Vibration analysis of base-isolated building near urban rail transit

Obtain the dynamic metro-roadbed force based on vehicle-track vertical coupling dynamics model and build the 2D FEM ground model with viscoelastic artificial boundary condition to analyze the vibration-response characteristics of ground surface. Compare the mechanical performances of three types of isolating elements, namely, laminated rubber isolator, cylindrical helix steel spring and disk spring and discuss the application feasibility of base-isolated technology in the field of urban rail transit. Employ a 4-floor frame model to analyze the vibration-responses of base-isolated structure with various vertical natural vibration characteristics, and propose the isolation design suggestions. The analysis results show that the load-frequency band is mainly within 10Hz, special 5Hz, which can induce the resonance of building structure and may fall into the sensitive range to human body. The horizontal and vertical dynamic responses should be taken into account simultaneously. The existing isolation elements and the bi-isolator proposed can be applied to decrease the vibration responses of buildings, if their vertical stiffnesses are adjusted appropriately or they are constructed in some proper compound forms. The vibration responses will be decreased about 70%, if the 1st natural frequency of base-isolated building is controlled to be less than 3Hz~5Hz and the structure is attached with a damping of 5%~10% damping ratio.