Optimal Designs Of Structure-MTMD Systems Under Stationary Random Excitations

Tuned mass damper(TMD) is widely used in practical projects at home and abroad forits effect of reducing the response of high-rise buildings under earthquake and windexcitations, and the relevant theory is becoming more mature. But TMD is usually designedmainly for a single vibration mode of a structure, so the concept of multiple tuned massdampers(MTMD) has been proposed. The use of multiple TMD in a structure can controldifferent vibration modes of structural systems. This dissertation studies optimal parametersdesign of structure-MTMD system in stationary random excitation and the work presented inthis dissertation contains the following aspects:Firstly, the damping mechanism and the random response analysis method of multipledegrees of freedom structure system with MTMD is introduced and discussed. To reducemean square values of different structural responses, the genetic algorithm is adopted tooptimize the position, quality, frequency ratio and damping ration of TMD, under theexcitation of white noise and filtered white noise separately.Secondly, this dissertation deduces the sensitivity of the mean square value of structuraldisplacement and acceleration for the parameters of structure-MTMD system, and then putsforward an optimization algorithm to optimize the parameters of structure-MTMD system,which provides the best comfort degree in the restriction of the static displacement ofstructure nodes and the displacement response under random excitation.The chapters optimize structure section size with the object of optimizing the meansquare value of structural acceleration and constraints of the mean square value of structuraldisplacement, the static displacement of structure nodes and the structural volume firstly.Then based on the above optimized structure, the mean square value of structural accelerationcan be minimized by optimizing the quality, frequency and damping ration of each of TMD,in the restriction of the mean square value of structural displacement and the quality ofMTMD. In addition, the chapters optimize the parameters of the structure-MTMD systemsimultaneously with the same constrains and compare the result with that of the above steppedoptimization strategy.Thirdly, the sensitivity of the mean square value of structural acceleration anddisplacement for the parameters of MTMD in the fluctuating wind excitation is deducedaccording to the formula of the mean square value of the high-rise building. To optimize themean square value of the structure, the sensitivity analysis method is adopted to optimize theparameters of MTMD, based on the case of earthquake and wind vibration excitationseparately. This chapter distinguishes the optimal parameters of MTMD in the fluctuatingwind and earthquake excitation lastly.Finally, the major contributions are summarized and the possible future works arediscussed.