Application of SFRC in steel-concrete composite beams subjected to hogging moment

This paper describes the effects of SFRC on improving the mechanical performance of composite steel and concrete beams subjected to hogging moment. Four specimens with different concrete slabs and different shear connectors were examined experimentally in this study. Steel fiber reinforced concrete (SFRC) was used for two specimens, and normal concrete was applied for the other two specimens. Different types of shear connectors, including shear studs and Perfo-Bond Strips (PBLs), were used on steel-slab interface of the specimens. Shrinkage of the normal and steel fiber reinforced concrete, load versus mid-span deflection relationship, crack formation and its propagation process, and slip development on the steel-slab interface were measured and investigated. The test results show that the inclusion of steel fibers decreased both the crack spacing and crack width of the concrete slab. The specimens with steel fiber reinforced concrete have relatively large initial cracking load, and crack width of the concrete slab can be controlled appropriately in the service stage. The effects of the SFRC on the ultimate load carrying capacity of the beam depend on the shear connectors applied on the steel-slab interface. The application of SFRC could enhance the load carrying capacity of the specimen with stud shear connectors, however, the effects of SFRC on the load carrying capacity of PBL specimen were found to be declined in some extent. Besides, the current specifications, such as AASHTO, EUROCODE-4 and JSCE, are typically conservative in predicting the ultimate load carrying capacity for composite beams under hogging moment.