Do you consider that your Purlins restrain unbraced length of top chord?
Do you consider that your Purlins restrain unbraced length of top chord?
(OP)
Hello guys,
I have a questions for you about unbraced length of a top chord. I have a supervisor and we are trying to design a big and long mall.(Span = 45m/147' and Length = 20@10 m / 20@33') To make it economical, he is thinking "We should assume that purlins restrain top chord beacuse of 5 mm Cold-Formed Profiles."
Though we are using bridging trusses, he insists that we should accept that purlins restrain in order to make it official. I made a research but cannot find anything that can be referred. I am telling him that it might restrain but we should not assume it does.
So, what is your opinion about this assumption. If you tell me a reference (such as book or a Standardt/Specification) I would be appreciated.
Thank you in advance.
I have a questions for you about unbraced length of a top chord. I have a supervisor and we are trying to design a big and long mall.(Span = 45m/147' and Length = 20@10 m / 20@33') To make it economical, he is thinking "We should assume that purlins restrain top chord beacuse of 5 mm Cold-Formed Profiles."
Though we are using bridging trusses, he insists that we should accept that purlins restrain in order to make it official. I made a research but cannot find anything that can be referred. I am telling him that it might restrain but we should not assume it does.
So, what is your opinion about this assumption. If you tell me a reference (such as book or a Standardt/Specification) I would be appreciated.
Thank you in advance.






RE: Do you consider that your Purlins restrain unbraced length of top chord?
RE: Do you consider that your Purlins restrain unbraced length of top chord?
The purlins likely will brace the top chord for out of plane buckling. Depending on the nature of the connections, however, they may not brace the top chord torsionally. In that case, the top chords would need to span between truss panel points for lateral torsional buckling checks.
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.
RE: Do you consider that your Purlins restrain unbraced length of top chord?