Experimental verification on nonlinear dynamic characteristic of a tuned liquid column damper subjected to various excitation amplitudes

In this study, nonlinear dynamic characteristics of a tuned liquid column damper (TLCD) varying with the amplitude of excitation input are investigated through shaking table tests and numerical model of a TLCD. The tuned mass damper (TMD) analogy of a TLCD is used to simplify the formulation, in which it involves equivalent viscous damping of the inherent nonlinear damping term of a TLCD. The equivalent TMD model of a TLCD shows that the dynamic behaviour of a TLCD is affected by the natural frequency, damping ratio and ratio of total liquid mass to the mass in horizontal column of a TLCD. Shaking table test is performed to obtain experimental transfer functions that describe the dynamic behaviour of a TLCD specimen subjected to a harmonic loading with various excitation amplitudes. Transfer functions for various excitation amplitudes are measured from shaking table acceleration to both the liquid displacement within a TLCD container and the control force produced by a TLCD specimen. In addition, the dissipation energy due to the inherent damping of a TLCD is measured from the shaking table test varying with excitation amplitude. The variation of design parameters of a TLCD according to the excitation amplitude is investigated by comparing the transfer functions obtained from the shaking table test to those derived from the TMD analogy of a TLCD. These results showed that both the natural frequency and the mass ratio of a TLCD are independent on the variation of excitation amplitude, while the damping ratio of a TLCD increases with larger excitation amplitude.