# Vertical Earthquake Analysis with Local Vertical Vibration Modes

Vertical seismic load effect is determined automatically.

Mode number should include vertical modes. Mode count is defined by user.

**Symbols**

* D =* Dead load

*Design vertical response spectral acceleration*

**S**_{av}=*Vertical seismic load effect*

**E**_{v}=Vertical response spectrum should only apply structures in Seismic Design Categories C, D, E, and F. Determining of vertical response spectrum, Vertical Response Spectrum is expressed in ASCE 7-16 Section 11.9.

According to 11.9.3, the design vertical response spectral acceleration, S_{av}, is determined as two-thirds of the value of S_{aMv} determined in Section 11.9.2.

The vertical seismic load effect, E_{v}, is determined in accordance with Eq. (12.4-4b).

It has been **determined** that the vertical earthquake effect has an effect on the building behavior as a certain proportion of the horizontal earthquake effect, as a result of the experiments and monitoring the movements of the buildings under earthquakes. According to the regulation, it is calculated in 2 different ways. It is calculated by using the spectrum only for structures in Seismic Design Categories C, D, E, and F.

In cases where the vertical earthquake effect is calculated with the spectrum, the mode representing the vertical movement on the relevant element should be calculated. Even if the number of modes is sufficient for horizontal earthquake effect, if the relevant mode is not available, the targeted mode number should be increased and the relevant mode should be included in the calculation. Otherwise, internal forces and displacements for vertical earthquakes affecting the element cannot be calculated correctly.

**Next Topic**