Research On Isolation Of Frame-shear Wall Structure Under Earthquake And Metro Vibration

Research on reaction of frame-shear wall structure under earthquake and subway vibration was carried out according to one multi-tower high-rise structure with an enlarged base. (It will be the tallest isolated building with multi-tower in the mainland of China after be built). The seismic action analysis under frequent earthquake and rare earthquake of the structure was finished using time-history method. Natural vibrations, story shear force, overturning moment of non-isolated structure and isolated structure were contrasted, and damping coefficient in horizontal direction was calculated. Variation of story displacement was plotted into curves and seismic response of story acceleration was analyzed. Application of seismic isolation in high-rise buildings was also discussed. Distribution and development of plastic hinge for isolated structure under rare earthquake was analyzed. Then, anti-overturning analysis of isolated structure under rare earthquake was carried out. Time-frequency analysis of acceleration time-history curve was carried out by Fast Fourier Transform method.1/3 times frequency course spectrum was used to perform bandpass filter of acceleration frequency-history curve and amplitude-frequency curve was obtained. Amplitude-frequency curve was changed into vibration acceleration level at every center frequency, and correction of z weighted factor was done. Analysis program of vibration comfort degree was compiled based on these calculation methods. Story acceleration under subway vibration was calculated using both simplified calculation method with single particle and elastic time-history method. Story acceleration time-history curve was changed into decibel by program of vibration comfort degree and comfort degree was evaluated according to limit values of national codes. The results show that natural vibration period of the isolated structure increases obviously and seismic action decreases. Story shear force is far less than that of anti-seismic structures. Horizontal reduction coefficient is lower under rare earthquake. Story displacement is centralized at isolation layer, while it approaches zero on superstructure. The isolated structure shows whole translational motion. Story acceleration is reduced significantly and the value changes slowly, which shows that comfort degree is improved. Plastic deformation is not highly developed and the structure can be used after simple reparation. Plastic hinges appear all at the end of frame beams, and no one is found at the end of frame columns. All isolation bearings are in the state of compression as overturning moment of isolated structure decreases rapidly, and the stability of the structure can be ensured. The results of simplified calculation method with single particle are higher than limit values. The results of elastic time-history method show that of the effect of reducing noise under metro vibration is fine due to consideration of favorable factors such as initial stiffness and the difference of tension and compression stiffness of rubber bearings. Peak values of story acceleration decrease obviously and are lower than limit values.