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

Abstract

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 ρl 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 ρl, 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.