Earthquake response characteristics on uplift of multilayered elastomeric isolator of base isolated high-rise building with setback elevation: A study on the effects of simultaneous action input from horizontal and vertical ground motion on earth quake response characteristics of base isolated high-rise building part 2

The earthquake response characteristics of the isolators in a base-isolated high-rise building with a set-back were examined numerically. A three-dimensional framework vibration model was subject to seismic response analysis using a software application that takes into account the bending stiffness of seismic shear walls and floor slabs. The tension and compression in the isolators was analyzed for three motion components, the two horizontal components as well as the vertical motion component, input simultaneously for each of 51 strong ground motion accelerograms recorded during actual earthquakes. The results showed that (1) axial stresses in isolators at the corners below the low-rise part are higher than those in isolators under the high-rise part, with more than a few of the strong motions inducing maximum tensile stresses exceeding σt = 1N/mm2 at these points, which is the conventional seismic performance design target in the design process, and also compressive stresses that exceed the critical stress; (2) the tension in these corner isolators under the low-rise section is affected more by the vertical component of strong motion than by the horizontal components; and (3) the effective maximum acceleration amplitudes of short-period vertical strong motion and of long-period horizontal strong motion can be adopted as suitable indexes for evaluating the strong-motion induced tension in these corner isolators of a base-isolated high-rise building with set-back.