Ocean Engineering, Vol. 343(2026) 123362, 2026. 1.

Title: Modified temperature-dependent reduction mechanical properties for ship structural steels: Toward improved thermo-structural design

Author(s): JeongHwa Yoo, Jung Kwan Seo

Abstract:

Structural analysis under accidental or extreme environmental conditions must accurately account for the changes in material properties that occur at elevated temperatures. For ship structures, the high-temperature softening behaviour of carbon steels is often evaluated using general building codes, such as the Eurocode for steel structures. However, these standards may not adequately reflect the characteristics of modern shipbuilding steels. To improve the accuracy of structural assessments under fire conditions, this study investigates the high- temperature mechanical properties of two widely used shipbuilding steels: mild steel Grade A and high tensile steel Grade AH36. Tensile tests were conducted at temperatures ranging from room temperature to 1000 ◦ C. The experimental results were compared with the reduction factors provided in the Eurocode for general carbon steels. Based on the findings, new reduction factors for elastic modulus, yield strength, and tensile strength were derived, and updated reduction curves were proposed. Furthermore, the applicability and effectiveness of the proposed reduction factors were validated through a comparative analysis of the ultimate strength of a plate- stiffener combination model representative of ship structures under fire loading.