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Combining Horizontal and Vertical Earthquake Effects per ASCE 7-16 with ideCAD

How does ideCAD define combined horizontal and vertical seismic load effect, according to ASCE 7-16, for two earthquake directions?

  • Seismic load effects including overstrength is determined automatically.


Em = Combined applied design force on the horizontal and vertical seismic load effects
Emh= The effect of horizontal seismic forces including overstrength
Ev = Vertical seismic load effect
Ωo = Overstrength factor

Seismic Load Effects Including Overstrength

The seismic load effect including overstrength ,Em, is calculated in appropriate combinations in accordance with Eq. (12.4-5) and Eq. (12.4-6) as follows: Horizontal Seismic Load Effect Including Overstrength

Eq. (12.4-7) is applied to determine the effect of horizontal seismic force,s including overstrength, Emh.

The maximum effect of seismic forces, QE, from orthogonal load combinations is modified by the redundancy factor, ρ, or the overstrength factor, Ω0, where required, and the effects of vertical seismic forces, Ev, are considered in accordance with Section 12.4 to obtain the seismic load effect, E. These orthogonal combinations should not be confused.

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