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Steel stilts - Wood house

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I am considering a seismic upgrade for an existing two story wood house that stands on 14 foot steel tube columns concentrically brace. The connections are butt welded to the columns.

These brace connections are not allowed in this seismic zone for new construction.

The two story wood framing can be analyzed as though its base is at the top of the steel braced frame.

Is there any concept or code that would prevent me using the flexibility of the wood to isolate the braced frame from the otherwise high shear loads due to its rigidity?

I am considering the Nonlinear Static Procedure (NSP) in the ASCE 41-06 “Seismic Rehabilitation of Existing Buildings”. My thought is that there is virtually no weight laterally and rigidly attached to the rigid steel frame. The horizontal and vertical wood diaphragms will absorb energy and possibly reduce seismic forces that would otherwise buckle the braces and fail the connections. The connections then might not require to be cut back for new steel gusset plates that would allow some yielding.

Otherwise I might consider this a voluntary upgrade and reduce the criteria to a level that the owner can afford.

David Merrick, SE

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