Creates earthquake spectra (horizontal and vertical) according to the ASCE 7 standard. You must also select the appropriate ASCE 7 revision from the list.
The horizontal design response spectrum is based on ASCE 7. Figure 9.4.1.2.6 (ASCE 7-2010) is shown below.
Ts=SD1/SDS & T0=Ts/5.
Above a period of four seconds, the horizontal spectrum acceleration changes.
The vertical spectrum is set to 20% of SDS (from 9.5.2.7.1) across the entire period range. Neither I nor R affects the vertical spectrum.