锈胀开裂钢筋混凝土粘结疲劳性能试验研究

重复加载和锈胀开裂均会导致钢筋混凝土粘结性能退化，进而对钢筋混凝土构件力学性能产生不利影响。该文开展了一系列偏心拔出试验，研究了重复加载以及锈胀开裂对粘结滑移性能的耦合影响规律。主要研究变量包括重复加载次数、应力水平以及钢筋锈蚀程度。结果表明:重复加载对非锈蚀试件和锈胀开裂试件粘结强度及峰值滑移没有显著影响，但会导致钢筋和混凝土之间不断累积残余滑移。重复加载后，粘结应力-滑移曲线形态特征与单调加载试件相似。该文还发现表面锈胀裂缝宽度对粘结强度、峰值滑移以及残余滑移的增长规律有明显影响。锈胀开裂会导致钢筋混凝土试件粘结疲劳寿命显著下降。基于试验数据及文献中研究结论，该文建立了重复及单调荷载作用下非锈蚀及锈胀开裂试件的局部粘结应力-滑移本构关系模型，推导得到了粘结疲劳寿命预测模型。

FATIGUE OF THE BOND BEHAVIOR OF CORRODED REINFORCED CONCRETE WITH CORROSION-INDUCED CRACKS

Repeated loading and cover cracking can result in bond degradation.Consequently,the mechanical properties of RC members are negatively affected.Through a series of loading tests on eccentric pullout specimens,the present study has investigated the combined effects of repeated loading and corrosion-induced cover cracking on the bond-slip behavior of corroded reinforced concrete.The investigated variables included the number of loading cycles,applied stress level and corrosion level.The test results indicated that the bond behavior of non-corroded or corroded specimens with longitudinal cracks under repeated loading was mainly characterized by accumulated slip increase,whereas the bond strength and the slip at the peak bond stress were not affected.After repeated loading,the bond stress-slip curves showed no significant difference with those of specimens subjected to monotonic loading.It was also found that the surface crack width due to corrosion had significant influence on the bond strength,the slip at the peak bond stress and the residual slip due to repeated loading.Based on the test results of this study and conclusions reported in the literature,a mathematical model for the bond stress-slip relationship of non-corroded or corroded specimens under repeated or monotonic loading was proposed with the surface crack width as the governing parameter.Moreover,an empirical equation for predicting the bond fatigue life was finally developed.