Equivalence of Friction and Viscous Damping in a Spring-Friction System with Concave Friction Distribution

• Published in: Journal of testing and evaluation 2021-01, Vol.49 (1), p.372-395
• Main Authors: Li, Shanshan, Wei, Biao, Tan, Hao, Li, Chaobin, Zhao, Xiaomiao
• Format: Article
• Language: English
• ISSN: 0090-3973; 1945-7553
• DOI: 10.1520/JTE20190885

With the aim of unifying the damping concept and evaluating the amount of damping in a structure, this paper investigates whether friction action can be equivalent to traditional viscous damping. The research focused on purely concave friction distribution cases, uniform friction distribution cases, and their combination cases in a spring-friction isolation system. The dynamic responses of a numerical method using friction action were compared with those of another numerical methods using equivalent viscous damping under sine wave ground motions. The comparison of results shows that the friction action can be converted to the equivalent viscous damping action with some errors by using an equation. The conversion accuracy of uniform friction distribution cases using the first term of the equation is much worse than that of the purely concave friction distribution cases using the second term of the equation. The reason for this being that the uniform friction distribution can prevent the structure from sliding back to its center after the ground motion; however, the viscous damping action does not have such a negative function. The comparison errors, between using the friction action and using the equivalent viscous damping, are directly proportional to the ratio of the component of uniform friction distribution to the component of purely concave friction distribution.