## 5 Conclusions  
In this work, we have presented a multiscale methodology for the assessment of the performance of steel-fiber reinforced concrete structures. We combine a material model to obtain the macroscopic properties, both elastic and fracture, and a structural model to quantify the effect of fiber addition. We apply this numerical approach for the analysis of post-tensioned SFRC dry joints, showing the ability of the framework to take into account different material compositions (e.g., concrete mix, fiber volume fraction) up to the macroscale, evaluating the shear capacity and ductility of the joint. This is remarkable since different design codes have proven to fail when predicting the shear strength and, most important, overestimate it in some cases.  
The results obtained for the nominal shear capacity of the joint are in agreement with other works in the literature in the case of no fiber addition. We report an increase of 57.6% of the shear capacity on average, when increasing the numbers of keys from 3 to 5.  
We have used this experimentally validated methodology to measure the effect of fiber addition in the structural performance. From our numerical simulations we observe that the addition of fibers increases the nominal shear capacity of the joint. In this sense, adding 0.5% of steel fibers, from a plain mix, leads to an average increase of 18.4% of the shear capacity. Further additions have less influence (of ca. 3%). Also, we propose an updated formula to that by [PERSON] et al. [17] but accounting for the volume fraction of fibers. However, the prestress value happens to be more influential on the shear capacity.  
Regarding the damage distribution, we observe a clear rise in ductility when the fiber content increases. This helps distribute better the shear capacity of the multiple keys. Fibers located at hot spots help arrest cracks, providing a more ductile response. Therefore, fibers could only be placed close the contact zone.  
The simulations presented in this study are only limited to one type of steel fiber. Thus, further investigations should be towards the analyses of different types of fiber mixes and other reinforced  
Figure 13: Nominal shear capacity in terms of prestress and fiber volume fraction: (**a**) \(\rm N_{k}=3\), (**b**) \(\rm N_{k}=5\).  
concrete structures (e.g., monitoring damage in girder box bridges, structural assessment of prestressed storage tanks, optimization of tunnel lining segment designs), since our methodology can be used without any loss of generality.  
Conceptualization, F.M.-C. and M.A.; methodology, F.M.-C. and H.C.; material simulations, F.M.-C.; structural simulations, J.M.-M. and M.A.; data processing, J.M.-M.; computer infrastructures and experimental data, H.C. All the authors wrote the manuscript. All authors have read and agreed to the published version of the manuscript.  
This research received partial funding from the project BIA2016-75431-R (Ministry of Economy and Competitiveness of Spain). The APC was funded by Universidad Loyola Andalucia.  
The authors acknowledge all the funding provided for the development of the research reported in this study.  
The authors declare no conflict of interest.