Seismic performance evaluation of Korean column-tree steel moment connections

The purpose of this study was to evaluate the seismic performance of existing Korean column-tree connection type in steel moment frames. The column-tree connection has frequently been used in steel moment frames because it is well known to provide high quality and economy with shop-welding and field-bolting in Korea and Japan. However, there have been no studies on the design details and ductility of column-tree connections. Therefore, in this paper, the seismic performance of non-composite and composite column-tree specimens was evaluated to investigate their problems. Full-scale specimens were fabricated with non-composite/composite strong axis and weak axis column-tree connections, respectively. The testing results showed that, although non-composite column-tree specimens reached a 5% story drift ratio, tiny cracks occurred at beam-to-column connections. In the case of composite specimens, the expected brittle fracture at the bottom flange was not detected. However, severe crushing of concrete slab occurred, and the bottom flange underwent great stress. Therefore, composite action should be considered when composite structures are designed because bottom flanges may fracture.