Nonlinear Viscous Damping-Based Negative Stiffness Isolation System with for Over-Track Complex Structures

The over-track complex structures are driven by transit-oriented urban development, leading to the necessity for advanced seismic performance upgrades. An innovative solution is presented in this study, involving the negative-stiffness amplification system-enabled isolation system (NSAS-IS) with nonlinear viscous damping to establish a flexible isolation layer beneath over-track buildings. The multi-benefit-based design procedure and easy-to-use formula are developed. Its effectiveness and comparative superiority over conventional ones, particularly in mitigating negative effects of over-track buildings on lower podiums, is confirmed by case studies. NSAS-IS with an optimized nonlinear viscous damping exponent exhibits a significant reduction in isolation-layer displacement and robustness against earthquakes.