Experimental study on the interfacial bond strength and energy dissipation capacity of steel and steel fibre reinforced concrete (SSFRC) structures

In this study, to address the problems faced while constructing steel reinforced concrete (SRC) structures, such as the positional conflicts between the shaped steel and steel bars or the difficulty in pouring concrete, we propose a novel 'Steel and Steel Fibre Reinforced Concrete' (SSFRC) composite structure, wherein the steel reinforcement cage in SRC is replaced with steel fibres. We designed 20 square-section specimens and performed push-out tests to evaluate the bond properties between the shaped steel and steel fibre reinforced concrete experimentally. The influence of the steel fibre volume rate (ρsf), length-to-diameter ratio (Le/D0), and thickness of concrete cover (Css) on the interfacial bond strength, energy dissipation capacity, and interfacial damage were investigated. In addition, the ultimate bond strengths of SSFRC and SRC were compared. The results indicate that the novel SSFRC composite structure increases the ease of construction and has an ultimate bond strength that is similar to that of SRC. The interfacial energy dissipation increases with the increase in Le/D0, ρsf, and Css, and the steel fibres slow down the development of damage in the concrete specimens. Based on the results, we present an economical and effective method for determining the critical thickness of the concrete cover for SSFRC members. The thicker the concrete cover, the slower the interfacial damage development during the later stages of the test.