I am designing steel pipe piles, for a site classified as SDC 'C', to support premanufactured electrical equipment cabinets. I am only designing the foundations.
The manufacturer of the cabinet does not provide any loading information other than the cabinet weight. They do not provide any information on the construction of the cabinet either.
In order to determine the loads to be resisted by the piles, I need to determine the SFRS of the cabinets so that I can select the appropriate seismic response coefficient for calculating the seismic loads.
Based on ASCE 7-16 Section 13.1.5, these should be considered nonbuilding structures similar to buildings so Table 15.4-1. But I don't know anything about the frame or bracing of the cabinet. So, I use Table 12.2-1 SFRS type H and R = 3.0.
I calculate the loads and then model the equipment, on the piles, in soil, in a 3D FEA program and limit the deflection at the pile head.
However, this 3rd party reviewer says that because of the piles, the SFRS should be classified as a cantilever column system or an inverted pendulum, corresponding to an R-value of 2.0 or 2.5 depending on how you classify the system, which I disagree with.
So, the big questions are:
Do the deep foundations change the SFRS of the equipment being supported?
Should the foundation elements effect the SFRS of the equipment?
Shouldn't the SFRS be specifically for the equipment being supported and not the foundation?
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Mae Benvenga P.E., P.Eng, M.ASCE
Daily Engineering Consultant, LLC
Fort Collins CO
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