Flexural behavior of large-scale U-shaped steel-concrete infilled composite beams with flat and embossed webs

Most popular shape of steel-composite beams is the exposed type in which wide-flange steel sections are connected to the reinforced concrete (RC) slab through shear connectors. However, recently innovative U-shaped steel-concrete infilled type composite beam sections are introduced which demonstrated promising structural performance. In these composite beams, the U-shaped steel section filled with concrete serves as formwork in fresh state of concrete while it behaves as main reinforcement during the service life of the structures. Although, active research has been conducted on former type, but research on the later infilled type beams seems insufficient. There exist several research questions which need to be addressed for optimized and efficient design of these innovative composite sections. In this paper, six large-scale U-shaped steel-concrete infilled composite beams with flat and embossed webs were tested to investigate their flexural behavior. The tested composite beams were designed with angle shear connectors which provide efficient shear transfer mechanism with economy. The main parameters of the tests were the shape of web and the spacing of the shear connectors. The effects of embossed web on horizontal shear transfer and its contribution to the flexural capacity were mainly focused. In addition, a detailed section analysis was conducted to comprehend the experimental observations.