Crashworthiness of Thin-Walled Square Steel Columns Reinforced Based on Fractal Geometries

2018 ◽  
Vol 72 (1) ◽  
pp. 215-225 ◽  
Author(s):  
Ali Dadrasi ◽  
Mehdi Beynaghi ◽  
Sasan Fooladpanjeh
Keyword(s):  
2007 ◽  
Vol 26-28 ◽  
pp. 337-340 ◽  
Author(s):  
Seung Sik Lee ◽  
Soo Ha Chae ◽  
Soon Jong Yoon ◽  
Sun Kyu Cho

The strengths of PFRP thin-walled columns are determined according to the modes of buckling which consist of local mode for short columns, global mode for long columns, and interaction mode between local and global modes for intermediate columns. Unlike the local and global buckling, the buckling strength of interaction mode is not theoretically predictable. Refined theoretical approaches which can account for different elastic properties of each plate component consisting of a PFRP thin-walled member are used. Based on both the analytical buckling loads and the experimentally measured buckling loads from literatures, the accuracies of Ylinen’s equation and modified AISC/LRFD column design equation for isotropic steel columns were compared. From the comparison, it was found that the modified AISC/LRFD column design equation is more suitable for the prediction of the buckling loads of PFRP thin-walled members than Ylinen’s equations.


2017 ◽  
Vol 11 (1) ◽  
pp. 244-257 ◽  
Author(s):  
Xingyou Yao

Background: Cold-formed steel structural sections used in the walls of residential buildings and agricultural facilities are commonly C-shaped sections with web holes. These holes located in the web of sections can alter the elastic stiffness and the ultimate strength of a structural member. The objective of this paper is to study the buckling mode and load-carrying capacity of cold-formed thin-walled steel column with slotted web holes. Methods: Compression tests were conducted on 26 intermediate length columns with and without holes. The tested compressive members included four different kinds of holes. For each specimen, a shell finite element Eigen-buckling analysis and nonlinear analysis were also conducted. The influence of the slotted web hole on local and distortional buckling response had also been studied. The comparison on ultimate strength between test results and calculated results using Chinese cold-formed steel specification GB50018-2002, North American cold-formed steel specification AISI S100-2016, and nonlinear Finite Element method was made. Result: Test results showed that the distortional buckling occurred for intermediate columns with slotted holes and the ultimate strength of columns with holes was less than that of columns without holes. The ultimate strength of columns decreased with the increase in transverse width of hole in the cross-section of member. The Finite element analysis results showed that the web holes could influence on the elastic buckling stress of columns. The shell finite element could be used to model the buckling modes and analysis the ultimate strength of members with slotted web holes. The calculated ultimate strength shows that results predicted with AISI S100-2016 and analyzed using finite element method are close to test results. The calculated results using Chinese code are higher than the test results because Chinese code has no provision to calculate the ultimate strength of members with slotted web holes. Conclusion: The calculated method for cold-formed thin-walled steel columns with slotted web holes are proposed based on effective width method in Chinese code. The results calculated using the proposed method show good agreement with test results and can be used in engineering design for some specific cold-formed steel columns with slotted web holes studied in this paper.


2010 ◽  
Vol 66 (4) ◽  
pp. 816-835
Author(s):  
Yoshiaki GOTO ◽  
Kosuke MIZUNO ◽  
Ghosh Prosenjit KUMAR ◽  
Yusuke FUJII

2009 ◽  
Vol 135 (12) ◽  
pp. 1481-1490 ◽  
Author(s):  
Yoshiaki Goto ◽  
Masayuki Muraki ◽  
Makoto Obata

2009 ◽  
Vol 1 (1) ◽  
pp. 40-43 ◽  
Author(s):  
Luís C. Prola ◽  
Igor Pierin

Most cold-formed steel columns display open and rather thin-walled cross-sections which mean that their structural behaviour is strongly affected by local and global buckling. Th e local mode, that occurs for shorter profi les, is characterized by (i) the local plate mode (LPM) characterized by the simultaneous flexural buckling of the web and fl anges and (ii) by the distortional mode (DM) characterized by the displacements of flange-stiff ener edges (that remain plane). The global mode occurring for long profi les is characterized by (i) the fl exural mode (FM) characterized by the translation of the whole section in the direction of the major principal axis and (ii) by the fl exural-torsional mode (FTM) characterized by the simultaneous translation and rotation of the whole section. Th e possibility of using the results of linear stability analysis in the national codes of thin-walled cold-formed steel structural elements (for instance, European and Brazilian Codes) arises, i.e. local and global buckling instability modes and corresponding bifurcation stresses determining the ultimate strength of members. Two powerful numerical methods are chosen to perform a linear stability analysis of a cold-formed steel structural member: (i) the Finite Strip Method, (i1) the Semi-Analytical Finite Strip Method (trigonometric functions are used in the approximation of displacement) used for simply supported boundary conditions, (i2) the Spline Finite Strip Method (‘spline’ functions are used in the approximation of displacement) used other boundary conditions and (ii) the Finite Element Method. The linear local and global stability results of for Z, C and rack cold-formed columns are used to obtain ultimate strength through the procedures adopted in the Eurocode 3, Part 1.3 and in the Brazilian Code (NBR 14.762/2001). The obtained numerical estimates by specifi cations are compared with experimental results available in literature.


Author(s):  
Qusay Al-Kaseasebh ◽  
Iraj H.P Mamaghani

Thin-walled steel tubular circular columns are widely used as cantilever bridge piers due to their geometric efficiency, aesthetic appearance, and high earthquake resistance. However, local buckling, global buckling, or interaction between both is usually the main reason of significant strength and ductility loss in these columns, which eventually leads to their collapse. This paper investigates the behavior of uniform circular (C) and graded-thickness circular (GC) thin-walled steel tubular columns under constant axial and cyclic lateral loading. The GC column with size and volume of material equivalent to the C column is introduced and analyzed under constant axial and cyclic lateral loading. The analysis carried out using a finite-element model (FEM), which considers both material and geometric nonlinearities. The accuracy of the employed FEM is validated based on the experimental results available in the literature. The results revealed that, significant improvements in strength, ductility, and post-buckling behavior of thin-walled steel columns obtained using the GC column.


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