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将直接强度法(DSM)用于钢管混凝土(CFT)截面的计算。基于已有的试验结果给出局部屈曲CFT截面的抗压和抗弯强度。欧洲规范EC 4不允许CFT截面使用薄壁型材,而AISC规范允许将钢管的宽厚比限值应用于薄壁型材。考虑薄壁钢管的局部屈曲和钢管约束效应将提高核心混凝土抗压强度,基于直接强度法给出CFT截面抗压和抗弯强度的计算公式。根据建议公式计算得到的承载力与试验结果以及AISC规范和EC 4的计算结果进行比较。同时给出轴向压弯作用下CFT构件强度相互作用的计算公式,并将计算结果与试验结果进行比较。结果表明,抗压、抗弯强度以及强度相互作用的计算公式,用于计算轴向荷载和压弯作用下CFT柱的承载力时,计算结果较为保守。
The direct strength method (DSM) is used to calculate the section of concrete filled steel tube (CFT). The compressive strength and flexural strength of locally buckled CFT sections are given based on the experimental results. The European Directive EC 4 does not allow the use of thin-walled sections for CFT sections, whereas the AISC specification allows the application of thin sections for steel sections with a ratio of aspect ratios. Considering the local buckling of thin-walled steel pipe and the restraint effect of steel pipe, the compressive strength of core concrete will be increased. Based on the direct strength method, the formula of compressive strength and flexural strength of CFT section will be given. The calculated bearing capacity calculated according to the proposed formula is compared with the test results as well as with the results of AISC code and EC4 calculations. At the same time, the formula for calculating the strength interaction of CFT members under axial compression bending is given, and the calculation results are compared with the test results. The results show that the formulas of compressive strength, flexural strength and strength are used to calculate the bearing capacity of CFT columns under axial load and bending load. The results are conservative.