Basic Mechanical Properties of Duplex Stainless Steel Bars and Experimental Study of Bonding between Duplex Stainless Steel Bars and Concrete

Abstract

In recent years, as a result of the large-scale use of stainless steel bars in production and life, people’s demand for stainless steel bars has increased. However, existing research information on stainless steel bars is scant, especially the lack of research on the mechanical properties of duplex stainless steel bars and the bonding properties of duplex stainless steel bars to concrete. Therefore, this paper selects 177 duplex stainless steel bars with different diameters for room temperature tensile test, and then uses mathematical methods to provide suggestions for the values of their mechanical properties. The test results show that the duplex stainless steel bar has a relatively high tensile strength of 739 MPa, no significant yield phase, and a relatively low modulus of elasticity of 1.43 × 105 MPa. In addition, 33 specimens were designed to study the bonding properties of duplex stainless steel bars to concrete. In this paper, the effects of concrete strength, duplex stainless steel reinforcement diameter, the ratio of concrete cover to reinforcing steel diameter, and relative anchorage length on the bond stress were investigated, and a regression model was established based on the experimental results. The results show that, with the concrete strength concrete strength from C25 to C40, the compressive strength of concrete increased by 56.1%, the bond stress increased by 27%; the relative anchorage length has been increased from 3 to 6, the relative anchorage length has doubled, and the bond stress has increased by 13%; and, the ratio of concrete cover to reinforcing steel diameter increased to a certain range on the bond stress has no significant effect and duplex stainless steel reinforcement diameter has little effect on the bond stress. The ratio of concrete cover to reinforcing steel diameter from 3.3 to 4.5 and the bond stress increased by 24.7%. A ratio of concrete cover to reinforcing steel diameter greater than 4.5 has no significant effect on the bond stress, with the average bond stress value of 20.1 MPa. The duplex stainless steel bar diameter has little effect on the bond stress for the diameters of 12 mm, 16 mm, 25 mm duplex stainless steel bar, and their average bond stress is 19.9 MPa.

Forecasting ultimate bond strength between ribbed stainless steel bar and concrete using explainable machine learning algorithms

“…This is in accordance with the results reported in previous literature (Islam et al. , 2020; Li et al. , 2021; Pauletta et al.…”

“…However, current determination of τ u between SS and concrete still heavily relies on labor-intensive and time-consuming bond tests. Some simple (non)linear models have also been developed using limited data (Islam et al, 2020;Li et al, 2020Li et al, , 2021Rabi et al, 2020;Wang et al, 2022;Xu et al, 2022), but the predictive performance of these models is unsatisfactory on the unseen data (Wang et al, 2022). Considering the abundance of experimental τ u values available in the literature, it becomes feasible to employ ML for rapid estimation of τ u for SS reinforcement.…”

Structural performance of stainless steel reinforced concrete members: A review

“…Nevertheless, these properties vary depending on the grade and the method of production. Austenitic and duplex stainless steels are the most common grades used as a reinforcement in concrete structures owing to the outstanding corrosion resistance, excellent structural behaviour, and ready availability [78,79]. These grades generally provide greater strength, strain hardening and ductility compared with carbon steel reinforcement.…”

“…With reference to the Young's modulus, BS 6744 [72] suggests using a value between 190-200 kN/mm 2 for different grades of stainless steel based on guidance given in EN 10088-1 [74]; for carbon steel, Eurocode 2 assumes that Young's modulus is equal to 200 kN/mm 2 [22]. However, several recent studies have shown that a lower Young's modulus value for stainless steel reinforcement may be more appropriate in design [16,79,84]. This is mainly because of the nonlinearity nature of constitutive behaviour of stainless steel reinforcement and is an area that requires more research, including reliability analysis, in the future.…”

“…More recently, Li et al [79] tested grade 1.4362 duplex SS embedded in concrete with different cover distances and concrete strengths. Similar to Rabi et al [21], the observed failure modes were either pullout or splitting failure.…”