spectral response acceleration 2

[omidyousof]

Why we use ss for 0.2 sec period and s1 for one sec period? why we not use just one of them?

 

[JedClampett]

Since no one has responded, I'll give it a try; Ss as modified to Sds usually controls in building design. But for certain building periods "T" and "R"s, the one second acceleration, S1, as modified to Sd1 is more important and starts to control. It has to do mostly with the natural frequency of the structure.

 

[GeoPaveTraffic]

You might get additional input if you post in the Structural engineering other technical topics form.

Mike Lambert

 

[wannabeSE]

I'll take a stab at this. The reason is based on some basic physics principles involving resonance. There is a frequency (fundamental period) which cause a oscillating structure to react the most with a given force. Different building have different fundamental periods. The S1 and Ss parameters are used to create a response spectrum which shows the seismic acceleration (g's) for different fundamental periods.