# Shear Capacity of Textile-Reinforced Concrete Slabs without Shear Reinforcement
## 5 Conclusions  
While numerous studies of FRP-reinforced concrete exist, experimental data and systematic studies on shear behavior of TRC are sparse. Despite similar raw materials (glass, carbon), grid-like textile reinforcement features certain differences compared to FRP bars, e.g. the smaller size and thus lower bending stiffness, the fixed transversal yarns, and the possible variation of cross-sectional dimensions in the longitudinal direction. The use of TRC aims at reducing the member sizes compared to conventional reinforced concrete. This leads to a typically reduced thickness in planar members (e.g., slabs), for which fewer experiments exist both in FRP and steel reinforced concrete.  
Despite these differences, the results from an experimental program on 27 slab segments show clear parallels in shear behavior. The formation of the critical shear crack from bending cracks and the similar failure mechanism (shear compression failure) are evident. The formation of longitudinal  
Figure 9: Comparison of experimental results to predicted shear force: (**a**) Critical shear crack theory (CST) [83; 84; 85]; (**b**) Model by [PERSON] et al. [46]; (**c**) Design formula from CSA S8-06-12 [53]; (**d**) Design formula from ACI 440.1R-15 [54].  
cracks in the layer of reinforcement combined with concrete spalling can be seen as reason for high scatter in otherwise identical members.  
By variation of shear span to depth ratio, the influence of direct load transfer from concentrated loads was investigated. It can be concluded that here, with a shear slenderness larger \(a/d=5\), no significant reduction of shear capacity occurs. However, a significant difference between \(a/d=4\) and 5 can be seen, which is a significant difference to reinforced concrete where an influence up to \(a/d<2.5\)-3 is typical. This might be a result from the bond characteristics of the textile reinforcement with its significant longitudinal crack formation in the layer of reinforcement.  
The variation of member height in the experimental program showed a reduction of relative shear capacity by increasing effective depth. A first approach to transfer models for consideration of size effect indicates that existing models can be used in TRC shear design.  
The comparison of the experimental results to predictions from existing models for shear resistance of FRP-reinforced concrete indicates promising results; several current, readily available models are able to predict the ultimate shear force obtained in the experiments presented here with sufficient accuracy. However, this observation is yet to be validated by comparison to larger data sets in future works. There, a systematic variation of the type of reinforcement (grid opening, yarn spacing), the modulus of elasticity and strength of the reinforcement, the reinforcement ratio, and the maximum grain size and compressive strength of the concrete is necessary.  
Conceptualization, J.B. and V.A.; experiments: J.B.; formal analysis, J.B. and M.C.; writing--original draft preparation, J.B.; writing--review and editing, V.A., J.H. and M.C.; visualization, J.B. and V.A.; supervision, J.H. and M.C.; project administration, J.H.; funding acquisition, J.B. and J.H.  
This research was funded by the German Federal Ministry of Education and Research (BMBF), grant number 03 ZZ0304I. The APC was funded by German Federal Ministry of Education and Research (BMBF), grant number 16 PGF0147.  
The authors give their thanks to solidian GmbH for donation of the carbon grid reinforcement used for the experiments. The authors are particularly thankful for the work of Mr. [PERSON] in preparing and testing the specimens.  
The authors declare no conflict of interest. The founding sponsors had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, and in the decision to publish the results.