**4. Final Conclusions**

On the basis of the presented research results, performed analyses, and literature review, the following conclusions were formulated:


B- and C-series beams is described by linear regression Equations (4) and (5). These equations could be a contribution to the extension of the standard [15], which now allow for approximating the deflections (δ) of steel-fibre-modified beams only as a function of crack mouth opening displacement (CMOD).


**Author Contributions:** Conceptualization, C.B. and M.K. (Maciej Ka´zmierowski); Investigation, M.K. (Maciej Ka´zmierowski); Methodology, C.B.; Supervision, M.K. (Mieczysław Kami ´nski); Validation, C.B.; Visualization, M.K. (Maciej Ka´zmierowski) and M.D.; Writing—original draft, M.K. (Maciej Ka´zmierowski). All authors have read and agreed to the published version of this manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
