Contribution of damping to the dynamic loads in seismic analysis

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Rubric:     Theoretical and experimental studies   
Annotation:
Development of linear equations of motion for seismic analysis is discussed in the paper. Surprisingly, there are still some non-trivial issues. The paper is a polemic one: the author does not agree with colleagues putting damping matrix into the right-hand part of the equation of motion. In the author’s opinion, the mistake is in the implementation of the Rayleigh damping model for the right-hand part of the equation. This is in the contradiction with physical logic, as damping in the Rayleigh model is not really “internal”: due to the participation of the mass matrix it works on rigid displacements, which is impossible for internal damping. The author is sure that physical logic should have a priority against any approximate mathematical model, so the contribution of the internal damping to the right-hand part of the equation shall be excluded before this or that model of internal damping is chosen. Besides, the author asks two more questions about the internal forces calculations. He hopes to get response from the colleagues on these issues.