The primary objective of the study was to establish the guidelines for screening, assessing, and ranking Indiana bridges for seismic upgrade. The outcome of the study is a complete strategy for the detailed structural assessment of Indiana highway bridges subjected to seismic forces. The structural evaluation is conducted using a nonlinear time-history analysis of the bridge for simulated or actual records. The specific soil conditions at the site are accounted in terms of the ground motion. From the time history analysis the maximum structural response including displacements, bending moments, shear and axial forces are computed. A weighted evaluation of the ratio of expected demand to available capacity is conducted next. A seismic rating is established based on the weighted evaluation. The bridges are classified into three different categories: high, moderate and low seismic risk. In the case of bridges falling in the high and moderate categories, the weighted seismic rating can be used to establish strengthening needs. The same type of analysis could be used to evaluate different strengthening schemes. In the case where the bridge inventory is substantial, the proposed strategy in this study would be more effective helped by a preliminary first level screening of the bridge population. Several first level screening procedures available in the United States are evaluated in this study. First level screening procedures are used in the qualitative ranking of seismic bridges with respect to seismic risk. They are simplified methods for use in extensive highway networks and are the first steps in a comprehensive evaluation strategy. The Indiana Department of Transportation has conducted a preliminary first level screening of the bridge population in the southern part of the state. Several bridges have been identified as presenting a high level of seismic risk. The approach proposed in this study could be used to further refine the preliminary ranking, and to evaluate different strengthening schemes. It must be pointed out that the soil-structure interaction of bridge structures is a developing area. Many questions remain to be answered regarding the proper modeling of the foundation and the surrounding soil. The proposed evaluation strategy can be improved by means of a field evaluation of dynamic characteristics of a representative sample of bridge foundations and soil conditions in the critical southern part of the state.

Report Number



structural performance, strengthening seismic evaluation, risk, HPR-2072

SPR Number


Project Number

HPR-2072 (029)

File Number


Performing Organization

Joint Highway Research Project

Publisher Place

West Lafayette, IN

Date of this Version