盐冻融环境下钢筋混凝土黏结-滑移本构模型

摘要

为了探索盐冻融环境下钢筋混凝土的黏结-滑移性能及其本构模型,通过自主研制的双向受压型钢筋混凝土拉拔装置和钢筋铣槽内贴应变片的测试方法,对经历了盐冻融循环作用的钢筋混凝土试件进行中心拉拔试验.结果表明:随着盐冻融循环次数的增加,试件的极限黏结强度呈线性下降趋势,自由端起滑荷载逐渐减小,劈裂破坏时的自由端滑移量先减小后增大;加载初期黏结应力峰值靠近加载端,随着荷载的增加,黏结应力峰值向自由端移动,且随试件盐冻融损伤程度的增加,峰值移动趋势愈趋明显.结合理论分析,获得了试件的黏结应力和滑移量沿锚固长度分布规律,并在此基础上构建了盐冻融环境下考虑位置函数的钢筋混凝土黏结-滑移本构模型.所得结果可为寒区氯盐环境下钢筋混凝土构件的有限元分析和耐久性评估提供理论依据.%To explore the bond-slip behavior and constitutive relationship between the steel bar and the concrete under the deicer-frost environment,through the self-made bidirectional compression type of reinforced concrete pull-out device and the test method in which strain gauges were pasted on the inner milling slot of steel bars,pull-out tests were conducted on reinforced concrete specimens subjected to salt-freezing cycles.Research results show that with the increase of salt-freezing cycles,the ultimate bond strength decreases linearly,the initial sliding load of free end drops gradually,the slippage of free end corresponding to the ultimate bond stress decreases first and then increases;the peak value of bond stress spreads from the loading end toward the free end with increase of loading,the spreading tendency of the peak value is more and more obvious with the increase of degree of freezing-thawing damage.Distribution laws of bond stress and slippage along anchorage length are obtained through theoretical analysis.Based on the above work,the reinforced concrete bond-slip constitutive equation is established under deicer-frost action with considering the position function,which could provide theoretical evidences for the reinforced concrete finite element analysis and the durability assessment under chloride environment of the cold region.