A Study on Experimental Shear Behavior of Fiber-Reinforced Elastomeric Isolators with Various Fiber Layouts, Elastomers and Aging Conditions

摘要

Fiber-reinforced elastomeric isolators are innovative devices for seismic isolation that employ fibers,udrather than steel, as reinforcement material. Their light weight and low cost could help to widen theudapplication of seismic isolation, to housing for example, and to buildings in highly seismic areas of theuddeveloping world. Experimental studies available in the literature have already demonstrated the suitabilityudof fiber-reinforcing isolators to protect buildings from earthquake. Theoretical analyses have beenudcarried out to describe the isolator behavior under compression and bending. However, no treatment ofudits behavior under compression and shear has been performed yet. This because of objective difficultiesuddue to the non-linearity both of the geometry and the properties of these materials. The present paperudproposes a simplified geometric model to describe the isolator’s deformed configuration under compressionudand shear, based on the observation of its experimental behavior. The results of compression andudshear tests carried out on 17 pairs of fiber-reinforced isolators are reported. The specimens have differentudcharacteristics as regards rubber typology (neoprene and low and high damping neoprene), reinforcementud(bi-directional or quadri-directional carbon fiber fabrics), shape factor, and aging (unaged and agedudspecimens). On the basis of the proposed model, an expression for the equivalent linear horizontal stiffnessudof fiber-reinforced isolators is proposed. This expression predicts well the experimental results. Theudpredictions are more uniform and accurate than those obtained from the stiffness expression of traditionaludisolators, which is commonly used in the literature also for fiber-reinforced isolators.