Research focus

Design and construction with ultra-high performance concrete (UHPC), shear load-bearing behavior of reinforced concrete components

Researcher

Kevin Metje, M.Sc.

Project description

In contrast to reinforced concrete components with shear reinforcement, there is still no generally recognized model for components without shear reinforcement that can be used to consistently capture the load-bearing mechanisms under shear loading. A comparison of different approaches and model concepts shows that the load-bearing components of the uncracked concrete compression zone, from crack interlocking or crack friction and from the dowel effect of the longitudinal reinforcement are interpreted and weighted differently.

In the case of steel fiber-reinforced bending beams, a load-bearing component of the fibers is added, which can cause a multiplication of the shear load-bearing capacity of components made of UHPC compared to a fiber-free component. The angle of inclination of the inclined shear crack determines its length and thus significantly the size of the load-bearing portion of the fibers activated in the shear crack.

The results of previous investigations into the shear load-bearing behavior of steel fiber-reinforced bending beams are empirically calibrated engineering models based on individual cases. However, these models are not physically reliable with regard to the formation and development of the critical shear crack, the mode of action of the fibers in this crack and the interaction with the other load-bearing mechanisms.

As part of the research project, the influence of the fiber content and the influence of a longitudinal compressive force (prestressing) on the inclination of the bending shear crack and the shear load-bearing capacity of steel fiber-reinforced UHPC bending beams are investigated experimentally and numerically. The aim is to identify the mechanisms responsible for the formation and development of shear cracks and to gain insights into the interaction of the different load-bearing mechanisms.

Publications

METJE, K.; LEUTBECHER, T., 2024. Shear design of ultra-high-performance fiber-reinforced concrete girders | Shear design of flexural beams made of steel fiber-reinforced ultra-high performance concrete. In: Congress documents 68th BetonTage: Shaping transformation. Ulm, May 14-16, 2024 Concrete Plant and Precast Technology. 90(5), 114. ISSN 0373-4331

METJE, K.; LÜTTICKE, S.; LEUTBECHER, T., 2024. Statistical Evaluation of UHPFRC Shear Verification Methods. In: FEHLING, E.; MIDDENDORF, B.; THIEMICKE, J., eds. Proceedings of HiPerMat 2024, 6th International Symposium on Ultra-High Performance Concrete and High Performance Construction Materials. Kassel, March 6-8, 2024. Kassel: kassel university press, pp. 141-144. Structural Materials and Engineering Series, Vol. 40. ISBN 978-3-7376-1159-6
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METJE, K.; LEUTBECHER, T., 2023. Verification of the shear resistance of UHPFRC beams - Design method for the German DAfStb Guideline and database evaluation. Engineering Structures. 277, 115439. doi:10.1016/j.engstruct.2022.115439
Appendix A. Supplementary Data 1. UHPC and UHPFRC Shear Data Base

METJE, K.; LEUTBECHER, T., 2022. Shear behavior of steel fiber reinforced UHPC flexural beams with compact cross-section. Concrete and reinforced concrete construction. 117(10), 812-825. doi:10.1002/best.202200046

METJE, K.; LEUTBECHER, T., 2022. Zur Querkraftbemessung von Biegeträgern aus stahlfaserverstärktem ultrahochfesten Beton - Teil 2: Datenbankauswertung und Überprüfung des Bemessungsansatzes/Design of ultra-high performance fiber-reinforced concrete girders subjected to shear - Part 2: database evaluation and review of design approach. Bauingenieur. 97(4), 122-130. doi:10.37544/0005-6650-2022-04-66

METJE, K.; LEUTBECHER, T., 2022. Zur Querkraftbemessung von Biegeträgern aus stahlfaserverstärktem ultrahochfesten Beton - Teil 1: Bemessungsansatz und Datenbank/Design of ultra-high performance fiber-reinforced concrete girders subjected to shear - Part 1: design approach and database. Bauingenieur. 97(3), 83-90-12. doi:10.37544/0005-6650-2022-03-67

METJE, K.; LEUTBECHER, T., 2021. Experimental investigations on the shear bearing behavior of prestressed ultra-high performance fiber-reinforced concrete beams with compact cross-section. Structural Concrete. 22(6), 3746-3762. doi:10.1002/suco.202100337
Supporting Information: Data S1. A: Shear tests / B: Time-dependent deformation and loss of prestress

METJE, K.; LEUTBECHER, T., 2020. Experimental investigations on the shear bearing capacity of UHPFRC beams with compact cross-section. In: MIDDENDORF, B.; FEHLING, E.; WETZEL, A., eds. Proceedings of HiPerMat 2020, 5th International Symposium on Ultra-High Performance Concrete and High Performance Construction Materials. Kassel, March 11-13, 2020. Kassel: kassel university press, pp. 9-10. Structural Materials and Engineering Series, Vol. 32. ISBN 978-3-7376-0828-2
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The project is funded by the Federal Ministry of Education and Research (BMBF) as part of the "Sustainable Universities" program. The aim of the funding is to develop and implement innovative concepts for environmentally friendly and resource-conserving campus design.

Important partners in the project are the city of Siegen, which provides support in the areas of mobility and climate protection, and the Institute for Environmental Research NRW, which provides scientific analysis and expertise. Siegen's municipal utilities are also involved in the implementation of sustainable energy solutions.