高温后带肋钢筋与混凝土黏结滑移关系预测模型

Prediction model of bond-slip relationship between steel bar and concrete after high temperatures

提出了一种适用于高温后带肋钢筋与混凝土黏结滑移关系的预测模型。根据拔出试验的破坏特征,将黏结滑移关系曲线的上升段按混凝土开裂与否分为两个阶段,分别建立力学模型以揭示锥楔作用的黏结机制。结合国家标准建议的钢筋外形,归纳了钢筋肋间距与直径之间的关系,提出了以肋间距为主要变化参数的高温后特征滑移,研究发现高温后黏结滑移关系曲线的下降段符合负指数函数衰减规律。除了高温作用对材性的影响之外,高温后界面滑移路径的改变也是影响黏结滑移关系的重要因素。与试验结果的对比表明,所提出的方法可对高温后配箍、短埋黏结试件的黏结滑移关系进行较准确的预测。

A prediction model for bond-slip relationship between steel bar and concrete after high temperature is proposed. According to the failure characteristics of pull out test,the ascending branch of bond-slip relationship curve is divided into two stages considering concrete cracking or not,mechanical models are established respectively with the purpose of revealing the wedging action bond mechanism. According to the national standard,the relationship between the rib space and the diameter of the steel bar is summarized. The characteristic slippage after high temperature with the rib spacing as the main parameter is proposed. It is found that the descending of bond-slip relationship curve is in accordance with the negative exponential decay law. In addition to the effect of high temperature,the changing interface slip-path is also an important factor affecting the bond-slip relationship. Comparison with the experimental results has shown that the proposed model could precisely predict the bond-slip relationship of specimens with stirrup and short buried reinforcement.