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Re: Seismic design metric factors for UBC chapter 16

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Why should the coefficient 1.25 be changed when working in S.I. units. 
Look at how C is used to calculate V.  Do a dimensional analysis of the
equation V=Z*I*C*W/Rw.

Z    gravity
I      dimensionless
W   force/ 1 gravity
Rw dimensionless
V    force

force = gravity * dimensionless * C * ( force/ gravity) / dimensionless

canceling out terms it leaves us with :

force = C * force

Thus C has no units and as a result will not change in a different set of

Note that T is specified in seconds which is also a metric unit and S is a
scale factor with no units.

Mark Gilligan