Impact of LRFD Seismic Bridge Design on Georgia


Co-PI: Iris Tien
Student: Borja Zorca

Summary: The state of Georgia recently adopted the American Association of State Highway and Transportation Officials (AASHTO) Load and Resistance Factor Design (LRFD) Specifications including Seismic Design of Bridges.  The LRFD Specifications have numerous changes to previous codes used by Georgia DOT, the most noteworthy being the definition of ground motion.  The new specifications require that bridges are designed for a 7% in 75 years design event.   This corresponds to a ground motion with a return period of approximately 1000 years.  Although most of Georgia is in a low-to-moderate seismic zone, the code results in higher seismic forces and more stringent seismic details.   This study will assess the impact of the code on bridge design practices and make recommendations as appropriate.