Semi-active piston tuned liquid column damper (SP-TLCD) for earthquake-loaded vibration suppression in structures: Functionality analysis and numerical system modelling

Tuned liquid column dampers (TLCDs) are passive devices used for structural vibration mitigation; however, the additional degree of freedom introduced by TLCDs may generate new resonant frequencies and amplify responses outside the target range. To overcome this limitation, this study proposes a semi-active piston tuned liquid column damper (SP-TLCD), which integrates passive TLCD behavior with semi-active control to enhance performance while maintaining low energy demand. The SP-TLCD employs floating pistons in the vertical columns to regulate liquid motion through magnetic braking, without the use of any mechanical transmission components, thereby controlling the structural response. Its performance was experimentally evaluated under the free vibration, the white noise, and the seismic excitations. The dynamic and static operating regions were identified based on structural acceleration. A numerical system model of the SP-TLCD–structure system was developed and validated using experimental data and independent seismic inputs. The results indicate that the proposed SP-TLCD model accurately reproduces the experimental response, achieving relative errors of 2.25% in root-mean-square displacement and 1.28% in maximum displacement, demonstrating the potential of the SP-TLCD model for application in semi-active damping systems and future control strategies.