Built-Up Battened Steel Columns Under Cyclic Lateral Loadings

Built-up steel columns with battens at regular interval along their height are suffered from compound buckling and large shear deformations under axial loads. During seismic overloads, the local instability of components prevent column sections to develop their full plastic moment carrying capacities and to allow the sufficient rotations required for expected ductility demands. In the present study, the double-channel battened members are subjected to constant axial compression and gradually increasing reversed cyclic lateral load. A specimen of double-channel battened column designed as per code provisions failed due to lateral instability prior to reaching its full plastic moment carrying capacity. The degradation of flexural strength and stiffness started from the onset of local buckling of flanges and webs of column section.Two modified detailing of battens are studied. Based on both analytical and experimental investigations, it is concluded that the seismic performance of battened double-channel beam-columns can be improved by closer spacing of battens in the plastic hinge region and further improvements can be obtained by "boxing" the plastic hinge regions.