Search Results (3)

Special-shaped concrete-filled steel tube (CFST) frames can be embedded in partition walls to improve space utilization, but their frame-level seismic behavior across joint types remains under-documented. This study examines six two-story, single-bay frames with cruciform, T-, and L-shaped CFST columns and three joint configurations: external hoops with vertical ribs, fully bolted joints, and fully bolted joints with replaceable flange plates. Low-cycle reversed loading tests were combined with validated ABAQUS and OpenSees models to interpret mechanisms and conduct parametric analyses. All frames exhibited stable spindle-shaped hysteresis with minor pinching; equivalent viscous damping reached 0.13–0.25, ductility coefficients 3.03–3.69, and drift angles 0.088–0.126 rad. Hooped-and-ribbed joints showed the highest capacity and energy dissipation, while replaceable joints localized damage for rapid repair. Parametric results revealed that increasing the steel grade and steel ratio (≈5–20%) improved seismic indices more effectively than raising the concrete strength. Recommended design windows include axial load ratio < 0.4–0.5, slenderness ≤ 30, stiffness ratio ≈ 0.36, and flexural-capacity ratio ≈ 1.0. These findings provide symmetry-based, repair-oriented guidance for transportation buildings requiring rapid post-earthquake recovery. Full article

To investigate the effects of parameters on the seismic performance of slender T-shaped RC walls subjected to a biaxial seismic action, a numerical model was established using a fiber-based cross-section and displacement-based beam–column element. The axial load ratio, shear span ratio, flange width to web height ratio, concrete strength grade, stirrup ratio, and longitudinal reinforcement ratio were selected for the parametric study, and the effects of these parameters on the performance degradation under biaxial loading were investigated. Furthermore, a sensitivity analysis of various parameters for the decrease was conducted. The results showed that the bearing and deformation capacities under biaxial loading were both decreased, and the total energy consumption was greater than that under uniaxial loading. The impacts of different parameters and loading paths on the decrease extent were significantly different, and the overall reduction was greater in the flange direction than in the web direction. Under the square loading path, the T-shaped wall had the greatest reduction in its seismic performance, followed by the eight-shaped and cruciform loading paths. The changes in the axial load ratio, shear span ratio, and concrete strength significantly affected the performance degradation under biaxial loading. Accordingly, it is recommended to reasonably consider the values of these three parameters in a multidimensional seismic design to maintain safety redundancy. Full article

In China, increasing the application ratio of hot-rolled H-shapes has become a severe problem that the government, academia, and engineering circles must vigorously address. Research on reasonable hot-rolled H-shapes built-up columns is one of the primary methods. After reviewing the various combination columns in the existing research, the paper proposes the new flanged cruciform H-shapes columns (FCHCs) made of three hot-rolled H-shapes. Using comprehensive imperfections given by the design standard, GB50017-2017, the paper analyzes the global buckling of FCHCs subjected to the axial compression load. The global buckling factor obtained is compared with the current national design code. Comparative analysis of seventy-two specimens of Q345 and Q460 steel found that the global buckling mode of FCHCs was flexural bending buckling around the axis of symmetry, and global torsional buckling and local buckling did not occur. Furthermore, the corresponding column curves in current design codes overestimate the dimensionless buckling strength of the novel FCHCs. Therefore, designers need to drop a class to select the global buckling factor within a specific range. Finally, new column global buckling curves are proposed based on a non-linear fitting of the numerical results according to the current national design codes. Full article