Experimental and model investigation on residual stresses in Q460GJ thick-walled I-shaped sections

Residual stresses can occur through a variety of mechanisms, and welding is one of mechanisms. This kind of stress variation through materials can be very complex and can vary between compressive and tensile stresses from layer to layer. A new type of high performance structural steel named by Q460GJ has been increasingly utilized in many large scale steel constructions in China, such as the National Stadium of China in Beijing (Birds Nest) and Canton Tower in Guangzhou. Q460GJ structural steel has a nominal yield strength of 460 MPa, which does not decrease significantly with the increase of steel plate thickness. Thus, Q460GJ structural steel is normally used in thick-walled welded sections. Nevertheless, the residual stresses on thick-walled sections may be more complex. Currently, only limited knowledge is available on the residual stress distribution of the members fabricated from high performance structural steel plates, especially for thick-walled sections. In this paper, the residual stresses in four welded medium-walled and four thick-walled H-section specimens fabricated from Q460GJ structural steel plates were studied by experimental tests. Residual stresses were measured by sectioning method, and the variation of residual stress through plate thickness was determined by slicing method. This study provides the magnitude and distribution of the longitudinal residual stresses. This paper also explores the effect of plate thickness on residual stress distribution and the interaction between flanges and webs. Finally, based on the statistical evaluation of the experimental results, a simplified multilayer residual stress model is proposed for predicting residual stress.