AN APPLICATION OF THE PROPER ORTHOGONAL DECOMPOSITION METHOD FOR NONLINEAR DYNAMIC ANALYSIS OF REINFORCED CONCRETE STRUCTURES SUBJECTED TO EARTHQUAKES Naim AYOUB 1,2 , Walid LARBI 1 , Joseph PAIS 2 , Lucie ROULEAU 1 , and Jean-François DEÜ 1 1 Laboratoire de Mécanique des Structures et des Systèmes Couplés (LMSSC) Conservatoire national des arts et métiers (Cnam) 292 rue Saint-Martin – 75141 Paris cedex3 naim.ayoub@lecnam.net, walid.larbi@lecnam.net, lucie.rouleau@lecnam.net, jean-francois.deu@cnam.fr 2 GRAITEC INNOVATION 17 Burospace – 91572 Bièvres cedex naim.ayoub@graitec.com, joseph.pais@graitec.com Abstract This paper presents an extension of the Proper Orthogonal Decomposition method (POD) to nonlinear dynamic analysis of reinforced concrete multistory frame structure where the material nonlinearity is modeled by the multi-fiber section. To test the effectiveness of this approach, we first perform a nonlinear dynamic analysis under a seismic excitation using a direct implicit time integration scheme. Then, based on structural response observations, POD modes were extracted and used to reduce the structural system subjected to different earthquakes. A comparison was made between full model and reduced model analysis in order to assess the effectiveness of this technique. Keywords: Reinforced concrete beam, Material nonlinearity, Multi-fiber section, Dynamic analysis, Reduced model, Proper Orthogonal Decomposition. 1445 COMPDYN 2021 8 th ECCOMAS Thematic Conference on Computational Methods in Structural Dynamics and Earthquake Engineering M. Papadrakakis, M. Fragiadakis (eds.) Streamed from Athens, Greece, 28 - 30 June 2021 Available online at www.eccomasproceedia.org Eccomas Proceedia COMPDYN (2021) 1445-1457 ISSN:2623-3347 © 2021 The Authors. Published by Eccomas Proceedia. Peer-review under responsibility of the organizing committee of COMPDYN 2021. doi:10.7712/120121.8572.19536