Development of a novel pendulum column base isolation system with vertical negative stiffness (PC-VNS) for pile-like...

This paper introduces a novel seismic base isolator termed the "pendulum column with vertical negative stiffness (PC-VNS)," which functions similarly to a pile foundation while incorporating quasi zero stiffness (QZS) characteristics to modify the structural foundation connection in weak soil and effectively extend the natural period. The system's nonlinear behavior enables it to reduce both displacement and acceleration, even when employing conventional damping coefficients of 5%. The theoretical framework was validated using MATLAB analyses of multiple earthquake records and finite element modeling in ABAQUS. Results from earthquake scenarios demonstrate the system's ability to avoid resonance phenomena while maintaining controlled responses with standard damping. Compared to a conventional fixed-base frame with a 0.4-second natural period, the PC-VNS system achieves a significant reduction in input energy in most cases. The performance of the system is strongly influenced by the maximum allowable range of motion, with improved results observed for smaller displacement limits. The pile-like behavior of the PC-VNS improves soil-structure interaction, contributing to both seismic isolation and foundation reinforcement, thereby offering a promising solution for earthquake-resistant design.