Nowadays, Textile Reinforced Concrete (TRC) has become a very popular strengthening technique for concrete structures. This paper presents an investigation on the applicability of TRC for strengthening reinforced concrete column. Both experimental and numerical studies are conducted to evaluate the confinement effects of various TRC strengthening schemes. The experimental study is performed on a series of six reinforced concrete square columns tested to failure. Two of them were un-strengthened as references, the other four were strengthened by one or two layers of Carbon Textile Reinforced Concrete (CTRC). The results indicated that the application of carbon TRC enhanced the ductility and ultimate strength of the specimens. Failure of all strengthened columns was together with tensile rupture of textile reinforcements at the corners of column. Finite element models of the CTRC strengthened columns based on ATENA software package were developed and verified with the experimental results. The analytical results show that in the specimen corner areas, textile reinforcements are subjected to a 3D complicated stress state and this may be the cause of their premature failure.

Nowadays, concrete is mostly prestressed with steel. But the application of prestressing steel is restricted in a highly corrosive environment area due to corrosion of prestressing steel, leading to a reduction in strength and may cause sudden failure. Carbon textile is considered an alternate material due to its corrosive resistance property, high tensile strength, and perfectly elastic. Prestressing is also the only realistic way to utilize fully ultra-high tensile strength in carbon textile material. In this study, experimental and numerical analyses were carried out for the flexural behaviour of prestressed and non-prestressed carbon textile reinforced concrete slabs. This study also focuses on the influences of textile reinforcement ratios, prestressing grades on the flexural behaviour of carbon textile reinforced concrete (TRC). Fifteen precast TRC slabs were tested, of which six were prestressed to various levels with carbon textile. The obtained results show that prestressing textile reinforcement results in a higher load-bearing capacity, stiffness, and crack resistance for TRC slabs. The first-crack load of the prestressed specimens increased by about 85% compared with those of non-prestressed slabs. Three-dimensional finite element models were developed to provide a reliable estimation of global and local response. The modeling techniques accurately reproduced the experimental behaviour. Doi: 10.28991/cej-2021-03091712 Full Text: PDF

Ăn mòn cốt thép trong bê tông là một trong những nguyên nhân chính gây ra hư hỏng và suy thoái cho kết cấu bê tông cốt thép. Bê tông cốt lưới dệt (TRC) là một công nghệ mới trong việc sửa chữa và tăng cường kết cấu bê tông, bao gồm cả tăng cường sức kháng uốn, sức kháng cắt và sức kháng nén. Bài báo này trình bày một số kết quả nghiên cứu thực nghiệm để xác định ứng xử chịu cắt của dầm bê tông có cốt thép đai bị ăn mòn được tăng cường bằng bê tông cốt lưới dệt (TRC). Sức kháng cắt của các dầm BTCT bị ăn mòn và của lớp TRC với hàm lượng cốt lưới dệt thay đổi sẽ được đánh giá chi tiết. Trong nghiên cứu này, có 18 dầm được thí nghiệm, trong đó có 12 dầm được gia tốc quá trình ăn mòn điện hóa trong thời gian 60 và 90 ngày để đạt được mức độ mất mát khối lượng lý thuyết 10% và 20% với cốt thép đai. Quá trình điện hóa được thực hiện đối với cốt thép đai trong đoạn chiều dài chịu cắt của dầm thí nghiệm. Các dầm đối chứng được thí nghiệm uốn ba điểm để xác định sức kháng cắt. Tám dầm BTCT bị ăn mòn được tăng cường với 2 và 3 lớp lưới sợi các bon, có cấu trúc dạng chữ U. Mục tiêu nghiên cứu của chương trình thí nghiệm này là xác định ứng xử chịu cắt của các dầm được tăng cường, bao gồm quan hệ lực – độ võng, cấu trúc vết nứt, sức kháng cắt và các dạng phá hoại. Kết quả thí nghiệm cho thấy, đối với các dầm bị ăn mòn mạnh, sức kháng cắt của các dầm được tăng cường bằng 2 và 3 lớp lưới sợi đã tăng lên 42,5% và 60,6%.

This research systematically compares the effectiveness of Carbon Fiber-Reinforced Polymer (FRP) and Fabric-Reinforced Cementitious Matrix (FRCM) in shear strengthening of reinforced concrete (RC) deep beams featuring web openings. Through a comprehensive experimental program, six RC beams were subjected to shear tests, considering variations in the number of layers for both FRCM and FRP, employing a U-wrapping configuration. Recorded parameters include load-deflection curves, ultimate strength, cracking patterns, failure modes, and strains in steel bars, allowing a comprehensive comparison between strengthened and un-strengthened RC beams. The study compares observed shear strengths from experiments with shear capacities predicted by proposed models for RC beams strengthened with FRCM and FRP, following codes such as ACI 440.2R-17, CSA S806-12, Eurocode 2, and ACI 549.4R-20. Increasing layers enhanced shear strengths and post-elastic stiffness. The presence of substantial openings led to early shear cracks and reduced strength. CFRP improved shear strength by 13.99% (1-layer) and 18.12% (2-layer), while FRCM strengthened layers by 20.2% (1 layer) and 29.3% (2 layers). FRCM outperformed in strength and stiffness, while FRP excelled in ductility and concrete confinement. Experimental and calculated results varied based on ACI, CSA, and Eurocode, with ACI providing consistent and accurate results. CSA’s calculation surpassed experiments, emphasizing its consideration of effective fabric design strain.

This study investigates the influence of various transverse reinforcement configurations on the torsional performance of glass fiber reinforced plastic (GFRP) reinforced concrete beams. A comprehensive experimental investigation includes five specimens, each characterized by unique transverse reinforcement designs in terms of stirrup spacing and inclination angles. The implementation of transverse torsional reinforcements within the beams exhibited a remarkable post-cracking hardening response, contributing to enhanced strength recovery. The experimental findings are subsequently compared with a reliable three-dimensional finite element model developed using the ABAQUS software. Finally, a parametric study is conducted to examine the influence of concrete and GFRP bar strength, along with longitudinal and transverse reinforcement ratios, on the torsional behavior of GFRP reinforced concrete beams. The results emphasize the significant impact of concrete tensile strength and transverse reinforcement on the cracking torque, while the parameters related to longitudinal reinforcement have only marginal effects.