Load-Transfer Mechanism and Bond-Stress Components in Steel and Steel Fiber–Reinforced Concrete Structure

In order to solve difficulties in the construction of composite steel-reinforced concrete structures, the rebar cage is replaced with steel fiber to form a steel and steel fiber-reinforced concrete (SSFRC) structure. Pushout tests of 20 square specimens were carried out to study the load transfer mechanism in SSFRC, and load-slip curves were obtained. The failures of all specimens were divided into four modes. The bonding stress transfer mechanism on the interface was analyzed thoroughly, and as a result, full-stage load transfer on bond slip could be divided into five stages and five limit states. Values for three bonding forces (chemical bond, mechanical bite, and friction) were calculated. Measured bond stress was highly consistent with that derived from the theoretical full-stage analysis. When loading was relatively high, bond stress increased with it but the increment between each stage was smaller. Further, when loading was close to ultimate, this increment experienced a major drop or even negative growth in the area near the free end. The flange of the H-shape steel provided greater maximum bond stress and greater overall bond force than the web under loading.