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Old 16th November 2009, 01:46 PM   #1
Chris Kenefick
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Join Date: Sep 2008
Posts: 30
Default Ridge beam problem

After having designed hundreds of ridge beams for 15+ years using Superbeam, I've had a request from a checking Consulting Engineer for the following :

"The open roof will need to act as a lateral prop to the walls hence we would request for the ridge beam to be designed for lateral loads currently considered"

Can anyone explain this and also how can I do this in Superbeam ?????
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Old 19th November 2009, 03:05 PM   #2
John Cranna
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Join Date: Jul 2008
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Default Re: Ridge beam problem

Dear Chris

I don't think the checking engineer knows what he is talking about. The idea of the ridge beam is to reduce the amount of lateral force/movement at the wall plate level by providing a much stiffer vertical support.

My experience has shown (via a 3D frame analysis program) that the mid span vertical defelction of a steel beam is equivalent to the lateral deflection of the timber joists that the steel beam is supporting. I limit the deflection of the steel beam to 8-10 mm. This can be in excess of the L/360, but this is to limit the lateral force on the wall.

If the loads on the steel beam are symmetrical then there should be no lateral load on beam. It is possible that wind load would cause an assymetrical load but I guess the forces would be much smaller the dead and live.
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Old 19th November 2009, 04:02 PM   #3
Chris Kenefick
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Default Re: Ridge beam problem

Thanks John, I tend to agree with your statement regarding the SE's knowledge, I queried his stance a couple of times and had two differing replies - it's sorted now as he requested that I upgraded the UB section, which I was quite happy to do and we won't be using this Lcal Authorities Building Control dept., ever again...
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