N. SUBRAMANIAM BOOK OF RCC DESIGN GAVE THIS SYNTEX
*SCALE FACTOR = (0.16/2) × (1.5 / 5) = 0.024SPECTRUM CQC 1893 X 2.078 ACC SCALE 0.024 DAMP 0.05 MISSOIL TYPE 2
IN THIS CASE ACC SCALE VALUE IS CALCULATED USING Z/2*I/R BUT IN STAAD HELP CONTENT VALUE OF SCALE FACTOR IS DEFINED AS "Linear scale factor by which the spectra data will be multiplied. Usually used to factor g’s to length/sec2 units. This input is the appropriate value of acceleration due to gravity in the current unit system (thus, 9.81 m/s2 or 32.2 ft/s2)".
WHICH ONE IS CORRECT?
hope this helps.
It can not be said wrong directly, as the book is not a help content of STAAD. But in STAAD Scale is used when user provides data for ground acceleration. Normally for codes, scale should be used 1 as already 'g' value has been multiplied internally with ground acceleration data. If the data are not normalized then you can use scale to normalize the same.
Base shear value shall be directly proportional to both the factors so It doesn't affect the result where you assign 9.81 and where Z/2*I/R. However I would recommend you to follow STAAD help as they are the one who developed the software.