Lateral deflection estimation of portal frame

• Apr 25, 2015

• #2

KootK

Structural

Oct 16, 2001

18,589

One good method is to apply virtual work to your portal method sub-assemblages using the moment diagrams that you determined using the portal method. I know, it sounds onerous. However, because your moment diagrams are just triangles, it simplifies quit nicely.

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• Apr 25, 2015

• #3

KootK

Structural

Oct 16, 2001

18,589

There's also a good method by Muto in the appendices to Priestley and Paulay's classic text on the seismic design of concrete and masonry buildings. You'd need to be able to bring some charts with you however.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

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• Apr 26, 2015

• Thread starter
• #4

GeorgeHolland

Structural

Mar 12, 2011

4

Hello KootK

Oh great, that's good news. Searched a long time on Web for references. Do you know a good example solution for this?

 

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• Apr 26, 2015

• #5

KootK

Structural

Oct 16, 2001

18,589

You can find virtual work examples most anywhere. The only place that I've seen the method developed specifically in conjunction with the portal frame method is in this book by Lynn Beedle Link

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

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• Apr 26, 2015

• #6

JAE

Structural

Jun 27, 2000

15,590

I had this portal deflection question posed to me at my graduate oral exams. The answer was that you can simply take the moment diagrams up the length of one column and use the moment area method to get the deflection quickly at the top. Similar to KootK's first post above.



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• Apr 26, 2015

• Thread starter
• #7

GeorgeHolland

Structural

Mar 12, 2011

4

Okay, so having had a look at virtual work and moment area method I think I've found a simple short hand technique for calculating inter storey deflections. Attached pdf of the approach, could anyone verify if this is the correct interpretation. I cant find a specific example online to compare with but tallies with a portal frame model[URL unfurl="true"]https://res.cloudinary.com/engineering-com/image/upload/v1430070456/tips/Portal_deflection_qq0liz.pdf[/url]

Seems to tally with computer results, any thoughts?

 

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• Apr 27, 2015

• #8

KootK

Structural

Oct 16, 2001

18,589

JAE's method definitely seems like the way to go. Virtual work is substantially more involved as you can't ignore the beams.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

 

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• Apr 27, 2015

• #9

Hokie93

Structural

Sep 9, 2007

375

In case you aren't familiar with it, there is a good discussion of this topic in Chapter 7 of "The Seismic Design Handbook", second edition, by Farzad Naeim. He covers lateral deflection of both moment frames and braced frames.

 

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