Improved response spectrum analysis procedure for an adaptive variable friction pendulum isolated structure considering frictional dependency.

The effectiveness of the conventional friction pendulum isolator (FPI) is limited in complex geographical environments and unpredictable earthquake events due to its complex frictional properties and the requirement for a unified setup target. With a view to addressing the aforementioned issues, in conjunction with an adaptive variable friction pendulum isolator (AVFPI), a simple and practical mechanical model is proposed. After applying the mechanical model with a friction-dependent influence model, an improved response spectrum analysis procedure (IRS) is proposed for variable friction pendulum isolation systems. Notably, the proposed procedure allows for the consideration of the effects of variations in velocity, temperature, and pressure on the friction characteristics without the necessity for nonlinear response history analysis (NRHA). The procedure commences with obtaining a numerical model of friction dependency through friction material examinations, then proceeds to verifying the reliability of both the friction dependency and mechanical model through prototype tests of AVFPIs. The following study presents a proposed correction method that depends on random vibration theory to establish a functional relationship between the pseudo-velocity spectrum and the velocity spectrum. Additionally, an association is established between the peak velocity and the generation of frictional heat. Finally, the procedure is evaluated based on the results of an NRHA that takes friction dependence into account through a numerically variable friction pendulum isolation system. The results of the study indicate that the IRS provides a more accurate and secure assessment of the isolator displacement at various temperatures than the response spectrum method, which does not account for the influence of frictional dependency. The failure to consider the influence of friction dependency in high-temperature environments produces an underestimation of isolator slip displacement and a subsequent increase in failure rates. The Polytetrafluoroethylene (PTFE) friction materials that are currently in widespread use exhibit a strong correlation with friction dependence and, as a consequence, cause relatively large displacements at temperatures that are both low and high. The results of this study present an opportunity to expand how response spectrum analysis techniques can be applied to friction pendulum isolation systems. • A simplified mechanical hysteresis model for adaptive variable friction pendulum isolators is proposed. • A new friction material was tested and the velocity, pressure stress and temperature dependence expressions were obtained for the new friction material. • An expression for the friction coefficient of an adaptive variable friction pendulum isolator that takes into account the effects of velocity, pressure stress, and temperature dependence during nonlinear response history analysis is presented. • An improved method for analysing the response spectrum of variable friction pendulum isolation systems is proposed. Notably, the proposed procedure allows the consideration of the effects of velocity, temperature and pressure variations on the friction characteristics without the necessity to proceed to a nonlinear response history analysis (NRHA). • In the improved method of response spectrum analysis of variable friction pendulum isolation system, based on the correction method of stochastic vibration theory, the functional relationship between the pseudo velocity spectrum and the velocity spectrum is established, and a simplified calculation method for calculating frictional heat by peak velocity response is proposed. [ABSTRACT FROM AUTHOR]