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为研究锈蚀对钢绞线与混凝土粘结性能的影响,设计制作了12根钢绞线混凝土粘结试件。通过对试件进行室内加速锈蚀及拉拔试验,得到各试件混凝土表面锈胀裂缝分布、混凝土表面应变分布及粘结应力-滑移曲线。分析了锈胀裂缝宽度对粘结应力分布、粘结强度及粘结应力-滑移关系的影响。通过拉拔试件的粘结应力与先张法试件传递长度范围内的粘结应力的关系,建立了以平均锈胀裂缝宽度为变量的钢绞线传递长度计算公式。结果表明:钢绞线粘结应力沿整个试件呈不均匀分布,粘结应力峰值随锈胀裂缝宽度的增大呈下降趋势;试件自由端产生初始滑移及最大粘结应力下的粘结强度分别随锈胀裂缝宽度的增大而下降;锈胀裂缝对粘结应力-滑移曲线的初始线性段影响显著,不同锈胀裂缝宽度试件的粘结应力-滑移曲线差异明显;传递长度计算公式可为钢绞线试件锈胀开裂下的传递长度计算提供参考。
In order to study the influence of corrosion on the bond performance between steel strand and concrete, 12 concrete specimens of strand concrete were designed and manufactured. Through accelerated corrosion and pull-out test in laboratory, the corrosion crack distribution, concrete surface strain distribution and bond stress-slip curve were obtained. The influence of the width of corrosive crack on the bond stress distribution, bond strength and bond stress-slip relationship was analyzed. Based on the relationship between the bond stress of the drawn specimen and the bond stress in the transfer length of the pre-tensioned specimen, the formula for calculating the transfer length of the strand with the average width of the rust crack as a variable was established. The results show that the bond stress of the strand is unevenly distributed along the entire specimen, and the peak value of the bond stress decreases with the increase of the width of the rupture. The initial slip at the free end of the specimen and the viscosity at the maximum bond stress The strength of the joint decreases with the increase of the width of the corrosive crack. The influence of the corrosion crack on the initial linear section of the bond-slip curve is significant. The difference of the bond stress-slip curve of the specimens with different corrosive crack widths is significant. The calculation formula of transmission length can provide a reference for the calculation of transmission length under the condition of corroded and cracked steel strand specimens.