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The influence of various seismic parameters on the seismic performance of rectangular reinforced recycled concrete columns was comprehensively revealed through collecting and screening experimental data from 53 rectangular recycled aggregate concrete columns. The research results showed that the bearing capacity of the specimens decreased and the ductility performance increased, which were attributed to the following factors. a. The increase in the replacement ratio and slenderness ratio of recycled coarse aggregate, and b. the reduction in the axial compression ratio and the strength of recycled aggregate concrete. The seismic design limitations and boundary conditions of this study are γ ∈ [0, 100%], n0 ∈ [0, 0.9], λ0 ∈ [5.06, 18.479], λ ∈ [1.09, 3.93], ρsl ∈ [1.01%, 2.45%], ρsv ∈ [1.4%, 5.33%], and f ∈ [C30, C50]. Thus, it is recommended that for the seismic design value of rectangular recycled aggregate concrete columns, the optimal longitudinal reinforcement rate be set at 1.59%. [ABSTRACT FROM AUTHOR]

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]