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vierendeel trusses

vierendeel trusses

vierendeel trusses

(OP)
I have a very interesting project coming up that will require the use of VERY LARGE vierendeel trusses.  I have looked through my steel texts, and my structural analysis texts, but can't find any information on them.  Does anyone know of a good reference for me to read up on this - just to get myself acquainted with this topic?

RE: vierendeel trusses

"Design of Welded Structures" by by Blodgett available from Linclon Arc Welding.

RE: vierendeel trusses

(OP)
Ah, the one book on my shelf I didn't think to look.
I will check it out!
Thanks!

RE: vierendeel trusses

Yeah.. I agree with jike.. its not even trusses. Its all fixed.  A lot of welding for sure.

Never, but never question engineer's judgement

RE: vierendeel trusses

Omer W. Blodgett's Design of Welded Structures discusses Welded Connections for Vierendeel Trusses in Section 5.13, Pages 5.13-1 to 8.

RE: vierendeel trusses

Wow, you people are too fast for me!

RE: vierendeel trusses

They are just basically 2 multi storey portal frames back to back, the analysis is similar.

Note that the deflection of a vierendeel is much higher than a normal truss of similar size and members. First time I did one I was surprised how much more.

csd

RE: vierendeel trusses

I've found StructuralEIT and COEngineeer to be "like lightining".  Always suspected them of Flash Gordon tendencies.  I bet their projects are always on time too!!

clown

RE: vierendeel trusses

(OP)
JAE-
That went over my head.  Was that a dig?

RE: vierendeel trusses

Obviously.  If that went over your head, you're already in the hole....  

Seriously though, the reason that Vierendeel trusses are plagued with so much more deflection is that shear contributes to the deflection to a much greater extent than with "normal" trusses with diagonals.

Mike McCann
McCann Engineering

RE: vierendeel trusses

A Vierendeel truss is just a moment frame turned sideways...just like a braced frame is just a typical truss turned sideways...

RE: vierendeel trusses

An engineering firm I know designed a temporary Vierendeel truss after I recommended that they rent an Acrow panel truss.  They said that the Acrow rental cost would have been too high.  So, the Vierendeel truss was specially fabricated but buckled as soon as they tried to lift one end.  They then had to repair and reinforce the truss.  A Vierendeel truss would not be my first chouce.  The joints are much more complicated due to their requirement to resist moments.  The design probably costs more than a more common truss.  The fabrication is probably also more expensive.  You will pay a higher price for a sleeker looking truss.

RE: vierendeel trusses

Blodgett has everything.  I find myself looking their first on a lot of issues.

RE: vierendeel trusses

Is there anything thats not covered by blodgett or Roarks!

RE: vierendeel trusses

How do you pronounce "Vierendeel"?

I've heard it said "veeeer - en - deal"
And I've heard it said "Vie - Ren - De - El"

I like the latter, but I would like to be correct.

"Is there anything thats not covered by blodgett or Roarks!" I don't know about Blodgett, because there's no index at the back of his books.

RE: vierendeel trusses

Not a dig...just an awkward compliment - recent months you two have seemed to pounce on posts quite well.

RE: vierendeel trusses

I've always heard it pronounced "veeeer - en - deal" - New York French.

"there's no index at the back of his books" - that's how he keeps the prices reasonable.

RE: vierendeel trusses

In the FWIW catagory:

I would be cautious about spending a whole lot of time studing the intricate details of a vierendeel truss at this time.

A lot of architects like to show them in the Concept Design stages becasue they look great. Quite a few get replaced by conventional trusses during the design (or construction) stage after the contractor tells the owner how much the vierendeel will cost.

Have shot myself (and my budget)in the foot a couple of times this way. Have gotten wiser to the game over the years.

RE: vierendeel trusses

I thought they use these trusses so you can put windows and stuff?  I dont think you can use diagonal member.  The architect wouldnt allow it i bet.

Never, but never question engineer's judgement

RE: vierendeel trusses

(OP)
Well, I don't really get involved in teh schematics of a project - although I am involved very early in this one.  We work with a lot of pretty big architects and have our projects covered in some architecture and engineering magazines (as well as local metro newspapers, but I am sure this is common for most).  The architects also work for clients for whom money is almost never an issue.  

I have yet to do a building with a braced frame because the architects always want the open spaces and don't want the restrictions of diagonals, so I am certain the vierendeel is here to stay for this project (our typical lateral resisting system is type II with wind connections).  In fact, if I understood the 10 minute discussion I had the other day with the project engineer, the complex geometry and large cantilevers is almost dictating its use.  I will find out much more in the coming days as I get introduced to the project more.  I will update if anyone is interested.

All of that being said, Blodgett has a very limited discussion on this topic.  I have also done a search on AISC and have come up with very little.  Does anyone know of any other references?

RE: vierendeel trusses

There's a vierendeel truss pedestrian bridge connected to the building I work in. It is clad; has a roof and windows.

I have some of the plan sheets; it's all full-pen welding at the joints.

Clear span - 220'
Width c/c of trusses - 22'
Height c/c of horizontal chords - 24'
There are bolted splices every 40" horizontal and at the midpoint of each vertical.

All members are A36 steel, built up "I" sections; all flanges are 20" wide.

The horizontal chords have 56" webs; web thickness varies from 5/8" to 1 1/8"; flange thickness varies from 1" to 2".

I couldn't find the web depth of the verticals but on an Elevation View, they're drawn the same size as the horizontals. Web thickness varies from 5/8"; flange thickness varies from 1" to 2 5/8".  to 3/4"

RE: vierendeel trusses

We have done a number of projects with Vierendeel pedestrian bridges after we had made that suggestion to the Architect. It never was a cost issue on these projects.

RE: vierendeel trusses

forgot to mention - all flange splices use 1 1/8" A490 bolts; all web splices are 7/8" A490.

A490 - what every ironworker loves. sad

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