Development of constitutive model of steel material in large strain region where progressive collapse of steel bridge occurs

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K14817
• 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: Gifu National College of Technology
• Principal Investigator: Mizuno Yoshinori 岐阜工業高等専門学校, その他部局等, 准教授 (90585093)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 材料構成則 / 延性き裂 / 相当塑性ひずみ

Outline of Final Research Achievements

To predict failure of steel bridges through FE analysis, which is caused by occurrence of ductile cracks, it is essential to employ a constitutive model that is capable of reproducing the strain response up to the large strain region where strain concentrates until ductile cracks occur. Thus, we targeted a local buckling section in a CFT column where large equivalent plastic strain enough to cause cracks due to local buckling occurs, and investigated a constitutive model. This model can appropriately express the hardening of steel material that occurs in the large strain region that exceeds the maximum load point during tensile tests. Herein, we investigated the relationship between the equivalent stress and the equivalent plastic strain beyond the maximum load point as well as the repeated behaviors in the large strain region. After confirming the consistency between the experiment and the analysis, the response of equivalent plastic strain at a strain of 100% or more was confirmed.

Free Research Field

構造工学

Academic Significance and Societal Importance of the Research Achievements

大ひずみ領域での鋼材の正確な材料構成則が明らかでないため，FE解析で塑性ひずみや応力の応答を精度よく算定できない．延性き裂発生直前までの大ひずみ領域でのひずみ応答を求める高精度な鋼材の材料構成則を用いれば，想定外の事態での構造物内のひずみの急激な上昇を予測し，これを抑制する手だてを講じることで，構造物のリダンダンシーやロバスト性を高めることが可能になる．そのため，鋼材に延性き裂が発生する大ひずみ領域までのひずみ応答を再現可能な材料構成則の検討を行った．