| With the rapid development of the world economy,the use of urban land tends to be tense.High-rise building and super high-rise building have entered a vigorous period of development,in which outrigger system is widely applied with the reason of its many advantages.However,it would not be a effective way to improve the structural safety under earthquake action if only the means by strengthening outrigger was employed to increase the system stiffness to enhance the lateral resistant ability.Therefore,recently,damped outrigger system is proposed and accepted by many researchers.In this study,to complete the seismic mitigation theory of the damped outrigger system,the detailed analysis and discussion were conducted to solve a series of issues,such as analysis of the simplified model,parameters optimization,dynamic investigation of the random dynamical system,power flow analysis and the study of the novel damping device.The main work and achievements are summarized as follows:The three methods like Laplace transformation and the inverse method,numerical assembly method and finite element method were compared to analysis distributed parameters system.The frame-shear wall structure was taken as an example to derive the corresponding orthogonality conditions for distrusted mass and distrusted stiffness system.Meanwhile,the first two methods had been verified to be reasonable with the results of the finite element method.The results show that these two methods have less error for the low-order frequencies and the results of the seismic response can be accepted.While the major difference for them is the process solving the frequency equation.Numerical assembly method was employed to derive the dynamic characteristic equations of the cantilever beam system,traditional outrigger system and damped outrigger system.Furthermore,the main parameters such as exterior column ratio,outrigger damping coefficient,outrigger location and outrigger number were adopted to investigate the influences of the dynamic characteristics.The results indicate that numerical assembly method has the rational calculation results;The larger exterior column stiffness leads to the higher value for pseudo frequency and damping ratio;Damped outriggers system is similar to the cantilever beam system with single or multi-Maxwell coupling dampers;The system frequencies increase with the damper damping coefficients increasing and trend to be a constant,while the peaks of the system damping ratios exist.The outrigger number greatly affects the dynamic characteristic of the damped outrigger and the larger damper damping coefficient contributes more to the system with the less outriggers,conversely,it may contributes more to system damping ratio but less to psudeo frequency."Maxwell dampers type method" and "virtual pseudo small mass method" were proposed and serve as the computation of seismic response.Sequently,finite element method was used to verify them;Based on H∞ performance index and the expanded state equation of the Clough-Penzien power spectrum model,the damping parameters and seismic mitigation effects of the damped outrigger system had been investigated;The research results show the optimal parameter and each system parameters obtained by them have the similar rules and can lead to the relatively excellent damping effects;The damping coefficients of the outrigger have a significant effect on the H∞performance index and stochastic response,while the influence of the external column stiffness ratio should not be neglected;There are little difference on the control effects between equivalent and un-equivalent of outrigger damping coefficient in their optimal value,but with consideration of the engineering application,the former is the recommendation for construction convenience and economy.With the power flow theory,the power equation of the common structure was derived.The energy flowing laws and damping performance of the damped outrigger system was developed by use the method of finite element power flow analysis.The research indicates that the average kinetic power and average elastic power are zero in one circle,while the average dissipation power and average input power are equal.When compared with section average power flow in different modal frequency for different system,damped outrigger system has the minimum value and its damped outrigger works as a role of energy sinks.Parameters optimization based on the section average power flow shows that the optimum outrigger damping will exist for the lower stiffness ration of exterior column,while the section power decreases to be a constant with the outrigger damping increasing.Orthogonal sequence decomposition method,Gauss Hermite direct integration method and Gauss Hermite descending dimension algorithm had been compared and verified by the Monte Carlo method.Sequently,the third method was used to investigate the control effects of the damped outrigger system subjected to determined and random earthquake excitation.The research results show that with the help of Gauss Hermite descending dimension algorithm,the calculative efficiency can be enhanced under the precondition of assuring the precision requirement.Furthermore,damped outrigger system can dissipates the excess energy and its vibration response quickly trends to be smaller;It is also relatively insensitive to parameters variation and has better robustness.Besides,the control effects still keep well with consideration of system parameters variation.TID(TID,Tuned Inerter Damper)type inerter was employed to control the building structures.SDOF and MDOF installed with TID under white noise excitation had been analyzed to derived the optimal damping and stiffness parameters;A hybrid control scheme for TID_TMD had been proposed by taking advantages of TID and TMD(TMD,Tuned Mass Damper).Finally,the parameters of TID outrigger system have been optimized and the corresponding damping effects has also been inverstigated.The research shows that the derived optimal parameters are rational;TID will contribute more control effects with increasing the mass ratio or selecting the appropriate installment position.TID_TMD not only can keep away the disadvantage of TID control for the low mode,but also can relive the TMD control problems such as space,installment and excess mass.The control effect of the TID outrigger system is limited and lies between no-outrigger system and traditional outrigger system,but TID can present the sufficient energy dissipation with the optimal damping which is smaller,The vibration equation of SDOF with RID(RID,Rotation Inertia Damper)based on Hamilton principle was derived and this damper was applied into the outrigger system.Dynamic characteristic equation and the expanded state equation of the Kanai-Tajimi power spectrum model were also derived.Based on that,the corresponding seismic mitigation performance had been investigated.The research results show that RID provide the larger damping force in a less physical mass.The vibration analysis method for RID is in accordance with the finite element method;RID damped outrigger system behaves the excellent damping performance and can dissipate the earthquake input energy in a short time.Furthermore,the mass parameter plays hardly a role on the dynamic characteristic while the other parameters such as external column stiffness ratio,outrigger position and RID damping coefficient contribute much more to the dynamic characteristic.Additionally,damping force plays a dominant role of the equivalent force of the RID,but less for rotational inertia force. |
