Behavior of Beam–Column Joint in Fully Encased Composite Column Subjected to Cyclic and Monotonic Loading

Structural joints help to transfer the load and the moment from the beam to the column. Connections are denoted as one of the most important aspects of a structure to be designed. This study has attempted to develop a better understanding of the behavior of joints in a composite structure. The experimental study consists of beam–column joints in four fully encased composite column specimens, two are tested against monotonic, and two are tested against cyclic loading conditions. Each of the specimens consists of a structural steel beam section (100 × 75 × 5 × 5 mm) and a structural steel column section (100 × 90 × 5 × 5 mm) with a combination of four 16 mm bars as longitudinal rebars and 8 mm bars as tie bars. The structural steel sections of the beam and column are joined by an extended endplate and four M20 bolts. 27 MPa concrete is used for each of the specimens to employ the composite action. The results and the designed specimens are validated against the AISC Design Guide 4, which has shown promising outcomes with acceptable deviations. It is observed that the composite specimens show a better performance in moment capacity against cyclic loading when compared to a bare steel specimen. Under monotonic loading, acute failure is observed, whereas cyclic loading induced progressive failure. Specimens subjected to cyclic loading have shown severe joint failure compared to the monotonic loading, whereas early concrete failure is seen on each specimen regardless of the loading conditions.