Study of residual stresses in I-section members and cellular members

Cellular or castellated members are steel I-section members with evenly spaced circular or hexagonal web openings. Most of the cellular members used nowadays are made starting from a hot-rolled I-section member, called the parent section. In the production process, the latter member is cut into two halves according to a certain pattern. Cellular members are produced by shifting these halves and welding them together again. Compared to their parent sections, these members have a more optimal material use in strong-axis bending. Residual stresses are present in both the parent sections and the cellular members. For plain-webbed I-section beams, such as the parent sections, it has been shown that these residual stresses can have a considerable adverse influence on the buckling failure behaviour of the members. It is expected that this will also be the case for cellular or castellated members. However, it is still unknown how the production process of these members will affect the already present residual stresses in the parent sections. This is currently being investigated by the authors in a larger research project about the global buckling failure of cellular members. This paper presents the authors’ experimental research concerning the residual stresses in cellular or castellated members and their parent sections. An overview is given of the results of residual stress measurements in 4 parent sections and 12 cellular members sections, after which these results are compared with literature. This way, an indication can be given of the influence of the production process on the residual stresses and the global buckling behaviour of cellular or castellated members.