改性再生混凝土框架中节点抗震性能试验研究

EXPERIMENTAL STUDY ON SEISMIC BEHAVIOR OF MODIFIED RECYCLED AGGREGATE CONCRETE INTERIOR BEAM-COLUMN JOINTS

通过对两榀再生粗骨料取代率为100%,粉煤灰等量取代率为15%的改性再生混凝土框架中节点的试验,探讨粉煤灰作为外加剂的改性再生混凝土框架节点的破坏机制、滞回曲线、刚度退化、能耗性能、延性特征等抗震性能。试验表明:改性再生混凝土中节点破坏过程均经历初裂、通裂、极限、破坏四个特征阶段;节点核心区破坏时混凝土呈酥裂状破坏,表现出明显脆性性质;梁根部适量配置纵筋,在核心区发生剪切破坏前,能够充分发挥变形能力,滞回曲线较为丰满;轴向压力的施加,改变了核心区主拉应力方向,延缓了节点裂缝的开展;再生混凝土试件具有一定的延性和耗能能力,能够满足抗震性能要求。

The tests were carried out for two modified recycled aggregate concrete interior joints with the recycled aggregate replacement ratio of 100% and the same amount of fly ash to replace 15%. Adding fly ash to recycled concrete joint,it was investigated seismic performance,such as failure mechanism,hysteretic behavior,stiffness degradation,energy consumption performance and ductile character. Results showed that the mechanical and failure process of modified recycled concrete frame joints went through four stages： the initial cracking,the full cracking,the ultimate and the failure stage. The shear failure happened in the joint core area,which indicated the obvious brittle damage of recycled concrete. The beam longitudinal reinforcement in proper amount could fully yield before shear failure in the joint,whose hysteretic curve was plump. The reasonable axial pressure changed the direction of the principal tensile stress and delayed the development of joint cracks. The RAC specimens showed a fine ductility and energy consumption performance.