Keynote Lecture

Dr. Roy Imbsen

“A new procedure for rapid post-earthquake safety evaluation of bridges"

As a part of the Data Interpretation Project of the California Strong Motion Instrumentation Program (CSMIP), a new procedure for rapid post-earthquake safety evaluation of bridges was developed, using existing strong motion records, earthquake characteristics data immediately available following a seismic event, and fragility databases, to assist responsible parties in making timely, informed decisions regarding post-earthquake bridge closures

This presentation summarizes the application of a newly developed procedure for the selected New Carquinez Bridge (NCB), and the ability to assess the damage immediately following an earthquake using the ground motion parameters of the earthquake event and fragility curves developed for the bridge so that a decision can be made on the continued use or closure of the bridge


Dr. Roy Imbsen has 47 years of experience as a practicing bridge engineer. His experience includes design, analysis, research and construction of transportation facilities. More recently, he is working with OSMOS USA to implement procedures for structural health-monitoring of highway bridges.

Dr. Imbsen has completed a project for AASHTO entitled Recommended LRFD Guideline Specifications for the Seismic Design of Highway Bridges, which was adopted by AASHTO in 2007. Additionally, he is advising Computers & Structures, Inc. (CSI) on how to enhance their software to support bridge engineers in the application of the new LRFD seismic design guidelines.

As President of Imbsen & Associates, Inc. (IAI), he led a team of bridge and highway engineers for 25 years. Dr. Imbsen’s experience covers a broad range of projects within the United States and several other countries. He is a registered Professional Engineer in 18 states and is the Engineer of Record on several major transportation facilities.

Additionally, Dr. Imbsen has been Principal Investigator on many bridge related research projects (sponsored by NSF, FHWA, AASHTO, NHI, SCDOT and Caltrans) covering bridge rating, wheel load distribution, thermal effects in concrete, computer program development for analysis and design and writing new design specifications.

Dr. Imbsen has been a pioneer in developing, implementing, teaching and applying seismic design principles to bridges since the San Fernando earthquake in 1971. He was a co-recipient of the AASHTO Dr. L.I. Hewes Award for the development of the first comprehensive seismic design specifications, which remained in effect for fifteen years.

He has directed and participated in the seismic upgrading of several major bridges including the Golden Gate Bridge, Benicia-Martinez Bridge, George Washington Bridge, I-40 Mississippi River Bridge in Memphis, Tennessee, Tobin Memorial Bridge

Dr. Imbsen developed the first FHWA Training Manual for Seismic Design of Highway Bridges in 1976, which has been updated several times. He is the Lead Instructor for the one-week FHWA Workshop designed to educate industry professionals to implement the latest technology for seismic design and retrofitting. Dr. Imbsen has given this workshop over 100 times throughout the United States and in several foreign countries