Nghiên cứu nút dầm-cột bê tông cốt thép bị cháy và chịu tải khác nhau có xét đến gia cường CFRP=Study on reinforced concrete beam-column joints subjected to different fires and loadings considering CFRP retrofitting

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Tác giả: Đẹt Đoàn Văn, Huy Võ Bá, Đinh Hoài Luân, Vui Cao Văn

Ngôn ngữ: vie

Ký hiệu phân loại:

Thông tin xuất bản: Tạp chí khoa học Đại học Mở Thành phố Hồ Chí Minh - Kỹ thuật và Công nghệ, 2024

Mô tả vật lý: tr.84-96

Bộ sưu tập: Báo, Tạp chí

ID: 252019

Thêm vào giỏ

Bài báo này nghiên cứu ứng xử và khả năng chịu lực của nút dầm-cột bê tông cốt thép sau cháy dưới tác dụng của tải trọng đơn và tải trọng lặp trong trường hợp có và không có gia cường bằng tấm sợi Carbon Fiber Reinforced Polymer (CFRP). Nghiên cứu thực nghiệm được tiến hành trên 09 mẫu nút dầm-cột bê tông cốt thép bị cháy với các thời gian cháy khác nhau. Một mẫu không cháy dùng để làm mẫu đối chứng. Tám mẫu còn lại được chia thành hai nhóm, mỗi nhóm gồm 04 nút bị cháy với các thời gian cháy 45 phút và 75 phút. Sau thí nghiệm cháy, hai mẫu trong mỗi nhóm được gia cường bằng tấm sợi CFRP, hai mẫu còn lại không gia cường. Một mẫu trong mỗi cặp được thí nghiệm tải trọng đơn, mẫu còn lại thí nghiệm tải trọng lặp. Kết quả thí nghiệm cháy cho thấy sau khi cháy bê tông chuyển từ màu xám sang màu hồng nhạt. Dưới tác dụng của tải trọng, các khớp dẻo hình thành trên vị trí dầm và các vết nứt chéo nhau xuất hiện tại vị trí giao nhau giữa dầm và cột. Kết quả thí nghiệm cũng cho thấy cháy làm suy giảm khả năng chịu tải của nút dầm-cột khoảng 11%. Nút sau cháy có gia cường có sức chịu tải lớn hơn 12.9 - 17.1% so với mẫu đối chứng.This paper investigates the postfire performance of reinforced concrete beam-column joints under monotonic and cyclic loadings with and without Carbon Fiber Reinforced Polymer (CFRP) retrofitting. Experiments were conducted on nine beam-column joints. One of these was not exposed to fire to be used as a control specimen. The other eight specimens were separated into two groups, which were exposed to 45-min and 75-min fires. After exposure to fire, in each group, one pair of joints were retrofitted with CFRP, while the other pair were not retrofitted. Of each pair, one joint was subjected to monotonic loading, while the other joint was subjected to cyclic loading. The results of fire tests indicated that, after fire exposure, the concrete color changed from grey to light pink. Under loading, a plastic hinge appeared at the beam end close to the column surface, and diagonal cracks appeared at the intersection of the beam and columns. The load-carrying capacity of joints was reduced by about 11% due to fire exposure. The ultimate load of CFRP-retrofitted joints was 12.9 - 17.1% higher than that of the control joint.

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