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.
