Re: Securing Rack Storage Legs To Floor
I am sorry but you all have missed the point of the video. This is a progressive collapse of a rack system. The old UBC had a requirement for protection of racks where impacts were possible. The IBC does not have any required protection from this type of an accident. Bolting the legs to the floor will not prevent, delay or slow down a progressive collapse.
The requirements for safety factors on racks can be found in
http://www.mhia.org/learning/resources/freedownloads/7977/specification-for-the-design-testing-and-utilization-of-industrial-steel-storage-racks-ansi-mh16-1-2008 for racks that do not have building structural loads. Where the IBC sends you to ASCE 7, you still won't find a specific requirement to limit impact damage, or measures to prevent a progressive collapse.
When you visit a Big Box Store or a Rack Supported Structure take a look really close. Do you see stiffeners or designed weak members that are specifically designed to prevent a progressive collapse?
If one cell in a rack is designed for 1000 pounds of storage, and the rack uprights carry 6 cells that is 6000 pounds on the uprights. If one set of uprights between two sets of cells has a failure the combined weight of all cells transfers to the adjacent uprights. The weight of the adjoing cells can as much as double within a fraction of a second. If the adjoining uprights fail, now that weight increases again. The problem becomes almost logrithmic.
So how many bolts are required? Not even the jury could tell you. Been there done that. And although information was presented to the ICC, no changes to the code have occured.
So what building official signed off on that rack? Why didn't it have impact protection?
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