The reinforced concrete-filled steel tube (RCFST) column solves several of the problems of the concrete-filled steel tube (CFST) column in practical engineering applications. Moreover, RCFST has a simple joint structure, high bearing capacity, good ductility, and superior fire resistance. From a structural safety perspective, designers prioritize the creep performance of CFST members in structural design. Therefore, the creep behavior of RCFST columns should be thoroughly investigated in practical engineering design. To study the influence of the creep behavior of RCFST columns under axial compression, this work analyzed the mechanical behavior of composite columns based on their mechanical characteristics under axial compression and established a creep formula suitable for RCFST columns under axial compression. A creep analysis program was also developed to obtain the creep strain-time curve, and its correctness was verified by existing tests. On this basis, the effects of the main design parameters, such as the stress level, steel ratio, and reinforcement ratio, on the creep behavior were determined and analyzed. The creep of the tested composite columns increased rapidly in the early stages (28 days) of load action; the growth rate was relatively low after 28 days and tended to stabilize after approximately six months. The stress level had the greatest influence on the creep of RCFST columns under axial compression, followed by the steel ratio. The influence of the reinforcement ratio on the creep behavior was less. The results of this study can provide a reference for engineering practice.

中文翻译：

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钢筋混凝土钢管柱在轴压下的蠕变行为。

钢筋混凝土钢管(RCFST)柱解决了钢管混凝土(CFST)柱在实际工程应用中的若干问题。此外，RCFST的接头结构简单，承载力高，延展性好，耐火性能优越。从结构安全的角度来看，设计师在结构设计中优先考虑 CFST 构件的蠕变性能。因此，应在实际工程设计中彻底研究 RCFST 柱的蠕变行为。为研究RCFST柱在轴压下蠕变行为的影响，基于复合柱在轴压下的力学特性分析了复合柱的力学行为，建立了适用于RCFST柱轴压下蠕变的蠕变公式。还开发了蠕变分析程序以获得蠕变应变-时间曲线，并通过现有试验验证了其正确性。在此基础上，确定并分析了应力水平、钢比、配筋率等主要设计参数对蠕变行为的影响。受试复合柱的蠕变在荷载作用的早期阶段（28 天）迅速增加；28 天后增长率相对较低，并在大约 6 个月后趋于稳定。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。并且其正确性得到了现有测试的验证。在此基础上，确定并分析了应力水平、钢比、配筋率等主要设计参数对蠕变行为的影响。受试复合柱的蠕变在荷载作用的早期阶段（28 天）迅速增加；28 天后增长率相对较低，并在大约 6 个月后趋于稳定。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。并且其正确性得到了现有测试的验证。在此基础上，确定并分析了应力水平、钢比、配筋率等主要设计参数对蠕变行为的影响。受试复合柱的蠕变在荷载作用的早期阶段（28 天）迅速增加；28 天后增长率相对较低，并在大约 6 个月后趋于稳定。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。和配筋率，对蠕变行为进行了确定和分析。受试复合柱的蠕变在荷载作用的早期阶段（28 天）迅速增加；28 天后增长率相对较低，并在大约 6 个月后趋于稳定。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。和配筋率，对蠕变行为进行了确定和分析。受试复合柱的蠕变在荷载作用的早期阶段（28 天）迅速增加；28 天后增长率相对较低，并在大约 6 个月后趋于稳定。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。应力水平对轴压下RCFST柱的蠕变影响最大，其次是钢比。配筋率对蠕变行为的影响较小。本研究结果可为工程实践提供参考。