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Experimental Research on Post-fire Fracture Failure of Q690D Steel Cross-shaped Welded Joints(PDF)


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Experimental Research on Post-fire Fracture Failure of Q690D Steel Cross-shaped Welded Joints
HUANG Xue-wei ZHANG Xiao-ge WEI Chen-chen ZHAO Jun GE Jian-zhou
(School of Mechanics and Safety Engineering, Zhengzhou University, Zhengzhou 450001, Henan, China)
Q690D steel high temperature experimental research fracture failure welded joint ultra low cycle fatigue
In order to study the fracture properties of Q690D high strength steel and welded joints at room temperature and after high temperature, the cross-shaped welded joints representing the actual local welding structure of the beam-to-column joints were selected, and a series of uniaxial tensile tests of Q690D steel and ER80-G weld metal at room temperature and after high temperature were conducted. The elastic modulus, yield strength, ultimate strength and elongation of steel and weld metal after high temperatures were obtained. The cross-shaped welded joints at room temperature and after high temperature were tested under monotonic loading and ultra low cyclic loading. The fracture mechanism of Q690D high strength welded joints was analyzed while the effect of post-fire temperature and loading condition on the fracture behavior of steel and welded joints was discussed. The results show that when the temperature is higher than 600 ℃, the post-fire strength of steel and welded joints decreases and the post-fire deformability increases. The strength of Q690D steel decreases after 800 ℃ high temperature, but the mechanical properties of ER80-G weld metal do not change obviously, causing the result that fracture failure of welded joint does not occur at the weld but at the base metal under monotonic loading after 800 ℃ high temperature. The bearing capacity and deformation capacity of welded joints under cyclic loading are lower than those under monotonic loading. The mechanical properties of steel, weld metal as well as the welded joints obtained from the tests are able to provide basic test data to develop fracture analysis models considering the post-fire effect.


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Last Update: 2021-09-01