Stainless steel tube weight load

[Atrium]

I'm building a sun cover for my open air atrium. Dimension is 8x8 ft. I'm building with clear cedar(ver expensive). In one direction, I'm placing 19 8ft 2x4 cedar boards tilted vertical and spaced 5 inches apart. Knowing the boards spanning 8 ft, anchored at both ends to the square frame, will sag as moisture penetrates during the winter. Question. I want to place on top of the 19 boards a stainless tubular beam! At the mid point and perpendicular to the 19 boards. The beam will attach via screws every 6 inches. The weight dry for each cedar board is 6.5 pounds. What should be the dimensions and thickness of the stainless (or other metal) to ensure support of these 19 boards? How do I factor holes drilled and water weight of boards? Any takers on this? Thank you!

 

[Greg Bernhardt]

I'm sorry you are not finding help at the moment. Is there any additional information you can share with us?

 

[Atrium]

Greg I'm not sure what additional information is required. I don't think this is a particularly complicated question or technical spec, so not sure why no responses. Anyone with metal expertise would have an answer off the cuff, no calc required. Thanks for checking in. Appreciate your forum monitoring.

 

[AlephZero]

Well, you haven't told us whether you are building this in the Arizona desert or somewhere with 10 feet of snowfall every winter, so how do you expect us to guess what the moisture content might be?

I think you need to talk to an engineer, architect, or buildings inspector who understands your local building code regulations, not get advice from random people on the internet.

 

[Atrium]

A rather strange response. This specific forum is asking technical questions, as per other postings. If you want to ask followup questions, simply ask but don't shut down a legitimate posting question by redirection. I btw, have received exceptionally good advice from "random people" on the internet. Pls don't respond unless you have something positive to add to my question. Thanks.

 

[zarajohn]

Hello,

I have a just little bit knowledge. The http://www.scoop.it/t/best-quality-industrial-products-and-servicespipes and tubes while tubes are by and large utilized for burden bearing or mechanical purposes. Stainless steels are composites containing iron, moderately low carbon, least 10.5% chromium and up to 30% nickel. Be that as it may they are commonly 18% chromium and 8% nickel. For expanded consumption resistance or for assembling necessities in particular applications, chromium may be expanded and different components, for example, manganese, aluminum, titanium and/or molybdenum may be included as needed.

Thanks

Zarajohn@

 

[dipstik]

based on http://www.wood-database.com/lumber-identification/softwoods/western-red-cedar/

and

http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch03.pdf

it looks like the weight can be as much as 4 times the original weight. the load will be somewhat uniform along the tube. Thus you can use the diagram here http://www.atcpublications.com/Sample_pages_from_FDG.pdf to determine the limit you want on the tube deflection. you can get I from here https://en.wikipedia.org/wiki/List_of_area_moments_of_inertia .
you should consider extra force due to trying to correct the deformation of the cedar beams. this will be the load required to flatten a bent beam. maybe 50 lbs or so, hard to say without doing another flexure model.

the holes will contribute a reduction factor, typical proportional to the volume loss of the beam. you may be able to get better estimates from group action equations found in the NDS, but that is typically for multiple fasteners in a single member. you will be removing material from the area with the most stress, and effectively contributing to tension in the wood against the tube. you could use weathered cedar data to ensure you don't induce splitting midspan.

hope that helps.

 

[berkeman]

A rather strange response. This specific forum is asking technical questions, as per other postings. If you want to ask followup questions, simply ask but don't shut down a legitimate posting question by redirection. I btw, have received exceptionally good advice from "random people" on the internet. Pls don't respond unless you have something positive to add to my question. Thanks.

It's a safety issue. I agree that you should consult your local building codes and the associated enforcement office. Since this is structural, you likely need to get a permit for it, and get it inspected and signed off at the end of the project. Thread is closed.