Experimental study on inerter-enhanced bistable nonlinear energy sink for frequency and energy robustness enhancement

This study presents an inerter-enhanced bistable nonlinear energy sink (BNESI) to enhance frequency and energy robustness of the control device in structural seismic performance. The paper analytically models various BNESI configurations for application in multiple-degrees-of-freedom (MDOF) systems. Shaking table tests on three two-story frame structures validate the frequency and energy robustness of the BNESIs. Experimental results demonstrate that BNESIs exhibit low sensitivity to shifts in structural frequencies and variations in earthquake energy levels, owing to their strong nonlinearity. BNESIs can achieve a reduction in structural dynamic responses exceeding 35 % with only about 20 % of damper stroke compared to traditional tuned mass dampers. BNESIs also effectively redistribute structural energy from lower to higher frequencies, enhancing energy dissipation and mitigating seismic responses. Numerical models align closely with experimental data, accurately capturing the dynamic behavior of BNESI-controlled MDOF systems. With high control efficiency, robust performance against frequency and energy variations, and low stroke demands, BNESIs present a promising solution for improving structural seismic performance.