Residual stress measurements on welded square box sections using steel grades of S235-S960

According to the previous research results the effect of residual stresses on the high strength steel members (HSS-S500 and higher steel grades) are less severe than for normal strength steel (NSS -steel grades of S235-S460) 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 welded square box sections. The test specimens are delivered by three different manufacturers using seven different steel grades (S235, S355, S420, S460, S500, 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 geometrical properties of the test specimens. The measured residual stresses are compared to the results of the previous test results and an improved residual stress model is developed based on the previous and the current test results. The developed residual stress model is applicable for welded square box sections having steel grades between S235 and S960.