Design Response Spectrum curve 1

[kmead]

Could someone please enlighten me on when and how to actually use the Design Response Spectrum Curve shown in figure 11.4-1 of ASCE 7-05? Section 11.4.5 indicates that "Where a design response spectrum is required by this standard and site specific ground motion procedures are not used, Design Response Spectrum curve shall be developed".
I can not seem to find where in the code it is required to use the Design Response Spectrum curve and I am also not sure once I develop the curve how to actually use it.

Any help would be greatly appreciated.

 

[larsacious]

Typically it is used when you are in seismic design categories B thru E. YOu don't really need to draw the response spectrum. You only need to determine which Sa formula you should use based on where your fundamental period falls (i.e. less than To, between To and Ts, between Ts and TL, and finally greater than TL).