Energy dissipation and damage on the interface of steel and steel fiber-reinforced concrete composite column

To address the problems faced with steel-reinforced concrete (SRC) in construction, such as positional conflicts between steel and steel bars or difficulty in pouring concrete, a novel "Steel and Steel Fiber-Reinforced Concrete" (SSFRC) composite structure was proposed. Push-out tests of 34 SSFRC composite columns were carried out in this paper to study the interfacial bond performance from the perspective of energy dissipation. Based on loading-displacement (P-D) curves, the interfacial energy dissipation (W-b) and energy dissipation factor (lambda) were introduced, and the influence of embedded length (L-e), steel fiber volume rate (rho(sf)), thickness of concrete cover (C-ss), and section type on W-b and lambda were analyzed. Test results indicated that circular column is better than square column in terms of W-b and lambda. The increase of L-e, C-ss, or rho(sf) is beneficial to the improvement of W-b, and lambda is positively correlated with rho(sf) and C-ss but negatively correlated with L-e. Additionally, the interfacial damage (D-a) was defined by the relationship between elastic deformation energy (W-a) and W-b. It can be concluded that the ascent of L-e and C-ss can effectively delay the appearance of D-a and inhibit the development of D-a, respectively, and D-a develops slowly with the increase of rho(sf) at the later loading stage.