| Steel-tube confined reinforced concrete column and regular reinforced concrete beam are the basic components of steel-tube confined reinforced concrete structure. Hereinto, as a new type of composite column, steel-tube confined reinforced concrete column structure is characterized by reinforced concrete filled in steel tube, by steel tubular shell disconnected at beam-column joints with a certain distance from steel tube top to beam bottom as well as steel tube bottom to beam top, which signifies that the steel tube is not through the joint area with no direct vertical loads but just act as a part of constraining the core concrete. Hence steel-tube confined reinforced concrete column has brilliant advantages of high bearing capacity, large elastic-plastic deformation capacity, preferable energy dissipation and excellent building templates savings. However, due to the enhancement of scape bearing capacity, the beam-column joints is difficult to achieve the design objective "strong joints and weak components" in most cases. Thus the key point of the promotion and application for this outstanding structure type is to find an effective form of strengthening for the joints.In this paper, two enhancement schemes for beam-column corner joints have been proposed for round steel-tube confined reinforced concrete structure, including the research of axial compression bearing capacity, the analysis for the relationships of various geometric parameters with nodal axial compression bearing capacity, and the summary of the rules and methods applicable to the design in order to describe the nodal axial compression bearing capacity quantitatively.By means of FEM software ABAQUS, the research contents are listed below:1) Compare the different axial compression bearing capacity for these three: Joints of Scheme I, Joints of regular reinforced concrete with the same parameters, Short column of Steel-tube confined reinforced concrete. Then consider the enhancement acts of different strengthening methods to the axial compression bearing capacity.2) Make numerical calculation of nodal axial compression bearing capacity with varying parameters in the joint area including steel-tube shell thickness, slot height, concrete strength grade and beam height. Afterwards analyze and compare the effects of various geometric parameters on the nodal axial compression bearing capacity.3) Combined with previous research theory and the finite element analysis results, derive an applicable formula for Scheme I with nodal axial compression bearing capacity. Then establish and analyze the node models with different column diameters and nodal beam width in order to examine the applicability and reliability of the formula.4) Study the nodal axial compression bearing capacity of Scheme II influenced by two varying parameters: biggest steel ring net spacing, steel ring total height in joint area. According to the analysis result, summarize and simulate the formula for the nodal axial compression bearing capacity for Scheme II. |
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