The constitutive relations and failure criterion were developed for circular concrete-filled steel tube (CFST) with high precision and wide applicability based on the fiber model method to overcome the limitations of existing constitutive relations and failure criteria for circular CFST flexural members. Then, on the basis of the test database including the parameters of circular CFST such as "length", "Diameter", "Thickness", "Yield strength", and "Compressive strength", the bearing capacity was calculated by the fiber model method. Finally, the accuracy and validity of the proposed constitutive relations and failure criterion were verified by comparing the calculated values with the "Test values" of the test database.

The test database consists of three tables. Table 1 is the axial compression test database, containing a total of 516 data sets. Table 2 is the pure bending test database, comprising 121 data sets. Lastly, Table 3 is the flexural compression test database, encompassing 365 data sets.

(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 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.