Experimental study on the flexural behavior of flat steel – concrete composite beam

In this study, a new type of composite beam named flat steel – concrete composite beam is suggested for the rapid development of assembly structures. Experiments were performed on seven flat steel – concrete composite beams and one traditional steel–concrete composite beam to investigate their flexural behaviors. The failure mode of bending-shear fracture for the flat steel – concrete composite beam is found while the traditional steel–concrete composite beam fails by compression-bending fracture. The plane cross-section assumption is applicable to the flat steel – concrete composite beam. Compared with the traditional steel–concrete composite beam, the flat steel – concrete composite beam exhibits higher flexural stiffness, higher moment capacity, and higher ductility capacity. Based on the design theory of the traditional steel–concrete composite beam, simplified models for estimating the flexural stiffness and ultimate moment capacity of the flat steel – concrete composite beam are proposed, and they agree well with the test data.