Buckling resistance of HSS box columns
| Titel | Title Knickversuche im Rahmen des Projekts Knicktragfähigkeit und Eigenspannungen geschweißter Kastenprofile aus höherfesten Stählen | Buckling tests in the frame of the project Buckling resistance and residual stresses of welded box sections made of high strength steels Förderer | Funding Bundesministerium für Wirtschaft und Klimaschutz (BMWK) / AiF/IGF |
Report 2023
Buckling resistance of HSS box columns
Buckled column in the test stand
Columns with welded box sections made of high-strength steels are characterized by a high flexural buckling load-bearing capacity with a low dead weight. The load-bearing capacity is influenced by geometric and structural imperfections. The residual stresses introduced by the welding process are of particular importance here. In the area of the weld seams, the cooling process creates tensile residual stresses that lead to compressive residual stresses due to the equilibrium that is established across the component cross-section. The latter, in combination with the compressive stresses from the effects, lead to earlier plasticization and failure of the columns.
The buckling resistance of columns made of high-strength steels with welded cross-sections is insufficiently covered in the current Eurocode 3 and the subsequent standard. The reasons for this are a lack of knowledge about the residual stresses caused by the welding process and the insufficient experimental and structural-mechanical validation of the buckling resistance. The present rules were validated for steels up to S355, so that the transfer of the results to higher-strength steels is very conservative, especially in the medium slenderness range. A realistic evaluation can increase the usable load-bearing capacities, in some cases considerably.
As part of the AiF-FOSTA research project P1588, the residual stress distributions and buckling load capacities of columns with welded box sections are being investigated. The parameters of energy input through the welding process, cross-section dimensions, buckling lengths and the strength of the steels are varied. The investigations are carried out experimentally and by numerical calculations for steels S460 to S960. The results lead to a re-evaluation of the assignment of the compression bars to buckling lines and to standardized residual stress distributions for structural-mechanical calculations.
The flexural buckling tests are carried out in the OML. Hereby, special supports from a special production facility are used for the tests. Supplementary welded structure simulations and numerical load tests (GMNIA) are used to develop the practically relevant parameter space.