With the continuous improvement of China’s economic strength and construction level, various steel structure buildings with beautiful appearance, high reliability and low self weight emerge in endlessly, such as large bridges, national gymnasium and so on. According to the requirements of the current new design concept, the design direction of steel structure building is larger, higher and more beautiful, that is, steel structure building with larger space span. However, these will lead to the increasing difficulty of steel structure design. In order to solve the above problems, cast steel joints have been more and more widely used in steel structure architectural design because of their own characteristics, which is known as the research hotspot in the engineering field. With the continuous progress and development of casting technology, the application range of cast steel joints is expanding. However, at this stage, there are still many casting defects in cast steel joints, such as pores and sand sticking, which will have an adverse impact on the overall mechanical properties of steel structure buildings with cast steel joints. At this stage, there is less research on the casting defects of cast steel joints, especially the fatigue performance, and the existing steel casting quality and safety evaluation system is not comprehensive, so it needs to be improved.
(1) When the distribution of casting defects is different, there will be great differences in the fatigue properties of cast steel joints.
(2) Compared with cast steel joints with multiple casting defects, cast steel joints with single casting defects have better fatigue performance.
(3) Compared with the size of casting defects, the location distribution of casting defects has a greater impact on the fatigue properties of cast steel joints. In the quality evaluation of cast steel joints, it is unreliable to only consider the size of casting defects at local positions. The distribution of multiple casting defects should be considered at the same time to evaluate the safety of cast steel joints.