轴压下圆形钢管混凝土短柱承载力的简化计算Simplified Calculation of Ultimate Strength for Axial-Loaded Circular CFT Stub Columns

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In this paper, the bearing mechanism of axial-loaded circular concrete-filled steel tube (CFT) stub column is analyzed. Based on experimental results, the increase coefficient of concrete strength and the reduction ratio of steel longitudinal stress are analyzed and determined. Then, the simplified calculation equations of circular concrete-filled steel tube stub columns subjected to axial load are proposed. Finally, 28 specimens are calculated with the proposed equations, and the calculated results agree with the experimental and normative ones very well.

1. 引言

2. 圆形钢管混凝土的受力机理

${N}_{u}={k}_{1}{f}_{c}{A}_{c}+{k}_{2}{f}_{y}{A}_{s}$ (1)

3. 圆形钢管混凝土轴压短柱承载力的简化计算

3.1. 核心混凝土纵向受压强度提高系数

$\delta ={f}_{y}{A}_{s}/{f}_{c}{A}_{c}$ (2)

${k}_{1}=0.394\delta +1.0156$ (3)

3.2. 圆钢管纵向强度折减系数

${k}_{2}=0.83$ (4)

4. 试验验证

Table 1. Comparison of ultimate strength between calculated results and experimental and normative ones of axial-loaded results of circular CFT stub columns

Figure 1. Regressive curve of k1 and δ

5. 结语

1) 采用混凝土纵向强度提高系数和钢管纵向强度折减系数建立圆形钢管混凝土轴压短柱承载力简化计算的公式，表达式简单，力学概念清晰，参数物理意义明确；

2) 用建议表达式对圆形钢管混凝土轴压试件进行计算，计算结果与试验结果吻合良好；

3) 建议公式可为该类构件的工程设计提供参考。

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