Non-linear behavior of Reinforced Concrete Members and Properties of CFT Structures

Composite members consisting of steel beam and CFT concrete column have been of great interest in the last few decades. Tubular columns are highly desirable in bending frames due to their high bending and twisting resistance and stiffness. Composite columns have considerable capabilities and efficiency due to the simultaneous benefit of the beneficial properties of steel and concrete materials. Also, the presence of concrete core in the CFT column causes the local buckling in the steel wall of these columns to be delayed. Therefore, proposing a suitable connection between the steel beam and the composite column makes it possible to take advantage of the potential benefits of these sections. Concrete in steel columns was initially used as a protective layer against impact and especially fire. This is because steel sections in extreme heat, very vulnerable and exposed to fire quickly lose their mechanical properties, as an example of the destruction of the two famous World Trade Towers 11 (WTC), September in America, which is one of the reasons The main effect of fire was to reduce and lower the mechanical properties of the steel used.