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StructuralEng, Consultant
Category: Structural Engineering
Satisfied Customers: 7185
Experience:  Structural Engineer
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I'm trying to find out the minimum size RSJ I will need to

Customer Question

Hi there, I'm trying to find out the minimum size RSJ I will need to span a garage door opening of 4350mm.
there is currently a rather primitive "Site made" gluelam beam made from 2 pieces of 1" plywood sandwiching a 1+1/2" softwood joist. I am replacing the garage door with a taller version which requires that I raise the height of the opening, the only way I can do this is to reduce the depth of the structural beam above, therefore the decision to changing from timber to steel. The existing beam is supporting a timberframe first floor at the gable end. Hope you can be of some help.
Submitted: 1 year ago.
Category: Structural Engineering
Expert:  StructuralEng replied 1 year ago.


Customer: replied 1 year ago.
Expert:  StructuralEng replied 1 year ago.

What is the span of the beam? What is the length of the joists that frame into it? I assume they're on one side only? It's supporting a single floor only? No attic and no roof?

Customer: replied 1 year ago.
Beam span is 4350mm, joists framing into it are 3600mm and yes, they're one side only. It supports a single floor which has a pitch roof above with attic space, however the roof trusses run parallel to the intended beam and are supported by the perpendicular exterior walls, so I'm assuming they aren't bearing any significant load to the intended RSJ?
Expert:  StructuralEng replied 1 year ago.

Thank you. Give me a few minutes to run some numbers.

Expert:  StructuralEng replied 1 year ago.

UC 152x152x37 is the smallest I beam you can use for this condition.

Customer: replied 1 year ago.
Ok, that is an awkward size to fit into the existing structure, is there a narrower beam I could use for instance 203 x 102 x 23, or would this not give adequate support?
Expert:  StructuralEng replied 1 year ago.

I selected the most shallow size to give you as much clearance as possible. The 203x102x23 will work, but only if you can provide lateral bracing to the beam at the ends and at the quarter points of the beam.

Customer: replied 1 year ago.
Ok that sounds good, what length should the end bearings be, and what would be the best method for sitting it onto the existing timber frame?
Expert:  StructuralEng replied 1 year ago.

4" bearing on wood

Expert:  StructuralEng replied 1 year ago.

Hello. Do you have any other questions for me on this topic. If you could rate my answer, I would appreciate it.

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