• Journal of Korean Society of Steel Construction
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• v.19 no.5
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• pp.463-472
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• 2007

This paper presents theoretical and finite element analysis results for the lateral-torsional buckling of I-girders with corrugated web under uniform bending. Lateral-torsional buckling is a major design aspect for flexural members composed of thin-walled I-section. However, torsional rigidities such as the warping constants of the I-girders with corrugated web are not fully understood yet. In this paper, bending and pure torsional rigidities of I-girders with corrugated web are first described using the results of previous researchers. Then, the location of the shear center and the warping constants are derived. Using the derived section properties of I-girders with corrugated web, the lateral-torsional buckling strength is determined. Finite element analyses are conducted and the proposed lateral-torsional buckling strength of I-girders with corrugated web is successfully verified. Finally, the effects of corrugation profiles of the web on the lateral-torsional buckling load of I-girders with corrugated web are discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.2A
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• pp.145-153
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• 2009

The lateral-torsional buckling strengths of the parabolic arches are investigated in this study. The curvatures of a parabolic arch vary along the center line of the arch. Thus, the problem is much more complicated comparing that of arches with constant curvature such as circular arches. Moreover, most of previous studies are limited to the circular arches. In this study, lateral-torsional buckling equations are derived for the arches with varying curvatures considering the warping effects. To obtain the buckling strength of parabolic arches, numerical solutions based on the finite difference technique are provided. The numerical solutions are compared with the those of previous researchers and finite element analyses. Then, the lateral-torsional strengths of parabolic arches are successfully verified. Finally, comparison study of critical buckling loads of parabolic arches with those of circular arches for the various rise to span ratios are discussed.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.3A
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• pp.149-160
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• 2012

Corrugated steel plates have several advantages such as high resistance for shear without stiffeners, minimization of welding process, and high fatigue resistance. To take advantage of these benefits, several researchers have attempted to use corrugated steel plate as a web of I-girders. The lateral-torsional buckling is the major design aspect of such I-girders. However, lateral-torsional buckling of the I-girder with corrugated steel webs still needs to be investigated especially for a real loading condition such as non-uniform bending. This paper investigated the lateral-torsional buckling strength of the I-girder with corrugated steel webs under linear moment gradient by using finite element analysis. From the results, it was found that the buckling behavior of the I-girder with corrugated steel webs differed depending on the number of periods of the corrugation. Also, a simple equation for the moment gradient correction factor of the I-girder with corrugated steel webs was suggested. The inelastic lateral-torsional buckling strength of the I-girder with corrugated steel webs was then discussed based on current design equations for ordinary I-girders and the results of finite element analysis.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.347-354
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• 2012

In this study, the equations of torsional and warping constants of a I-shaped plate girder with sine corrugated web are suggested. Because of geometric characteristics of the section, a I-shaped plate girder with corrugated web shows high out-of-plane stiffness, shear strength, and torsional stiffness. Torsional constant and warping constant definitely affect lateral-torsional buckling loads. Therefore, exact estimation of the sectional properties is quite important. But, it is difficult to estimate these properties by former methods. So, this study was focused on suggestion of the rational equations to calculate torsional and warping constants. In order to investigate the effects of geometric characteristics of sine-corrugated webs on torsional stiffness and warping torsional constant, finite element analyses for pure torsional behavior and warping torsional behavior of I-shaped plate girders were performed. By regression analyses of the analytical results, rational equations of the torsional constant and warping constant were suggested. Suggested equations for the properties were validated based on the analytical results of lateral-torsional buckling of simply supported I-shaped plate girder. By suggested equations, torsional and warping constants of I-shaped plate girders with a sine-corrugated web can be rationally estimated and more exact lateral-torsional buckling load can be simply calculated.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.13-24
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• 1993

The tangent stiffness matrices of the plane frame and the thin-walled space frame are derived by using the principle of virtual displacement. In case of the plane frame, the shape function and stiffness matrices are presented for the rigid-hinged condition. For the unsymmetric thin-walled space frame, the elastic and geometric stiffness matrices in three cases of the unrestrained torsion, the restrained torsion, and the restrained anti unrestrained torsion are evaluated by using the various Hermitian polynomials as the shape function. Numerical examples for the lateral buckling analysis of the space frames and the circular arch illustrate the accuracy and convergence characteristics of the derived formulations.

• Journal of Korean Society of Steel Construction
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• v.18 no.4
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• pp.447-456
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• 2006

In this study, a torsional test for U-type steel box girders was performed to observe the effects of the kind of panel for top lateral walateral bracings on the torsional behavior of the U-type steel girder system. For the structural tests, the test specimen with a two-thirds scale of the system actually constructed in the field was used. In the torsional test to observe the efects of top lateral bracings, the most economical arrangement of the top lateral bracing was found to be the panel width to length ratio of 1:1.5 with the inclined angle of $40^{\circ}$.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.5
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• pp.39-52
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• 1993

For the lateral-torsional buckling analysis of the thin-walled space frame and circular arch with the unsymmetric cross section, the tangent stiffness matrices are derived by introducing Vlasov's assumption for the thin-walled beam and using the principle of virtual displacement. In the cases of the unrestrained torsion and the restrained torsion, the elastic and geometric stiffness matrices corresponding to semitangential rotation and semitangential moment are evaluated by using the Hermitian polynomials as the shape function. In order to illustrate the accuracy and convergence characteristics of the derived formulations, numerical examples for the lateral-torsional buckling analysis of the hinged circular arch under pure bending and uniform compression are presented and compared with the analytic solutions of references.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.1
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• pp.1-12
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• 1993

Tangent stiffness matrices are derived for the torsional and lateral stability analysis of the space beams and framed structures with the symmetric thin-walled section by using the principle of virtual displacement. In the cases of restrained torsion and unrestrained torsion, the elastic and geometric stiffness matrices are evaluated by using the Hermitian polynomials which represent the displacement field of the beam element in simple flexure. Numerical examples illustrate the accuracy and convergence characteristics of the derived formulations.

• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.153-165
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• 1999

In order to trace the lateral-torsional post-bucking behaviors of thin-walled space frames with non-symmetric cross sections, a geometrically non-linear finite element formulation is presented by applying incremental equilibrium equations based on the updated Lagrangian formulation and introducing Vlasov's assumption. The improved displacement field for non-symmetric thin-walled cross sections is introduced based on inclusion of second order terms of finite rotations, and the potential energy corresponding to the semitangential rotations and moments is consistently derived. For finite element analysis, tangent stiffness matrices of thin-walled space frame element are derived by using the Hermition polynomials as shape functions. A co-rotational formulation in order to evaluate the unbalanced loads is presented by separating the rigid body rotations and pure deformations from incremental displacements and evaluating the updated direction cosines and incremental member forces.

• Journal of Korean Society of Steel Construction
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• v.17 no.1 s.74
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• pp.45-52
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• 2005

The object of this study was a cold-formed steel wall stud panel sheathed by gypsum boards. In the beam-analysis, the panel was treated as a simple beam with a uniform lateral loading. The deflections were calculated by considering the primary factors that reduced the stiffness of the panel. In the column-analysis, the panel was treated as a bearing wall with an axial load. By using an energy method, nominal axial strength could be evaluated by considering both flexural buckling and torsional-flexural buckling. All calculations were programmed and compared with the results of the experiment. In the beam-analysis, experimental deflections were close to theoretical deflections. In the column-analysis, the experimental values were also close to theoretical values in axial strength.