ABSTRACT
The special integrated seismic protection system used to protect the steel viaducts of the Caracas – Tuy Medio Railway in Venezuela comprises bearings equipped with dissipating hysteretic elements that work only during the occurrence of well-determined seismic events. This is made possible by the presence of sacrificial steel elements (fuses) within the devices that during normal service and up to a pre-determined value of horizontal loads impede displacements in desired directions. Under such conditions the devices behave like standard bearings; when the threshold limit imposed for horizontal loads is exceeded, the fuses shear off and thus do not constitute a restraint to displacements in the directions previously blocked. Thus, the hysteretic steel elements are activated to dissipate seismic energy by opposing displacement and serve to control bridge deck movement. The hysteretic elements are produced by FIP Industriale S.p.A and are made of special austenitic stainless steel whose mechanical properties are not altered under the effects of temperature increases developed during the dissipation process.
