**12. Category identification, ranking, and prioritization of the I-24 bridge embankments in Western Kentucky**

In the KESR model, three categories are sought out to specify the failure risk of each embankment during a designated seismic event. A category for each bridge embankment along I-24 in western Kentucky is assigned. The assigned category is based on the three ranking parameters: the (*C/D)min.* ratio, the embankment displacement, and the liquefaction potential. Definition of the three categories (*A*, *B*, and *C*) is provided in Table 3. All 127 bridge embankments along I-24 in western Kentucky were analyzed using the procedures provided in the flowchart of Figure 6. The yield factor, (*C/D)min.* ratio, displacement, and liquefaction potential for each embankment are identified, and a seismic embankment category is assigned. Further prioritization within each category was carried out based on the significance of the three ranking parameters. The embankments are ranked starting from the one with the highest seismic risk. For instance, a bridge embankment in category *A* with a ranking of *A*1 is more susceptible to damage than a bridge embankment with a ranking of *A*2 or *A*3. The same also applies for categories *B* and *C*. The ranking comprises a priority list that will be provided to senior state engineers, who may utilize its information to take appropriate actions. Based on the priority list, accurate soil data for those embankments with the highest risk may be needed in order to accurately identify their risk.

Due to its immense size, the full listing of the 127-embankment ranking and prioritization is not presented. However, a sample ranking and prioritization list for all embankments in McCracken County is presented for the 250-year seismic event (Table 7). Some of the embankments, which are in Category *B* during the 50-year seismic event, fall in Category *A* during the 250-year seismic event. For instance, the analysis of Bridge # 73-0024-B00118 in McCracken County to resist the 50-year seismic event results in a displacement of 4.6 centimeters (1.8 inches), and thus falls in category *B*. The analysis for the same bridge to resist the 250-year seismic event results in a displacement of 27.3 centimeters (10.7 inches) and thus is considered to fall in Category *A*. None of the embankments in McCracken County fall within category *C* since the assigned *PGA* for McCracken County is the highest among all counties along I-24 in western Kentucky, in addition to the associated liquefaction potential. This is not the case for Christian, Lyon, Trigg, and Caldwell counties.



potential is shown in Zatar et al. [12, 13].

**embankments in Western Kentucky** 

needed in order to accurately identify their risk.

counties.

Liquefaction potential of few embankment sites along I-24 in western Kentucky is estimated using standard penetration tests (*SPT*) provided by the 'Kentucky Transportation Cabinet, Department of Materials and Geotechnical Testing.' For the rest of the bridge embankments along I-24 in western Kentucky, any judgment of the liquefaction potential is solely based on the surrounding soil type. The soil type is obtained from the *USGS* and *USDA* maps. A detailed method to predict the liquefaction

**12. Category identification, ranking, and prioritization of the I-24 bridge** 

In the KESR model, three categories are sought out to specify the failure risk of each embankment during a designated seismic event. A category for each bridge embankment along I-24 in western Kentucky is assigned. The assigned category is based on the three ranking parameters: the (*C/D)min.* ratio, the embankment displacement, and the liquefaction potential. Definition of the three categories (*A*, *B*, and *C*) is provided in Table 3. All 127 bridge embankments along I-24 in western Kentucky were analyzed using the procedures provided in the flowchart of Figure 6. The yield factor, (*C/D)min.* ratio, displacement, and liquefaction potential for each embankment are identified, and a seismic embankment category is assigned. Further prioritization within each category was carried out based on the significance of the three ranking parameters. The embankments are ranked starting from the one with the highest seismic risk. For instance, a bridge embankment in category *A* with a ranking of *A*1 is more susceptible to damage than a bridge embankment with a ranking of *A*2 or *A*3. The same also applies for categories *B* and *C*. The ranking comprises a priority list that will be provided to senior state engineers, who may utilize its information to take appropriate actions. Based on the priority list, accurate soil data for those embankments with the highest risk may be

Due to its immense size, the full listing of the 127-embankment ranking and prioritization is not presented. However, a sample ranking and prioritization list for all embankments in McCracken County is presented for the 250-year seismic event (Table 7). Some of the embankments, which are in Category *B* during the 50-year seismic event, fall in Category *A* during the 250-year seismic event. For instance, the analysis of Bridge # 73-0024-B00118 in McCracken County to resist the 50-year seismic event results in a displacement of 4.6 centimeters (1.8 inches), and thus falls in category *B*. The analysis for the same bridge to resist the 250-year seismic event results in a displacement of 27.3 centimeters (10.7 inches) and thus is considered to fall in Category *A*. None of the embankments in McCracken County fall within category *C* since the assigned *PGA* for McCracken County is the highest among all counties along I-24 in western Kentucky, in addition to the associated liquefaction potential. This is not the case for Christian, Lyon, Trigg, and Caldwell


**Table 7.** Seismic ranking for I-24 bridge embankments in McCracken County for a 250-year event County, western Kentucky

One complete example of the calculation procedures to identify the seismic risk of a bridge embankment in McCracken County is provided in Zatar and Harik [16]. Similar procedures are followed in order to identify the seismic risk of all the 127 bridge embankments in all seven counties along I-24 in western Kentucky. Full details and results of the ranking and prioritization of the bridges along I-24 in western Kentucky are provided in the Kentucky Transportation report [11].

Bridge Embankments – Seismic Risk Assessment and Ranking 229

*Department of Civil Engineering, University of Kentucky, Lexington, Kentucky, USA* 

The support of the Federal Highway Administration, Transportation Cabinet of the Commonwealth of Kentucky, and Kentucky Transportation Center is gratefully acknowledged.

[1] Buckle, I. G., and Friedland, I. M. (1995). *Seismic retrofitting manual for highway bridges*.

[2] United States Geologic Survey (*USGS*), '*Geologic quadrant maps of the United States*'

[5] Seed, R., and Harder, L. (1990). "SPT-based analysis of cyclic pore pressure generation and undrained residual strength." *Proceedings of the H. Bolton Seed Memorial Symposium*,

[6] Ambraseys, N. N., and Menu, J. M. (1988). "Earthquake induced ground displacements." *Earthquake Engineering and Structural Dynamics*, volume 16, pp. 985-

[7] Street, R., Wang, Z., Harik, I., Allen, D., and Griffin, J. (1996). *Source zones, recurrence rates, and time histories for earthquakes affecting Kentucky*. Report No. KTC-96-4, Kentucky Transportation Center, University of Kentucky, 194p (Addendum

[8] Dodds, A. M. (1997). *Seismic deformation analysis for Kentucky highway embankments.* M.

[9] Seed, H., Idriss, I., and Arango, I. (1983). "Evaluation of liquefaction potential using field performance data." *ASCE Journal of Geotechnical Engineering*, 109(3), pp. 458-

[10] Seed, H. B., Tokimatsu, K., Harder, L. F., and Chung, R. M. (1985). "Influence of SPT procedures in soil liquefaction resistance evaluations." *ASCE Journal of Geotechnical* 

[11] Zatar, W. A., Yuan, P., and Harik, I. E., "Seismic ranking of bridges on or over I-24 in western Kentucky." Research Report KTC, Kentucky Transportation Center, University

[12] Zatar, W. A., Harik, I. E., Sutterer, K. G., Dodds, A., and Givan, G., "Bridge embankments: Part I - Seismic risk assessment and ranking." *ASCE Journal of* 

Report No. FHWA-RD-94-052, Federal Highway Administration, May, 309P.

[3] United States Department of Agriculture (*USDA*), '*Soil conservation service'* [map]. [4] Sutterer, K., Harik, I., Allen, D., and Street, R., (2000). "Ranking and assessment of seismic stability of highway embankments in Kentucky," Research Report KTC-00-1,

Kentucky Transportation Center, University of Kentucky, 98 pages.

University of California-Berkeley, Vol. 2, pp. 351-376.

Sc. Thesis, University of Kentucky.

*Engineering*, 111(12), 1425-1445.

*Performance of Constructed Facilities*, June 2008.

of Kentucky, 2007.

Issam E. Harik

**Acknowledgement** 

**14. References** 

[map].

1006.

1998).

482.
