Probabilistic concept for deformation-based design of hybrid elements like composite beams
Final Report Abstract
In this project, jointly conducted by the TU Berlin and the RPTU in Kaiserslautern, the foundation for a design approach based on the deformation capacity and the deformation requirements of the structural components was established. The project was carried out by pursuing a total of five objectives in systematic steps. Firstly, experimental, numerical and analytical investigations for different material combinations (steel - concrete, timber - concrete) as well as for different commonly used static systems (single-span beams, continuous beams) were conducted (objectives 1 and 3). Based on these studies, a probabilistic approach was employed to determine the required partial safety factors for the hybrid single-span beams under consideration (objective 2). This analysis considers the isolated effects of internal deformations and redistributions, taking their variations into account. In a subsequent step, two-span steel composite girders with different material properties and varying degrees of shear connection were examined and experimental, numerical, and analytical assessments were conducted. These evaluations were again used for probabilistic analyses which, unlike the studies on single-span girders, also incorporated the internal redistribution of the external forces. Building on the results of the first three project steps, an initial concept for distinguishing component behavior concerning deformation characteristics was developed (objective 4). The concept was extended to cover continuous beams. The categorization developed consequently forms the basis for a differentiated approach to structural safety, enabling the differentiation and optimization of the required partial safety factors in design standards. In the final step, rotational capacity and moment redistributions were analyzed in relation to the design of the composite joint and the degree of reinforcement (objective 5). This allowed for the evaluation of interacting influences, which led to different failure modes, as well as varying required safety factors. Through this research project, the foundation was laid for investigating and evaluating hybrid beams with different material combinations and composite joint properties. The approach enables the integration of system behavior effects into structural safety considerations, with a specific focus on taking the ductility of individual component element behavior into account in the structural design, without altering the desired safety level. This way, ductile component behavior can be specifically rewarded and the economic efficiency of the design can be improved. To make the results applicable for a practical use in structural engineering, further analyses at the system level are necessary to validate the generalizability of the approach and identify potential application limits. Another goal is the development of a universally applicable design approach for hybrid beams, which adequately accounts for the various influences on the safety levels stemming from material, composite joint and system effects. In future research, the scope of the studies should be expanded to include additional material combinations, such as carbon fiber-reinforced polymers and concrete (CFRP concrete composite), which are increasingly used in structural strengthening.
Publications
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Beitrag zur Berechnung von Verbundträgern mit elastischem Verbund. Stahlbau, 83(4), 278-288.
Zhou, Donghua; Pahn, Matthias & Kurz, Wolfgang
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Zuverlässigkeitstheoretisches Konzept für die verformungsorientierte Bemessung von Verbundträgern, 20. DASt-Forschungskolloquium Essen, 2016
Korpas, G. & Geißler, K.
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Deformation-based reliability concept for composite beams, Proceedings of the 8th International Conference on Composite Construction in Steel and Concrete, Wyoming, 2017
Kurz, W.; Kostadinova, N.; Geißler, K. & Korpas, G.
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Trag‐ und Verformungsverhalten von Verbundfugen mit elastischem Verbund. Stahlbau, 86(11), 1036-1045.
Kostadinova, Natali & Kurz, Wolfgang
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Ermittlung der Sicherheitselemente bei der verformungsorientierten Bemessung von hybriden Trägern. Stahlbau, 87(2), 115-127.
Geißler, Karsten & Korpas, Gregor
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Untersuchungen zum Trag- und Verformungsverhalten von Verbundfugen mit Kopfbolzendübeln. Dissertation, Technische Universität Kaiserslautern, 2019
Kostadinova, N.
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Beitrag zur dehnungsorientierten sicherheitstheoretisch begründeten Berechnung von hybriden Trägern mit nachgiebiger Verbundfuge, Dissertation, Technische Universität Berlin, 2020
Korpas, G.
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Bewertung und Beurteilung des Trag- und Verformungsverhaltens von geklebten Stahlverbundträgern unter Berücksichtigung der Dauerfestigkeit der Verbundfuge, Dissertation, Technische Universität Kaiserslautern, 2023
Kludka, M.
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Untersuchungen zum Trag- und Verformungsverhalten von hybriden Trägern zur verformungsorientierten Bemessung, Dissertation, Technische Universität Kaiserslautern, 2023
Hauser, P.
