# Bending Behavior of Corroded H-Shaped Steel Beam in Underground Environment
## 6 Conclusions  
In this study, the mechanical properties of corroded steel were first investigated. Subsequently, the bending performance of H-shaped steel beams that corroded under sustained loading in a sulfate environment was investigated. The following conclusions were drawn from the experimental investigation:  
1. In the sulfate environment, uniform corrosion and uneven corrosion occurred simultaneously. Pits appeared on the surface of the steel and the number and diameter of the pits increased with the corrosion time. When the corrosion time reached 180 d, the diameter of the pits was less than 3 mm.
2. Four different fracture modes were observed for the steel under monotonic tension; namely, flat fracture, oblique fracture, step fracture, and multiple fracture. The corrosion degree and corrosion morphology were the key factors influencing the fracture mode.
3. The yield strength and ultimate strength of the corroded steel decreased as the corrosion rate increased. The relationship between the yield strength and the corrosion rate, and the relationship between the ultimate strength and the corrosion rate, can be expressed by a polynomial.
4. The corrosion did not change the failure mode of the H-shaped steel beams. The bearing capacity and stiffness of the H-shaped steel beams was reduced by corrosion, and the degree of decrease was related to the corrosion rate. When the corrosion rate reaches 11.92%, the ultimate load and yield load are reduced by 20.66 and 15.15%, respectively. In addition to the corrosion rate, sustained loading may further reduce the bearing capacity.
5. Corrosion combined with a sustained load in a sulfate environment reduced the ductility of H-shaped steel beams. The bending test results reveal that the ductility decreased as the sustained load increased. When the corrosion rate reaches 11.92%, the ultimate load and yield load are reduced by 20.66 and 15.15%, respectively. Both the ductility index and the dissipation index can represent the ductility of corroded steel beams.
6. Equations for calculating the yield load and ultimate load of corroded H-shaped steel beams were derived, respectively. The results obtained by these two equations are similar to the measured values of the corroded H-shaped steel beams.  
Conceptualization, J.X.; Data curation, [PERSON]; Methodology, [PERSON] and J.S.; Funding acquisition, [PERSON] and H.C.; Writing--original draft, J.S.; Writing--review & editing, [PERSON] and H.C. All authors have read and agreed to the published version of the manuscript.  
The financial support provided by the National Natural Science Foundation of China (grant numbers 51978657 and 52008387), Postdoctoral Research Foundation of China (2019M652008), and the Key R&D project of Xuzhou City (grant number KC19199) is gratefully acknowledged.  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to the data also forms part of an ongoing study.  
The authors declare that they have no known competing financial interests or personal relationships that could have influenced the work reported in this paper.