Peer-to-Peer Standards Exchange

We are looking for clarification on how to apply the resultant lateral force, Fht, to our rooftop equipment (box shape).

Should the force, Fht, be distributed along the projected area of one side of the unit at a time? (Checking for both positive and negative direction).

Is there a requirement to distribute the force along both the windward and leeward sides of the equipment concurrently. If so, what is the appropriate way to distribute the force between the windward and leeward sides?

A reviewer on our current job is asking us to apply Fht to both the windward and leeward faces concurrently. This would mean we have a total horizontal load on the equipment of 2*Fht. We are arguing this is not required and would double the net horizontal force on the equipment. 

Thank you for your time,

#ASCE7-22
#WindandWindLoads
#Tornado

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Trystan Golden
GKM & Associates
Souderton PA
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The forces on components and cladding specified in Chapters 29 and 32 are intended to assure adequate anchorage and bracing of the components, rather than design of the component walls.  The forces Fh and Fht are to be applied to the windward face of the component, considering all possible wind directions, at or above the centroid of the component.  There is no requirement to apply this force to both windward and leeward faces simultaneously.

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Ronald Hamburger, SE
Consulting Principal
Simpson Gumpertz & Heger
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