Structural Engineering steel beam
aventino68
| Posted in Construction Techniques on
Have our 36ft x 50 ft roof extending out a further 12 ft off the front of our 1:12 flat roof cottage build. So I need an I beam 50ft long that will be supported by poles at each end to support the roof and the wood I Joists making up the roof construction. I would have thought there were simple tables utilising snow loads for our area (Napanee Ontario) and spans that would make this not an over complicated job for a structural engineer. Can any engineers tell me if this a complicated design problem?
Replies
Yes. No.
But you might get better results if you let the engineer suggest structural solutions.
Why not trusses and no beam at all?
That would be a 12 ft cantilever if there was no beam and posts holding it up. I'm basically replacing a wall with a beam and posts at each end. I looked at cantilever but with the snow loads in my area, the size of the roof structure possibly required and the complexity of the calculations required for a cantilever I decided it was too difficult. The design is basically like the photo which ironically came from a steel tables pdf I found online.
Is there a driver for a flat roof?
that being said, any steel place should be able to help with your calculations.
There are calculators online as well.
https://webstructural.com/beam-designer.html for example.
Tables for design loads are available. (need to verify these are current and apply to your jurisdiction.)
http://fore-engineering.ca/includes/SCAN0003.pdf
Play a little and you likely will see that trying to get a single 50 foot span will be a challenge. the photo you posted looks to be less than half of that distance.
This is just a thought process, and you really need the advice of an engineer.
I agree with the above that you need to get an engineer involved before you get too far down the line. For a 50' span carrying snow load you may be in the range of at a 24" to 27" deep steel beam. Total weight of the beam will likely be over 4,000# and columns, footings, lateral bracing, and connection details of this beam will need to be carefully thought out and planned.
The links unclemike42 gave you might be a good starting place for planning purposes, but a 50' span beam with both high snow load and wind uplift loads and potentially very little room for bottom flange lateral bracing is definitely not a DIY kind of job.
You also should consider beam erection and logistics. Getting a 50' long 4500# piece of steel into place in an existing structure is no joke.
If this were me I would be seriously considering finding somewhere to put some interior columns to break up this span a bit.
Good luck with the project.
Please share the final result later)))
This is not a simple Span Table resolution. There's much more to it.
Engage a structural engineer to determine the best solution for the structure as a whole.