BFRP网格-PCM薄面黏贴加固钢筋混凝土板抗弯性能

来源期刊:中南大学学报(自然科学版)2020年第4期

论文作者:汪昕 丁里宁 贺卫东 程方 吴智深

文章页码:1085 - 1086

关键词:BFRP网格;PCM;黏结性能;钢筋混凝土板;抗弯加固

Key words:basalt fiber reinforced composite(BFRP) grid; polymer cement mortar(PCM); bond behavior; reinforced concrete(RC) slab; flexural strengthening

摘    要:针对老旧桥梁桥面板出现结构损伤与材料老化,结合玄武岩纤维增强复合材料(BFRP)网格与聚合物砂浆(PCM)提出一种新的加固技术以提升钢筋混凝土板的抗弯性能。首先,采用双剪试验研究BFRP网格与混凝土界面的黏结荷载,共制备18个试件,试验变量包括网格种类、网格厚度、PCM种类以及界面剂;其次,浇筑6块钢筋混凝土板,通过四点弯曲试验系统地分析网格种类、网格厚度、网格布置方式以及PCM种类对加固板抗弯性能的影响。研究结果表明:界面剂能有效提高BFRP网格与混凝土之间的黏结荷载;当BFRP网格与混凝土表面的黏结长度大于有效黏结长度时,BFRP网格强度利用率达到90%以上,黏结荷载高于相同情况下玄武岩纤维布/BFRP板与混凝土的黏结荷载;BFRP网格与PCM形成的薄面加固层能显著提高钢筋混凝土板的开裂荷载、屈服荷载以及极限荷载,同时减小最大裂缝宽度并改善裂缝分布;在整个加载过程中,BFRP网格-PCM薄面加固层与混凝土板协同变形,加固板最终发生混凝土压碎或FRP网格断裂破坏,并未出现剥离破坏;传统钢筋混凝土构件抗弯承载力计算方法适用于预测BFRP网格加固后板的抗弯承载力。

Abstract: In view of the old bridge decks which suffer from structural damage and material degradation, a new strengthening technique for improving the flexural behavior of reinforced concrete(RC) slabs was proposed by combining basalt fiber reinforced composite(BFRP) grid and polymer cement mortar(PCM). Firstly, the bond load was studied according to double-lap shear test with 20 specimens, and the variable parameters included the grid type, grid thickness, PCM type and interface treating agent. Secondly, 6 slabs were fabricated and tested in the four point flexural experiments. The effects of the grid type, grid thickness, grid layout and PCM type on the flexural behavior of strengthened slabs were systematically analyzed. The results show that the interface treating agent can effectively improve the bond load between the BFRP grid and concrete. When the bond length is larger than the effective bond length, the strength utilization ratio of the BFRP grid is more than 90%, and the bond load is higher than that of the basalt fiber sheet/BFRP plate under the same condition. The thin strengthening layer formed by the BFRP grid and PCM can significantly increase the cracking load, yield load and ultimate load of the strengthened slabs, reduce the maximum cracks width and improve the distribution of cracks. During the whole loading process, the strengthening layer and the slabs deform in coordination, and the slabs finally suffer from concrete crushing or FRP grid rupture without debonding. In addition, the traditional calculation method of flexural capacity for RC members is suitable for that of slabs strengthened with BFRP grid.

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