• Computational Structural Engineering
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• v.7 no.1
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• pp.69-81
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• 1994

This paper summarizes a dynamic analysis of the shallow circular arches under dynamic loading, considering the geometric nonlinearity. The major emphasis is placed on the development of computer program, which is utilized for the analysis of the nonlinear dynamic behavior and for the evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and a finite element analysis procedure is used to solve the dynamic equation of motion. A circular arch subject to normal step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of arches are estimated using the non-dimensional time, load and shape parameters and the results are also compared with those from the linear analysis. It is found that geometric nonlinearity plays and important role in the analysis of shallow arches and the probability of buckling failure is getting higher as arches become shallower.

• Journal of Korean Society of Steel Construction
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• v.24 no.3
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• pp.337-348
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• 2012

This study investigated the characteristics of bifurcation and the instability due to the initial imperfection of the space truss, which is sensitive to the initial conditions, and the calculated buckling load by the analysis of Eigen-values and the determinant of tangential stiffness. A two-free nodes model, a star dome, and a three-ring dome model were selected as case studies in order to examine the unstable phenomenon due to the sensitivity to Eigen mode, and the influence of the rise-span ratio and the load parameter on the buckling load were analyzed. The sensitivity to the imperfection of the two-free nodes model changed the critical path after reaching the limit point through the bifurcation mode, and the buckling load level was reduced by the increase in the amount of imperfection. The two sensitive buckling patterns for the model can be explained by investigating the displaced position of the free node, and the asymmetric Eigen mode was a major influence on the unstable behavior due to the initial imperfection. The sensitive mode was similar to the in-extensional mechanism basis of the simplified model. Since the rise-span ratio was higher, the effect of local buckling is more prominent than the global buckling in the star dome, and bifurcation on the equilibrium path occurring as the value of the load parameter was higher. Additionally, the buckling load levels of the star dome and the three-ring model were about 50-70% and 80-90% of the limit point, respectively.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.3 s.18
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• pp.57-65
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• 2005

When arch ribs are subjected unsymmetrical load, buckling strength Is lower than strength of arch ribs subjected symmetrical load. However, A few study about the buckling strength of arch ribs subjected unsymmetrical load is performed compare with study about arch ribs subjected symmetrical load. Several researchers(Deutch : 1940, Chang : 1973, Harrison : 1982) studied about arch ribs subjected unsymmetrical load and they found that unsymmetrical loading reduces the critical buckling load. But, their results are limited parabolic arch ribs. This paper focuses on circular arch ribs subjected to unsymmetrical loading. The result shows that the ratio of live and dead load length to cause smallest critical buckling load of arch ribs is $0.6{\sim}0.7$ under geometric nonlinear condition and $0.5{\sim}0.6$ under both material and geometrical nonlinear conditions.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.2
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• pp.39-48
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• 1990

For shallow circular arches with large dynamic loading, use of linear analysis is no longer considered as practical and accurate. In this study, a method is presented for the dynamic analysis of the shallow circular arches in which geometric nonlinearity is dominant. A program is developed for analysis of the nonlinear dynamic behavior and for evaluation of the critical buckling loads of the shallow circular arches. Geometric nonlinearity is modeled using Lagrangian description of the motion and finite element analysis procedure is used to solve the dynamic equations of motion in which Newmark method is adopted as a time marching scheme. A shallow circular arch subject to radial step load is analyzed and the results are compared with those from other researches to verify the developed program. The critical buckling loads of shallow arches are evaluated using the non-dimensional parameter. Also, the results are compared with those from linear analysis.

• Journal of Korean Association for Spatial Structures
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• v.4 no.3 s.13
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• pp.103-109
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• 2004

The lowest load when the equilibrium condition becomes to be unstable is defined as the buckling load. The primary objective of this paper is to be analyse stability boundaries for star dome under combined loads and is to investigate the iteration diagram under the independent loading parameter. In numerical procedure of the geometrically nonlinear problems, Arc Length Method and Newton-Raphson iteration method is used to find accurate critical point(bifurcation point and limit point). In this paper independent loading vector is combined as proportional value and star dome was used as numerical analysis model to find stability boundary among load parameters and many other models as multi-star dome and arch were studied. Through this study we can find the type of buckling mode and the value of buckling load.

• Magazine of the Korean Society of Agricultural Engineers
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• v.34 no.4
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• pp.97-105
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• 1992

The main purpose of this paper is to present the buckling loads of tapered columns due to dynamic concept. The ordinary differential equation governing the bucking loads for tapered columns is derived on the basis of dynamic concept. Three kinds of cross sectional shape are considered in the governing equation. The Improved Euler method and Determinant Search method are used to perform the integration of the differential equation and to determine the buckling loads, respectively. The hinged-hinged, hinged-clamped, clamped-clamped and free-clamped end constraints are applied in numerical examples. The buckling loads are reported as the function of section ratio, and the effects of cross-sectional shapes are investigated. The buckling load equation, which are fitted by numerical data, are proposed as a function of section ratio. It is expected that these equations can be utilized in structural engineering field.

• Journal of Korean Society of Steel Construction
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• v.9 no.3 s.32
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• pp.323-332
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• 1997

This study is aimed at investigating the buckling characteristics of single layer latticed domes with triangular network pattern under the partially concentrated equipment loading in the cases of both having a geometrical imperfection and not having.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.3A
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• pp.457-464
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• 2006

Fiber-reinforced composite materials due to their high specific strength, high stiffness and light weight are becoming increasingly used in many engineering industry, especially in the aerospace, marin and civil, etc. In this paper, the buckling load and mode shapes of composite laminates with elliptical cross-section including transverse shear deformations are analyzed. For solving this problems, a versatile flat shell element has been developed by combining a membrane element with drilling degree-of-freedom and a plate bending element. Also, an improved shell element has been established by the combined use of the addition of enhanced assumed strain and the substitute shear strain fields. The combined influence of shell geometry and elliptical cross-sectional parameter, fiber angle, and lay-up on the buckling loads of elliptical cylinder is examined. The critical buckling loads and mode shapes analyzed here may serve as a benchmark for future investigations.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.2
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• pp.36-43
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• 2010

In this study, the buckling loads and mode shapes characteristic of circular and non-circular(elliptical) closed composite shells were analyzed. To analyses the buckling behaviors, we develop and report an improved generalized shell element called 4EAS-FS through a combination of enhanced assumed strain and the substitute shear strain fields. A flat shell element has been developed by combining membrane element with drilling degree-of-freedom and a plate bending element. The combined influences of length, thicknesses, cross-sectional parameters, and fiber-angle on the critical buckling loads and mode shapes of circular and non-circular(elliptical) closed shells are examined.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.11
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• pp.520-526
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• 2019

I-type girders are widely applied as very economical sections in plate girder bridges. There has been research on developing composite laminated panels, curved plates reinforced with closed-end ribs, and new forms of ribs and compression flanges for steel box girders. However, there is a limitation in analyzing the exact cause of local buckling caused by an I-type girder's webs. Therefore, an I-type girder's web was modeled using the finite element analysis program LUSAS 17.0 before and after reinforcement. We checked for the minimum thickness criteria presented in the Korea highway bridge design code, and the cause of buckling after performing a linear elastic buckling analysis of dead and live loads was analyzed. Before reinforcement, an eigenvalue (λ₁) at the 1st mode was 0.7025, the critical buckling load was smaller than the applied load, and there is a buckling. After reinforcement, when applying vertical and horizontal stiffeners to the web part of the girder at support, a Nodal line was formed, the eigenvalue was 1.5272, and buckling stability was secured. To improve buckling trace of the girder at the support, an additional plate was applied to the web at the support to ensure visual and structural safety, but buckling occurs at center of web. The eigenvalue (λ₁) was 3.5299, and this method is efficient for reinforcing the web of the support.