METAL BUILDING BASIC COLUMN REACTION CALCULATION - ASCE 7 1

[prince samson]

Hey guys,

Iam designing a foundation system for a metal building system, The column reactions will be given by the metal building supplier in future, but to arrive at the size of foundation, I myself calculating the basic column reaction for the metal building by manual hand calculation as per ASCE7-10. Iam using Whirlwind metal building column reaction forces as a go-by. I see this wind load case "LnW1_L2E = Longitudinal Wind, case 1, Wind Left Edge Zone 2E" for which I need the calculation procedure as per ASCE 7. Other load cases such as WL1, WR1, etc., i figured it out. Would be helpful someone can share the entire calculation for all column reactions. Thanks in advance !!! Snap shot attached for easy reference​

 

[SteelPE]

To be honest, whenever I attempt to give preliminary foundation sizes for a metal building I usually only check the main dead, snow and wind loads on the frame and then increase the footing a size or two. I also make sure everyone knows what we are up against, and that the foundation design will need to be revised once the final reactions are issued by the manufacturer.

Every metal building is slightly different... and even had different load cases. Once you get the reaction, if you have any questions, call the manufacturer. I have found them to be helpful when trying to figure out what is going on with their "add" reactions).

One funny bit, these reactions look exactly what I would receive from a Nucor Supplier. I know some of these companies will use the larger manufacturers to design their building and then slap their name on the side. So while you might think you are getting a building by Whirlwind, you may be getting a building designed by a large manufacturer fabricated by Whirlwind (or possibly even Nucor).

 

[oengineer]

Another book you may want to get a hold of is Foundation and Anchor Design Guide for Metal Building System. I just worked on a project in which I was not provided any column reactions and this book was very helpful in dealing with that.

For this situation, I determined the wind load information for the area my project was located in and analyzed it as single-span gable rigid frame (see image below).

I used STAAD to run the analysis, but you can use structural analysis formulas from a textbook (see image below) or spread sheets.

 

[prince samson]

@ oengineer, that's very helpful, instead of taking the column reactions from standard tables, could you please share any literature or worked example which explains how to apply the wind loads calculated from envelope method as per ASCE 7-10 on transverse and longitudinal frames on metal buildings. Also the formulas for static load calculation is from which book or literature ? looks too good.

 

[SteelPE]

prince samson,

Have you ever worked on a metal building before? The systems have no diaphragm capacity (at least the ones I have witnessed have no capacity) That is why every line is a rigid frame. The girts distribute the wind load directly to the frames. Each end wall will either be a rigid frame or have a brace frame in it. The side wills will either have a portal frame or an X brace along the length somewhere. Roof X bracing is typical used the wind loads from the end wall to the side wall lateral force resisting system and is usually located in the bay where the roof bracing is located.

Roof purlins are typically continuous members. So, depending on the length of your building, you could just figure out the gravity load in your frames figuring the roof as a continuous member.

Seems like a lot of work to go through for a preliminary foundation design. You will still need to review the numbers provided by the manufacturer before issuing a set of drawings for construciton.

 

[oengineer]

@ oengineer, that's very helpful, instead of taking the column reactions from standard tables, could you please share any literature or worked example which explains how to apply the wind loads calculated from envelope method as per ASCE 7-10 on transverse and longitudinal frames on metal buildings. Also the formulas for static load calculation is from which book or literature ? looks too good.

The book that I obtained the frame formulas from is Structural Engineering Formulas by Ilya Mikhelson.

Using STAAD for the structural analysis & a spread sheet for determining the the wind pressures (based on ASCE 7), I calculated the frame reactions. I would think the formulas shown in my previous post (from Structural Engineering Formulas by Ilya Mikhelson) would be sufficient for the determining the column reactions. I was conservative when I applied the distributed loads to my frame, since I did not have any column reactions from a metal building vendor.

See if you can get a hold of the ASCE710 Wind Load spreadsheet calculator by Alex Tomanovich (see image below).

 

[oengineer]

Alex Tomanovich has another good spread sheet to use for frame analysis as well (see image below).

This would be helpful as well for the analysis.