[Structural Engineering]

Jiepeng Liu, Yi Zhao, Yuanlong Yang*, Yohchia Chen. Bending capacity and elastic stiffness for a novel configuration of cold-formed U-shaped steel and concrete composite beams. Journal of Structural Engineering, 2019, 145(10): 04019106.

Keywords:Bending capacity; Elastic stiffness; U-shaped steel; Composite beam; Shear connection.

High Lights:

>Anovel cold-formed U-shaped steel and concrete composite beam (RCUCB)is studied experimentally.

>Typical flexural failure was observed in the experiment.

>RCUCB can achieve plastic bending capacity and excellent deformability due to its integral action.

>A modified method for determining the shearconnection degree of RCUCB is proposed.

>Practical calculation methods for bending capacity and elastic stiffness calculation method are presented.

Abstract:

This paper discusses a novel cold-formed U-shaped steel and concrete composite beam (RCUCB) for which a reinforcement truss is furnished to stiffen the open steel U-section. Inverted U-shaped reinforcements are assembled to enhance the interface between a concrete flange and a beam web, which includes the bottom reinforcement, concrete fill, and steel U-section. A longitudinal bottom reinforcement is installed to control the slip between the concrete web and the steel U-section. Ten specimens were tested under bending moment, and all exhibit a typical flexural failure. Significant integrity for the RCUCB can be achieved through the enhancement of the reinforcement truss and inverted U-shaped reinforcement. A modified method for determining the shear connection degree of the RCUCB is proposed, which con- siders the contributions from the inverted U-shaped reinforcement, neck concrete, and reinforcement truss. Two transformed section methods were adopted to determine the elastic stiffness. In addition, a simplified bending capacity calculation method is presented.