Flexural behavior of steel-MPC based high performance concrete composite beams subjected to hogging moments.

• A novel MPC based high performance concrete (HPC) was introduced into composite beam. • Four-point bending tests were performed on three composite beam specimens. • Effect of the parameters on the negative flexural behavior of specimens were compared and discussed. • A model for the shear stiffness of stud connector embedded in MPCHPC slabs was proposed. • The deflection and negative flexural capacity of specimens were calculated and analyzed. The main objective of this study was to evaluate the negative flexural behavior of steel- magnesium phosphate cement based high performance concrete (MPCHPC) composite beams by conducting four-point bending tests. Three composite beams were designed and tested by varying the longitudinal reinforcement ratio ρ l and MPCHPC strength. The failure modes, load–deflection behavior, elastic stiffness, flexural capacity, relative slip, strain distributions, crack development and crack width of specimens were investigated. The test results indicated that with the increase of ρ l , the initial stiffness and yield load of the specimens slightly increased and the crack width decreased, while the effects on the cracking load and ultimate flexural capacity were not significant. The MPCHPC strength had a greater effect on cracking load and early crack width, but had a minor effect on the initial stiffness, yield load, ultimate flexural capacity and the late-stage crack width of the specimens. Furthermore, the formula for evaluating the shear stiffness of stud connectors embedded in MPCHPC slabs was proposed based on previous push-out tests. Finally, the deflection and negative flexural capacity of steel-MPCHPC composite beams were calculated and analyzed by adopting existing codes and simplified plasticity models. [ABSTRACT FROM AUTHOR]