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The paper presents a static analysis of the buckling and post-buckling state of thin-walled cold-formed steel (TWCFS) lipped channel section beam-columns subjected to eccentric compression. Eccentricity is taken into consideration relative to both major and minor principal axes. An analytical–numerical solution to the buckling and post-buckling problems is described. The solution is based on the theory of thin plates. Equations of equilibrium of section walls are derived from the principle of stationary energy. Then, to solve the problem, the finite difference (FDM) and Newton–Raphson methods are applied. Linear (buckling) and nonlinear (post-buckling) analyses are performed. As a result, pre- and post-buckling equilibrium paths are determined. Comparisons of the obtained numerical results, FE simulation results, and experimental test results are carried out and presented in comparative load-shortening diagrams. Additionally, a comparison of the buckling forces and buckling modes obtained from theoretical analysis and experiments is presented. [ABSTRACT FROM AUTHOR]

Steel-concrete composite structures are very attractive because of their characteristics, which can be emphasised by using cold-formed steel instead of hot-rolled ones. This paper presents possible analytical approaches and a parametric finite element study of cold-formed steel-concrete composite beams in bending. Analysed beams are formed of back-to-back cold-formed steel channels and concrete slabs connected by demountable shear connectors. A solid concrete slab on a profiled metal sheet analysed. Also, the study investigates the influence of corrugated web between the back-to-back channels of different thicknesses. In the case of a corrugated web, the distance between the shear connectors is increased. Furthermore, different degrees of shear connection, shear connector quality, and their arrangements are considered. An analytical study is based on full and partial shear connection assumptions and non-linear bending resistance. It is shown that the steel channel thickness and degree of shear connection significantly influence the beam bending capacity as well as concrete slab configurations. Conversely, a discrete connection between steel elements has a minor effect. A comparison of the maximum obtained bending capacities in FE analyses is in good agreement with analytical approaches for full and partial shear connections. [ABSTRACT FROM AUTHOR]

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The paper makes an in-sight analysis of four actual steel-intensive envelope solutions existing on the market adaptable to steel structural systems. The solutions enable flexible modular construction, fast fabrication and erection times and easy disassembling. The analyses consider the heat transfer analysis including phase shift, amplitude attenuation and temperature amplitude ratio and the energy balance analysis. Considering the sustainability approach, the study is completed by an environmental impact analysis on Life-Cycle, by considering the production and end-of life stages. Although the selected systems from similar thermal resistances, the results show a certain variation of analysed parameters such as amplitude attenuation and temperature amplitude ratio (TAV). The energy balance analysis shows that the heating, solar gain and hot water preparation are responsible for the supplied energy. The emitted house energy break-down is almost equally shared among transmission, ventilation and sewage energies. The Life-Cycle Assessment (LCA) analysis proves that the end-of-life of the systems play an important role in the environmental impact of analysed systems, reversing the initial ranking of systems.

The intense urbanization process Romania has known during the industrialization period of the 1960-70s led to an exponential shortage in urban housing. Similar to other countries, but more specifically to the former Eastern block, Romanian state-financed collective dwellings were erected starting from standardized projects of Reinforced Concrete Large Prefabricated Panels (RCLPP) blocks of flats, generating nowadays a particular built stock of identical buildings and several apartment types, widespread throughout the entire country. These buildings currently house 60% of the urban population of Romania that own 96% of the apartments, as opposed to the European trends regarding the number of owner-occupied barely reaching 60%. Even though at not even half of their intended lifespan, the collective dwellings do not satisfy basic comfort conditions such as cooling and ventilation, being in an urge of retrofitting and upgrading. Individually applicable cooling systems undertaken by the owners have proved to be acceptable, but did not, however, contribute to a decrease in the overall energy consumption of the buildings. The present paper analyses the individual cooling systems being currently applied in Romanian apartments as opposed to a global-holistic system on block level, in terms of energy consumption and efficiency, flexibility of owner controlled indoor microclimate. The results show the potential of introducing renewable energy sources as viable alternatives for the existing systems.