Probabilistic lateral stability and shear failure limit states of bridge natural rubber bearings

Abstract

This study presents the results of a parametric analysis on a wide range of geometries of bridge natural rubber bearings for the definition of consistent limit states. This range, defined as a matrix depending on the shape factor, slenderness ratio, and device width, ensures maximum homogeneity of the studied population based on values typically found in practice for bridge applications. The effects of typical axial loads are also considered. Numerical analyses are performed on a finite element model previously developed by the authors that is capable of simulating shear failure and buckling limit states. Each specimen undergoes a numerical pushover analysis to obtain the critical shear strain and the type of ultimate limit state achieved. The results of the numerical analyses are first presented to show the influence of the investigated parameters on the type of limit state and the corresponding value of critical deformation. Design charts are constructed for practicing engineers. In addition, this work addresses the framework of performance-based design of bridges, with the objective of defining convenient damage states for the construction of bridge fragility curves. For this purpose, the statistical importance of each studied bearing pad or seismic isolator with respect to the whole population is taken into account to develop probabilistic capacity models. A slenderness threshold is validated for isolators to distinguish between potential limit states.