Residual stresses in welded I-shaped sections fabricated from Q460GJ structural steel plates

Abstract A new type of high-performance structural steel named by GJ steel, has been widely used in many large scale structures like National Olympic Stadium (Birds Nest), new CCTV Headquarters and Canton Tower in China. However, previous studies on 460 MPa GJ steel are very limited. In this study, the residual stresses on eight full scale I-shaped sections welded by flame-cut Q460GJ (“Q” means yield strength) steel plates including five doubly symmetric sections and three singly symmetric sections, were investigated by experimental tests. By using sectioning method, it was found that the deformation of curved strips was one part of circular curve. The results from the circular curve correction method are generally identical to the results from a new curve correction method named by “straightening measurement”. Then the residual stress distributions on Q460GJ welded I-shaped sections were obtained. It was concluded that residual stresses were related to sectional dimensions and flanges and webs were influenced with each other. Compared with the existing residual stress distribution models, the residual stresses on sectional flanges obtained in this study are much smaller, while no significant difference is found for sectional webs. It is also found that the flange tips are all under compression rather than tension, and the average value of the peak tensile residual stresses on flanges is only about 0.5f y . Finally, the residual stress levels at typical locations of I-shaped sections were summarized and suggested.