What are the results of response spectrum analysis?

Based on the above graph, the following results are made.

1. Zero Period Acceleration (ZPA) is also known as rigid body motion:

   This is the limiting value of Sa/g at very low time periods (i.e. very high frequencies). The system will be relatively rigid. Hence at this frequency, the system simply follows the ground motion.

2. Peak Response: The most critical natural frequency (resonant frequency) for which the system shows maximum response. The natural frequency of the building structure should not coincide with the resonant frequency. Because maximum response corresponds to high induced stresses in the structure.
3. Sa/g value increases from ZPA to the resonant frequency.
4. Sa/g value decreases from the resonant frequency.
5. The peak occurs in a certain frequency range only.