钢管微膨胀混凝土轴压短柱长期变形研究

Research on Long-term Deformation of Concrete-filled Steel Tubular Stubs with Expansive Additive Under Axial Loading

针对钢管混凝土拱桥中普遍采用的钢管微膨胀高性能混凝土,考虑轴压比、加载龄期等因素的影响,进行了圆钢管微膨胀混凝土轴心受压短柱的长期变形试验研究。采用逐步积分法,将5种不同混凝土收缩、徐变模型进行适当修正,应用于钢管微膨胀混凝土轴心受压短柱的长期变形分析,并将分析结果与试验结果进行对比。分析了含钢率、加载龄期、持荷时间、混凝土强度等因素对钢管微膨胀混凝土构件长期静力性能的影响。研究结果表明:修正后的EC2,MC90及AFREM模型在分析加载龄期不超过28d的钢管微膨胀混凝土构件在轴向荷载作用下的长期变形性能时具有较高的精度;核心混凝土时效作用对钢管微膨胀混凝土构件长期静力响应的影响显著。

Aimed at high performance concrete-filled steel tubular（CFST） with expansive additive which has been widely adopted in CFST arch bridges,considering the influence of axial compression ratio and loading age,test study of long-term deformation of circular CFST stubs with expansive additive under axial loading was carried out.Using step-by-step integration method,5 different concrete models of shrinkage and creep were modified,then modified models were applied to long-term deformation analysis of CFST stubs with expansive additive.Analysis result and test result were compared.The influences of ratio of steel area over concrete area,loading age,duration of loading,strength of the core concrete,etc.on the long-term static performance of these CFST specimens were analyzed.Results show that the modified models EC2,MC90 and AFREM can well predict the long-term deformation performance of CFST stubs with expansive additive loaded before 28 days.Time-effects of core concrete have considerable influence on the long-term static response of CFST specimens with expansive additive.