Large uplift forces

[Lion06]

AISC has a detail on page 14-9 of the 13th edition manual (Fig 14-7(b)) that I'm trying to find a design example for for all of the components. Does anyone know where to find one?

 

[Lion06]

I think I just found an example in Blodgett on page 3.3-13. I'll let you know.

 

[ToadJones]

the column clips or the anchors?

 

[Lion06]

The channels, stiffeners, and welds. I believe I have a handle on the checks, but my boss would like me to find an example.

 

[ToadJones]

I found a paper buy some guys at Bechtel on the anchorage if interested, I can post.

 

[slickdeals]

http://www.bechtel.com/assets/files/TechPapers/design-of-anchor-reinforcement.pdf

 

[Lion06]

Yes, please do!

 

[ToadJones]

There, I had slickdeals post it for me

 

[Lion06]

That paper looks like it is just for designing reinforcement to lap with the anchors to get away from App. D calcs for breakout. Is that true?

Not quite what I'm looking for.

 

[ToadJones]

I have had to design a few large base anchorage/ base plates in the past for both moment and uplift.
To be perfectly honest, I designed them one a piece-by piece basis using basic stress analysis, ASD and applying allowables where I could. I have always found Blodgett to be VERY practical and I used many of the same approaches.
Most of the large bases you see basically try to get away from having a plate in bending by substituting what is basically a built up beam to take the bending while transmitting tensile forces to the anchorage.

 

[Lion06]

I'm trying to figure out the design of the stiffeners to the column flange.

 

[ToadJones]

Blodgett addresses this, no?

 

[Lion06]

I didn't find it. Do you know where he does? The example I found just gives the stiffener thickness.

 

[LSPSCAT]

Blodgett Section 3.3 Pages 3-20 - 3-27

He also tackles stiffened seats - basically what you are doing upside down in Section 5.3. Note that Salmon and Johnson have updated ideas on calculating the stiffened seat with some different equations for the capacity of the stiffener. (Basically trying to isolate a portion of the stiffener and treat it as a column and them applying some flat plate theory limitations)

Have fun! Its a great problem to investigate in heavy industrial work.

 

[westheimer1234]

i didnt know bechtel post "technical papers" on their website..

anyway, i am still hurting from the interview i had with them 2 weeks ago.. asking me about expansion joint for long piperack modules.. which i probably gave a stupid answer coz i didnt get the job.. =(

 

[Lion06]

I don't see where Blodgett addresses the actual stiffener design. I am talking about the stiffeners in the channel in problem 3 om page 3.3-13.

I'm just using the provisions from AISC spec section J10.8, which kicks you back to E6.2 or J4.4, depending on the slenderness. J10.8 also allows you to use kl=0.75h.

Does this seem reasonable?

 

[ToadJones]

sounds reasonable...
As I alluded above, in situations where there isn't a specific design example, just apply your knowledge as you see fit and bounce it off a few guys to see if there is anything you might have missed.
I have run into situations like this a lot doing heavy industrial work.
This is probably why companies like Bechtel wind up with teams of guys doing research for them.