Metal Building Foundation Design with Overstrength Factor

[bgsmith]

I am engineering a foundation design for a pre-manufactured metal building. I have received reactions from the metal building company. The maximum reactions they have listed for uplift are for seismic combinations that include an overstrength factor of 3 multilplied by the uplift caused by a longitudinal seismic load. For foundation anchors and footing design does the overstrength factor need to be included? If I remove the overstrength factor then a wind combination becomes the governing load. Any ideas would be appreciated.

 

[JAE]

I would use the magnified loads for the anchorage to the foundation.

For the foundation uplift designs you would use the 0.9D + 1.0E (for LRFD) or the 0.6D + 0.7E (ASD).

 

[bgsmith]

Thanks JAE,

Adding the vertical seismic load is it your understanding that I would use the LRFD ASCE combination of (0.9-0.2Sds)D + 3(overstrength factor)*Qe for achorage design?

 

[JAE]

Yes.