Experimental investigation of CFT column to steel beam connections under cyclic loading

• Experimental study on two types of bolted connection to CFT column under cyclic load.
• Flat and curved extended end-plates bolted to CFT column with through steel rods.
• Through beam connection type with an additional bolted bracket without any welding.
• Both types of connection showed stable behavior to drift ratio greater than 5%.
• All joints exhibited ductile failure due to plastic hinging in beams away the column.

Four half-scale interior connections with steel beams and concrete filled tubular (CFT) columns were tested, under cyclic displacement controlled load. Square and circular steel tubular columns were considered with two different types of connections. (i) Shop welded, flat and curved extended end-plates bolted to the CFT column with steel rods passing through the column and (ii) a through beam connection type, where the beam passes through the joint and is connected with an additional bolted bracket without using any welding between the beam and the column. The experiments demonstrated that all the subassemblies performed in a ductile manner to large displacements with no apparent signs of local distress in the tube wall. Rods passing through the columns in both cases were effective. Both circular and rectangular end-plate connections showed similar performance. Also, the through beam connections behaved very well.