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Truss camber

Truss camber

Truss camber

(OP)
We have a 123 ft. long by 10 ft. deep steel truss. The customer drawing specifies the required camber at each of the panel points. How does one go about fabricating the truss with the camber in place? Step by step instructions would be great.

Thanks.

RE: Truss camber

I would assume that you are building more than one truss and therefore have a jig of some sort.

Simply snap a straight line at the bottom chord and measure up at the panel points.  Build the truss following these new points.

RE: Truss camber

Most truss companies, including the one I work for use lasers to build trusses. The camber is built into the program and projected on the table. Without lasers, snapping a line would probably be the best method.

 

RE: Truss camber

Actually this isn't true. Floor trusses are built with "Camber", the table in which the floor trusses are built is Cambered. Most if not all truss manufactures do NOT build camber into the truss.  Only "special" Long span and Pole barn truss Manufactures build with "camber". Inquire this at all long span manufactures.

RE: Truss camber

EwpDesigner,
I note that you are a new member, but you are getting off on the wrong foot by commenting on an old thread that "Actually this isn't true."  The thread is about a long span steel truss, thus your post makes no sense.  

RE: Truss camber

hokie...you beat me to it.

RE: Truss camber

I am responding to the "The camber is built into the program and projected on the table" WHICH IS FALSE. That's all just being accurate not argumentative, which has nothing to do with old posts or new member!

RE: Truss camber

Just how do you know that icfbunt's statement is false?  He says his company does it that way, which sounds feasible to me.  The part of his statement which could be questioned is "Most truss companies".  I still think you owe him an apology.

RE: Truss camber

Because I have been in the Manufacturing of Components
(Floor trusses,Wall panels, Roof trusses etc...) for the last 12 years. Familiar with Many truss tables and multiple software programs.

RE: Truss camber

I have worked with a fair amount of wood truss manufacturers, in the pass twenty-five years. Some built with camber in the trusses, others don't. Some only camber pitch trusses over 30' or 36' and flat trusses over 25' or 30'. But camber is a judgment call (based on what their clients want) on how much the truss will deflect/creep and when.
The reason for camber is deflection and wood creep. Creep will happen over ten plus years. Now you can build the trusses flat and have a sight downward bow in the ceiling from day one and let it creep down. You can use camber for a flat ceiling from day one and then let it creep. Or you can use camber for a upward ceiling from day one so that it will be a flat ceiling in ten years.
As for software programs, when camber was wanted but could not be inputted into the program, typically the manufacturer cut the webs a 1/8" to 1/4" short to camber pitched trusses. Flat trusses were just "bent" in the jig for camber.

Garth Dreger PE
AZ Phoenix area

RE: Truss camber

I can see this is turning into an argument. Forward your response to an actual P.E. that Seals truss drawings for a living. The Truss engineering analysis shows US TRUSS Designers LL Deflection, DL Deflection, TL (Total Load) Deflection, Horizontal Deflection. ETC.......We are NOT responsible for long term CREEP that WILL occur over time. Read the TPI (Truss Plate Institue) and WTCA (Wood Truss Council of America) and ICC (International Code Council).
and The IRC 2009.  In those you will also find that Truss designers and Manufactures are not responsible for a whole array of things that the Engineer of record is.  Now if you think that trusses "Creep" at 10 years you are a Magician!
I suppose you recommend nailing the bottom chord of the trusses to all interior walls also?? Then you will wonder why their are excessive drywall cracks and in some instances walls literally seperating from the subfloor.
I suggest visiting a truss line and look at the Steel table in which they are built, notice it is straight. Now try to "bend" the trusses.  I can design the trusses you mentioned with Minimal LL and TL deflection and NO bracing, but you won't like the Price.........So end of discussion for me, some people just like to argue a point in which they don't have hands on experience with.

RE: Truss camber

ComponentsDesigner, I am a actual PE in Arizona and California, not a magician and I have
1) Design wood trusses (off and on) since 1984 and sealing them since 1992.
2) I understand the CYA that the WTCA, TPI, etc. states about the responsibility for wood trusses.
3) If you read my note I said "...camber is a judgment call (based on what their clients want)..." The clients being the framers who have to deal with the callbacks on their jobs.
4) I have also gone out to jobs (not many, but a few) ten years down the road and have seen the creep in the ceiling.

Garth Dreger PE
AZ Phoenix area

RE: Truss camber

If you fellows want to argue about wood trusses, why not start another thread rather than tacking on to an old one about steel trusses?

RE: Truss camber

hokie66, I apologize for answering a comment, that was not about the the original question, that I felt was inaccurate in an argumentative way.  

Garth Dreger PE
AZ Phoenix area

RE: Truss camber

Garth,
Not your fault, and no apology necessary.  Your comments were entirely appropriate.

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