Hi all, Are the reduced superstr

[VoyageofDiscovery]

Hi all,

Are the reduced superstructure earthquake forces and moments, resulting from the application of appropriate Response Modification Factors, used when analyzing groups of piles?

VOD

 

[bridgeman1]

VoyageofDiscovery,

No, the pile group (or any foundation for that matter) must be calculated with an R-factor of 1.0 (i.e. elastic) or the plastic moments generated by the column(s), whichever is smaller. This is based on the capacity design approach, where it is assumed that you'll hit one of the two criteria before the other.

Each case is different, but more often than not the plastic loads govern. The R-factor reduction should only be used where energy dissipation is to be expected, and piles typically are expected to remain elastic.

I hope this helps.

 

[VoyageofDiscovery]

bridgeman1,

Thanks for your response, I see the forest from the trees

Regards

VOD