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.Weight Calculation 2

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Stemy

Mechanical
Jun 26, 2015
6
I'm designing a steel rack to hold 45,000 lbs of steel sheets. For the life of me I can't remember how to figure out the load on each post and how to calculate size of base plate need for under each post.. Any help would be greatly appreciated. TIA..
 
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The frame will be made out of 6" square tubing, 3/8" thick walls.. The rack will be 12' tall x 6' deep and 12' wide. There will be 3" x 3" 1/4" thk. angle iron that will hold each shelf. Each shelf will be roughly 5400 bounds.
Floor is 6" concrete.
 
Why don't you draw up a plan view and a section cut of the rack. You might get a better response.

Also, would probably be nice to know how many shelves.
 
Determining loads to vertical supports should be simple, you only have 4 of them. Looks like the baseplate is offset from the centerline of the tube steel, so that will need to be considered in your baseplate analysis. AISC has a document that may be helpful: Design Guide 1: Base Plate and Anchor Rod Design

I don't see any bracing on your detail. Where is the project located, do you need to consider seismic effects on this 12ft tall rack? 6" concrete may have issues with breakout dependent on concrete strength and overturning load on the racks. Are racks braced adequately to resolve any lateral load and protect life safety?

Edit: Can't quite make it out from the view, but are you considering the solid plates at each shelf level as bracing?
 
On each side there is angle iron. That will hold the shelfs. i have a middle tube on each side and on top and bottom i have two tube in the middle.

racking_s0w6ob.jpg

racking2_pgdpty.jpg
 
ANSI has several design standards focused to the design/detailing of steel racks. I'd suggest glancing over ANSI MH 16.1. Also sounds like you would do well to consult with a local structural engineer who has experience in steel rack design to assist with anchorage, baseplate, and detailing for any lateral loads. We cannot provide free engineering and design on this forum. If you have a specific question, we'd be happy to help, but sounds like you may not be far enough along in the analysis.
 
I'm just looking for help with determining loads on the post and base plates.
 
Alright, where's the confusion coming from, what have you tried so far to determine these loads, and why do you think your methods are incorrect? Is the load distributed equally across each shelf (appears so from the photo), if so, why can't you distribute the tributary area from the shelf weight to the narrow edge angles, and use basic statics to distribute the load from the angles to the columns? Add up each angle and you get the load on the baseplate.

My concerns still should be considered, however, regarding lateral loads and anchorage for these kinds of heavy racks.

Edit: To clarify, lateral loads induce additional stresses in the design members, and also will increase/decrease peak loading on the columns and baseplates, therefore, they need to be determined to get the forces in the plates.
 
I'm not worried about the rack. I'm worried about the slab. Four 12kip point loads within a 72sf area? No way it'll survive.
 
6" concrete 4,000 psi. #4 bar on 18" squares
 
Ask the manufacturer for the total rack weight and the capacity of the shelves. Divide the total load by 4 to get the maximum load on a corner base plates. The base plate loads may be less if the bottom horizontal members rest on the concrete. The base plate loads may be greater due to overturning of the rack.

 
Stemy:
Given your OP question and your apparent resistence to listen to, or understanding, what you are being told above, all good advice; you should really be asking your boss these questions, so he/she knows what you know and what you don’t know, so they can guide you accordingly, and keep you and your company out of serious trouble. You should not be doing this problem alone, without your immediate supervision watching over your shoulder. You’re dangerous and don’t seem to know that either.
 
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