## 5 Conclusions  
The bond property between deformed steel bars and hybrid fiber-reinforced concrete was examined in this study through experimental methods. The effects of concrete strength, protective layer thickness, embedded length and steel bar diameter on the bond property were analyzed. Additionally, a calculation formula for the characteristic bond strength value between deformed steel bars and hybrid fiber-reinforced concrete was proposed. Based on the test results, a constitutive relationship for the average bond stress-slip curve of basalt-polypropylene hybrid fiber-reinforced concrete and steel bars was established. The following main conclusions are drawn:  
1. The failure modes between the bond of basalt-polypropylene hybrid fiber-reinforced concrete and steel bars are essentially identical to those of the bond between conventional reinforced concrete and steel bars, which include three primary failure modes: concrete split failure, split-shear failure and steel bar pull-out failure.
2. The bond-slip curve characteristics between basalt-polypropylene hybrid fiber-reinforced concrete and steel bars are essentially equivalent to those of the ascending section in ordinary reinforced concrete. However, upon concrete cracking, the basalt-polypropylene  
Figure 17: Comparison between the prediction model and other measured curves. (**a**) [PERSON] et al. [21]; (**b**) [PERSON] et al. [8]; (**c**) [PERSON] et al. [22]; (**d**) [PERSON] et al. [23].  
hybrid fiber provides additional lateral restraint, resulting in a higher ultimate bond strength for basalt-polyppropylene hybrid fiber-reinforced concrete and steel bars. The descending section of the curve is gentler.
* Through a comparative analysis of the influence of concrete strength, protective layer thickness, embedded length and steel bar diameter on the ultimate bond strength, a prediction model for the ultimate bond strength of steel and hybrid fiber-reinforced concrete was established.
* Based on experimental data, the effects of bond strength and slip amount on the bond-slip curve were comprehensively considered, and a mean bond stress-slip constitutive relationship between basalt-polyppropylene hybrid fiber-reinforced concrete and steel bars was established through statistical regression analysis.  
Conceptualization, B.W.; Funding Acquisition, B.W.; Investigation, B.W., D.H. and G.G.; Methodology, B.W. and G.G.; Software, D.H. and G.G.; Supervision, G.G.; Validation, D.H.; Visualization, D.H.; Writing--Original Draft, B.W.; Writing--Review and Editing, G.G., D.H. and H.Z. All authors have read and agreed to the published version of the manuscript. Funding support was provided by the National Natural Science Foundation of China (52078415), the Shaanxi Provincial Key R&D Program (2022 KW-36), the Scientific Research Fund of the Institute of Engineering Mechanics, China Earthquake Administration (Grant No. 2020 EEEVL0415), the Collaborative Innovation Center Project of Shaanxi Provincial Department of Education (20 JY034), the Youth Innovation Team of Shaanxi Universities (2019-2022). Institutional Review Board Statement: Not applicable. Informed Consent Statement: Not applicable. Data Availability Statement: Not applicable.  
The authors thank the anonymous reviewers and editors for their constructive comments on this manuscript. The authors declare no conflict of interest.