Composite Behavior between Steel and Concrete Systems for Lateral Loads

Structural systems that combine steel and reinforced concrete provide increased stiffness and resistance at minimal cost, but stress transfer between the two materials is needed. This paper addresses these stress transfer requirements. The composite structural systems used for resisting lateral loads are reviewed, and the stress transfer demands for different systems are described. These demands are often quite large and localized. The stress and force transfer capacities are then evaluated, and design strategies for concrete filled tube (CFT) and encased steel section (steel reinforced concrete or SRC) are presented. The work shows that mechanical shear transfer devices can be avoided with many SRC applications, but significant transfer problems exist for braced frames with CFT columns. An ongoing research study into the requirements for braced frames with CFT columns is briefly described.