Resistance of cold-formed high strength steel circular and polygonal sections — Part 1: Experimental investigations

• Experimental investigations on the resistances of the cold-formed high strength steel circular and polygonal sections were performed.
• Mechanical properties of the high strength steel material S650 were investigated.
• Initial geometric imperfections according to EC3 and 3D laser scanning method were compared.
• Calibration of corner and flat coupon tests to ductile damage material models were conducted.

This paper presents results from experiments performed on cold-formed high strength steel circular and polygonal sections. The test specimens were conceived to provide necessary information for development of tubular towers for wind turbines. A total of 32 high strength steel specimens were tested under uniaxial compression. Various thicknesses, openings and geometric imperfections were studied. Sixteen specimens without opening and sixteen specimens with opening were tested under axial compression in order to investigate influences of opening on the resistances. Tensile tests of coupon specimens taken from flat part, circular part and corner part were used to investigate basic properties of high strength steel material S650 and to evaluate influence of corner on the material strength and ductility. Initial geometric imperfections of the specimens were determined by using a 3D laser scanning method. The coupon test results were used to calibrate the ductile damage material models for modelling of fracture. Results from the experiments are fully described in this paper.