Seismic response evaluation of bridges under differential ground motion: a comparison with the new Algerian provisions

Seismic response of extended structures, such as bridges, must take into account spatial variability of earthquake ground motion (SVGM). Eurocode 8 (EC8) and the Algerian bridge seismic regulation code (Regles Parasismiques applicables au domaine des Ouvrages d'Art; RPOA) are among the rare bridge design codes that introduced simplified approaches for SVGM. This paper aims at evaluating the accuracy of the method proposed by the RPOA through comparison with more refined approaches and the EC8 provisions. Various bridges are considered and the results show that the RPOA's simplified method does not give satisfactory results and clearly overestimates the seismic demand. The solution proposed in this paper is to modify some provisions, and the new approach gives results which are in better agreement with the other methods.