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Re: Factors

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Good explanation Steve. A coincidence; talked to an engineer yesterday who is designing substations in the New Madrid area.

Neil Moore, SE
shingle springs ca

On 2/21/2015 10:19 AM, V. Steve Gordin wrote:

These parameters are from the basis of seismic design in the US - ASCE7-10 (Minimum Design Loads for Buildings and Other Structures).

Ss is a mapped, short period, spectral response acceleration parameter
<> (essentially, a location-specific seismic acceleration) - an important component for the determination of the seismic force. Ss=2.6 is very high, higher than for
most of California.  Most of the equipment we design for is usually rated
for Ss<=2.2. This is not to say Ss cannot be higher - it can, in some areas of California and, particularly, in the New Madrid Seismic Zone.

Ip is the importance factor for the calculation of the seismic force on
non-structural components (ASCE7-10 Chapter 13). Ip=1.5 for hazardous (health or physical) or essential (hospital) installations, and 1.0 for other cases. The force computed based on Ss and several other factors is scaled up by Ip to get the design seismic force.


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