en Structure-Earthquake Structure-Earthquake Research Paper Research Paper The seismic behavior of frame bridges is generally evaluated using nonlinear static analysis with different plasticity models hence this paper tends to focus on the effectiveness of the two most common nonlinear modeling approaches comprising of concentrated and distributed plasticity models. A three-span prestressed concrete frame bridge in Tehran, Iran, including a pair of independent parallel bridge structures was selected as the model of the study. The parallel bridges were composed of identical decks with the total length of 215 meters supported on different regular and irregular substructures with non-prismatic piers. To calibrate the analytical modeling, a large-scale experimental and analytical seismic study on a two-span reinforced concrete bridge system carried out at the University of Nevada Reno was used. The comparison of the results shows the accuracy of analytical studies. In addition, close correlation between results obtained from two nonlinear modeling methods depicts that the lumped plasticity approach can be decisively considered as the useful tool for the nonlinear modeling of non-prismatic bridge piers with hollow sections due to its simple modeling assumption and less computational time. Frame bridges, Pushover-based nonlinear static procedures, Discrete finite element models, Lumped plasticity approach, Distributed plasticity approach 217 225 http://ijce.iust.ac.ir/browse.php?a_code=A-10-145-2&slc_lang=en&sid=1 A. R. Rahai rahai@aut.ac.ir 180031947532846005813 180031947532846005813 Yes Amirkabir University of Technology S. Fallah Nafari saeideh.fallah.n@gmail.com 180031947532846005814 180031947532846005814 No Amirkabir University of Technology