Castellated beam design

[auswhat]

I have to design a beam, as light as possible, in normal steel and since my shears are not high, i wanted to use a twin web box girder with castillated webs. I have to design it to the British Standard. Does anyone know of a good reference where i can get a step by step design procedure for a castellated beam?

 

[Taro]

Although not geared towards British standards, Design of Welded Structures, by Blodgett, covers this topic using US ASD procedures. The book can be ordered from Lincoln Electric for US$15 at

http://www.lincolnelectric.com.

It's a cheap investment for a good steel reference book.

 

[RiBeneke]

Many years ago the British Steel Construction industry set up an organisation called Constrado. They published worked examples on many designs including castellated beams. Maybe they, or their successor, have something still in print.

 

[euler69]

Does anyone know where I can find information on justifying a castellated beam capacity in a non-simple span condition? I have to be able to justify some castellated beams that are used in continous span conditions. They have been modified by adding end plates and are bolted together. I already looked at Blodgett's design example and he only addresses a simple span condition. I also e-mailed the eng. dept for AISC and they have no advice/suggestions for a castellated beam design. They refered me back to Blodgett. Where did Blodgett develop the means of calculating castellated beams. Was it God sent? I know they are designed similar to a Vierendeel truss, but I have never designed either!

 

[Lutfi]

SMI fabricates smart beam (their trade mark) for castillated beams. They have calculations, load tables, cad details and more at their web site

http://www.smisteelproducts.com/English/About/About.html

Also Dr. Omer Blodgett's "Design of Welded Structures" has a dedicated portion on the design of these beams.

My favorite part about them is you lose no weight, increase depth (I) and gain lots of strength plus the web openings can be used for other trades.

Good luck

 

[flamby]

On the flip side, your castellated beam may be sensitive towards lateral tortional buckling, web buckling or web crippling. I do not prefer these for these potential hazards, as well as for increased fabricational efforts.

 

[euler69]

Lutfi:
I have already contacted SMI and I have their excel spreadsheet for non-composite castellated beams. SMI only addresses simple span conditions. I on the other hand have a non simple span condition (cantilever or 2 span or more). I have already looked at Blodgett's example and it only addresses a simple span. I also have "Castelite's" catalog w/ interaction diagrams. I have been told from SMI that these only address simple spans.

 

[dbuzz]

Knowles, P.R.,
Design of castellated beams for use with BS 5950 and BS 449
The Steel Construction Institute, 1985
ISBN 0 86200 039 4, 54 pages, 21 figures, A4 paperback

Provides the designer with design methods, safe load
tables, and interaction curves to enable suitable
castellated beam sizes to be selected and analysed.
Ultimate capacities are included suitable for designs to
limit state concepts, as given in BS 5950, whilst the
safe load tables are based on permissible stresses in
accordance with BS 449.

 

[fleisher]

In the latest edition of my STAAD program, they say they do castellated beam design as per Blodgett and some paper by Redstone. Again, they only support simply support beams. Maybe you want to call them and ask why...I would suppose because that is the way any text does it.