Effect of the actual distribution of applied stresses on global buckling of isotropic and transversely isotropic thin-walled members: Numerical examples

In this paper, one investigates the local-plate, distortional and global buckling behavior of thin-walled steel beams subjected to non-uniform bending moment diagrams, i.e. under the presence of longitudinal stress gradients. One begins by deriving a novel formulation based on Generalized Beam Theory (GBT), which (i) can handle beams with arbitrary open cross-sections and (ii) incorporates all the effects stemming from the presence of longitudinally varying stress distributions. This formulation is numerically implemented by means of the finite element method: one (i) develops a GBT-based beam finite element, which accounts for the stiffness reduction associated to applied longitudinal stresses with linear, quadratic and cubic variation, as well as to the ensuing shear stresses, and (ii) addresses the derivation of the equilibrium equation system that needs to be solved in the context of a GBT buckling analysis. Then, in order to illustrate the application and capabilities of the proposed GBT-based formulation and finite element implementation, one presents and discusses numerical results concerning (i) rectangular plates under longitudinally varying stresses and pure shear, (ii) I-section cantilevers subjected to uniform major axis bending, tip point loads and uniformly distributed loads, and (iii) simply supported lipped channel beams subjected to uniform major axis bending, mid-span point loads and uniformly distributed loads — by taking full advantage of the GBT modal nature, one is able to acquire an in-depth understanding on the influence of the longitudinal stress gradients and shear stresses on the beam local and global buckling behavior. For validation purposes, the GBT results are compared with values either (i) yielded by shell finite element analyses, performed in the code ANSYS, or (ii) reported in the literature. Finally, the computational efficiency of the proposed GBT-based beam finite element is briefly assessed.

Download Full-text

STRENGTH EVALUATION OF COLD-FORMED STEEL COLUMNS USING THE RESULTS OF FINITE STRIP AND FINITE ELEMENT LINEAR STABILITY ANALYSIS

Engineering Structures and Technologies ◽

10.3846/skt.2009.04 ◽

2009 ◽

Vol 1 (1) ◽

pp. 40-43 ◽

Cited By ~ 1

Author(s):

Luís C. Prola ◽

Igor Pierin

Keyword(s):

Stability Analysis ◽

Linear Stability ◽

Linear Stability Analysis ◽

Steel Columns ◽

Finite Strip ◽

Strip Method ◽

Finite Strip Method ◽

Global Buckling ◽

Cold Formed Steel ◽

Thin Walled

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.

Download Full-text

Buckling of Composite Thin-Walled Members

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.326-328.1733 ◽

2006 ◽

Vol 326-328 ◽

pp. 1733-1736 ◽

Cited By ~ 2

Author(s):

Seung Sik Lee ◽

Soon Jong Yoon ◽

Sung Yong Back

Keyword(s):

Civil Engineering ◽

Glass Fibers ◽

Engineering Application ◽

Maintenance Cost ◽

Construction Time ◽

Specific Strength ◽

High Specific Strength ◽

Buckling Behavior ◽

Global Buckling ◽

Thin Walled

The use of pultruded fiber reinforced polymeric (FRP) members in civil engineering applications can greatly reduce construction time and maintenance cost of structures, because pultruded members have high specific strength and excellent corrosion resistance compared to steel and concrete. Pultruded members for civil engineering application are mostly made of a polymeric resin system reinforced with E-glass fibers and, as a result, they have low elastic moduli. Therefore, stability is an important issue in the design of pultruded members. In this paper, the results of an experimental investigation into the global buckling behavior of pultruded thin-walled members subjected to axial compression are presented. The analytical solutions are validated through a comparison with the results of FE analysis as well as the experimental results.

Download Full-text

Optical Measuring Technique for the Investigation of Built-Up Cold-Formed Steel Structural Members

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.473.343 ◽

2011 ◽

Vol 473 ◽

pp. 343-351 ◽

Cited By ~ 1

Author(s):

Iveta Georgieva ◽

Luc Schueremans ◽

Guido De Roeck ◽

Lincy Pyl

Keyword(s):

Local Buckling ◽

Structural Members ◽

Distortional Buckling ◽

Residential Housing ◽

3D Motion Analysis ◽

Vertical Displacements ◽

Global Buckling ◽

Cold Formed Steel ◽

Thin Walled ◽

Displacement Transducers

The construction industry uses cold-formed steel (CFS) sheets in the form of galvanised thin-walled profiles and corrugated sheets. In the past decade, CFS profiles have been competing with their hot-rolled counterparts as primary structural members of industrial halls, office buildings and residential housing of up to 3-4 storeys. The spans and column heights achieved with CFS profiles are ever larger. Due to the large slenderness of these members, adequate strength and stability are necessary, as well as reliability in design. Thin-walled members go through buckling during all stages of their working life. Local buckling appears at loads sometimes much lower than the design load. Distortional buckling seriously reduces the member resistance. It interacts with warping and lateral-torsional buckling, being significant for these asymmetric open sections. To restrict these effects, builders employ double sections - usually two standard cold-formed shapes bolted together to form a built-up section. These sections have the advantages of symmetry, higher stability and strength. The design of built-up members involves many uncertainties - although the European standard includes guidelines on the prediction of local, distortional and global buckling, the partial integrity and interaction between the parts of the composed members is still not studied. To study the actual behaviour, built-up members are tested in bending. An optical device for 3D motion analysis measures the displacement of points of interest on the specimen. Two interacting cameras use parallax to obtain the position of an arbitrary number of reflective markers glued to the specimen. The device tracks the movement of the markers in a 3D coordinate system without any contact with the specimen. Standard displacement transducers measure vertical displacements to validate the results. The paper gives an appraisal of the applicability of the method, a summary of the difficulties faced and the outcome of the test campaign.

Download Full-text

Experimental Research on Concrete Filled Thin-Walled Steel Tube Long Columns

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.400-402.551 ◽

2008 ◽

Vol 400-402 ◽

pp. 551-557 ◽

Cited By ~ 2

Author(s):

Bao Zhu Cao ◽

Yao Chun Zhang ◽

Yue Ming Zhao

Keyword(s):

Experimental Research ◽

Local Buckling ◽

Steel Tube ◽

Element Analysis ◽

The Finite Element Analysis ◽

Global Buckling ◽

Thin Walled ◽

Relationship Of ◽

The Relationship ◽

Theoretical Results

Experimental research on square and octagonal concrete filled thin-walled steel tube long columns of 6 specimens in axial compression and 8 specimens in eccentric compression is undertaken. The relationship of global buckling bearing capacity of the columns and local buckling of the steel tubes is obtained. The test indicates that local buckling occurs in steel tube of each column before it reaches ultimate capacity, and has little effect on global buckling performance. The ultimate load decreases obviously with the increase of slender ratio and eccentricity. The ductility of columns increases with the increase of steel ratio in composite sections. Composite beam element of ANSYS is adopted in the finite element analysis. The theoretical results are agreed well with test..

Download Full-text

Crushing behavior and crashworthiness optimization of multi-cell square tubes under multiple loading angles

Proceedings of the Institution of Mechanical Engineers Part D Journal of Automobile Engineering ◽

10.1177/0954407019869127 ◽

2019 ◽

Vol 234 (5) ◽

pp. 1497-1511 ◽

Cited By ~ 1

Author(s):

Zhichao Li ◽

Subhash Rakheja ◽

Wen-Bin Shangguan

Keyword(s):

Energy Absorption ◽

Deformation Mode ◽

High Energy ◽

Absorption Efficiency ◽

Absorption Capacity ◽

Thin Walled Structures ◽

Cell Structures ◽

Global Buckling ◽

Thin Walled ◽

Crushing Behavior

Thin-walled structures are widely used as energy absorbers in automotive vehicles due to their lightweight and high-energy absorption efficiency. In order to improve the energy absorption characteristics of thin-walled structures subjected to different loading angles, different types of novel multi-cell structures are proposed in this paper. The numerical method is used to study the crushing behaviors of the proposed multi-cell structures under different loading angles. It is found that the proposed multi-cell structures have considerably small initial peak force under axial load and avoid the appearance of global buckling deformation mode under oblique loads. Moreover, reasonably distributed wall thickness for each square tube in the thin-walled structure can enhance its energy absorption capacity under different loading angles.

Download Full-text