مقاله انگلیسی اثربخشی بتن مسلح نساجی کربنی در تقویت برشی تیرهای بتن آرمه
Abstract
Keywords
Introduction
Research significance
Experimental investigation
Results and discussion
Conclusions
Declaration of Competing Interest
Acknowledgments
References
ABSTRACT
This paper will present the shear behavior of the corroded stirrups reinforced concrete (RC) beams strengthened with textile reinforced concrete (TRC). The shear resistance contributions from the corroded RC beams and carbon TRC at various volume ratios were carefully examined. Eighteen beams were tested, including twelve subjected by an electrochemically accelerated aging technique for 60 and 90 days to obtain the theoretical mass loss in their stirrups of 10% and 20%, respectively. The stirrups were locally corroded in the shear span. After the corrosion accelerating treatment, corrosion cracks on concrete surfaces were marked, and their widths were measured to observe their distributions. A three-point bending test was applied to obtain the shear performances of the corroded beams subjected to the monotonic and repeated loading. Eight corroded RC beams were strengthened using 2 and 3 U-wrap layers of bidirectional carbon textile. The shear behavior will be discussed, including the ultimate capacity, failure mode, loaddeflection, load–strain relationship, and crack distributions. Compared to the controlled specimens, the averaged shear strength of corroded specimens decreased by 16.08% and 25.34%, corresponding to the degree of corrosion ranging from 12.3% to 23.6%. The experimental results also demonstrate that the shear capacities of the corroded RC beams strengthened with carbon TRC had been improved 60.6% compared to the severely corroded controlled specimens.
Introduction
Deficiencies in existing RC structures may become serious due to natural ageing, increased required load capacity, deterioration caused by corrosion, and other causes. Corrosion of embedded reinforcing steel is widely accepted as the primary contributor causing premature damage of RC structures, including reducing steel reinforcement area, loss of bond strength, and loss of concrete area, influencing the concrete cover and cross-section. Currently, there are numerous methods available to retrofit RC beams in flexure and shear, each with relative advantages and weaknesses. The most preferable, efficient and practised techniques for shear strengthening are RC jacketing and FRP wrapping [1]. However, using section enlargement with RC to enhance shear capacity, the thickness of the jacket, in typical cases higher than 70–100 mm, leads to the increased total mass of the structure and decreasing esthetics in architecture. This method is also not very suitable for RC structures in corrosive environments. In contrast, FRP wrapping has advantages over concrete jacketing methods such as less thickness, lower weight and better constructability.