L-shaped concrete-filled steel tubular (CFST) columns, a kind of structural member appropriate for high-rise buildings, not only avoid the defect of conventional square columns protruding from the wall but also have the green and low-carbon properties of steel structures appropriate for fabricated construction. To learn more about their axial compression behavior, refined 3D finite element models were established using the general finite element software ABAQUS. The reliability of the models was subsequently verified based on failure tests and load–displacement relation tests on eight L-shaped specimens. The axial compression mechanism of L-shaped CFST columns was investigated using the verified finite element models. Further systematic parameter analysis was carried out to investigate the influence of parameters such as steel strength, concrete strength, length ratio of long limb to short limb, the angle between the two limbs, and combination methods on the axial compression behavior of L-shaped CFST columns. The results demonstrate that the angle between the two limbs has a significant impact on the stress distribution of concrete and steel pipes. The corner effect increases as the angle between the two limbs decreases. The combination of F-type specimens can better exert the constraint effect of steel pipes on concrete, while the triangular cavity of unequal-limb specimens and specimens with an included angle of 60° cannot effectively trigger the interaction between steel pipes and concrete. The initial stiffness of L-shaped CFST columns increases with an increase in concrete strength and a decrease in limb length ratio, which is not sensitive to changes in steel strength and the included angle. The peak bearing capacity of the specimens increases with increases in steel strength and concrete strength and a decrease in the limb length ratio. Compared to C-type and Z-type specimens, the initial stiffness of F-type specimens is slightly higher, and the peak bearing capacity is significantly increased.

Hillside buildings are particularly vulnerable to earthquakes owing to their structural configuration; however, research addressing this issue remains limited. This study investigates the effectiveness of high-damping rubber bearings (HDRBs) in enhancing the seismic resilience of hillside structures. Five numerical models were analyzed using non-linear time-history (NTH) analysis, including two flat-plane structures (one isolated and one with a fixed base) and three dropped-layer structures on hillside terrain (one with base isolation, one with inter-story isolation, and one with a fixed base). Deformation history integral (DHI) modeling was employed to simulate the HDRBs. Six earthquake ground motions from the PEER database and one scaled from 0.2–0.8 g were used to assess the seismic responses of the buildings. The results indicate that HDRBs significantly improved the seismic performance. The flat-plane isolated system (FIS) model achieved a nearly 90% reduction in peak roof acceleration compared to fixed-base structures. The dropped-layer isolated system (DIS) and dropped-layer inter-story isolated system (DIIS) models exhibited reductions of approximately 80% in the peak roof acceleration. Furthermore, the isolated structures demonstrated up to 78% reduction in the maximum inter-story drift, along with significant decreases in the story shear forces and overturning moments. Compared with non-isolated dropped-layer structures, the DIS and DIIS models showed reductions of 70% and 55% in the base shear force, respectively. The results highlight the efficacy of HDRBs in energy dissipation and their significant role in enhancing the seismic resilience of mountain structures.

L-shaped concrete-filled steel tubular (CFST) columns have attracted increasing attention in recent years due to their favorable seismic performance and their ability to reduce column protrusions into interior wall surfaces. Existing studies on L-shaped CFST columns have mainly focused on a specific cross-section form, and the mechanical behavior of L-shaped CFST columns with different limb length ratios and inter-limb angles has not yet been sufficiently investigated. To further examine the axial compressive performance of L-shaped CFST columns, this study designed and tested eight L-shaped CFST columns by considering the cross-section form, limb-length ratio, and inter-limb angle as key parameters. In addition, a simplified formula for predicting the axial load capacity of L-shaped CFST columns was proposed based on the unified theory. The test results indicated that the cross-section form significantly affects both load-carrying capacity and ductility. For the equal-limb specimens, the peak load of the C-type specimen was 8% and 9% higher than that of the A-type and B-type specimens, respectively, whereas the displacement ductility coefficient of the A-type specimen was 48% and 47% higher than that of the B-type and C-type specimens, respectively. Compared with the unequal limb specimens, the equal limb specimens exhibited an increase in peak load of more than 20%; moreover, the displacement ductility coefficients of the A-type and B-type specimens increased by 48% and 61%, respectively. Increasing the inter-limb angle enhanced the peak load but reduced the ductility, and it led to a gradual shift in the failure mode from local buckling of the steel tube to overall bending. The findings of this study contribute to a more comprehensive understanding of the mechanical behavior of L-shaped CFST columns and can provide reference for their design and optimization.