IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
(OP)
Hi all,
can someone help me? I don't understand if i have to use response modification factor when i design foundations (overturning, soil pressure....) or if i need to work in elastic condition (no ductile-dissipative foundations).
can someone help me? I don't understand if i have to use response modification factor when i design foundations (overturning, soil pressure....) or if i need to work in elastic condition (no ductile-dissipative foundations).






RE: IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
RE: IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
I'm designing a building with ordinary shear walls. I calculated the Sms Sm1, Sds Sd1, The base shear, the R factor (5) and overstrngth factor (4.5). I use the modal analisys and I reduce the spectrum with R factor for section design.
My question is: For the overturning and for the soil design have I to use the reduced spectrum or i have to increase it with the overstrenght factor?.
I make this question because I'm italian and in Italy we have to design the foundations with the elastric spectrum, and it sounds strange to design a foundation with a reduced spectrum.
thank you
RE: IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
You do not generally have to increase the foundation design forces by the overstrength factor. I've seen folks design the attachment of their piles to the cap per the overstrength. But, I've never seen someone design the entire slab per the overstrength.
RE: IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
thanks very much
RE: IBC SEISMIC FOOTING RESPONSE MODIFICATION FACTOR
The foundation just need to be designed for conventional load combination, make sure you include the siesmic vertical component and redundency factor (if applicable).