distribute the load more evenly across the bay. Wire deck channels provide additional support for the beam level as well. Wire decks are safe to use in spite of beam deflection. 

Wood panels, on the other hand, can fall through the beams if they get wet or if beam deflection occurs. For this reason, wire decks are a much better and more viable option to combat deflection.

Wire decking on application
Old fashioned scale

Uniformly Distributed Loads

This brings us to our second strategy – Uniformly Distributed Loads (UDL).

UDLs are another way to combat excessive deflection. Again, deflection is expected, but evenly distributing the load between the front and back beams helps combat deflection beyond the formula provided. 

Pallet rack beams deflect when the heaviest capacity rests in the center of the beam or on one beam more than the other. If the product is uniformly loaded across the whole beam length, deflection is much less likely to occur. Evenly distributing loads is general practice for pallet rack storage. 

Properly Loaded Beams

When using pallet racking, it is essential to properly load your beams. Avoid the following load styles when possible, or take the necessary safety precautions:

forklift truck in a storage warehouse lifting boxes

Line Loads

Line loads occur when the product’s heaviest weight is concentrated on a single line (think heavy rolls of material on their side like sheet metal or kegs). Drum cradles are a line load solution that help evenly disperse capacity across the shelf level. 

Point Loads

Point loads are loads where the weight is concentrated at one or more specific points. Avoid wire decking when handling point loads. Steel decking or other solid decking is much better for such scenarios.

Concentrated Loads

Concentrated loads are smaller loads that aren’t large enough to reach both beams. Wire decks are necessary to prevent pallets from falling through the system.

Beam Replacement

Finally, if deflection is over the allowable limit and wire decking isn’t an option, you must replace the beams. Opt for higher capacity beams and uniform loads to avoid re-deflection and damage. 

Need a pallet rack inspection? Call us at 800-722-5908 to speak with one of our experienced pallet rack specialists.

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