How are damping values used during response-spectrum analysis?
Extended Question: Damping values are defined in two sections, including the Definition of Response Spectrum Function and the Definition of Response Spectrum Cases. How are these damping values used?
Answer: Structural damping is integral to the response-spectrum curve chosen for analysis. The damping value of this curve should be specified in the Definition of Response Spectrum Cases. During analysis, the response-spectrum curve will be automatically adjusted from the specified damping value to that present in the model.
Structural damping influences response-spectrum analysis in the following ways:
- It affects the shape of the response-spectrum input curve when modal damping differs from that of the response-spectrum curve. Generally, this is the case when dampers are present in the model.
- It affects the amount of statistical coupling between the modes used for certain response-spectrum modal combination methods (CQC, GMC).