When CYPECAD carries out a dynamic analysis (modal spectral) to calculate the seismic action, users have the option to not consider any floors below ground level in the dynamic model. To do so, the option “Consider the floors below ground level in the dynamic model” has to be deactivated.
On the other hand, when designing in accordance to some seismic standards, the minimum base shear condition must be met when a dynamic analysis (modal spectral) is applied. This minimum value is equal to a percentage of the shear at the base of the structure (base shear), which is calculated using a static method.
As of the 2014.g version, the calculation of the base shear takes into account the deactivating of the “Consider the floors below ground level in the dynamic model” option. In other words, if users deactivate this option, the program only takes into account the floors above ground level when calculating the base shear using the static method.
