Seismic Vulnerability Assessment of Multi Span Reinforced Concrete Bridges in Republic of Macedonia

Being located in the central part of the Balkans, Republic of Macedonia has an economically strategic position for the region. Conditions of bridges are therefore significant in assessment of the entire seismic risk for the regional transportation network. This paper deals with vulnerability of road bridges typical for the Republic of Macedonia by use of an expanded multiple stripe analysis method approach. Typical bridges were selected based on an inventory study, which included statistical analyses of in situ collected data on all vital structures along the main roads and highways in the territory of the Republic of Macedonia. The results from the performed statistical analysis showed that most of these bridges represented reinforced concrete bridges with main girders. To define the vulnerability of these bridges, representative examples of variable geometrical characteristics were selected. Their values were adopted in combination with the values obtained from the statistical analysis. Vulnerability curves were obtained analytically by nonlinear dynamic analyses and use of different sets of ground motions scaled to different intensity levels. PGA was used as a measure of intensity. Based on nonlinear behaviour of the bridges and development of displacements in the bearings, four damage levels were defined. The soil-structure interaction was also taken into account in the analysis of the representative bridges. The seismic response of the typical reinforced concrete girder bridges was at an acceptable level.