Analysis of damping performance and seismic response control with a novel first-floor negative stiffness structural system

Conventional seismic systems often face limitations regarding performance efficiency. Despite the considerable potential of negative stiffness and inerter technologies, their synergistic application as a centralized mechanical isolation layer in the first story of multi-story buildings remains an under-explored avenue. This paper introduces a novel first-floor negative stiffness (FFNS) structural system. The system is a centralized arrangement of viscous dampers and an inertial negative stiffness device (INSD) in the first story to achieve an adjustable structural response reduction ratio and achieve seismic response control. The mechanical relationships between the response reduction ratio, negative stiffness ratio, and inherent damping are derived. Parametric analyses indicate that adjusting the negative stiffness ratio enables the simultaneous mitigation of structural displacement and acceleration. Theoretical derivation and experimental validation of the designed INSD confirm its capability to provide stable, frequency-dependent negative stiffness. Furthermore, comprehensive numerical simulations on a benchmark structure subjected to short-, medium-, and long-period seismic waves validate the system's effectiveness. The FFNS system significantly reduces inter-story drifts, floor accelerations, and shear forces, exhibiting performance comparable to or even superior to traditional seismic isolation systems, particularly under long-period ground motions. The FFNS system thus presents a versatile and effective alternative for the seismic protection of buildings.