Choice of in-structure damping model: Do we have an answer?
Recent researches have shown that the optimal distribution of dampers is sensitive to the choice of the in-structure damping models. Common practice is to use the classical viscous damping model originated by Rayleigh, through his famous „Rayleigh dissipation function‟. The main advantage of this model is that the orthogonality of the modes is preserved; thereby rendering the classical modal analysis for undamped vibration readily applicable to damped vibration as well. In a controlled frame, addition of external dampers makes the damping non-classical and the orthogonality of modes no longer exists. So use of the classical in-structure damping model (Rayleigh model) for controlled frames is not convincing and no justification is provided in the literature for the choice of this damping model. In this paper, the effect of choice of the damping models on the optimal distribution of dampers is investigated. It is observed that the optimal distribution of dampers could change based on the choice of the damping models. The results raise a huge concern regarding the realism of the optimality criterion achieved in terms of response reduction when a particular damping model is assumed with no specific justification.