| As its large aspect ratio and small damping,and its inherent natural frequency being close to the predominant frequency of strong wind,high-rise structure is extremely sensitive to the wind loading.Wind loading becomes the major control factor of high-rise structural design.In order to reduce excessive wind-induced displacement and acceleration of high-rise structure and improve the safety and comfort of the high rise structure,a bidirectional variable friction pendulum tuned mass damper(bidirectional VFPS-TMD)system is proposed to be installed atop high-rise structure to reduce its wind-induced vibration response.In order to enhance the performance efficiency of TMD system,an adaptive genetic algorithm is proposed to optimize its structural parameters.The main contents of this dissertation are as follows:The dynamic equation of high-rise structure top with bidirectional VFPS-TMD system is established and deduced.The procedure to solve this dynamic equation by state space method is introduced.Based on simplified FE model,the time history of along-wind loads in 90-degree wind direction of the Canton Tower is numerically simulated by the harmonic superposition method and the quasi-static assumption and research results from the wind tunnel test.The wind-induced vibration control performance of high-rise structure with atop bidirectional VFPS-TMD system is verified and analyzed.Under the different recurrence intervals of design wind loading,the wind-induced vibration control efficiency of bidirectional VFPS-TMD system is investigated considering different damping ratios of the main structure,mass ratios of the TMD system with the main structure,different fixed friction coefficients and different frictional models of the TMD system.Results from the numerical analysis showed that the vibration control efficiency of the proposed passive damping system could reach at the level of 45.6% and 52.6% for the wind-induced displacements in X and Y directions were under design wind speed with 100-year return period.While the vibration control efficiency of the wind-induced acceleration response in X and Y directions were 41.6% and 41.8% under design wind speed with 10-year return period.By comparing the hysteresis curve and statistical results of the wind-induced displacement and acceleration responses from the TMD systems with varied and constant friction coefficient models,the mechanism of energy dissipation and vibration reduction of the proposed TMD system was analyzed.A procedure to minimize the wind-induced displacement or acceleration response atop the main structure by utilizing the bidirectional VFPS-TMD system is proposed by the self-adaptive genetic algorithm in this dissertation.The adaptive crossover,mutation operator and adaptive penalty function are introduced in the genetic algorithm to deal with the constraints of the wind induced inter-story drift,wind-induced displacement and acceleration response at the top floor.The variation rates in the slide friction coefficients,the radius of the slide in two directions are optimized by the proposed optimization procedure.The optimized results from both the self-adaptive and basic genetic algorithms are compared to verify their efficiencies in the optimization design.Finally the effect of setting different penalty values for the displacement and acceleration constraints on the optimization design results of bidirectional VFPS-TMD system are studied.Comprehensive analysis shows that bidirectional VFPS-TMD system can effectively reduce the wind-induced vibration response of high-rise structures.The proposed adaptive genetic algorithm can be utilized to optimize the structural parameters of the VFPS-TMD system and obtain the best structural performance in vibration control and reduction.Meanwhile the bidirectional VFPS-TMD system has good features in the self-resetting and self-centering.Therefore,the bidirectional VFPS-TMD system is indeed a very effective passive damping device. |
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