Investigation of the bending behaviour of cold formed steel beams used in conical silo roofs

This study aimed to investigate the bending behaviour of cold-formed steel beam members as a part of the conical silo roof experimentally and numerically. Accordingly, a four-point bending test was applied in the experimental study. The experiments were carried out in two cases: simple and pinned support. The study considered the orientation of the radial beams and the distance between the circular beams. The effects of the variables on the moment carrying capacity, buckling behaviour, lateral translation and rotation of the beams were investigated. The experimental results show that decreasing the distance between circular beams increases the moment-carrying capacity of simply supported radial beams. However, this effect is not observed for pinned supported members. In addition, it was determined that the lateral translation and rotation angles of the beams decreased as the distance decreased, which changed the failure behaviour of the radial beams. Face-to-back orientation was found to be the most effective beam orientation. The numerical study was conducted to validate experimental results and investigate untested variables. The effect of mesh types, mesh sizes and geometric imperfections at different amplification factors were examined in the convergence analyses. The analyses revealed the need to identify local and global imperfections in the model. In the verification analysis, the experimental members' moment carrying capacity, failure modes and moment-displacement curves were compared and the results were consistent. The parametric study considered the ratio of the height to the thickness (h/t) of the radial beams and the thickness of the circular beams. The results indicated that as the h/t ratio increased, the moment-carrying capacities decreased. Using circular beams with varying thicknesses had a limited effect on the moment carrying capacity. In addition, the results of the experimental and numerical studies were compared with the AISI S100 specification. It was determined that the AISI S100 specification approaches were in good agreement with the experimental and numerical results.