Improvement of Load-carrying Capacity and Fatigue Performance of Steel Structural Members by Residual Stress Control with Local Heat Treatment

• Project/Area Number: 16H06098
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Single-year Grants
• Research Field: Structural engineering/Earthquake engineering/Maintenance management engineering
• Research Institution: Osaka University (2018); Nagoya University (2016-2017)
• Principal Investigator: Hirohata Mikihito 大阪大学, 工学研究科, 准教授 (50565140)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Project Status: Completed (Fiscal Year 2018)
• Budget Amount: ¥10,920,000 (Direct Cost: ¥8,400,000、Indirect Cost: ¥2,520,000); Fiscal Year 2018: ¥2,210,000 (Direct Cost: ¥1,700,000、Indirect Cost: ¥510,000); Fiscal Year 2017: ¥3,510,000 (Direct Cost: ¥2,700,000、Indirect Cost: ¥810,000); Fiscal Year 2016: ¥5,200,000 (Direct Cost: ¥4,000,000、Indirect Cost: ¥1,200,000)
• Keywords: 鋼構造 / 溶接 / 残留応力 / 熱処理 / 構造工学 / 疲労 / 耐荷力

Outline of Final Research Achievements

Simple heat sources such as high frequency induction heating and ceramic heaters can be used for on-site heat treatment. Using these heat sources, a method was proposed for converting the residual welding stress that adversely affects the load-bearing and fatigue-resistance performance of steel structural members into a stress distribution that is advantageous for various performances of the members. Experiments to identify the optimum heating conditions by heat treatment using various heat sources and simulations by thermal elastic-plastic analysis were performed. Furthermore, loading tests and fatigue tests were conducted to confirm the improvement effects of load resistance and fatigue resistance by heat treatment.

Academic Significance and Societal Importance of the Research Achievements

セラミックヒーターを用いた熱処理により，圧縮力を受ける部材の残留応力を除去する技術を提案し，残留応力の除去により耐荷性能が向上する効果を確認した．また，この熱処理過程をシミュレーションする方法を構築し，実構造部材に対して熱処理条件を探索するためのツールとして提示した．また，高周波誘導加熱装置を用いた熱処理により，繰り返し荷重を受ける部材の耐疲労性能を向上する熱処理方法を提示した．鋼橋において疲労損傷の多いカバープレート構造および面外ガセット構造に対し，残留応力の除去により耐疲労性が向上する効果を確認した．これらの結果は鋼橋部材の機能向上ならびに維持管理に資する有意義な技術を提供するものである．

Research Products

• [Journal Article] Numerical Study on Post-weld Heat Treatment of Non-stiffened Welded Box Section Member (2019)
  • Author(s): May Phyo Aung, Mikihito Hirohata
  • Journal Title: International Journal of Steel Structures Volume: 印刷中 Issue: 5 Pages: 1521-1533
  • DOI: 10.1007/s13296-019-00230-6
  • Peer Reviewed
• [Journal Article] Characteristics of Residual Stresses Generated by Induction Heating on Steel Plates (2018)
  • Author(s): May Phyo Aung, Masaaki Nakamura, Mikihito Hirohata
  • Journal Title: Metals Volume: 8-25 Pages: 1-14
  • Peer Reviewed / Open Access
• [Journal Article] Effect of PWHT with Sheet-type Ceramic Heater on Compressive Behaviors of Non-stiffened Welded Steel Box Columns (2018)
  • Author(s): May Phyo Aung, Hirohata Mikihito
  • Journal Title: World Journal of Engineering and Technology Volume: 6 Pages: 50-67
  • Peer Reviewed / Open Access
• [Presentation] Improvement of Residual Stress on Gusset Welded Joints by Heat Treatment with Induction Heating (2018)
  • Author(s): AUNG May-Phyo, HIROHATA Mikihito and KITANE Yasuo
  • Organizer: Ninth International Conference on Advances in Steel Structures
  • Int'l Joint Research
• [Presentation] Applicability of Sheet-type Ceramic Heater for PWHT on Welded Steel Structural Members (2017)
  • Author(s): MAY Phyo Aung, HIROHATA Mikihito
  • Organizer: 溶接構造シンポジウム2017