seismic retrofit

[Robert222]

Existing condition: 2 story wood framed house on slope.
I am doing seismic retrofit.
1) How to investigate if the existing footing is appropriate? Do i need to dig or call soils engineer? I have never seen anybody to be doing this when doing seismic retrofit.
2) How to retrofit wood diaphragms if i don't want to remove existing flooring at floors or existing roofing at roofs (too expensive). That means i can't add any nails to diaphragms to have them stiffer.
thanks.

 

[Bagman2524]

IBC has soil classifications A-E for seismic analysis. You might be able to classify the soil based on general soil knowledge of the area, local government geotech information, other soil reports nearby or take new soil samples. Cross braced systems are usually best for resisting seismic loads. If the existing structure cannot handle the existing seismic loads, you will have to add structural support somewhere.