Mohamad Al Ali

Compressed Thin-Walled Cold-Formed Steel Members with Closed Cross-Sections

The paper presents fundamental information about experimental-theoretical research oriented to determinate the resistance of thin-walled compressed steel members. The investigated members had closed cross-sections made from homogeneous materials. The theoretical analysis in this research is oriented to determinate the resistance of mentioned members according to relevant standards, while the experimental investigation is to verify the theoretical results and to investigate the behavior of mentioned members during the loading process.

Analysis of the resistance of thin-walled cold-formed compressed steel members with closed cross-sections. Part 1

From the material and geometric point of view, the thin-walled cold-formed profiles have specific specialties, which their design must responsibly take into account. In the terms of their resistance, an important issue is the effectiveness of mutual interaction between several webs. The local stability requirements related to unfavourable buckling effects of their compressed parts are very significant. Favourable effects, related to membrane stresses and post-critical behaviour are also important. Different calculation procedures with different results in the relevant standards and their confrontation with experimental results indicated the need for further investigation of post-critical behaviour of these members. The paper is divided into two parts. Part 1 presents fundamental information about experimentaltheoretical research oriented to determinate the resistance of thin-walled compressed steel members. The investigated members had closed cross-sections made from homogeneous materials. The theoretical analysis in this research is oriented to determinate the resistance of mentioned members according to European and Slovak standards, while the experimental investigation is to verify the theoretical results and to investigate the behaviour of mentioned members during the loading process. Part 2 will be focused on the numerical analysis of the results, as well as on the 3D-modelling and simulation of experimental tests. References 1. Mamalis A.G., Manolakos D.E., Ioannidis M.B., Kostazos P.K., Dimitriou C. Finite element simulation of the axial collapse of metallic thin-walled tubes with octagonal cross-section. Thin-Walled Structures. 2003. Vol. 41. Issue 10. Pp. 891–900. 2. Rasmussen J.R. Kim. Bifurcation of locally buckled point symmetric columns – Experimental investigations. Thin-Walled Structures. 2006. Vol. 44. Issue 11. Pp. 1175–1184. 3. Chen Ju, Young Ben. Cold-formed steel lipped channel columns at elevated temperatures. Engineering Structures. 2007. Vol. 29. Issue 10. Pp. 2445–2456. 4. Nuno Silvestre, Young Ben, Camotima Dinar. Non-linear behaviour and load-carrying capacity of CFRPstrengthene lipped channel steel columns. Engineering Structures. 2008. Vol. 30. Issue 10. Pp. 2613–2630. 5. Kwon Young Bong, Kim Bong Sun, Hancock Gregory J. Compression tests of high strength cold-formed steel channels with buckling interaction. Journal of Constructional Steel Research. 2009. Vol. 65. Issue 2. Pp. 278–289. 6. Rogers C.A., Yang D., Hancock G.J. Stability and ductility of thin high strength G550 steel members and connections. Thin-Walled Structures. 2003. Vol. 41. Issues 2–3. Pp. 149–166. 7. DiPaolo B.P., Tom J.G. A study on an axial crush configuration response of thin-wall, steel box components: The quasi-static experiments. International Journal of Solids and Structures. 2006. Vol. 43. Issues 25–26. Pp. 7752–7775. 8. Yuan-Qi Li, Zu-Yan Shen, Lei Wang, Yan-Min Wang, Hong-Wei Xu. Analysis and design reliability of axially compressed members with high-strength cold-formed thin-walled steel. Thin-Walled Structures. 2007. Vol. 45. Issue 4. Pp. 473–492. 9. Gardner L., Saari N., Wang F. Comparative experimental study of hot-rolled and cold-formed rectangular hollow sections. Thin-Walled Structures. 2010. Vol. 48. Issue 7. Pp. 495–507.

Resistance of Compressed Thin-Walled Cold-Formed Steel Members with Regard to the Influence of Initial Imperfections

Thin-walled cold-formed profiles have specific specialties, which must responsibly have their design taken into account. Local stability requirements related to unfavourable buckling effects of their compressed parts are highly significant. Favourable effects, related to membrane stresses and post-critical behaviour are also important. The paper deals with the influence of initial imperfections and presents fundamental information about experimental and theoretical-numerical research to determine the load-bearing capacity of thin-walled cold-formed compressed steel members. The investigated members consist of closed cross-sections. The theoretical-numerical analysis has been oriented towards the investigation and modelling of initial imperfection effects, caused by production processes, on the load- bearing capacities of the mentioned members. The experimental investigation has been realized to verify the theoretical results and to investigate the behaviour of these members during the loading process.

The Welding Process as a Local Issue with Global Consequences

The welding process causes transient thermal stresses and non-continuous plastic strains around the weld due to the induced high temperatures. Uneven heating and cooling during the welding process cause a residual stresses in the welded member. The paper deals with the local influence of welding process and its global consequences at the creation and final redistribution of welding stresses. The paper also presents a verification of Modified empirical formulae, developed by the author, using experimental results of research program oriented to the effects of welding stresses and beams local stability [1, 2 and 3].

Development of Plastic Zones during the Thermal Cycle of Welding

The high temperatures induced during the welding process cause transient thermal stresses and non-continuous plastic strains around the weld. Uneven heating and cooling processes together with these plastic strains result in residual (welding) stresses, [1]. This paper deals with the development of plastic zones, related to welding stresses and their effects on the bearing capacity from a Civil-engineering perspective.

Experimental Investigation and Theoretical Analysis of Polystyrene Panels with Load Bearing Thin-Walled Cold-Formed Elements

The paper presents preliminary results of theoretical and experimental analysis of the resistance of construction panels at compressive loading. Panels, made on the base of polystyrene foam in combination with thin-walled cold-formed elements, should be used as a load-bearing wall panels for simple and small structures. Investigated panels, with dimensions 1.0x2.5x0.15 m, are formed by six thin-walled elements of U-profile with a thickness of 0.8 mm, which are stabilized by glued polystyrene board EPS 100 S, 150 mm thick. Sufficient number of strain gages and inductive sensors were used for the experimental measurement of strains and deflections. Strain gauges and inductive sensors were both-sided suitably located on each tested panel. Spatial calculation model was created within software SCIA and ANSYS. Geometrically nonlinear analysis was used for the numerical solution. Based on the numerical and experimental results, the efficiency of polystyrene boards on the stability of used thin-walled steel elements was determined.

Theoretical and Experimental Stress-Strain Analysis of Compressed Steel Members with Closed Cross-Sections

Abstract The paper presents fundamental information about experimental and theoretic-numerical research to determinate the load-carrying capacity of thin-walled cold-formed compressed steel members. The investigated members have closed cross-sections made from homogeneous materials. The theoretic-numerical analysis in this paper is oriented on the modeling of the initial deviations effects, caused by production process, on the load-carrying capacities of mentioned members, while the experimental investigation is to verify the theoretical results and to investigate the behavior of mentioned members during the loading process.