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ASCE 7 Cl. 12.4.2 & 12.5.4

ASCE 7 Cl. 12.4.2 & 12.5.4

ASCE 7 Cl. 12.4.2 & 12.5.4

I am designing a steel structure in Seismic Design category E using Equivalent Lateral Force procedure. As per Cl. 12.5.4, I should consider 100% seismic load in one direction + 30% seismic load in perpendicular direction.
As per Eq. 12.4.1/12.4.2, I should also consider Ev+-Eh.
Should I apply 30% Ev while combining it with Eh, i.e. 100%Ehx + 30% Ehz + 30% Ev? Or should I consider full effect of vertical seismic load, i.e. 100%Ehx + 30% Ehz + 100% Ev?

RE: ASCE 7 Cl. 12.4.2 & 12.5.4

My first thought would be to use 100%Ehx + 30% Ehz + 100% Ev but I'm not near the code right now.

RE: ASCE 7 Cl. 12.4.2 & 12.5.4

Thanks JAE.
When you have a moment, could you pleae look into the code and let me know your views.

RE: ASCE 7 Cl. 12.4.2 & 12.5.4

100%. Code actually handles vertical seismic load by using a fraction of the dead load and dumping it in with dead load in the combinations (see, so should always be 100% Ev barring either of the exceptions listed in, whether you have orthogonal loading or not.

RE: ASCE 7 Cl. 12.4.2 & 12.5.4

Thanks MarkHirschi for your response.


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