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This summary report is based on the experimental and numerical research of thin-walled cross-section’s compression resistance and shear strength of their joints carried out in St. Petersburg State Polytechnical University and HAMK University of Applied Sciences, Sheet Metal Centre. Current situation on Russian market concerning the usage of cold-formed thin-walled cross-sections is aimed to find out a base foundation to start up a stipulation of the elements under discussion in the building industry (Kolesov et al. 2007; Peleshko, Urchenko 2009; Zhmarin 2012). Some questions about the compression resistance of such cross-sections were raised on different conferences (Vatin, Sinelnikov 2013; Winter 1952; Yu Wei-Wen et al. 1996) by scientific community and by companies such as Rautaruukki Oyj (Finland). Steel galvanized C-and U-profiles and thermo-profiles are types of thin-walled cross-sections that are normally used in small houses construction (Shatov 2011; Smaznov 2011). Thermo-profiles have slots in web that decrease the thermal flow through the web, but have a negative effect on strength of the profiles (Schafer, Pekoz 1998; Vatin, Popova 2006). These profiles were an object of the research. Investigations carried out included tests to prove the compression resistance of the thin-walled cross-sections and shear strength of stud-to-rack joints. Numerical modelling of thin-walled cross-sections (Cheng, Schafer 2007) was done with contemporary analysis software (SCAD Office, Lira) (Kriksunov et al. 2010; Perel'muter et al. 2009) using the finite element method (FEM) (Bayan et al. 2011; Gordeeva, Vatin 2011; Rasmussen 2009).

Summary. Two different types of finite element models to simulate the steel columns supported by sandwich panels are developed in this paper and validated by the full-scale tests by Hedman-Petursson (2001) at ambient temperature. The bracing forces in self-drilling screws, the effect of connections in horizontal joints, effects of the lateral stiffness of self-drilling screws are studied using the developed FE models. Effect of different configurations of loading eccentricity on the buckling resistances of steel columns supported by sandwich panels are further analyzed in this paper.

Currently, structural fire design is moving from prescriptive approach to performance-based approach. One of the key essential techniques for performance-based approach is the numerical analysis technique of steel structures in fire using advanced calculation models. In this paper, the selected structural fire analysis procedure from 2D temperature analysis to structural response using LS-DYNA was studied and validated by the fire tests of a simply supported beam, a simple steel frame and a both axially and rotationally restrained steel column. 2D implicit temperature analysis is efficient in these cases and sufficient accuracy was achieved. Using explicit solver, structural response in fire can be simulated up to collapse with the considerations of the temperature-dependent material nonlinearity and possible contacts in joints. Both beam element models and shell element models were developed, and the structural responses were compared with the fire tests from literature. Results show that the developed modeling techniques using LS-DYNA explicit solver can effectively capture the key behavior of steel structures in fires. This key behavior includes deformation responses of beam and column, axial forces developed due to restraints and fire resistance time.

<p>This paper includes buckling analysis of reticular-stretched steel cold formed profile web as a single plate based on classical theory of elasticity. Numerical method used throughout the research was finite-element method (FEM). Results of the research have good correlation with tests.</p>