• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.41 no.11
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• pp.865-873
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• 2013

In this paper, numerical methods for wrinkle prediction of thin membrane were studied by finite element analysis. Techniques using membrane and shell elements were applied for triangular membrane. In case of membrane element method, the wrinkling was accounted for by the wrinkle algorithm of property modification, which was implemented to ABAQUS as a user subroutine. In case of shell method, geometrically nonlinear post-buckling analysis was performed to obtain the wrinkle deformation explicitly. The wrinkling deformation was induced by seeding the mesh with a random geometric imperfection. The results were investigated focusing on the mesh convergence and the solution accuracy.

• Computational Structural Engineering
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• v.9 no.3
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• pp.187-197
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• 1996

An explicit direct time integration method based solution algorithm is presented to predict dynamic buckling response of Euler column. On the basis of large deflection beam theory, a plane frame finite element is formulated and implemented into the solution algorithm. The element formulation takes into account geometrical nonlinearity and overall buckling of steel structural frames. The solution algorithm employs the central difference method. Using the computer program developed by the author, dynamic instability behavior of Euler column under impact loading is investigated by considering the time variation of load, load magnitude, and load duration. The free vibration of Euler column caused by a short duration impact load is also studied. The validity and efficiency of the present formulation and solution algorithm are verified through illustrative numerical examples.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.91-103
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• 2014

High performance steel for bridges(HSB 800) with a minimum tensile stress of 800MPa was recently developed. However, the study for local buckling behavior of plate girders considering interactive effects of flanges and webs is still insufficient. In this study, the flange local buckling(FLB) strength of plate girders with HSB 800 was evaluated by nonlinear finite element analysis. The flanges and webs of plate girders having I-section were modeled as 3D shell elements in the nonlinear analysis. Initial imperfection and residual stress were imposed on the plate girder. The high performance steel was modeled as a multi-linear material. Thus, parametric study of compression flanges with a compact, noncompact and slender web was performed. The flange local buckling behavior of plate girders was analyzed, and the nonlinear analysis results were compared with the nominal flexural strength of both AASHTO LRFD(2012) and KHBDC LSD(2012) codes.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.32 no.6A
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• pp.399-409
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• 2012

The flexural behavior of HSB plate girder with a non-slender web, due to inelastic lateral-torsional buckling, under uniform bending was investigated by the nonlinear finite element analysis. Both homogeneous sections fabricated from SM570-TMC, HSB600 or HSB800 steel and hybrid sections with HSB800 flanges and SM570-TMC web were considered. The flanges and web of selected noncomposite I-girders were modeled as thin shell elements and the geometrical and material nonlinear finite element analysis was performed by the ABAQUS program. The steel was assumed as an elasto-plastic strain hardening material. Initial imperfections and residual stresses were taken into account and their effects on the inelastic lateral-torsional buckling behavior were analyzed. The flexural strengths of selected sections obtained by the finite element analysis were compared with the nominal flexural strengths from KHBDC LSD, AASHTO LRFD, and Eurocode and the applicability of these codes in predicting the inelastic lateral torsional buckling strength of HSB plate girders with a non-slender web was assessed.

• Journal of Korean Society of Steel Construction
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• v.29 no.2
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• pp.123-134
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• 2017

Ultimate axial strength of longitudinally stiffened cylindrical steel shells for wind turbine tower was investigated by applying the geometrically and materially nonlinear finite element method. The effects of radius to thickness ratio of shell, shape and amplitude of initial imperfections, area ratio between effective shell and stiffener, and stiffener spacing on the ultimate axial strength of cylindrical shells were analyzed. The ultimate axial strengths of stiffened cylindrical shells by FEA were compared with design buckling strengths specified in DNV-RP-C202. The shell buckling modes obtained from a linear elastic bifurcation FE analysis as well as the weld depression during fabrication specified in Eurocode 3 were introduced in the nonlinear FE analysis as initial geometric imperfections. The radius to thickness ratio of cylindrical shell models was selected to be in the range of 50 to 200. The longitudinal stiffeners were designed according to DNV-RP-C202 to prevent the lateral torsional buckling and local buckling of stiffeners.

• Journal of Korean Society of Steel Construction
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• v.24 no.2
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• pp.217-231
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• 2012

The flexural behavior of HSB I-girder with a non-slender web attributed to inelastic lateral-torsional buckling under uniform bending was investigated using nonlinear finite element analysis of ABAQUS. The girder was assumed to have a compact or noncompact web in order to prevent premature bend-buckling of the web. The unbraced length of the girder was selected so that inelastic lateral-torsional buckling governs the ultimate flexural strength. The compression flange was also assumed to be either compact or noncompact to prevent local buckling of the elastic flange. Both homogeneous sections fabricated from HSB600 or HSB800 steel and hybrid sections with HSB800 flanges and SM570-TMC web were considered. In the FE analysis, the flanges and web of I-girder were modeled as thin shell elements. Initial imperfections and residual stresses were imposed on the FE model. An elasto-plastic strain hardening material was assumed for steel. After establishing the validity of the present FE analysis by comparing FE results with test results in existing literature, the effects of initial imperfection and residual stress on the inelastic lateral-torsional buckling behavior were analyzed. Finite element analysis results for 96 sections demonstrated that the current inelastic strength equations for the compression flange in AASHTO LTFD can be applied to predict the inelastic lateral torsional buckling strength of homogeneous and hybrid HSB I-girders with a non-slender web.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.2
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• pp.103-114
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• 1992

A study result of buckling reliability is presented for the axially compressed imperfect elastic cylinder. Multi-mode analysis program is developed from Karman-Donnell Equation for the calculation of the buckling load of the cylindrical she1l. Geometric intial imperfection is approximated by double Fourier series of which coefficients are assumed random variables with jointly normal distribution characteristics. Crude Monte Carlo simulation technique is used to calculate the probabilistic failure properties of several cases with various imperfection Conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.1A
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• pp.79-87
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• 2008

This paper investigates the in-plane stability of fixed shallow arches. The shape of the arches is parabolic and the uniformly distributed load is used in the study. The nonlinear governing equilibrium equation of the general arch is adopted to derive the incremental form of the load-displacement relationship and the buckling load of the fixed shallow arches. From the results, it is found that buckling modes (symmetric or asymmetric) of the arches are closely related to the dimensionless rise H, which is the function of slenderness ratio and the rise to span ratio of such arches. Moreover, the threshold of different buckling modes and buckling load for fixed shallow arches are proposed. A series of finite element analysis are conducted and then compared with proposed ones. From the comparative study, the proposed formula provides the good prediction of the buckling load of fixed shallow arches.

• Transactions of the Korean Society of Automotive Engineers
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• v.2 no.3
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• pp.13-20
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• 1994

The effects of prebuckling on the buckling of laminated composite cylindrical shells are investigated. Both axial compression and lateral pressure are considered for laminated composite cylindrical shells with length to radius ratios usually associated with container vessels. The shell walls are made of a laminate with several symmetric ply orientations. The study was made using finite difference energy method, utilizing the nonlinear bifurcation branch with nonlinear prebuckling displacements. The results are compared to the buckling loads determined when prebuckling displacements are neglected.

• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.289-299
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• 2012

The goal of this paper is to apply the multi-step Taylor method to a space truss, a non-linear discrete dynamic system, and analyze the non-linear dynamic response and unstable behavior of the structures. The accurate solution based on an analytical approach is needed to deal with the inverse problem, or the dynamic instability of a space truss, because the governing equation has geometrical non-linearity. Therefore, the governing motion equations of the space truss were formulated by considering non-linearity, where an accurate analytical solution could be obtained using the Taylor method. To verify the accuracy of the applied method, an SDOF model was adopted, and the analysis using the Taylor method was compared with the result of the 4th order Runge-Kutta method. Moreover, the dynamic instability and buckling characteristics of the adopted model under step excitation was investigated. The result of the comparison between the two methods of analysis was well matched, and the investigation shows that the dynamic response and the attractors in the phase space can also delineate dynamic snapping under step excitation, and damping affects the displacement of the truss. The analysis shows that dynamic buckling occurs at approximately 77% and 83% of the static buckling in the undamped and damped systems, respectively.