Fatigue durability improvement of welded parts of steel bridges by local heat treatment with portable heat source

2015 Fiscal Year Final Research Report

• Project/Area Number: 26820184
• Research Category: Grant-in-Aid for Young Scientists (B)
• Allocation Type: Multi-year Fund
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Nagoya University
• Principal Investigator: HIROHATA Mikihito 名古屋大学, 工学(系)研究科(研究院), 准教授 (50565140)
• Project Period (FY): 2014-04-01 – 2016-03-31
• Keywords: 鋼橋 / 溶接 / 熱処理 / 疲労 / 残留応力

Outline of Final Research Achievements

In order to improve fatigue durability of welded parts of steel bridges with complicated geometric 3-dimensional shapes, a technique of local heat treatment with a portable heat source was developed. A series of experiment was carried out on specimens modeled a steel plate deck with U-shaped rib, in which a lot of fatigue damages are reported. A thermal elastic-plastic analysis method was investigated for simulating the heat treatment process.
It was confirmed that the welding residual stress was reduced by 80% through the heat treatment. Furthermore, a method for saving heat energy during the heat treatment was proposed. It was shown that the fatigue durability was improved by the heat treatment under the condition of relatively low applied stress level.

Free Research Field

構造工学