Hysteretic Behavior And Design Criterion Of Composite Steel Frame-Reinforced Concrete Infill Wall Structural System With FR Connections

A composite steel frame-reinforced concrete infill wall(SRCW), in which the steel and concrete components work integrally through mechanical connectors. When this composite system is subjected to low earthquakes, it can keep its integrality by that the concrete wall provide protection to the steel frame. The uppermost advantage is that the cracks in the walls may be repaired after a moderate earthquake, and if the steel frame still keep its integrality, the badly damaged concrete walls can be replaced. The another important advantage of this system is its convenience for construction, since the columns and girders can be used as forms and form supports for efficient casting of the concrete. Because the SRCW structural system has favorable seismic resistant performance subjected to earthquakes, it has been applied in some engineering in recent years. It is newly type seismic resistant system with widely engineering application. But the study to this system, especially the work for the seismic resistant performance was behind the engineering practice.This paper was aimed at the investigation of the seismic behavior of the composite steel frame-reinforced concrete infill wall structural system with FR connections (strong axis) through a combined experimental and analytical research program.The primary part of this research was conducted a cyclic loading test on one two-story, one-bay specimen, which represented the bottom two stories of a six-story prototype structure at approximate one-third scale. The test showed that this system provided sufficient strength redundancy. Favorable ductility and energy dissipation was provided. At the design lateral load level, 85% of the lateral shear force was transferred from the steel frame to the infill through the headed studs, and approximately 65% of the overturning moment was carried by the steel columns.On the basis of the experimental results, this paper applied nonlinear finite element method to simulate the system, in which, the four main influential factors, such as numbers of the headed studs, reinforcement ratios, compressive strength of the concrete and vertical loads from upper stories aretaken into consideration. Some important conclusions are drawn.At last, advices for seismic design based on tests and FEM analysis are presented.This study can be useful for revising design code, guiding design of engineering, and providing good basis for further research to this structure.