Đánh giá hiệu quả gia cường bằng tấm CFRP trên dầm bê tông dự ứng lực dùng cáp không bám dính bị nứt trước

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Tác giả: MINH TRIẾT NGUYỄN, VĂN QUÝ NGUYỄN, VŨ PHƯƠNG PHAN

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Tạp chí Xây dựng, 2024

Mô tả vật lý: tr.119

Bộ sưu tập: Metadata

ID: 379555

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Các nghiên cứu về sửa chữa gia cường dầm bê tông dự ứng lực dùng cáp không bám dính (UPC) bị hư hỏng (nứt) trước bằng tấm sợi polyme (FRP) dán ngoài vẫn còn rất hạn chế. Do đó, nghiên cứu này khảo sát thực nghiệm hiệu quả gia cường của tấm FRP sợi cacbon (CFRP) trên dầm UPC có vết nứt trước. Chương trình thử nghiệm bao gồm bốn dầm UPC kích thước lớn với tiết diện chữ T được gia cường bằng tấm CFRP dán dọc và hệ neo dạng chữ U (U-wraps). Kết quả thử nghiệm cho thấy chỉ sau khi các vết nứt mở lại, hệ thống gia cường bằng tấm CFRP mới làm việ. Do đó, trong cả giai đoạn sử dụng và giai đoạn bền, các dầm được gia cường thể hiện khả năng làm việc tốt hơn so với dầc hiệu quả. Tấm CFRP giúp kháng ứng suất kéo, kiểm soát các vết nứt và do đó làm giảm sự suy giảm độ cứng của dầm bị hư hỏng trước không được gia cường về độ võng, chiều rộng vết nứt và khả năng chịu tải của dầm. Ngoài ra, hiện tượng bong tách của tấm CFRP dán dọc đã được ngăn chặn một cách hiệu quả bằng cách sử dụng các neo U-wraps và do đó giúp gia tăng sự đóng góp của các tấm CFRP dán dọc vào khả năng chịu lực của dầm. Từ khóa: Vết nứt trước
gia cường
tấm CFRP
cáp không bám dính.Research efforts on the pre-cracked unbonded prestressed concrete (UPC) beams strengthened with externally bonded fibre-reinforced polymer (FRP) systems are still very limited. Thus, this study intends to experimentally investigate the efficacy of FRP strengthening composites on UPC beams with pre-cracks. The experimental program comprised four large-scale UPC beams with a T-section strengthened with longitudinal carbon FRP (CFRP) sheets and CFRP U-wrap anchors. The experimental results showed that only after cracks reopened the CFRP strengthening system became effective. The CFRP composites carried tensile stress, controlled cracks and thus reduced the stiffness degradation of the precracked beams. As a result, in both the serviceability stage and ultimate stage, the CFRP-strengthened beams had better performances as compared to the unstrengthened counterpart concerning the deflection, crack width and load-carrying capacity of the beam. In addition, the premature debonding of the longitudinal CFRP sheets was effectively averted by the use of U-wrap anchors, which increased the contribution of the longitudinal CFRP sheets. Keywords: Pre-cracks
strengthening
CFRP composites
unbonded prestressing tendons.

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