03-SP03 Recommended LRFD Guidelines for the Seismic Design of Highway Bridges MCEER/ATC Joint Venture, NCHRP 12-49 Project Team 2003 ATC/MCEER 498 75 The Recommended Guidelines consist of specifications, commentary, and appendices developed to be compatible with the existing load-and-resistance-factor design (LRFD) provisions for highway bridges published by AASHTO. This two-volume set offers the Specifications in Part I and the Commentary and Appendices in Part II. The new, updated provisions are nationally applicable and cover all seismic zones, as well as all bridge construction types and materials. They reflect the latest design philosophies and approaches that will result in highway bridges with a high level of seismic performance. This report contains numerous innovative and updated requirements and procedures, including: state-of-knowledge seismic hazard maps developed by the USGS; recommended design earthquakes and performance objectives; guidance on assessment of liquefaction and design solutions; new soil factors and spectral shapes; seismic design requirements for steel bridges; “no analysis” design concepts; some seismic resisting systems and elements not permitted in the current AASHTO provisions; capacity spectrum design procedures; displacement capacity verification (“Pushover”) analysis; and cost comparisons and implications. Equations, figures, and tables appear throughout this report. Load and resistance factor design (LRFD). Seismic performance. Bridges. Construction. Procedures. Requirements. Hazard maps. Seismic design analysis. Liquefaction. Displacement capacity verification analysis. Seismic resistance capacity. Steel bridges. American Association of State Highway Officials (AASHTO). Capacity spectrum design procedures. Pushover analysis.