A Study of the Coupled Horizontal-Vertical Behavior of Elastomeric and Lead-Rubber Seismic Isolation Bearings

Keywords: Lead rubber (LR) bearings.  Low-damping (LDR) bearings.  Elastomeric bearings.  Lateral displacement.  Vertical stiffness.  Finite element (FE) analyses.  Seismic isolation.  Seismic performance.  Equivalent linear static (ELS) procedures.  Ground shaking.

Abstract: This report presents an analytical and experimental investigation of the coupled horizontal-vertical response of elastomeric and lead-rubber bearings focusing on the influence of lateral displacement on the vertical stiffness.  Component testing was performed with reduced scale low-damping rubber (LDR) and lead-rubber (LR) bearings to determine the vertical stiffness at various lateral offsets.  The numerical studies included finite element (FE) analysis of the reduced scale LDR bearing.  The results of the experimental and FE investigations were used to evaluate three analytical formulations to predict the vertical stiffness at a given lateral displacement.  The results of simulations performed with three components of excitation were used to evaluate an equivalent linear static (ELS) procedure for the estimation of the vertical load due to the vertical ground shaking.  References, tables, and figures are included; the four accompanying appendices can be found in PDF on an accompanying CD-ROM.