30SiMn材料PC钢筋预载断裂分析研究

Fracture of Prestressed Concrete Reinforced by 30SiMn Steel Bar in Pre Tensioning

ＰＣ（ＰｒｅｓｔｒｅｓｓｅｄＣｏｎｃｒｅｔｅ）钢筋在施加预张应力时，镦头根部发生断裂是目前钢筋使用中出现的主要问题．力学测试和组织分析表明，镦头根部断裂的主要原因是镦头加热过程中钢筋强度降低，钢筋使用中的一些不规范行为造成钢筋长度上的差异，导致一组钢筋中各钢筋之间应力分配不均匀．当镦头根部的抗拉强度衰减至低于母体材料屈服强度以下，并且钢筋使用时一组钢筋长度上的差别超过钢筋局部伸长量时，由于钢筋失去利用均匀变形调整各钢筋间的应力分配的能力，而造成超载的钢筋早期断裂．

Fracture of the button head root section occurred at the pretensioning stage of prestressed concrete reinforced by steel bar. Mechanical property tests and microstructure studies have related the cause of failure to strength decrease in the heading process. Nonuniform stresses in the steel rods arise owing to different length of the specimens. Excessive elevation of stresses occurs at the root section, and it causes the reinforced steel bars to fracture locally where pretensioned.