expanding an opening on existing tilt up panel

[MelStud]

I need to cut an opening on an existing tilt up panel. There's already a 9' door opening but they want a 20'x20' door so we need to make that opening bigger. We have no information about the panels (no size, thickness or rebar info). Given the size of the new opening I want to frame it. I need some guidance on how to do this, does the framing goes around/inside the opening? Does it go outside (to the inside of the building, attached to the panels)? See sketches attached. thanks

 

[clarke1973]

I'm sure I'm stating the obvious here but you need to have more information before you can simply go cutting into the panel.
Have you established whether the tilt ups are load bearing? If so, are they stability elements (i.e shear walls)?
If they are simply facade elements, or even just vertical load bearing panels, a steel lintel frame around the inside of the cut opening could be used to transfer the load.
You need to have an engineered solution though. I would start by establishing the relationship of the panels with the building structure. You can then then find out other properties such as reinforcement, concrete strength using various non destructive testing.

 

[msquared48]

This is usually handled with steel tube or I sections at the inside of the new opening to take the vertical and lateral loads.

Usually the new tube sections extend from the floor slab to or very near the roof diaphragm.

Looks like you will be cutting a lot of vertical steel at the panel edges, as well as lintel steel.

Mike McCann, PE, SE (WA)

 

[3DDave]

You should hire a structural engineer to make a site visit.

Your sketch shows that you will leave one panel fragment levitated in the air by something and that fragment will have minimal edge distance to a large opening in the fragment. Much like a guillotine blade.

This looks like a disaster in the making.

 

[KootK]

Like Mike, I usually see steel members installed on the interior side of the panels with the vertical members running full height or near to it. If nothing else, that's often required in order to get reinforcing membesr to function adequately as wind columns. The sketch below is for reinforcing new panels with concrete beams and pilasters and is taken from the ACI document on tilt-up panel design. Pretty much the same concept.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.