## 7 Summary, Conclusions and Outlook  
In the present paper, an overview of applying the Shear Crack Propagation Theory (SCPT) for shear in slender members without shear reinforcement was provided. In general, the SCPT accounts for the equilibrium of forces and material constitutive behavior, as well as compatibility of the kinematic behavior, and correlates the elementary effects of the shear behavior (crack localization, crack propagation, cantilever action, shear transfer in the uncracked concrete part of concrete, aggregate interlock, dowel action and crack bridging action) in one all-encompassing algorithm. In order to compare the theoretical results from the the SCPT analysis with the experimental values, the results of two new beam shear subtests in the form of a three-point bending test were presented. For verification, the focus of the evaluation was on the experimentally observed shear crack geometry, the crack kinematics in terms of the crack opening at the height of the tensile flexural reinforcement, the maximum concrete strain in the top fiber of the compression zone and the ultimate failure load. Close to the final shear failure, a slight deviation between the theoretical values and experimental results exhibiting a nonlinear material behavior was observed, indicating room for further development. The SCPT provides well-suitable results in comparison with the experimental data and allows to analyze the different load-carrying mechanisms during the entire range of the loading history. With regards to the detailed analysis of specimen B1-1, the following statements can be made:  
* The relative shear contribution of the uncracked concrete zone is up to 100% at low load levels and reduces to \(\sim\)30% close to failure. The absolute capacity of the uncracked zone increases with the flattening crack propagation angle until it slightly reduces at higher load levels due to increased vertical stresses at the crack tip resulting from a cantilever action of the concrete teeth. * After a rather steep increase of the relative shear contribution of the fracture process zone for small shear crack rotations, this relative contribution remains constant at 10-20% of the total shear capacity during the further loading process. The shear contribution of the FPZ becomes more effective with the flattening crack propagation angle and does not vanish or significantly reduce at higher load levels. * The aggregate interlock is activated rather late during the loading process, since sliding of the crack lips is required, which is observed after the vertical crack path turns into a more horizontal crack path. Nevertheless, the relative shear force contribution resulting from the aggregate interlock is \(\sim\)40% at failure and, thus, is the most effective shear-carrying mechanism at that point. * The dowel action effects are immediately activated, resulting from a vertical component of the crack opening. The shear force taken by the dowel action increases until a maximum is reached, depending on the assumed constitutive behavior. In the case of B1-1, the relative shear contribution of the dowel action amounts to a maximum of \(\sim\)30% and slightly reduces to \(\sim\)20% at failure. In the future, the SCPT will be further validated and extended on the basis of an extensive experimental campaign including several beam shear tests with systematically varying boundary conditions (e.g., reinforcement ratio, aggregate size, and the shear slenderness). Furthermore, refined constitutive behavior models will be implemented specifically focusing on the effects of the aggregate interlock and dowel action. The effects of normal forces and the consideration of shear reinforcement are also going to be an object of future research efforts. In the end, an advanced and generalized SCPT algorithm will be used to derive simplified but mechanically consistent approaches for most of the common shear design purposes. Conceptualization, M.S. and M.C. ; methodology, M.S. and M.C. ; software, M.S., S.W. and M.C. ; validation, M.S. and M.C.