Bearing capacity of rectangular concrete-filled steel tube (CFST) and dumbbell shaped CFST under axial compression, eccentric compression, and pure bending stress states

# Test database for bearing capacity of rectangular CFST and dumbbell shaped CFST under axial compression, eccentric compression, and pure bending stress states 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.

# 矩形钢管混凝土（CFST）与哑铃形截面钢管混凝土轴压、偏压及纯弯受力状态下承载力试验数据库
纤维模型法借助材料本构关系与内力合成技术，可精准便捷地求解截面内力，无需建立单元刚度矩阵，兼具简洁性与实用性，已被广泛应用于钢管混凝土（CFST）的承载力分析中。材料本构关系是决定纤维模型法计算精度的核心因素。本文针对钢管混凝土材料本构关系开展研究并建立修正模型，分别构建了适用于矩形截面钢管混凝土与哑铃形截面钢管混凝土力学性能分析的纤维模型法。基于试验数据库中的几何尺寸参数与材料强度参数（如"长度"、"直径"、"宽度"、"壁厚"、"屈服强度"、"抗压强度"等），采用纤维模型法计算构件承载力，并与试验数据中的"试验值"进行对比，以验证纤维模型法及所建立本构关系的计算精度与适用性。
## 数据说明
本试验数据库共计包含6张数据表。表1.1为矩形截面轴压试验数据库，共包含428组数据；表1.2为矩形截面纯弯试验数据库，共包含84组数据；表1.3为矩形截面压弯试验数据库，共包含208组数据。表2.1为哑铃形截面轴压试验数据库，共包含20组数据；表2.2为哑铃形截面纯弯试验数据库，共包含4组数据；表2.3为哑铃形截面压弯试验数据库，共包含30组数据。
在表1.1至表1.3及表2.1至表2.3中："References"代表数据来源。"Length"代表构件长度，以符号*L*表示，单位为mm。"Width"代表矩形截面短边宽度，以符号*B*表示，单位为mm。"Height"代表矩形截面长边宽度，以符号*H*表示，单位为mm。"Diameter"代表哑铃形截面两端圆形单管的截面直径，以符号*D*表示，单位为mm。"Thickness"代表构件外钢管壁厚，以符号*t*表示，单位为mm。"Eccentricity"代表试验荷载作用点至构件截面形心轴沿强轴方向的水平距离，以符号*e*表示，单位为mm。"Eccentricity ratio"代表哑铃形截面偏心距与截面回转半径的比值，通常表示为*e*/2*i*，其中*i*代表截面强轴方向组合荷载作用面的回转半径。"Slenderness ratio"为反映构件稳定性的重要参数，与截面形式相关，以符号*λ*表示。"Height-thickness ratio"代表矩形截面高度与钢管壁厚的比值，合理的高厚比可保障构件承载力充分发挥，以符号*H*/*t*表示。"Yield strength"代表钢管的屈服强度，以符号*f*y表示，单位为MPa。"Compressive strength"代表混凝土的标准抗压强度，以符号*f*ck表示，单位为MPa。"Elastic modulus of steel"代表钢材的弹性模量，以符号*E*s表示，单位为MPa。"Test values"代表构件极限承载力的试验结果：其中表1.2、表1.3、表2.1及表2.3对应抗压承载力，表1.2与表2.2对应抗弯承载力。抗压与抗弯承载力均采用符号*N*u表示，单位为kN；抗弯承载力额外采用符号*M*u表示，单位为kNm。
注：(1) 本次试验数据来源于国内外文献，涉及不同的混凝土强度指标。为便于对比分析，本文将各类强度指标统一换算为轴心抗压强度*f*ck：当圆柱体抗压强度*f*c’≤40MPa时，立方体抗压强度*f*cu,k=1.25*f*c’；反之，*f*cu,k=*f*c’+10。轴心抗压强度*f*ck可通过公式*f*ck=0.88×0.4×(*f*cu,k)^(7/6)计算得到。(2) 本试验数据库采用长度、直径、偏心距等参数描述构件信息。当参考文献中未直接提供上述参数时，通过原文献中其他已知参数换算得到。(3) 当文献中未明确给出钢管弹性模量时，统一采用标准化取值*E*s=206000MPa以方便计算分析。(4) 为使试验数据库直观清晰，本数据库统一采用mm作为长度单位、MPa作为强度单位、kN作为力的单位、kNm作为弯矩单位。当参考文献中各类数据的单位与本数据库不一致时，均进行单位换算。