Seismic isolators are constructed from multiple layers of elastomer (usually natural
rubber) reinforced with steel plates; they are, therefore, very stiff in the vertical
direction, but soft in the horizontal direction. The buckling of these bearings under
compression load is a well-understood phenomenon and has been widely studied. It is
therefore unexpected that the buckling analysis for compression predicts that
the isolator can buckle in tension at a load close to that for buckling in
compression. The linear elastic model that leads to both compression and
tension buckling is an extremely simple one, so it might be argued that
the tensile buckling may be an artifact of the model itself rather than a
property of the isolator. To test the simple theoretical model we have conducted
a numerical simulation study using a finite element model of a multilayer
elastomeric bearing. We find that the prediction of tensile buckling by the
simple linear elastic theory is indeed accurate and not an artifact of the
model.
Keywords
steel-reinforced elastomeric seismic isolators, tension and
compression buckling, linear theory, nonlinear finite
element analysis
