BRIDGE ISOLATION WITH HIGH-DAMPING RUBBER BEARINGS -ANALYTICAL MODELLING AND SYSTEM RESPONSE

摘要

High-damping rubber (HDR) bearings are used in seismic isolation applications for buildings and bridges,although no models are currently available for the accurate description of the shear force–deformationresponse under bidirectional loading. A strain rate-independent, phenomenological model is presentedwhich effectively represents the stiffness and damping of HDR bearings for a range of shear strains. Themodel decomposes the resisting force vector as the sum of an elastic component, obtained from ageneralised Mooney–Rivlin strain energy function, and a hysteretic force, described by an approachsimilar to bounding surface plasticity. The proposed model is used in a series of parametric studies ofisolated bridge systems with ground motion of varying intensity. It is found that, while the HDR bearingsystem is effective at design levels of earthquake intensity, at higher levels of ground motion, significantinelastic demand may be experienced in bridge piers. Capacity design philosophy, which requires aductile failure mechanism for any level of earthquake intensity, implies that ductility must be provided inthe piers, and the interaction between pier yielding and bearing response must be understood.