To explore the influence of microexpansive concrete self-stress on the performance of steel pipe concrete, the expansion rate test of microexpansive concrete confined by steel tube was carried out with different expansion rates. Then, the mechanical properties of high-strength steel tube-confined microexpansive concrete (HSTCMC) short columns were conducted by the uniaxial compression test. The length-to-diameter ratio, the expansion rate of the microexpansive concrete, and the steel tube thickness were investigated in the study. Furthermore, the ABAQUS software was employed to analyze the microexpansive mechanism of the concrete, and it was verified by the uniaxial compression test. The test results show that the concrete possesses a remarkable volume expansion phenomenon, which was up to 150 με after four days of maintenance time. The mechanical properties of the HSTCMC short columns were greatly improved compared to the control RC pier. The yield and ultimate strength of the HSTCMC short columns can be enhanced to 8.9% and 14.6%, and with the content of expansive agent that increased from 8% to 12%. The finite element analysis results highlighted that the end constraint at the two ends has the biggest influence on the mechanical performance of the HSTCMC short columns, followed by the thickness of the steel tube and the content of the expansive agent. It should be noted that the self-stress of microexpansive concrete will be decreased with the increase in the length-to-diameter ratio, when the length-to-diameter ratio is less than four. Furthermore, the constraint effect of the circular steel tube on the microexpansive concrete is better than that of the rectangular section steel tube.

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微膨胀混凝土自应力对钢管混凝土性能影响的试验研究

为探讨微膨胀混凝土自应力对钢管混凝土性能的影响，对钢管约束的微膨胀混凝土进行了不同膨胀率下的膨胀率试验。然后，通过单轴压缩试验对高强钢管约束微膨胀混凝土（HSTCMC）短柱的力学性能进行了测试。在研究中研究了长径比、微膨胀混凝土的膨胀率和钢管厚度。进一步利用ABAQUS软件对混凝土的微膨胀机理进行分析，并通过单轴压缩试验进行验证。试验结果表明，混凝土具有显着的体积膨胀现象，可达150 με经过四天的维护时间。与对照钢筋混凝土墩相比，HSTCMC 短柱的力学性能有了很大的提高。HSTCMC短柱的屈服强度和极限强度分别提高到8.9%和14.6%，膨胀剂含量从8%提高到12%。有限元分析结果表明，两端的端部约束对HSTCMC短柱的力学性能影响最大，其次是钢管的厚度和膨胀剂的含量。需要注意的是，当长径比小于4时，微膨胀混凝土的自应力会随着长径比的增加而降低。此外，