A Study On Flexural Capacity Of Steel Reinforced Concrete Hidden Beam

In the subway, garage, large conference room and other projects that require large-span or high-load floor, hidden- beam floor is often adopted to reduce the altitude of floor and increase the available space of the structures. Steel-reinforced concrete(SRC) hidden-beam structure is a type of hidden-beam floor in which steel is embedded for higher load-bearing capacity and larger stiffness of floor. This can help to meet the actual requirements for larger spans and higher loads in some projects. In this paper, the bending resistance of SRC hidden beam and the methods for designing the structure were studied with a combination of experimental research and theoretical analysis. The research yielded two formulas for calculating the stiffness of SRC hidden beam and several methods for calculating the flexural load-bearing capacity of its normal section, thus providing a basis and support for the application and design of this structure in projects.A static loading test was conducted on six SRC hidden beam specimens. The analysis focused on the influences of some key parameters(such as the height of hidden beam’s section, size of steel’s section, and type of steel) on the load-bearing capacity and stiffness of SRC hidden beams experiencing bending. The results indicated that the steel was firmly embedded in concrete, showing little sliding displacement at the interface, and that the SRC hidden beams had high load-bearing capacity, large stiffness, and high ductility. Besides, it was found that the SRC hidden beams using cellular steel and those using solid-web steel had similar load-bearing capacity and stiffness. So the cellular steel was a more economical alternative for designing SRC hidden beam.Based on the experimental results, two formulas for calculating the flexural stiffness of SRC hidden beams were developed using the stiffness center method and curvature method respectively. It was found that the results yielded by the stiffness center method were closer to the experimental results. Moreover, a comparative analysis of different methods for calculating the flexural load-bearing capacity of a hidden beam’s normal section was performed based on existing procedures and theories. Then formulas were developed for calculating the flexural load-bearing capacity of the normal sections of SRC hidden beams using different types of steel. These research findings will provide a useful reference for the application and study of SRC hidden beam.