Finite Element Analysis of Axial Compression Behavior of L-Shaped Concrete-Filled Steel Tubular Columns with Different Combinations

Abstract

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.

Accelerated Bridge Construction Case: A Novel Low-Carbon and Assembled Composite Bridge Scheme

“…This technology can greatly promote ABC, but there are still the following problems for this project: (1) The standard size of the prefabricated capping beam is 42.3 m and the overall weight is 700 t. The lifting weight is more than 200 t even if it is divided into three segments for assembly and the requirements for the trafficability of large-scale transport routes and the hoisting capacity of the equipment are extremely high. (2) The large number of assembly interfaces will bring the problems of the high demand of assembly accuracy, complex connection details and the low reliability of the connection quality. (3) The small number of superstructures and the low degree of standardization will lead to low production efficiency even if using the smart precast field.…”

“…The local stability, load lateral distribution and other structural responses of the DGH composite girder have been verified by loading tests. As shown in Figure 7, ⃝: H-shape steel girder, 2 ⃝: corrugated steel-concrete composite bridge deck, 3 ⃝: girder-end crossbeam, L and B refer to the span of girder and the width of the deck and n and d refer to the number and spacing of girders).…”

“…In recent years, under the background of the increasing traffic demand in China, a new expressway for urban traffic and reconstruction and extension projects for existing highways have gradually spread [1,2]. Urban standard-span bridges (20-40 m spans) are numerous and commonly found in densely populated, traffic-concentrated, and environmentally sensitive areas.…”

“…Structural description of the DGH composite girder (unit: m). (Remark: 1⃝: H-shape steel girder,2 ⃝: corrugated steel-concrete composite bridge deck, 3 ⃝: girder-end crossbeam, L and B refer to the span of girder and the width of the deck and n and d refer to the number and spacing of girders).…”