这些指导规范涉及美国目前定义地震危险的方式的重大变化，以及公路桥梁抗震设计的最新进展。它还反映了AASHTO LRFD桥梁设计规范和LRFD抗震桥梁设计指导规范中地震危险定义的变化、隔离器设计和施工的行业趋势，以及设计规范中影响隔震支座设计和测试的规定。新版本经过修订，并通过添加附录B进行了大幅扩展，附录B包含14个设计示例:两座基准桥梁和每座桥梁的六个设计变更。

These Guide Specifications address major changes in the way seismic hazard is now defined in the United States, as well as changes in the state of the art of seismic isolation design for highway bridges. It also reflects changes in the definition of the seismic hazard as now defined in the AASHTOLRFD Bridge Design Specificationsand theGuide Specifications for LRFD Seismic Bridge Design, industry trends in the design and construction of isolators, and provisions in the design specifications that impact the design and testing of isolation bearings. This new edition has been revised and greatly expanded with the addition of Appendix B, which contains 14 design examples: two benchmark bridges and six design variations of each one.