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为研究低周反复荷载作用下贯穿于再生混凝土节点的纵向钢筋粘结性能,制作2榀再生混凝土框架中节点并进行试验。通过在柱两侧梁端的纵筋上预埋应变片,得到纵筋荷载-应变滞回曲线。根据同一根纵筋上两个测点应变差来计算区段内的平均粘结应力,进而获得了加载过程中节点试件通裂阶段、极限阶段、破坏阶段的纵筋相对粘结强度。试验结果表明,在试件通裂阶段和极限阶段,纵筋保有较为稳定的粘结应力,能够满足再生混凝土构件钢筋与混凝土之间通过粘结应力传递应力及协调变形的要求。粘结应力分布与钢筋直径有关,钢筋直径越大粘结应力退化越严重;柱侧梁端截面受压区混凝土达到极限压应变时,纵筋受压强度不能得到充分发挥,受压钢筋应力相对滞后。
In order to study the longitudinal reinforcement bonding performance of recycled concrete joints under low cyclic loading, the joints in 2 榀 recycled concrete frames were made and tested. The longitudinal load-strain hysteresis curve is obtained by embedding the strain gauges on the longitudinal bars of the beam ends on both sides of the column. According to the strain difference between the two measuring points on the same longitudinal bar, the average bond stress in the section is calculated, and the relative bond strength of the longitudinal reinforcement at the cracking stage, the ultimate stage and the failure stage of the specimen in the loading process is obtained. The experimental results show that the longitudinal bars maintain a relatively stable bond stress during the cracking and ultimate stages of the specimens, which can meet the requirements of transferring stress and coordinating deformation between the reinforcing bars and the concrete of the recycled concrete members through the bond stress. The distribution of bond stress is related to the diameter of rebar. The larger the diameter of rebar, the more serious the degradation of bond stress. When the ultimate compressive strain reaches the ultimate compressive strain of concrete in the end section of column side column, the compressive strength of longitudinal reinforcement can not be fully exerted, Lag