• Journal of Korean Society of Steel Construction
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• v.14 no.5 s.60
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• pp.665-674
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• 2002

The back-to-back and box-shaped headers used in light gauge steel structures have some disadvantages, i.e., construction efficiency and cost competitiveness. As such, cold-formed steel L-shaped headers have been developed and are used actively in advanced nations. However, this system has not been used in Korea because of inadequate investigation and adaptation efforts and lack of application example. Thus, this research evaluated the structural performance of L-header using buckling analyses and bending tests. Test results were compared using the AISI design criteria. Test results showed that local buckling and distortional buckling governed buckling behavior in gravity loads and uplift loads, respectively. These results were consistent with the calculated nomial strengths using the AISI design criteria.

• Steel and Composite Structures
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• v.29 no.3
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• pp.379-389
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• 2018

In this research, the explicit closed-form local buckling solution of steel plates in contact with concrete, with both loaded and unloaded edges elastically restrained against rotation and subjected to eccentric compression is presented. The Rayleigh-Rize approach is applied to establish the eigenvalue problem for the local buckling performance. Buckling shape which combines trigonometric and biquadratic functions is introduced according to that used by Qin et al. (2017) on steel plate buckling under uniform compression. Explicit solutions for predicting the local buckling stress of steel plate are obtained in terms of the rotational stiffness. Based on different boundary conditions, simply yet explicit local buckling solutions are discussed in details. The proposed formulas are validated against previous research and finite element results. The influences of the loading stress gradient parameter, the aspect ratio, and the rotational stiffness on the local buckling stress resultants of steel plates with different boundary conditions were evaluated. This work can be considered as an alternative to apply a different buckling shape function to study the buckling problem of steel plate under eccentric compression comparing to the work by Qin et al. (2018), and the results are found to be in consistent with those in Qin et al. (2018).

• Journal of Korean Association for Spatial Structures
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• v.7 no.3 s.25
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• pp.119-124
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• 2007

Due to the deficit of section of web, the buckling strength of cellular beam become smaller than that of H-beam. In this thesis, we evaluate the buckling strength of web-post through non-linear F.E.M with opening distance-diameter ratio and opening diameter - web thickness ratio as essential variables. And also analyzes this comparing with the standard indicated in BS5950 Part 1.

• Structural Engineering and Mechanics
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• v.9 no.6
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• pp.541-555
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• 2000

Pultruded cross-sections are always thin-walled due to constraints in the manufacturing process. Thus, the buckling strength determines the overall strength of the member. The elastic buckling of pultruded angle sections subjected to direct compression is studied. The lateral-torsional buckling, very likely to appear in thin-walled cross-sections, is investigated. Plate theory is used to allow for cross-sectional distortion. Shear effects and bending-twisting coupling are accounted for in the analysis because of their significant role. A simplified approach for determining the maximum load of equal leg angle sections under compression is presented. The analytical results obtained in this study are compared to the manufacturer's design guidelines for compression members as well as with the design specifications for steel structural members. Experimental results are obtained for various length specimens of pultruded angle sections. The results presented in this paper correspond to actual pultruded equal leg angle sections being used in civil engineering structures.

• Structural Engineering and Mechanics
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• v.5 no.3
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• pp.269-281
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• 1997

The overall buckling mode in a composite steel-concrete beam over an internal support is necessarily lateral-distortional, in which the bottom compressive range displaces laterally and twists, since the top flange is restrained by the nearly rigid concrete slab. An efficient finite element method is used to study elastic lateral-distortional buckling in composite beams whose steel portion is tapered. The simplified model for a continuous beam that is presented herein is a fixed ended cantilever whose steel portion is tapered, and is subjected to moment gradient. This is intended to give an insight into distortion in a continuous beam that occurs in the negative bending region, and the differences between the cantilever representation and the continuous beam are highlighted. An eigenproblem is established, and the buckling modes and loads are determined in the elastic range of structural response. It is found from the finite element study that the buckling moment may be enhanced significantly by using a vertical stiffener in the region where the lateral movement of the bottom range is greatest. This enhancement is quantified in the paper.

• Structural Engineering and Mechanics
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• v.40 no.6
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• pp.783-800
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• 2011

This paper addresses the finite strip formulations for the stability analysis of viscoelastic composite plates with variable thickness in the transverse direction, which are subjected to in-plane forces. While the finite strip method is fairly well-known in the buckling analysis, hitherto its direct application to the buckling of viscoelastic composite plates with variable thickness has not been investigated. The equations governing the stiffness and the geometry matrices of the composite plate are solved in the time domain using both the higher-order shear deformation theory and the method of effective moduli. These matrices are then assembled so that the global stiffness and geometry matrices of a moderately thick rectangular plate are formed which lead to an eigenvalue problem that is solved to determine the magnitude of critical buckling load for the viscoelastic plate. The accuracy of the proposed model is verified against the results which have been reported elsewhere whilst a comprehensive parametric study is presented to show the effects of viscoelasticity parameters, boundary conditions as well as combined bending and compression loads on the critical buckling load of thin and moderately thick viscoelastic composite plates.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.178-188
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• 2007

In this paper, a half-scaled substructure test was performed to evaluate the buckling and structural safety of an existing transmission tower subjected to wind load. A loading scheme was devised to reproduce the dead and wind loads of a prototype transmission tower, which uses a triangular jig that is mounted on the reduced model to which the similarity law of a half length was applied. As a result of the preliminary numerical analysis carried out to evaluate the stability of a specimen for the design load, it was confirmed that the calculated axial forces of tower leg members were distributed to $80{\sim}90%$ of an admissible buckling load. When the substructured transmission tower was loaded by 270% of its maximum admissible buckling load, it was failed due to the local buckling that is occurred in joints with weak constraints for out-of-plane behavior of leg members. By inspection of load-displacement curves, displacements and strains of members, it is considered that this local buckling was due to additional eccentric force by unbalanced deformation because the time that is reached to yielding stress due to the bending moment is different at each point of a same section.

• Journal of Korean Society of Steel Construction
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• v.14 no.2
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• pp.357-364
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• 2002

The study performed a series of flexural tests on Closed Cold-Formed Steel Sections for stud, joist, and roof truss. Results were compared with analytical values. Each 2.4-m long and 0.9-m wide specimen consisted of two steel beams set at 0.46 m interval. The steel beams were attached to the specimens using either plaster board or ply wood. Another specimens did not use any attachment material. Positive and negative bending tests were conducted to investigate the composite behavior, including the effects of plaster board or ply wood on the buckling behavior of steel beam. Full-scale roof truss tests were also performed to study the buckling behavior and failure mode of the truss members.

• Structural Engineering and Mechanics
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• v.11 no.1
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• pp.89-104
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• 2001

This paper reviews the author's work on the development of relationships between solutions of the Kirchhoff (classical thin) plate theory and the Mindlin (first order shear deformation) thick plate theory. The relationships for deflections, stress-resultants, buckling loads and natural frequencies enable one to obtain the Mindlin plate solutions from the well-known Kirchhoff plate solutions for the same problem without much tedious mathematics. Sample thick plate solutions, deduced from the relationships, are presented as benchmark solutions for researchers to use in checking their numerical thick plate solutions.

• Structural Engineering and Mechanics
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• v.81 no.2
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• pp.179-194
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• 2022

The bending, buckling and free vibration responses of functionally graded material (FGM) beams are investigated semi-analytically by the scaled boundary finite element method (SBFEM) in this paper. In the concepts of the SBFEM, the dimension of computational domain can be reduced by one, therefore only the axial dimension of the beam is discretized using the higher order spectral element, which reduces the amount of calculation and greatly improves the calculation efficiency. The governing equation of FGM beams is derived in detail by the means of the principle of virtual work. Compared with the higher-order beam theory, fewer parameters and simpler control equations are used. And the governing equation is transformed into a first-order ordinary differential equation by introducing intermediate variables. Analytical solutions of the governing equation can be obtained by pade series expansion in the direction of thickness. Numerical example are compared with the numerical solutions provided by the previous researchers to verify the accuracy and applicability of the proposed method. The results show that the proposed formulations can quickly converge to the reference solutions by increasing the order of higher order spectral elements, and high accuracy can be achieved by using a small number of the elements. In addition, the influence of the structural sizes, material properties and boundary conditions on the mechanical behaviors of FG beams subjected to different load types is discussed.