Composite reinforced concrete beam of embedded double skin steel plates

The study intends to develop double skin composite beams using smart utilizing of proper properties of concrete and steel by incorporating steel frame likewise ribbed I-Steel section within concrete. The adopted built-up steel frame consists of upper and lower mild steel flanges connected by ribs using deformed steel bars and equivalent to customary shear reinforcement in quantity and provided as ribs within target frame besides shear resistance. The study considered an experimental program to investigate the effectiveness of introduces mode upon ultimate strength and related issues such as flexural ductility, flexural stiffness, plastic hinge formation, and failure mechanism in addition to comparative analysis with traditional reinforced concrete beam in the scope of assigned structural characteristics. The experimental results exhibit that the incorporated double skin steel within concrete without flexural reinforcement exhibited 78% of RC model ultimate strength where the ratio of volume fraction in steel-concrete-steel to reinforcement ratio in reinforced concrete beam is (1.5064). The powerful observed enhancement of the proposed ribbed I-steel section could be related to fully skin friction provided by fully connected upper and lower steel plates that affect the concrete confinement positively.