scope:

APPLICABILITY

This document presents Guide Specifications for the seismic isolation design of highway bridges and is supplemental to the AASHTO LRFD Bridge Design Specifications (the Design Specifications) and the AASHTO Guide Specifications for LRFD Seismic Bridge Design (LRFD Seismic). Fundamental requirements for seismic isolation design are provided.

Information provided herein for bearings used in implementing seismic isolation design are supplemental to Design Specifications, Section 14. These provisions are necessary to provide a rational design procedure for isolation systems incorporating the displacements resulting from seismic response. If a conflict arises between the provisions of these Guide Specifications and those in the Design Specifications or LRFD Seismic, or both, the provisions contained herein govern.

These Guide Specifications are intended for isolation systems that are essentially rigid in the vertical direction and therefore isolate in the horizontal plane only. In addition, these Guide Specifications are intended for isolation systems that do not have active or semi-active components.