Bridge Seismic Retrofitting Practices in the Central and Southeastern United States

This paper conducts a detailed review of the seismic hazard, inventory, bridge vulnerability, and bridge retrofit practices in the Central and Southeastern United States CSUS . Based on the analysis of the bridge inventory in the CSUS, it was found that over 12,927 bridges 12.6% are exposed to 7% probability of exceedance PE in 75-year peak ground acceleration PGA of greater than 0.20 g, and nearly 3.5% of bridges in the CSUS have a 7% PE in 75-year PGA of greater than 0.50 g. Since many of the bridges in this region were not designed with explicit consideration of the seismic hazard, many of them are in need of seismic retrofitting to reduce their seismic vulnerability. While several of the states in the CSUS have retrofitted some of their bridges, systematic retrofit programs do not currently exist. The review of retrofit practices in the region indicates that the most common retrofit approaches in the CSUS include the use of restrainer cables, isolation bearings, column jacketing, shear keys, and seat extenders. The paper presents an overview of the common approaches and details used for the aforementioned retrofit measures. This paper serves as a useful tool for bridge engineers in the CSUS as they begin to perform systematic retrofit of vulnerable bridges in the region. DOI: 10.1061/ ASCE BE.1943-5592.0000128 CE Database subject headings: Bridges; Earthquakes; Rehabilitation; Seismic effects; Geological faults; United States. Author keywords: Bridges; Earthquakes; Retrofit; New Madrid Seismic Zone; State of the art.