## 6 Discussion and Conclusions  
This paper combines global variance-based sensitivity analysis, (i.e., the Sobol' method) with a fiber finite element model of SFRC beam's flexural behavior to identify material properties whose uncertainty contributes the most to the uncertainty in the flexural behavior of an SFRC beam. To illustrate the proposed approach, a case study SFRC beam is presented. Results of the case study showed that the material parameter whose variance affected the variance of first-crack force and displacement the most (i.e., had the highest Sobol' index) was concrete tensile strength. The variance of the yield point was mostly affected by the variance of residual tensile strength of concrete and yield strength and elastic modulus of the longitudinal reinforcement. Finally, residual tensile strength was the dominant source of uncertainty for the beam's collapse point.  
The results of the sensitivity analysis can be used to efficiently reduce the variance of SFRC beams' flexural behavior, by reducing the variance of the material properties with high Sobol' indices. For example, the variance of SFRC's residual tensile strength, primarily caused by the random dispersion of fibers, can be reduced using casting procedures that lead to a more predictive distribution of fibers in the structural element (e.g., horizontal instead of vertical casting), by increasing the fiber content [6] or using advanced computational models to simulate the position and orientation of fibers in an SFRC element, reducing the uncertainty in the distribution of steel fibers along the structural element [43]. Furthermore, the results can help in understanding how changing the values of certain material properties will affect the flexural behavior of the SFRC beam. For example, in the presented case study it was identified that increasing the residual tensile strength will not significantly affect first-crack displacement and force, relevant for serviceability limit-states, but will affect the yield and collapse point.  
It should be noted that the results of the Sobol' analysis depend on the assumed probability distributions and their mean and variance values. Therefore, the results presented herein apply for the case of the assumed probability distributions for considered material properties (Table 1). Certain material properties might have low Sobol' indices, due to the assumed low coefficient of variation, not due to their small relevance to the SFRC beam behavior. Furthermore, the limitations of the numerical model, such as its conservative estimation of collapse displacement, should be kept in mind.  
Lastly, generalizing the conclusion obtained in this case study to beams of different geometric and material properties requires further analysis. Nevertheless, the presented methodology is applicable to beams of different dimensions and material properties, using the proposed numerical model or more advanced numerical models.  
Conceptualization, P.B. and N.B.; methodology, P.B. and N.B.; software, N.B.; validation, P.B. and N.B.; writing--original draft preparation, P.B., N.B. and D.K.; writing--review and editing, P.B., N.B. and D.K.; visualization, N.B.; supervision, P.B. and D.K.; funding acquisition, P.B. and D.K. All authors have read and agreed to the published version of the manuscript.  
The publication of this research was supported by the company \"Construction Center Ltd.\" from Subotica, Serbia.  
The second author appreciates insights provided by Professor [PERSON] from the University of California, Davis and Professor [PERSON] from the Chair of Structural Dynamics and Earthquake Engineering, ETH Zurich.  
The authors declare no conflict of interest.