Residual stress measurements on cold-formed HSS hollow section columns

According to the previous research results the effect of residual stresses on the high strength steel members (HSS) are less severe than for normal strength steel (NSS) structures. Residual stresses have a significant influence on the global stability behaviour of steel structures, therefore the application of the existing buckling curves developed for NSS structures might lead to uneconomic design for HSS structures. To investigate the residual stress distribution in HSS members residual stress measurements are carried out on cold-formed square hollow sections. The test specimens are delivered by three different manufacturers using five different steel grades (S420, S460, S500, S700, S960). Based on the test results the shape and the intensity of the measured longitudinal residual stresses are determined and evaluated. The measured values of the residual stress patterns are evaluated in the function of the yield strength and the geometric properties of the test specimens. The measured residual stresses are compared to the results of the previous experiments and an improved residual stress model is developed based on the previous and current test results and which model is usable for cold-formed square hollow sections having various steel grades.