Hydrodynamic Characteristics,Design,and Performance Evaluation Methods Of Tuned Liquid Dampers With Internal Damping Devices

Wind-induced load and response of super high-rise buildings under typhoon and strong wind are controlling factors affecting the structural safety and residence comfort.Tuned liquid damper(TLD)with internal damper devices can meet the requirement of optimal damping,but lacking of sufficient test data for reference on the damping characteristics.The existing linearized damping model cannot well predict test results and is difficult to apply due to the presence of the undetermined parameter.The relevant specification lacks recommendations for the design of TLD with internal damper devices,and practical and reliable evaluation methods for TLD’s vibration damping performance.Moreover,the parameters of complex multi-source coupled systems are difficult to identify effectively,which reduces the accuracy of tuning control.In this study,the large-scale shaking table test,signal parameter identification technology,mathematical statistics method and numerical simulation analysis of structure-TLD system are implemented to explore these issues in depth and detail,which provides important technical support for the wind-induced vibration control design of super high-rise buildings.The main research contents and achievements of the thesis are as follows:(1)TLD performance parameters detection method.An efficient detection method for TLD performance parameters is proposed based on the white noise excitation.The stochastic simulation method is applied to generate the time history of displacement excitation corresponding to the power spectral density(PSD)of the white noise excitation.Large-scale shaking table tests are conducted to obtain free surface wave height variation.The wave height signals are decoupled by using the second-order blind identification method based on complex mode theory,and modal parameters are identified by using the modified Bayesian spectral density approach(MBSDA)and curve-fitting method.The effectiveness of the proposed method is verified by shaking table tests of TLD without damping devices.(2)Hydrodynamic characteristics of TLD with horizontal damping devices.Largescale shaking table tests are conducted on TLD with screens to investigate the effect of solidity ratio,excitation amplitude,and location of screens on hydrodynamic characteristics of TLD.The parameter identification results show that the first-order modal frequency and mode shapes are not affected by the changes of above three variables,and consistent with those of TLD without damping devices.The first-order modal damping ratio,that presents obvious nonlinear characteristics,has monotonous power function with the excitation amplitude and solidity ratio,but decreases as the screens move away from the water tank center.The theoretical model can well estimate the damping ratio when the solidity ratio is less than 0.6,and the excitation amplitude is greater than 0.003.(3)Hydrodynamic characteristics of TLD with vertical damping devices.A series of large-scale shaking table tests are conducted on TLD with baffles and paddles to preliminarily build a basic database of the dynamic characteristics of TLD with damping devices.The experimental results show that the added mass produced by vertical damping devices reduces the modal frequency of TLD,which is different from screens.The effect of the added mass should be considered in the design,and this effect is not enough to be used to realize the frequency tuning of TLD.This conclusion is fundamentally different from that of the existing finding that the frequency increases gradually with the increase of the baffle angle,which means that the rotatable baffles does not have the tuning function.The modal damping ratio,that presents obvious nonlinear characteristics,increases with the increase of the excitation amplitude and paddle width,but decreases with the increase of the liquid depth ratio.The influence of paddles on the modal frequency is less than that of baffles.(4)Damping ratio model and design method of TLD with paddles.A nonlinear empirical model of the damping ratio of TLD with paddles is established based on the statistical analysis of data in the basic database,and the accuracy of the model is verified using test data.The design method of TLD with paddles is proposed according to the proposed nonlinear empirical model and the modal frequency model of TLD with paddles.The practicability and effectiveness of this method are verified through the implementation the TLD design of windinduced vibration control for single and multi-tower super high-rise buildings.(5)Evaluation method of TLD damping performance.An evaluation method of TLD damping performance is established.The decoupling and parameter identification method are conducted on structure-TLD system signals to obtain dynamic characteristics parameters of the coupled system.The frequency and damping ratio of the original structure and TLD are obtained by reconstructing the system state matrix to evaluate the vibration damping performance of TLD.Numerical simulation results show that the structural and TLD modal parameters identified by MBSDA have high accuracy,and the effectiveness of the proposed method is illustrated by the evaluation of the multi-TLD control scheme of a practical project.