其他摘要：Based on the study of two similar buildings equipped with seismic instrumentation, finite element models are developed and calibrated using seismic signals of input and response, recorded on the two buildings in August 2006. One building was constructed on a traditional rigid foundation and the other was isolated with a Base Control System (BCS). These numerical models are used to carry out an exhaustive comparison of the buildings’ dynamic behavior and to evaluate the isolation system performance. The isolated building’s behavior is weakly nonlinear, because the dynamic properties of isolators depend on displacements and frequencies. The stiffness and the damping coefficient of the isolators are considered as constants, these approximations allow the use of commercial finite element software to study the dynamic response due to the seismic excitation. The dynamic equations are numerically integrated in time domain, considering the non proportional damping caused by viscous dampers as a nonlinear load term. Acceleration at different buildings’ levels, base displacements, axial forces and bending moments on different columns, base shear and dissipated energy are compared for the two considered cases, BCS and the fixed base building model. The results show an effective reduction of accelerations and seismic loads in the isolated building to less than one third of the values corresponding to the rigid base building. The strategy of including some vertical flexibility and vertical damping in the isolators and admitting some small rocking motion of the building is also validated; considering that in the present case the vertical movements contribute to dissipate 20 % of the seismic energy.
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