A Lot of Help!

[nocheepgas]

I know the naysayers will advise me to keep away from this:
I have the structural welding ability, just lack some engineering knowledge. A buddy has an existing set of steel stairs (lying on the ground) they are well made industrial type stairs with a diamond plate tread. 7.25" rise with approximate run of 9". He wants (me) to install them around the back of his house, wrapping a platform and 5 new steps around a corner of his home. The kicker is that the platform and ensuing walkway will need to be cantilievered to avoid inhibiting access to the garage. I 've looked at some Residential Steel beam and Column Load Tables http://www.toolbase.org/PDF/DesignGu...SpanTables.pdf but they might as well be in Arabic for what I can get out of them
Here's some rough sketches of the project. Anybody out there willing to help me size a few columns and beams?

[Portable Welder]

The easiest way would be to stick with the 10" channel, However you diddnt mention what size your channel is If its 10" junioe at 8.4 Lb it would propbably be to light.

If its 10" at 15.3 your set, 2 of them running parallel 3' apart.

Whats the surface going to be! A pan with concrete or wood. eather wat you should be fine.

Column size 3x3x3/16" or 4x4x1/8".

I would be concerned about the size of wood lamb.

I dont like the fact that you only have a 9" tread however.

The way you tie the channel together at the joints will be of concern, you will want your flanges to run continuous even if it means welding a stiffener from one flange to another.

[nocheepgas]

I think I will advise him to have a professional engineer the structure, then I will be happy to weld it! It seems the outer columns will have to support both the weight of the walkway and the steps and that the inner columns would be approximately weight neutral, with the cantiliver wanting to lift that portion of the structure.

BTW: The run on the existing stairway is 9" but the treads are 12" long, extending beyond the tread on the next riser.