HPFL-黏钢联合加固混凝土方柱早龄期轴压性能

Early axial compression performance of square columns strengthened with HPFL and bonded steel plates

采用加筋高性能砂浆(HPFL)-黏钢联合加固混凝土方柱进行轴心抗压试验,测试加固柱早期承载能力,分析素混凝土柱和钢筋混凝土柱加固后的破坏机理。在试验分析的基础上建立HPFL-黏钢联合加固RC方柱轴心受压承载力计算公式。研究结果表明:加固层与原结构共同工作性能良好;在加固层约束作用下,加固柱核芯混凝土处于三轴受压状态,早龄期极限承载力得到显著提高,变形能力增强;加固钢筋混凝土柱破坏时,沿螺栓在柱纵向形成主要破坏带,同时柱中部砂浆及混凝土压碎外鼓,角钢压弯,纵筋压屈,钢绞线在角钢尖角处剪断,部分箍筋被拉断;加固素混凝土柱破坏时,在柱中部呈现出斜向剪切裂缝;由于角钢角部倒角有限,钢绞线较早被切断,可通过增大角钢阳角处的倒角或将混凝土柱倒角后黏贴钢板来进一步提高加固柱后期延性。

Axial compressive tests were conducted to investigate the early load-carrying capacity of the square concrete columns strengthened with high performance ferrocement laminate（HPFL） and bonded steel plates. The failure mechanism of the strengthened plain concrete columns and the strengthened RC columns were analyzed. Based on experimental analysis of the RC strengthened square columns, the formulae of the axial compression bearing capacity were proposed. The results show that the reinforcing layer works together with the original columns as a whole. Under the constraint effect of the reinforcing layer, the core concrete of the strengthened columns is in triaxial compressive stressed condition, and the load-carrying capacity increases obviously at the early-age, and deformation capacity is also improved. When the strengthened RC columns were in failure, the main damage zones came into being along the longitudinal bolts, and the mortar and concrete were crushed and bulged outward in the middle of the columns. In addition, the angle bars and the longitudinal steel bars buckled, and the steel wires were cut off at the corner of the angle bars, and some stirrups ruptured. When the strengthened plain concrete columns were in failure, the diagonal shear cracks came into being in the middle of the columns. Because of the limited chamfer size of angle bars, the steel wires were cut off earlier. Enlarging the chamfer size of angle bars or bonding steel plates after chamfering the original columns, the post-peak ductility would be improved.