The fiber model method utilizes material constitutive relationships and internal force synthesis techniques to accurately and conveniently determine the internal force of the section, without the need to establish an element stiffness matrix. It is simple and practical, and has been widely used in the bearing capacity analysis of concrete filled steel tube (CFST). The material constitutive relationship is an important factor determining the calculation accuracy of the fiber model method. This article studies and establishes a modified model for the constitutive relationship of CFST materials, and establishes the fiber model method for the mechanical performance analysis of rectangular CFST and dumbbell CFST, respectively, Based on the geometric size parameters and material strength parameters (such as "length", "Diameter", "Width", "Thickness", "Yield strength", "Compressive strength", etc.) in the experimental database, the fiber model method is used to calculate the bearing capacity of the component and compare it with the "Test values" in the experimental data to verify the calculation accuracy and applicability of the fiber model method and the established constitutive relationship.

Data description

The test database contains a total of 6 tables. Table 1.1 shows the axial compression test database for rectangular sections, with a total of 428 sets of data; Table 1.2 shows the pure bending test database for rectangular sections, with a total of 84 sets of data; Table 1.3 shows the database of compression bending tests for rectangular sections, with a total of 208 sets of data. Table 2.1 shows the database of axial compression tests for dumbbell shaped sections, with a total of 20 sets of data; Table 2.2 shows the pure bending test database for dumbbell shaped sections, with a total of 4 sets of data; Table 2.3 shows the database of compression bending tests for dumbbell shaped sections, with a total of 30 sets of data.

In Tables 1.1 to 1.3 and 2.1 to 2.3:

"References" represents the source of data.

"Length" represents the length of the component, represented by the symbol L, with units in mm.

"Width" represents the width of the short side of a rectangular section, represented by the symbol B, with units in mm.

"Height" represents the width of the long side of a rectangular section, represented by the symbol H, with units in mm.

"Diameter" represents the cross-sectional diameter of a single circular tube at both ends of a dumbbell shaped section, represented by the symbol D, with units in mm.

"Thickness" represents the wall thickness of the outer steel pipe of the component, represented by the symbol t, with units in mm.

"Eccentricity" represents the horizontal distance along the strong axis between the point of application of the test load and the central axis of the component section, represented by the symbol e, with units in mm.

"Eccentricity ratio" represents the ratio of the eccentricity of a dumbbell shaped section to the radius of rotation of the section, usually expressed as e/2*i*, where i represents the radius of rotation of the combined load surface in the strong axis direction of the section.

"Slenderness ratio" represents an important parameter reflecting the stability of a component, which is related to the cross-sectional form and is represented by the symbol λ.

"Height-thickness ratio" represents the ratio of the height of a rectangular section to the thickness of a steel pipe. A reasonable height thickness ratio can ensure the full play of the bearing capacity of the component, represented by the symbol H/t.

"Yield strength" represents the yield strength of the steel pipe, represented by the symbol *f*y, with units in MPa.

"Compressive strength" represents the standard compressive strength of concrete, represented by the symbol *f*ck, with units in MPa.

"Elastic modulus of steel" represents the elastic modulus of steel, represented by the symbol *E*s, with units in MPa.

"Test values" represent the experimental results of the component's ultimate bearing capacity, with Table 1.2, Table 1.3, Table 2.1, and Table2.3 representing compressive bearing capacity. Table1.2 and Table2.2 representing flexural bearing capacity, respectively. The symbol *N*u is used for both compressive and flexural bearing capacity, with units in kN, and the symbol *M*u is used for flexural bearing capacity, with units in kNm.

Note:

(1)The test data is derived from domestic and international literature, involving different concrete strength indicators. For the convenience of comparative analysis, this paper unifies the different strength indicators into axial compressive strength f*ck: when the compressive strength of the cylinder, *f*c’<=40MP, the compressive strength of the cube, *f*cu,k=1.25*f*c’; otherwise, *f*cu,k=*f*c’+10. The axial compressive strength *f*ck can be calculated using the formula *f*ck=0.88x0.4x(*f*cu,k)7/6.

(2) The test database uses parameters such as length, diameter, and eccentricity to describe the member information. When these parameters are not directly provided in the reference literature, they are obtained by converting other known parameters in the original literature.

(3) In the absence of a specific value for the elastic modulus of the steel pipe in the literature, a standardized value of Es = 206,000 MPa is uniformly adopted to facilitate computational analysis.

(4) In order to make the test database clear at a glance, the length unit of the test database is mm, the strength unit is MPa, the force unit is kN, and the moment unit is kNm. When the units of various data in the reference literature are different from those in the test database, unit conversion is performed.