Optimal intensity measure of post-tensioned girder highway bridge using fragility curves

Over the last decade, Algeria has realized the highway project. It covers more than 1,200 km joining Algeria's eastern and western borders in the northern part of the country. This region is characterized by a high level of seismic activity. In total, this project contains more than 530 bridges, knowing that the design of these bridges was carried out with a simplified method namely the coefficient method, and does not comply with the requirements of the new Algerian seismic code for bridges RPOA-2008. For this reason, the development of fragility curves for these structures is necessary. This paper aims to develop analytical fragility curves for component and system fragility curves for post-tensioned girder highway bridges that represent the most common configuration in Algeria taking into account different spectral intensity measurements and the soil class based on the shear wave velocity specified in the Algerian bridge design code. Incremental dynamic analysis (IDA) is performed longitudinally on the bridge. Sixty seismic ground motions are scaled and employed for the time history nonlinear analysis. A variety of intensity measurements are chosen and the optimal intensity measurement with the lowest dispersion is proposed.