Horizontal Component:
The numerical values of design displacements, velocities, and accelerations for the horizontal component Design Response Spectra are obtained by multiplying the corresponding values of the maximum ground displacement and acceleration by the factors given in Table 1 given below. In Figure 1, the base diagram consists of three parts: the bottom line on the left part represents the maximum ground displacement, the bottom line on the right part represents the maximum acceleration, and the middle part depends on the maximum velocity. The horizontal component Design Response Spectra in Figure 1 of this guide correspond to a maximum horizontal ground acceleration of 1.0g. The maximum ground displacement is taken proportional to the maximum ground acceleration, and is set at 36 inches for a ground acceleration of 1.0 g. The displacement region lines of the Design Response Spectra are parallel to the maximum ground displacement line and are shown on the left of Figure 1. The velocity region lines slope downward from a frequency of0.25 cycles per second (cps) or Hertz (Hz) (control point D) to a frequency of 2.5 cps (control point C) and are shown at the top. The remaining two sets of lines between the frequencies of 2.5cps and 33 cps (control point A), with a break at a frequency of 9 cps (control point B), constitute the acceleration region of the horizontal Design Response Spectra. For frequencies higher than33 cps, the maximum ground acceleration line represents the Design Response Spectra.
a. Maximum ground displacement is taken proportional to maximum ground acceleration, and is 36 in. for ground acceleration of 1.0 gravity.
b. Acceleration and displacement amplification factor are taken from recommendations given in Newmark, N. M., John A. Blume, and Kanwar K. Kapur, “Design Response Spectra for Nuclear Power Plants,” American Society of Civil Engineers (ASCE) Structural Engineering Meeting, San Francisco, April 1973, (ADAMS Accession No. ML13207A044).
a. Maximum ground displacement is taken proportional to maximum ground acceleration and is 36 in. for ground acceleration of 1.0 gravity.
b. Acceleration amplification factors for the vertical design response spectra are equal to those for horizontal design response spectra at a given frequency, whereas displacement amplification factors are 2/3 those for horizontal design response spectra. These ratios between the amplification factors for the two design response spectra are in agreement with those recommended in Newmark, N. M., John A. Blume, and Kanwar K. Kapur, “Design Response Spectra for Nuclear Power Plants,” American Society of Civil Engineers (ASCE) Structural Engineering Meeting, San Francisco, April 1973, (ADAMS Accession No. ML13207A044).