Experimental and numerical investigation of cold formed sigma profiles behaviour under axial and eccentric loading

In this study, characteristic behaviours of cold formed sigma profiles such as ductility, energy dissipation, load carrying capacity under axial load, major, minor and biaxial moment cyclic loadings were investigated due to the fact that experimental studies in literature are mainly performed on monotonic loadings. Sigma profile's cross-section and lengths are determined according to critical buckling modes of local, distortional or global that determines load carrying capacity of cross-section and critical half wave lengths and buckling load factors corresponding to buckling modes. A total of 90 experiments composed of 45 monotonic loading and 45 cyclic loading on cold formed sigma profiles with determined lengths of 500 mm, 1000 mm and 1500 mm. On determining hardening parameters experimentally, experimental and numerical behaviours under monotonic and cyclic loading compared using analysis results performed by ABAQUS software. Moreover, with two parametric study, sigma profile's stability space determined by a number of 2555 finite element analysis performed under monotonic loading and load capacities compared with AISI-S100-12 standard. Accordingly, it is concluded that AISI standard in current status is quite conservative and it has higher potential for improvement for profiles whose lips are in tension stress. It is observed that generally in numerical and experimental studies under cyclic loading, energy dissipation capacity of samples with their lips in tension are higher than those samples with lips in compression. Due to the fact that they can dissipate energy, sigma profiles with different cross-sections and slenderness under cyclic loadings can be charaterized for stiffness and strength degradation and their usage in buildings could be increased by creating envelope curves.