Metal Building Foundation Design with Overstrength Factor

Question

Metal Building Foundation Design with Overstrength Factor

bgsmith (Structural)

(OP)

12 Dec 07 11:28

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 (Structural) · Answer 1 · 2007-12-12 11:53:57

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 (Structural) · Answer 2 · 2007-12-12 12:18:45

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 (Structural) · Answer 3 · 2007-12-12 13:05:55

RE: Metal Building Foundation Design with Overstrength Factor

JAE (Structural) 12 Dec 07 13:05

Yes.

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Metal Building Foundation Design with Overstrength Factor