The Earthquake Engineering Online Archive

Two-Dimensional Finite Elasticity Analysis of the Stability of Multilayer Elastomeric Bearings

Simo, Juan C.; Kelly, James M.

UCB/SESM-1981/06, Dept. of Civil Engineering, University of California, Berkeley, 1981-11, 46 pages (500/C23/81/06)

A formulation for the solution of elastic stability problems embedded in the general setting of two-dimensional finite elasticity has been presented, together with two-dimensional constitutive equations capable of modeling the typical behavior of multilayer elastomeric bearings. This constitutive model is an extension to the range of large displacements of the constitutive equations for a transversally isotropic solid. Physically meaningful expressions for the elastic constants involved in the model have been derived. It has been shown that the resulting formulation is in agreement with that of Haringx when the assumptions of beam theory hold. The numerical examples presented illustrate this conclusion. In addition, boundary conditions enforcing unilateral end constraint have been discussed. They play a key role in the elastic stability of the bearing, as illustrated in the numerical example presented. This type of boundary condition, rather than a form of material instability, explains the progressive reduction in lateral stiffness and eventual instability observed in the experimental testing of seismic isolation bearings.

Available online: http://nisee.berkeley.edu/documents/SEMM/SEMM-81-06.pdf (1 MB)