Study on Algorithms for Semi-Active Control of Isolation System with Variable Friction

Semi-active tuned mass dampers under combined variable actions of friction forces and external disturbances

“…The structural values in Table 1 refer to the first mode of vibration since the control of the only lower modes is usually enough to mitigate the vibrations. The used values should represent in a realistic way the system in accordance with the literature (Chung et al 2011;Eason et al 2013;Kim and Lee 2019;Lu et al 2018b) and design recommendations (Kim and Lee 2018). In general, for civil structures, it is usually assumed μ r < 10.0% (Jabary and Madabhushi 2018) and ξ d > ξ s (CEN 2004(CEN , 2008Shi et al 2018a).…”

“…The goal of this variable damping model is that the friction force to be like the desired control force. This model is an alternative strategy for dissipation the external excitations under specific configurations (Chung et al 2011;Shi et al 2018a;Lu et al 2004).…”

“…The force balance of the α/2 angle in the horizontal directions is where the friction force u(t), which is controlled indirectly by the normal friction force N(t), is defined by Coulomb's model as (Chung et al 2011) where μ is the friction coefficient of the force defined as tan(α/2), and |•| is the absolute value. sgn(•) indicates that the control force produced by a variable damper is opposite to the direction of the current damper motion (i.e.…”

“…They act passively since they create reactive forces solely in response to the motion of the structure and they are not externally driven (OPCM 2005;SPES 2017). Their main problem is that they may not be suitable when the system is excited by a non-design earthquake (Chung et al 2011;Lai et al 2016). For instance, an extreme earthquake, difficult to prevent, with a long-period waveform may induce unexpected displacements (Zacchel et al 2017; Zacchei et al 2018;Maddaloni et al 2017;Chung et al 2011).…”

“…Several studies are available in the literature on SA-TMDs, which are divided with respect to different mechanical systems, e.g. with variable friction (Chung et al 2011;Gaul and Becker 2014;Shi et al 2018a;Pinkaew and Fujino 2001), variable stiffness (Nagarajaiah and Sonmez 2007;Nagarajaiah and Varadarajan 2005;Eason et al 2013), magnetorheological (MR) dampers (Oliveira et al 2015;Gu et al 2017aGu et al , 2017bXia et al 2016;Bahar et al 2010;Aggumus and Cetin 2018;Zapateiro et al 2009), and energy transition controls (Shuliang et al 2011).…”