Final Report Summary - STABELAS (Stability of composite structures for civil engineering applications) This research project has mainly been oriented towards stability theory of elastic, elasto-plastic and damaged structural systems (beam and plate systems). The project has covered multidisciplinary aspects, such as structural modelling, theoretical mechanics, civil engineering applications and physics applications, numerical analyses and applied mathematics modelling. The originality of the research approach was in the effort to cover in a unified framework both civil engineering applications such as bridge decks, a typical macro-structure, but also nanotechnology applications for nano-structures. It has been recently shown that some scale effects may appear for both types of structural systems. Gradient and nonlocal mechanics are mathematical theories that are able to capture some scale effects typically observed in micro-structured or heterogeneous media.The research focus has been on the main instability problems of usual structural members encountered in civil engineering, namely the in-plane and the out-of-plane buckling of beam systems, and the local and global buckling of plate systems. Applications of such research can be found in the field of timber engineering, reinforced concrete engineering, steel structures, steel-concrete composite structures, and composite structures in general. This research part was divided into four directions: 1) the lateral-torsional buckling phenomenon (including the lateral-torsional buckling of micro-structured media);2) the buckling of damaged systems (including the stability of softening continuum damage mechanics systems); 3) the influence of the micro-structure on the stability of structural members (including gradient and nonlocal elasticity structures); and 4) the stability of higher-order shear structural theories treated as gradient elasticity media.The project started in September 2011 and lasted to the end of August 2012 (one academic year). Results of the research have been very satisfactory, and have been presented at a number of conferences, and published, or submitted for publication, in several high quality journals. The researcher has also taken part in supervisory work for Master / PhD students at the host institution (University of Oslo), and he has been a guest editor of one of the most important journal in his area of interest, the Journal of Engineering Mechanics, accompanied by an extensive reviewing activity. The researcher's scientific credibility has increased by undertaking the project, and because the scientific domain of the research is at the crossing point of formal methods for structural engineering and applied mathematics, the researcher will have no difficulty to find partners for joint actions, like the French CNRS, the National Institute of Applied Sciences (INSA of Rennes), the University of Rennes 1, the University of South Brittany (UBS) and other universities in France. Second, from the European Community standpoint, long-term potential benefit of the training will be made concrete by the fellow's intention to pursue his research following the very project theme, and, by exploiting his strengthened expertise, as a professor of civil engineering.