Study On Isolation And Design Optimization Of High-rise Buildings On Triple Friction Pendulum Bearings

Triple friction pendulum bearing has recievied much attention by engineers due to its versatile behaviors under different levels of earthquakes and has been used in low-rise buildings and bridges.To date,due to the increasing demand for isolation of high-rise buildings,the theoretical analyses,experimental tests and finite element analyses have been carried out on isolation and design optimization of high-rise buildings on triple friction pendulum bearings.The main work is summarized as follows:(1)The friction material(polytetrafluoroethylene)of the triple friction pendulum bearing is tested.The double shear method is used to obtain the friction coefficients under different vertical pressures and shear velocities.In addition,the mechanical properties of the triple friction pendulum bearing are tested.The hysteretic properties of the bearing are analyzed by low cyclic loading and simulated by Open See,the results of the test demonstrate the effectiveness of the numerical model.(2)The theoretical model of the building isolated with triple friction pendulum bearings is developed.The finite element models of base-fixed building,the isolated building using single friction pendulum bearings and the building isolated with triple friction pendulum bearings are developed.The isolation mechanism of the high-rise building using triple friction pendulum bearings is investigate by the frequency and time domain analyses of the two isolated buildings.To minimize the seismic responses,an evaluation function is developed to indicate the isolation effect and the genetic algorithm is applied to seek for the optimal parameters of triple friction pendulum bearings.Seismic responses of the building isolated with triple friction pendulum bearings are calculated and compared with those of the building isolated using the single friction pendulum bearings and the base-fixed building,respectively.In addition,the designed displacements of different hazard levels are calculated by equivalent linearization method.(3)The program for simulating wind speed and wind load is developed based on the linear auto-regressive model and the wind-induced responses of the building isolated with triple friction pendulum bearings are analyzed.An analytical model for isolated high-rise building with triple friction pendulum bearings and magnetorheological damper installed on the top floor is proposed.The membership functions of the fuzzy logic controller are designed by the multi-objective optimization method to reduce the wind-induced responses without diminishing the baseisolation effect.To evaluate the optimal fuzzy logic controller,the responses of the building using the humandesigned fuzzy logic controller and the building without control under the wind and earthquake loads are calculated.The seismic and wind-induced responses of the building controlled by the optimal fuzzy logic controller are compared with those of the building using the human-designed fuzzy logic controller and the building without control.The effect of different control algorithms on wind and seismic responses of the isolated building are investigated.(4)The multi-objective optimization method is used to optimize the parameters of triple friction pendulum to reduce both seismic and wind-induced responses simultaneously.The bearing parameters which make the best isolation effect of the structure on the condition that the wind-induced responses meet the requirements by Chinese code are selected.In addition,the responses of the structure under wind loads and different earthquake levels are compared when the bearing parameters are different.(5)The specimen of a scaled high-rise building isolated with triple friction pendulum bearings is tested on a shaking table under earthquakes with different intensities and the isolation performance of the triple friction pendulum bearing is investigated.The test results show that the triple friction pendulum bearing has a good seismic isolation performance in high-rise buildings and provide the reference of the application of triple friction pendulum bearings in high-rise buildings in the future.In addition,the numerical model of the high-rise structure isolated with triple friction pendulum bearings is developed by Open Sees,the effectiveness of the numerical model has been validated by comparing with the test results.(6)A computational model of the building isolated with triple friction pendulum bearings,which can consider the bearing impact and uplift is used to conduct the incremental dynamic analysis and the collapse probabilities of the structure under various earthquake levels are calculated.The trial and error method is used to determine the bearing capacities to make the collapse probability of the structure less than 10%.In order to investigate the effect of the model which considers bearing impact and uplift on the seimic responses of the structure,the seismic responses of the structure which does not consider the bearing impact and uplift are also calculated and compared to that which considers bearing impact and uplift.In addition,the collapse probabilities of the structure are calculated when different models for bearings are used.