Study on post-fire ultra-low cycle fatigue properties of Q690 high strength steel post fire

被引：0
|
作者：
Xue X. [1 ,2 ]
Wang F. [1 ]
Shi Y. [1 ,2 ]
Wang W. [1 ,2 ]
机构：
[1] School of Civil Engineering, Chongqing University, Chongqing
[2] Key Laboratory of New Technology for Construction of Cities in Mountain Area, Chongqing University, Ministry of Education, Chongqing
来源：
Jianzhu Jiegou Xuebao/Journal of Building Structures | 2023年 / 44卷 / 06期
关键词：
energy dissipation capacity; high strength steel; metallographic structure; overheat temperature; ultra-low cycle fatigue test;
D O I：
10.14006/j.jzjgxb.2022.0631
中图分类号：
学科分类号：
摘要：
To evaluate the residual post-fire seismic performance of steel structures, it is necessary to clarify the ultra-low cycle fatigue performance. Ultra-low cycle fatigue test of 23 groups of Q690 high strength steel (HSS) after high temperature was carried out, considering temperature, cooling method and fatigue strain amplitude as variables. The post-fire fatigue life and cyclic stress-strain curve of Q690 HSS were obtained. The ultra-low cycle fatigue performance and energy dissipation capacity of Q690 HSS were analyzed, the post-fire ultra-low cycle fatigue failure mode of Q690 HSS was discussed. The microstructure of Q690 HSS was observed, and the influence of microstructure on ultra-low cycle fatigue performance was discussed. The results show that Q690 HSS still has good energy dissipation capacity after fire, and its cyclic stress-strain curve shows a full shape. Natural cooling after experiencing 600 ℃ can play a tempering effect, which increases the fatigue life of Q690 HSS by 23.4% compares to that without heating. The cooling methods have a significant influence on the peak stress of Q690 HSS after experiencing 900 ℃. The peak stress of Q690 HSS cooling from 900 ℃ by water immersion is 1.77 times that of natural cooling. The metallographic structure of Q690 HSS changes after high temperature and affects its ultra-low cycle fatigue performance. Except for the Q690 HSS cooling from 900 ℃ by water immersion, there are evident fatigue source, fatigue arcs and instantaneous fracture zone in the fracture of Q690 HSS. The increase of fatigue strain amplitude increases the spacing of the fatigue arc. © 2023 Science Press. All rights reserved.
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页码：119 / 128
页数：9
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