Past, present and future of seismic evaluation of bridges in Kentucky

Western Kentucky is situated in the heart of the New Madrid seismic zone. In recognition of this high seismic risk, a study was initiated in 1986 to determine the vulnerability of the highway system in western Kentucky. The study concluded that a total of 111 bridges are likely to fail on a selected primary 'emergency' system. A number of these bridges have been retrofitted and the rest are scheduled for retrofit. In addition to these bridges, two double deck bridges crossing the Ohio river have been evaluated for possible collapse. The study on these bridges was mandated by FHWA following the collapse of the Bay Bridge and the elevated portion of I-880 during the 1989 Loma Prieta Earthquake. At present, a study is underway to develop earthquake time histories, design spectra, and maps of horizontal acceleration for use in the design of new bridges and in the seismic evaluation of existing bridges and appropriate retrofitting schemes.