# Structural Behavior of Large-Scale I-Beams with Combined Textile and CFRP Reinforcement
## 6 Conclusions  
In this study, three large-scale I-beams with mixed CFRP and textile reinforcement were tested to failure. Evaluation of results, accompanying numerical analysis and theoretical discussion led to the following conclusions:  
Figure 16: Theoretical and experimentally obtained \(M\)-\(\kappa\) curve for FT01 (**left**) and FT02 (**right**).  
* Production of beams with CFRP and textile reinforcement is feasible with methods available in precast production plants.
* Impregnated textile CFRP grids are well suited as shear reinforcement for I-beams with large effective depth, creating a dense crack pattern and bridging shear cracks efficiently. Through their short anchorage length, straight yarn ends were suitable to anchor shear reinforcement in tension and compression chord.
* Compatibility of CFRP bars and CFRP textiles is given when strain limits of different reinforcement types are considered in design. Premature rupture and premature spalling of concrete needs to be prevented.
* Calculation of ultimate load at bending failure with variation of linear strain distribution and with geometrical and physical non-linear FE-calculation delivers accurate results.
* Prediction of deflection with existing hand-calculation methods derived for steel- or FRP reinforced concrete is feasible if realistic tensile strength is assumed, accounting for eigen stress caused e.g., by concrete shrinkage. FE-calculations are suitable for SLS, as well.
* Shear failure of compressive struts of specimen FT02 can be explained through further reduction of compressive strength by dense textile reinforcement in the web compared to the reduction factor \(\
u_{1}\) from [64] assumed in design.
* Beam FT03 with 500 mm planar splice of the main reinforcement in mid-span failed prematurely at about 53% of the identical beam FT01 without splice. Splitting of concrete cover in the plane of pre-formed stirrup reinforcement was identified as failure mechanism. Pre-formed open glass FRP grids were inadequate for an effective lateral confinement of the splice.  
Future research should focus on detailing specifications for mixed CFRP bar/textile reinforcement. Studies on staggered prestressing might increase utilization ratio of CFRP reinforcement. Shear design models accounting for contribution of distributed textile shear reinforcement and concrete are to be developed in the future. Additional experimental studies on beams with large effective depth dimensioned for shear failure are required for this purpose.  
Conceptualization, J.B., J.H. and F.J.; Formal analysis, [PERSON] and J.H.; Funding acquisition, [PERSON], F.J. and J.B.; Investigation, J.B. and M.S.; Methodology, J.H. and J.B.; Project administration, J.H.; Resources, F.J. Software, M.S.; Supervision, [PERSON] and F.J.; Validation, [PERSON] and J.H.; Visualization, J.B. and M.S.; Writing--original draft, J.B. and M.S.; Writing--review and editing, [PERSON] and F.J. All authors have read and agreed to the published version of the manuscript.  
This research was funded by German Federal Ministry of Education and Research (BMBF), grant numbers 03 ZZ0312C and 03 ZZ0312G. The APC was funded by German Federal Ministry of Education and Research (BMBF), grant number 16 PGF0247.  
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.