Fatigue Durability Evaluation of Steel Bridges Based on Probability Theory

Research Project

Project/Area Number	18K13819
Research Category	Grant-in-Aid for Early-Career Scientists
Allocation Type	Multi-year Fund
Review Section	Basic Section 22020:Structure engineering and earthquake engineering-related
Research Institution	Nagoya University
Principal Investigator	Shimizu Masaru 名古屋大学, 工学研究科, 助教 (30735006)
Project Period (FY)	2018-04-01 – 2021-03-31
Project Status	Completed (Fiscal Year 2020)
Budget Amount *help	¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000) Fiscal Year 2020: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000) Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000) Fiscal Year 2018: ¥2,080,000 (Direct Cost: ¥1,600,000、Indirect Cost: ¥480,000)
Keywords	鋼床版 / Uリブ / ルート / 疲労 / き裂進展速度 / き裂進展経路 / 確率 / 溶接 / ばらつき / 鋼橋
Outline of Final Research Achievements	Two-dimensional analyses were performed on the U-rib welded joint, and the effects of penetration and welding size on the root stress were investigated. In addition, the influence of the loading position was examined through the three-dimensional analysis. The influence line of the stress generated at the welding root was created. Based on the results of the traffic volume survey, the vehicle type composition and the passing position of the vehicle were given by the probability distribution, and crack occurrence probability was examined. The position of the lane mark has a large effect on the probability of crack occurrence. The fatigue life is the shortest when the loading position directly above the U-rib weld is the most frequent passage position. It was found that the probability of fatigue crack occurrence decreases as the passage position moves away from the U-rib weld.
Academic Significance and Societal Importance of the Research Achievements	鋼床版Uリブ溶接部から発生する疲労き裂に対して，確率的な手法で疲労寿命を与えることができた．また，本手法は鋼床版Uリブ溶接部のみに限らず，公称応力を定義することができない溶接継手や，二次応力が支配的となる溶接継手に対して適用できると考えられる．