论文部分内容阅读
在室内环境中对8个混凝土圆柱体试件进行长达800余天收缩徐变测试,对比了混凝土、钢管混凝土、钢管膨胀混凝土圆柱体的收缩徐变时程规律,得到了钢管膨胀混凝土收缩徐变特性。试验结果表明:钢管膨胀混凝土收缩应变较小,受膨胀剂的影响,初期收缩变形基本为0;钢管膨胀混凝土徐变变形在100 d内变化较大,100 d后基本处于平稳状态,与未添加膨胀剂钢管混凝土徐变系数时变规律基本一致。在合理假设钢管混凝土徐变机理前提下,依据继效流动理论和多轴应力下徐变理论,提出钢管混凝土徐变系数终值估算方法;钢管膨胀混凝土徐变模型中徐变系数终值由可恢复的滞后弹性变形、不可恢复的初始急变塑性变形和不可恢复的黏性流变变形三部分函数分别求极值相加所得,同时结合钢管膨胀混凝土实测徐变的时变规律,提出钢管膨胀混凝土徐变系数简化计算模型,与试验结果相对比,该模型计算式简洁,预测结果较为准确。
The creep tests of 8 concrete cylindrical specimens for more than 800 days were carried out in an indoor environment. The shrinkage and creep time history of concrete, concrete filled steel tube and steel tube expanded concrete was compared. The shrinkage and creep of the expanded concrete of steel tube was obtained. characteristic. The experimental results show that the shrinkage strain of the steel pipe expansion concrete is small, and the initial shrinkage deformation is almost zero due to the expansion agent. The creep deformation of the steel pipe expansion concrete changes greatly in 100 days and basically stays stable after 100 days, The creep coefficient of expansive concrete filled steel tube is basically the same. Based on the theory of continuation flow and the theory of creep under multi-axial stress, the final value of creep coefficient of concrete-filled steel tube (CFST) is put forward on the premise of reasonable assumption of creep mechanism of CFST. The final value of creep coefficient in creep model of CFST is Recovery elastic lag, unrecoverable initial rapid plastic deformation and irreversible viscous rheological deformation of the three functions were obtained by adding the extreme, combined with the measured steel pipe expansion creep time-varying law, proposed steel pipe expansion of concrete Creep coefficient simplified calculation model, compared with the test results, the model calculation formula is simple, the prediction result is more accurate.