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在现代建筑和桥梁中,膨胀钢管混凝土备受青睐,但有关其时变性能的研究却比较匮乏。为数值模型标准提供新的试验数据支持,对混凝土初凝时(如混凝土浇筑5d后)的膨胀钢管混凝土承载力进行研究,以真实反映施工实际。研究11根膨胀钢管混凝土短柱在混凝土不同阶段承受不同大小轴向荷载时的性能。其中,7根柱子进行破坏试验,以分析长期效应对极限承载力的影响。基于相应的试验结果,研究4种现有混凝土模型EC2,MC90,AFREM及B3的准确度,分析钢管混凝土的长期性能。结果表明:向混凝土施加80%强度的预应力,而不是正常允许值的40%～50%时,线性徐变假定适用于膨胀钢管混凝土构件。在正常服务年限里,约束情况对膨胀钢管混凝土构件无影响,EC2模型可用于分析膨胀钢管混凝土构件的时变性能。
Expanded CFST is favored in modern buildings and bridges, but the research on its time-varying properties is scarce. To provide new experimental data for numerical model standards support, concrete initial setting (such as concrete pouring 5d) after the expansion of concrete-filled steel tube capacity to study, to truly reflect the actual construction. The performance of eleven concrete filled steel tube short columns subjected to different axial loads at different stages of concrete was studied. Among them, seven columns were subjected to failure test to analyze the effect of long-term effect on ultimate bearing capacity. Based on the corresponding test results, the accuracy of four existing concrete models EC2, MC90, AFREM and B3 was studied and the long-term performance of CFST was analyzed. The results show that the linear creep assumptions apply to concrete-filled steel tubular members when 80% strength prestressed concrete is applied instead of 40% ~ 50% of the normal allowable value. During the normal service life, the constraint condition has no effect on the CFST members. The EC2 model can be used to analyze the time-varying performance of the CFST members.