Damping
Posted: 23 Dec 2023, 08:36
I have to carry out Linear time history analysis for a 2% damped structure as per Indian code. But Code give spectra for 5% damping only. Code asks to amplify the spectral values by 1.2 for 2% damped spectra. How to consider this in spectral matching. I have tried following cases and all have resulted in different results of matched time history.
Case1. Target spectra defined for 5% damping. 1.2 Scale factor considered in Step3 spectral matching.
Case 2. Target spectral uploaded from input file. Input file contains 5% damped spectral acceleration multiplied with 1.2. While uploading, 2% damping is selected.
Case 3. Target spectral uploaded from input file. Input file contains 5% damped spectral acceleration multiplied with 1.2. While uploading, 5% damping is selected.
In all the three cases the target spectra values are same. But the spectral matching results are different. How?
Case1. Target spectra defined for 5% damping. 1.2 Scale factor considered in Step3 spectral matching.
Case 2. Target spectral uploaded from input file. Input file contains 5% damped spectral acceleration multiplied with 1.2. While uploading, 2% damping is selected.
Case 3. Target spectral uploaded from input file. Input file contains 5% damped spectral acceleration multiplied with 1.2. While uploading, 5% damping is selected.
In all the three cases the target spectra values are same. But the spectral matching results are different. How?