VILNIUS TECH Library invites you to follow the published new dissertations. The dissertation „Optimization of steel frame thinwalled member cross-sections“ („Plieninių rėmų plonasienių elementų skerspjūvių optimizacija„) prepared by VILNIUS TECH, Mantas Stulpinas. The dissertation was prepared in 2019–2025. Scientific Consultant – Prof. Dr Algirdas Juozapaitis.
The dissertation was defended at the public meeting of the Dissertation Defense Council of the Scientific Field of Civil Engineering in the Aula Doctoralis Meeting Hall of Vilnius Gediminas Technical University at 1 p.m. on 6 June 2025.
The dissertation investigates steel thin-walled structures and their calculation methods. The load-bearing capacity of steel thin-walled structural elements subjected to combinations of compression and compression-bending forces is limited by different buckling modes. The local buckling mode is predominant in thin-walled structures. It has been established that thin-walled cross-sections with internal or edge stiffeners are more effective. The distortional buckling mode appears in the cross-sectional stiffeners. Ultimately, the structures are subjected to global buckling. Therefore, the selection of an optimal thin-walled structural cross-section is a complex process. The main goal of the dissertation is to optimize steel thin-walled structures and their cross-sections. The possibilities of forming thin-walled cross-sections and calculation and optimization methods are investigated to achieve the dissertation’s goal. The dissertation consists of four parts, including an Introduction, three chapters, Conclusions, and References. The Introduction reveals the investigated problem, the importance of the dissertation, and the object of research. It describes the purpose and tasks of the paper, research methodology, scientific novelty, the practical significance of results, and defended statements. The Introduction ends by listing the author’s publications on the dissertation’s subject and presentations made at conferences and defining the structure of the dissertation. The First Chapter revises the literature used. It presents calculation methods of steel thin-walled structures, introduces thin-walled built-up cross-sections, and reviews studies on cross-section optimization. Finally, it presents the investigated steel thin-walled cross-sections of portal frames. At the end of the chapter, conclusions are drawn, and the tasks for the dissertation are reconsidered. The Second Chapter formulates the optimization problem for the cross-section of thin-walled steel structures. It describes a developed and verified method for calculating the resistance of internal stiffeners of steel thin-walled cross-sections to distortional buckling to obtain more efficient cross-sections. The Third Chapter addresses the optimization problems of column and portal frame element cross-sections. It proposes closed-type thin-walled cross-sections for portal frame elements, which are more efficient than open-type cross-sections, and suggests a solution for portal frame joints with optimal cross-sections. Five articles were published on the dissertation topic: two in scientific journals referred to in the Clarivate Analytics Web of Science database, one in the international journal database, and two in peer-reviewed international conference proceedings.
Doctoral dissertation readers can search via VILNIUS TECH Virtual Library.
