Per ASCE7-16 section 13.3.1 for non

[calvin21]

Per ASCE7-16 section 13.3.1 for nonstructural components

For vertical cantilever systems Fp shall be assumed to act in any horizontal direction ASCE 7-16For vertical cantilever systems Fp shall be assumed to act in any horizontal direction.

I am anchoring an electrical equipment with 4 anchors down to a slab. Does that section imply I need to design each anchor for uplift/shear force I get by adding 100%Fp in one direction + 30%Fp in the other direction ?
Or just use the resultant of Fp and Fv and apply that horizontally along the shorter direction for max. uplift. ?

thread507-342310

 

[JoshPlumSE]

A slab is not a vertically cantilevered system. Therefore, you'd just use 100% of the Fp applied independently in any two orthogonal directions that you choose. Each of those forces would be concurrent with a vertical force of 0.2Sds*Wp, of course.

It's not a bad idea to use 100% + 30%. But, the code doesn't specifically require it.

 

[dold]

In component isolator design (and generally anchoring any component), it is common to apply Fp at the angle which produces the highest tension and compression forces in any given anchor. Generally speaking, this will occur when Fp is oriented across the corners. For example, if your equipment is a square with sides A and B (equal for a square, obviously), this angle would be tan^-1(B/A) = 45degrees for a square. This provides the highest uplift at each corner due to the fact that, while the moment arm "d" is larger, you only have one anchor resisting the uplift. (edit to say: you can always get lost in the forest by figuring out strain compatibility, etc, etc, etc where you have more than 4 anchors, but remember that your equipment isnt perfectly rigid either...)

Check out page 952 (of the pdf) this FEMA doc with great design examples: [URL unfurl="true"]https://www.fema.gov/sites/default/files/2020-07/fema_nehrp-seismic-provisions-examples_p-1051_7-2016.pdf[/url]