STRUCTURAL ANALYSIS OF TEMPORARY BOARD-UP 5

[fadre]

I've been given the task of structurally analyzing this board up but I'm having a hard time figuring out the process. I've already calculated for the windload but i don't know where to go from there. Sorry if it's such a basic question. Thanks in advance.

 

[klaus.]

why do people think structural calculation and design so easys that everybody can do it ???

 

[MIStructE_IRE]

Are you a structural engineer?

 

[fadre]

No I'm not which is why I'm having a particularly hard time with this task.

 

[SRIVINAY]

generally i will start my design from the top of the structure. for example if i am designing a ware house after knowing actions on the structure first i will design sheeting then purlins then trusses then columns then base plat and foundation in a flow

 

[EZBuilding]

Is that a rope or chain in the back of the sign? Make sure you specify it needs to have a minimum compressive capacity...

 

[XR250]

You need to hire a Structural Engineer. If not, could you be specific about your GPS coordinates so I can avoid that area?

 

[fadre]

That's actually a rebar behind the sign. Welded to a GI bar. I wasn't the one who designed it, they just asked me if I could compute it. I just wanted to learn how really. Thank you for the ones who aren't making fun of my thread. I went here for help, not sarcastic answers.

 

[fadre]

I guess I'll have to start from the GI sheet-purlins-GI pipe-Steel bar? I'll have to analyze them one by one?

 

[klaus.]

@Fadre
we are not making fun of you... but qualified structural engineers should to the job designing structures
What can happen if something goes wrong you can see in New Orleans and other accidents
If your 'board' is not designed properly it might blow away in a strong wind and kill somebody ....

 

[fadre]

There's a proper way of saying it then. I get your point but the other guy didn't have to be sarcastic. I mean I'm trying to learn here. I'm trying to analyze it so I could check if it's capable. Come on guys, I just need some help.

 

[WinelandV]

You say that you're supposed to design the "board up". Does that just mean the 27 ga. green sheet? Or are you to analyze the whole system? (concrete foundation, rebar "brace", the purlins, and the pipe)

Assuming you mean the latter, the general workflow is:
- figure out your geometry such that you can start determining loads.
- determine your loads
- apply your loads to the features that receive those loads
- chase those loads through the system into the ground (this is where knowing how the structure will behave comes in).

In your case, the wind blows (could be from L-R, or R-L, so you'll need to check both directions) on the green sheet - likely checked via a manufacturer's specification sheet. Green sheet is connected to the purlins at some spacing, load is transferred to the purlins at these location, likely a bolt or a screw - connector needs to be checked for the load. Looks like the purlins are going to transfer the wind load to the pipes via weak axis bending and shear - purlins to be checked for those internal forces. Purlins are connected to the pipes, check the connection. Pipes are now loaded, and here's where things get funky:

- is the concrete foundation only to resist sliding, or is it sized to take over-turning moment?
- how often is the rebar "brace" occurring? I have doubts of the rebar's compressive capacity at 2+ meters of length. Unless they're absolutely huge.

After that, you need to size your foundations for whatever reactions forces you need them to take. (The soil-nail rebar embed detail seems dubious to get to calc out.. you may need to call for a field load test to show that you have enough capacity.)

This is the 30,000 ft view. There's all kinds of little bits inside of each of those steps. When I was a new engineer, I was given tasks and let loose to figure it out on my own, but my boss/mentor was also reviewing what I was doing at the end of each day. Hopefully whoever gave you this task is going to be over your shoulder, pointing/pushing/nudging you in the right direction.

On the other hand, if this just something that you're supposed to whip out because it's "not a big deal, it's just a stupid view blocker", then you need to push back that you don't have the necessary experience for this.

 

[fadre]

Thanks so much @winelandv
I'll actually be computing this with a structural engineer tomorrow. I actually want to transition to structural engineering which is why I just wanted the general procedure for this. For sure I won't let them build this if it is unsafe to start with. Thank again, I appreciate your help.

 

[fadre]

And to answer your question, yes I have to analyze the whole system.

 

[MIStructE_IRE]

If its for learning purposes only then the below link will give you some good guidance. As you can see, its no simple task if you’re not an engineer..

http://www.crawley.gov.uk/pub_livx/groups/operational/documents/plappother/pub208452.pdf

Your employer’s insurer might not be terribly pleased about this btw.

 

[WinelandV]

That's a great resource, MIStructE_IRE. Thanks for sharing that!

 

[fadre]

Oh wow. Thanks so much @MIStructE_IRE
This is such a good reference. These are hard to find. Appreciate it.