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TY - THES AU - Schmidt, Maximilian TI - New findings on shear behaviour in reinforced concrete members without shear reinforcement PB - Rheinisch-Westfälische Technische Hochschule Aachen VL - Dissertation CY - Aachen M1 - RWTH-2026-02391 SP - 1 Online-Ressource : Illustrationen PY - 2026 N1 - Veröffentlicht auf dem Publikationsserver der RWTH Aachen University N1 - Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2026 AB - To enable climate-friendly concrete constructions, design methods are required that are not only sufficiently reliable but also optimised in terms of material use and resource efficiency. The basis for such methods lies in realistic descriptions of load-bearing capacity through models with low statistical variability. A deeper understanding of structural behaviour also enables the identification of capacity reserves, which is particularly relevant for the assessment and continued use of existing structures. Against this background, research into reinforced and pre-stressed concrete structures under shear loading remains highly relevant. The core of this thesis is the flexural-shear behaviour of reinforced concrete structures without shear reinforcement. Despite extensive research over the past 100 years, fundamental questions concerning the shear transfer mechanisms and their interaction remain the focus of current investigations. The basis of the present study is a test series comprising 22 simply supported beams subjected to a point load, in which a selected spectrum of the most influential parameters was varied. The use of modern measurement techniques, digital image correlation across the entire shear span and fibre-optic strain measurement along the longitudinal reinforcement, enables a more detailed analysis of shear crack kinematics. Building on these measurements, the dominant load-bearing mechanisms and their interaction, particularly dowel action of the longitudinal reinforcement, aggregate interlock, stress transfer in the fracture process zone and in the uncracked concrete zone above the crack tip, are characterised and quantified. The experimental and theoretical investigations were carried out within a project founded by the German Research Foundation (DFG), project number 420545423, under the direction of Univ.-Prof. Dr.-Ing. Martin Claßen. For the evaluation of the individual shear transfer mechanisms, constitutive models from the literature are initially employed. Based on refined measurements, these models are extended and further developed to allow a more accurate representation of the key shear transfer mechanisms. In particular, novel experimental investigations into aggregate interlock and dowel action are carried out. For a comprehensive description of dowel action, a new model is derived that accounts for both the influence of axial tensile forces in the longitudinal reinforcement and the propagation of dowel cracks. Based on large-scale experimental studies on aggregate interlock using an innovative test setup, the calibration factors of the Rough Crack Model are redefined. Both models are used in this thesis to quantify the contributions to shear resistance. Finally, the Shear Crack Propagation Theory (SCPT) is validated. This physically based model combines all relevant shear transfer mechanisms into a unified framework as a function of crack propagation, while satisfying compatibility conditions. The good agreement between the model predictions and the experimental results regarding shear capacity, shear crack kinematics and strain distribution, confirms the validity and effectiveness of the modelling approach. LB - PUB:(DE-HGF)11 DO - DOI:10.18154/RWTH-2026-02391 UR - https://publications.rwth-aachen.de/record/1029553 ER -