Theoretical And Experimental Investigations Of Vibration Control For Magnetorheological Tuned Liquid Column Damper (MR-TLCD)

Structural vibration control technology and the state of art of tuned liquid column damper (TLCD) were critically reviewed. The problems of classical semi-active TLCD were identified. Some excellent properties of MR dampers, such as simple construction, larger continuously adjustable damping force as well as fast response time, and characteristics of TLCD, such as economics, simple figuration, were combined to develop Magnetorheological tuned liquid column damper (MR-TLCD) that can accomplish semi-active control. Equations of motion of a building and a bridge structure incorporated with MR-TLCD were formulated by Lagrange equation. The control performances of MR-TLCD were simulated in the case of wind-induced response. Further, enhanced vibration control performances of MR-TLCD were demonstrated by experimental investigations of both passive and semi-active control scheme of the coupled SDOF—MR-TLCD. The main contents were summarized as follows:(1) Rotary Shear MR damper (RSMRD) was developed to meet the requirement of testing and engineering applications. The Boltzmann function formulation of relationship between the peak of coulomb friction damping force of MR damper and its input current was investigated based on mechanical properties test results of MR damper. It was proved that Bingham model based on Boltzmann function was reasonable. The mechanical characters of the MR damper were further described to solve the problem that Bingham model fails to capture the hysteretic curve of MR damping force and velocity around zero velocity, and the hysteretic model of RSMRD was calibrated with an improved hysteretic model with an additional inertial force item, where each parameter was identified by intelligent particle swarm optimization.(2) The control device MR-TLCD was developed. MR-TLCD excited by harmonic load was tested under seven input currents, and the dynamical equation of MR-TLCD with damping ratio correction factor was derived. The relationship of damping ratio correction factor and input current was fitted by dynamic magnification factors of theoretical and experimental analysis. By comparing semi-active control test analysis, it was further demonstrated that dynamical model of MR-TLCD with damping ratio correction factor was feasible.(3) The equations of motion of the combined structure-MR-TLCD system for the test cases or practical MR-TLCD were established by Lagrange equation. The analysis methods in time domain and frequency domain were proposed. The passive control performance of the coupled structure—MR-TLCD system subjected to random wind load was simulated. The results showed that the damping effect on peak and root mean square of SDOF structure varied with input current of MR-TLCD and mass ratio, and the control performance of acceleration response was better than that of displacement.(4) The passive control performance of the bridge with MR-TLCD was analyzed to expand the application of the control device MR-TLCD. The displacement and acceleration response of the system subjected to harmonic and random wind load was simulated. It is concluded that there are the minimum mean dynamic magnification factor ratio as well as the optimal input current for each of the four section styles of MR-TLCD. The acceleration control performance of bridge torsional peak and root mean square is superior to the displacement.(5) From the point of energy dissipation force of MR-TLCD based on the dynamical equation of the coupled SDOF—MR-TLCD, the energy situation of MR damping force and TLCD liquid restoring force was detailed. The Simple Bi-State (SBS) semi-active control algorithm and Two-Stage Bi-State (TSBS) semi-active control algorithm were developed based on energy dissipation. It was demonstrated that both the SBS algorithm and the TSBS algorithm based on MR-TLCD device had good obvious performance of vibration control by theoretical simulation analysis and experimental data of semi-active control. When the TSBS algorithm is adopted, the control system is easier to be stabilized.(6) The semi-active control device of the coupled SDOF—MR-TLCD was manufactured to verify the semi-active vibration control performance of MR-TLCD and compared with theoretical simulation. The real-time control system dSPACE was employed in the test set-up to realize the controller algorithms, which included passive off/on and semi-active control algorithms such as; SBS, TSBS and off-and-toward-equilibrium. Response value and damping percentage of the structure peak and root mean square were analyzed, and the control performance of MR-TLCD was further evaluated.