Behavior of beam-to-column connection of CFT column system under seismic force

As a part of the U.S.-Japan Cooperative Earthquake Engineering Research Program on Composite and Hybrid Structures, eleven concrete filled steel tubular column (CFT) to structural steel beam connections were tested under reversed cyclic loading to investigate the effects of high material strength, configuration and geometry of connections, column axial load and loading direction on the shear strengths and deformation capacity. This paper presents the test results and discusses the shear behavior of CFT connections. All the specimens reached their ultimate panel shear strengths at least to be 1.3 times of the design panel ultimate strengths by AIJ-SRC (1987) formula, whose scope of application is for medium to low material strengths and not for high material strengths tested in this study. This means that the current AIJ-SRC formula can be conservatively used for high material strengths. The deformation capacity of the connections was also verified to have enough ductility.