Optimal design of cold-formed steel lipped channel beams: Combined bending, shear, and web crippling

The load carrying capacity of cold-formed steel (CFS) beams can be enhanced by employing optimisation techniques. Recent research studies have mainly focused on optimising the bending capacity of the CFS beams for a given amount of material. However, to the best of authors’ knowledge, very limited research has been performed to optimise the CFS beams subject to shear and web crippling actions for a given amount of material. This paper presents the optimisation of CFS lipped channel beams for maximum bending, shear, and web crippling actions combined, leading to a novel conceptual development. The bending, shear and web crippling strengths of the sections were determined based on the provisions in Eurocode 3, while the optimisation process was performed by the means of Particle Swarm Optimisation (PSO) method. Combined theoretical and manufacturing constraints were imposed during the optimisation to ensure the practicality of optimised CFS beams. Non-linear Finite Element (FE) analysis with imperfections was employed to simulate the structural behaviour of optimised CFS lipped channel beams after successful validation against previous experimental results. The results demonstrated that, the optimised CFS sections are more effective (bending, shear, and web crippling actions resulted in 30%, 6%, and 13% of capacity increase, respectively) compared to the conventional CFS sections with same amount of material (weight). The proposed optimisation framework can be used to enhance the structural efficiency of CFS lipped channel beams under combined bending, shear, and web crippling actions

Combined bending and shear behaviour of slotted perforated steel channels: Numerical studies

Cold-formed steel studs and purlins with staggered slotted perforations in webs are used in building structures to produce a better thermal performance of the profiles and for the energy efficiency of structures. On the other hand, the slotted webs result in an unfavourable effect in terms of the structural performance of the element, prominently their shear, bending and combined bending and shear strengths. Relatively little research has been reported on this subject despite its importance. Many research studies have been undertaken to examine the behaviour of conventional cold-formed steel (CFS) channel sections subject to combined bending and shear. To date, however, no research has been carried out to investigate how CFS channels with staggered slotted perforations behave under combined bending and shear actions. An extensive study on this area is therefore essential. Finite element (FE) models of CFS channels with staggered slotted perforations were developed to investigate their combined bending and shear capacity. A parametric study was conducted in detail by developing FE models based on the validation process with available experimental data. This paper presents the FE analysis details of CFS channels with staggered slotted perforations subject to combined bending and shear actions and the FE results. New design equations were also proposed to predict the combined bending and shear capacity of steel channels with staggered slotted perforations

Effect of rosiglitazone on the frequency of diabetes in patients with impaired glucose tolerance or impaired fasting glucose: a randomised controlled trial

Background Rosiglitazone is a thiazolidinedione that reduces insulin resistance and might preserve insulin secretion. The aim of this study was to assess prospectively the drugs ability to prevent type 2 diabetes in individuals at high risk of developing the condition