Vol. 22, No. 3, pp. 286-297 (2026)
STUDY ON POST-FIRE MECHANICAL PERFORMANCE OF Q460QENH WEATHERING STEEL WITH THREE COOLING METHODS
Bing-Sen Wang 1, Hang Yin 1, 2, *, Li-Juan Zheng 3, Er-Nian Zhao 1 and Kai Yan 1
1 Key Laboratory of Building Structural Retrofitting and Underground Space Engineering (Shandong Jianzhu University), Ministry of Education, Jinan 250101, China
2 Collage of Civil Engineering, Tongji University, Shanghai 200092, China
3 Shandong Lukan Group Co., Ltd, Jinan 250101, China
*(Corresponding author: E-mail:This email address is being protected from spambots. You need JavaScript enabled to view it.)
Received: 27 March 2025; Revised: 23 August 2025; Accepted: 23 August 2025
DOI:10.18057/IJASC.2026.22.3.4
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ABSTRACT
Monotonic tensile tests were performed to investigate the mechanical behavior of Q460qENH weathering steel after exposure to temperatures ranging from 20°C to 1000°C, considering three different cooling methods: cooling in air (CIA), cooling in water (CIW), and cooling in fire-fighting foam (CIF). The tensile fracture surfaces were analyzed using scanning electron microscopy (SEM), and the post-fire mechanical properties were systematically evaluated. The results revealed that the fracture surfaces under CIA and CIF conditions exhibited similar dimple morphologies, while the number of dimples decreased progressively with increasing temperature under CIW conditions. Both the cooling method and the exposure temperature exerted only a limited effect on the elastic modulus. A distinct yield plateau in the stress - strain curve disappeared under all cooling conditions after exposure to temperatures of 800 °C or higher. Under CIA and CIF conditions, the yield strength decreased markedly after exposure to temperatures above 600 °C, while the ultimate tensile strength remained relatively stable. In contrast, under CIW conditions, the yield strength initially declined but recovered to nearly its original value after exposure to 700 °C, accompanied by a pronounced increase in ultimate strength. The CIW process was found to reduce ductility but enhance Brinell hardness. Furthermore, a mathematical model was developed to describe the post-fire mechanical properties under different cooling conditions, providing theoretical support for assessing the residual load-bearing capacity of steel structures following fire exposure.
KEYWORDS
Q460qENH weathering steel, Cooling methods, Monotonic tensile, Post-fire mechanical properties, Mathematical model
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