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To study the seismic behavior of unsymmetrical steel reinforced concrete column, cyclic loading tests were carried out on 12 columns with T-shaped section steel and 12 columns with L-shaped section steel. The test parameters included shear span ratio, axial compression ratio, stirrup ratio and presence of cross tie. Mechanical process, failure mode, hysteretic characteristics, skeleton curves, ductility and energy dissipation ability were taken into comparison. The result indicates that unsymmetrical steel reinforced concrete column possesses good seismic performance under constant axial compression and cyclic horizontal load. The failure modes include bonding failure, shear-bond failure, shear compression failure and shear-composition failure. Obvious asymmetry phenomenon of positive and negative hysteresis loop are shown. The span ratio has great influence on failure mode and shear-composition failure usually takes place in L-shaped steel section column. With the increase of axial compression ratio, the ductility decreases, which is obvious in L-shaped steel section column. The ductility and bearing capacity of the T-shaped steel section columns are improved greatly with the increase of stirrup ratio, but not obvious for T-shaped steel section column with smaller span ratio. Cross ties can improve bearing capacity, limit strength and stiffness degradation and enhance deformation capacity of L-shape steel section columns clearly. [ABSTRACT FROM AUTHOR]

Concrete-filled steel tubular columns have been studied extensively worldwide. Such columns provide stable energy dissipation, which is ideal for earthquake engineering application. However, most applications use rectangular steel tubular sections. In the location of wall intersections, these sections often create sharp corners, which are architecturally displeasing. In some facilities such as schools and correctional facilities, sharp corners are even prohibited due to their potential hazard to occupants. To resolve the issue, concrete-filled crisscross steel tubular columns (CCSTCs) have been proposed. Three half-scaled specimens were constructed and tested under cyclic displacement loading history. The experimental results were used to calibrate numerical models of the components and further used to examine the seismic behavior of a three-story prototype office building located in Los Angeles. The results showed the proposed CCSTC has excellent energy dissipation and postearthquake performance, and hence it can be used as an alternative lateral force resisting system for seismic applications. [ABSTRACT FROM AUTHOR]