PSI - Issue 64

First page Table of contents Previous page 980 Next page Last page

ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ Available online at www.sciencedirect.com ^ĐŝĞŶĐĞ ŝƌĞĐƚ

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

Procedia Structural Integrity 64 (2024) 1334–1338

SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Fatigue behavior of CFRP strengthened ultra-high strength steel Yining Zhang a , Lili Hu a, * a School of Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China Abstract Ultra-high strength steel (UHSS) with exceptional mechanical properties is gaining widespread use across various industries. However, research on strengthening UHSS with surface cracks using Carbon Fiber Reinforced Polymer (CFRP) is limited. Accordingly, a series of CFRP strengthening UHSS Q890 and Q960 experiments with surface cracks are carried out under fatigue loading. Two loading programs, the maximum stress equal to half yield strength f y and 200 MPa, are designed. Surface cracks at the weld root were pre-cracked, and a single layer of CFRP was applied adhesively to both sides of the butt-welded UHSS. First, the results show that when subjected to a maximum stress of 0.5 f y , the fatigue life decreases as the steel grade increases. The strengthening effect is 1.07 and 1.34 times for Q890 and Q960, respectively. Second, when subjected to a maximum stress of 200 MPa, the fatigue life decreases as the steel grade decreases. Excellent strengthening effects of 1.89 and 2.60 times were obtained for Q890 and Q960, respectively. Finally, it is observed that CFRP delamination and rupture are the main fracture modes. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers Keywords: Ultra-high strength steel; CFRP, fatigue; surface crack; butt-weld 1. Introduction Ultra-high strength steel (UHSS) gradually wins applications in various fields due to its high strength, high crashworthiness, and weight reduction Hammarberg et al. (2020). Fatigue cracks in welded steel connections typically start at the weld root and can cause sudden failure, presenting a significant challenge for steel structures Yamada and Nagatsu (1989). However, welding conditions for UHSS are stricter than normal steel Tümer et al. SMAR 2024 – 7th International Conference on Smart Monitoring, Assessment and Rehabilitation of Civil Structures Fatigue behavior of CFRP strengthened ultra-high strength steel Yining Zhang a , Lili Hu a, * a School of Ocean and Civil Engineering, Shanghai Jiao Tong University, Shanghai, China Abstract Ultra-high strength steel (UHSS) with exceptional mechanical properties is gaining widespread use across various industries. However, research on strengthening UHSS with surface cracks using Carbon Fiber Reinforced Polymer (CFRP) is limited. Accordingly, a series of CFRP strengthening UHSS Q890 and Q960 experiments with surface cracks are carried out under fatigue loading. Two loading programs, the maximum stress equal to half yield strength f y and 200 MPa, are designed. Surface cracks at the weld root were pre-cracked, and a single layer of CFRP was applied adhesively to both sides of the butt-welded UHSS. First, the results show that when subjected to a maximum stress of 0.5 f y , the fatigue life decreases as the steel grade increases. The strengthening effect is 1.07 and 1.34 times for Q890 and Q960, respectively. Second, when subjected to a maximum stress of 200 MPa, the fatigue life decreases as the steel grade decreases. Excellent strengthening effects of 1.89 and 2.60 times were obtained for Q890 and Q960, respectively. Finally, it is observed that CFRP delamination and rupture are the main fracture modes. © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers Keywords: Ultra-high strength steel; CFRP, fatigue; surface crack; butt-weld 1. Introduction Ultra-high strength steel (UHSS) gradually wins applications in various fields due to its high strength, high crashworthiness, and weight reduction Hammarberg et al. (2020). Fatigue cracks in welded steel connections typically start at the weld root and can cause sudden failure, presenting a significant challenge for steel structures Yamada and Nagatsu (1989). However, welding conditions for UHSS are stricter than normal steel Tümer et al. © 2024 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

* Corresponding author. E-mail address: lilihu@sjtu.edu.cn * Corresponding author. E-mail address: lilihu@sjtu.edu.cn

2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers 2452-3216 © 2024 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of SMAR 2024 Organizers

Made with FlippingBook Digital Proposal Maker