Suboptimal Rayleigh Damping Coefficients in Seismic Analysis of Viscously-Damped Structures


An optimization method for the consistent evaluation of two Rayleigh damping coefficients is proposed. By minimizing an objective function such as an error term of the peak displacement of a structure, the two coefficients can be determined with response spectral analysis. The optimization method degenerates into the conventional method used in current practices when only two modes of vibration are included in the objective function. Therefore, the proposed method with all significant modes included for simplicity in practical applications results in suboptimal damping coefficients. The effects of both spatial distribution and frequency content of excitations as well as structural dynamic characteristics on the evaluation of Rayleigh damping coefficients were investigated with a five-story building structure. Two application examples with a 62-story high-rise building and a 840 m long cable-stayed bridge under ten earthquake excitations demonstrated the accuracy and effectiveness of the proposed method to account for all of the above effects.


Civil, Architectural and Environmental Engineering

Keywords and Phrases

Response Spectral Analysis; Cable Stayed Bridges; Damping; Function Evaluation; Spectrum Analysis; Structural Dynamics; Tall Buildings; Application Examples; Conventional Methods; Damping Coefficients; Dynamic Characteristics; Earthquake Excitation; Objective Functions; Optimization Method; Rayleigh Damping

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Article - Journal

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© 2014 Institute of Engineering Mechanics (IEM), All rights reserved.

Publication Date

01 Dec 2014