Flexural fatigue mechanism of steel-SFRC composite deck slabs subjected to hogging moments

• Published in: Engineering structures 2022-04, Vol.256, p.114008, Article 114008
• Main Authors: Xiang, Da, Liu, Yuqing, Gu, Minjie, Zou, Xiaojie, Xu, Xiaoqing
• Format: Article
• Language: English
• Subjects: Calculation method; Composite deck slabs; Composite materials; Concrete slabs; Decks; Failure modes; Fatigue failure; Fatigue performance; Fatigue tests; Fiber composites; Fibers; Finite element method; Hogging moment; Influence factors; Materials fatigue; Mathematical analysis; Metal fatigue; Parameters; Rebar; Reinforced concrete; Reinforcing steels; Service loads; Slabs; Steel; Steel fiber reinforced concrete; Steel fiber reinforced concretes; Steel fibers; Steel structures; Stiffness; Theoretical analysis
• ISSN: 0141-0296; 1873-7323
• DOI: 10.1016/j.engstruct.2022.114008

•The fatigue behaviors of steel-SFRC composite slabs under hogging moments were experimentally investigated.•The effects of SFRC’s strength parameters and slab’s structural parameters are numerically and theoretically clarified.•The calculation method of the rebar stress amplitude that governs the slab fatigue life is developed and validated. This paper aims to investigate the flexural fatigue mechanism of the steel-steel fiber reinforced concrete (SFRC) composite deck slab under hogging moments. Firstly, fatigue tests were implemented on two full-size slab specimens reinforced by different steel fibers, i.e. mill-cut steel fibers (MF) and corrugated steel fibers (CF). The failure mode, steel-concrete composite action, and crack behavior were measured and discussed. It finds that the fatigue failure of the composite slab under hogging moments was governed by the fracture of rebar in tension. Under service loads, the use of MF achieves lower stress amplitude of rebar in tension (Δσs) by 6–9% and higher slab stiffness by 2–7%, compared with CF. Subsequently, both finite element and theoretical analysis are employed, through which the influence mechanisms of SFRC’s strength parameters (fL, fR1, fR3) and slab’s structural parameters on Δσs are clarified, and the calculation method of Δσs is developed. Results showed that Δσs can be reduced by up to 7% with a 1.19 MPa increase in fL and by 12% as fR1/fL is raised by 0.4, whereas the effects of the fR3 are minimal where a reduction of lower than 1% is obtained as fR3/fR1 goes up by 0.4. The advantage of MF can be attributed to its better improvement on fL and fR1 than CF. It also reveals that steel members with greater bending stiffness can attract higher moments, which decreases the moment sustained by the SFRC layer and thus reduces Δσs. The proposed calculation method yields satisfactory prediction accuracy and is capable of capturing the effects of strength and structural parameters.