The Vertical Component
The numerical values of design displacements, velocities, and accelerations in these spectra are obtained by multiplying the corresponding values of the maximum horizontal ground motion (acceleration = 1.0 g and displacement = 36 in.) by the factors given in Table 2.
The vertical component Design Response Spectra corresponding to the maximum horizontal ground acceleration of 1.0 g are shown in Figure 2. 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 2. The velocity region lines slope downward from a frequency of 0.25 cps (control point D) to a frequency of 3.5 cps (control point C) and are shown at the top. The remaining two sets of lines between the frequencies of 3.5 cps and 33 cps (control point A), with a break at the frequency of 9 cps (control point B), constitute the acceleration region of the vertical Design Response Spectra. It should be noted that the vertical Design Response Spectra values are 2/3 those of the horizontal Design Response Spectra for frequencies less than 0.25; for frequencies higher than 3.5, they are the same, while the ratio varies between 2/3 and 1 for frequencies between 0.25 and 3.5. For frequencies higher than 33 cps, the Design Response Spectra follow the maximum ground acceleration line.
Note:
Since the acceleration values below 2.5 cps and 3.5 cps for Horizontal Design Response Spectra and Vertical Design Response Spectra respectively are NOT given in the Figures 1 and 2 above, the acceleration values corresponding to 2.5 cps (for Horizontal Design Response Spectra) and 3.5 cps (for Vertical Design Response Spectra) are entered for 0.1 cps in the respective directions.
Similarly, the accelerations values above 33 cps and up to 60 cps are entered as 1.0 g in the respective directions.
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