The New Seismic Retrofitting Manual for the U.S. Highway Bridges - Part I: Bridges

Seismic Retrofitting Manual for Highway Structures, Part I: Bridges will be issued in 2006 by the Federal Highway Administration, and will update existing bridge seismic vulnerability mitigation suggested practice. Recently completed by the Multidisciplinary Center for Earthquake Engineering Research, the manual offers better guidance on regular bridge retrofitting, evaluating, prioritizing, and screening than the 1995 Seismic Retrofitting Manual for Highway Bridges, which it replaces. The author presents an overview of the manual's performance-based philosophy and describes implementation procedures. Two seismic hazard levels are specifically addressed, as well as retrofit category selection, performance levels, amplification factors, soil site classes, anticipated service life, and bridge importance. Strategies for structural response improvement are then provided through a wide structural retrofit measure selection and several approaches. Recent philosophy on geotechnical foundation issues such as liquefaction and lateral spreading potential, as well as hazardous sites (e.g. near a fault), are summarized.