Salam
I am designing a 2 storey building columns are 12 " x 15", building is in seismic zone 3 so detailing require SMRF. for ties spacing according to ACI-308-08 section 21.5.3.2 the option a governs with d/4. my question is tie spacing becomes 2.625 inches as i consider d=12-1.5=10.5 for 12" side. Is this correct? is this practical spacing? should i increase the column dimension?it is not workable then column dimension of 12 inches cannot be used for SMRF.
Regards