• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5979-5986
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• 2013

This study carried out a geometrical nonlinear dynamic analysis of laminated composite shell structures. Based on the first-order shear deformation shell theory and nonlinear formulation of Sanders, the Newmark method and Newton-Raphson iteration are used for dynamic solution considering nonlinear effects. The effects of radius, fiber angles, and layup sequences on the nonlinear dynamic response for various parameters are studied using a nonlinear dynamic finite element program developed for this study. The several numerical results were in good agreement with those reported by other investigators for square composite plates, and the new results reported in this paper show the significant interactions between the radius, fiber angles and layup sequence in the laminate. Key observation points are discussed and a brief design guideline of laminated composite shells is given.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.683-694
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• 2004

Advanced analysis and optimal design of semi-rigid space steel frames were presented. The advanced analysis can predict the combined nonlinear effects of connection, geometry, and material on the behavior and strength of semi-rigid frames. The Kishi-Chen power model was used to describe the nonlinear behavior of semi-rigid connections. Geometric nonlinearity was determined using stability functions. Material nonlinearity was determined using the Column Research Council (CRC) tangent modulus and the parabolic function. The direct search method proposed by Choi and Kim was used as optimization technique. One by one, the member with the largest unit value evaluated using the LRFD interaction equation were placed adjacent to a larger member selected from the database. The objective function was assumed to be the weight of steel frame, while the constraint functions were load-carrying capacities, deflections, inter-story drifts, and the ductility requirements. The member sizes determined using the proposed method were compared to those derived from the conventional LRFD method.

• Journal of Korean Society of Steel Construction
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• v.15 no.6 s.67
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• pp.661-672
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• 2003

The advanced analysis and optimal design of semi-rigid frame were presented. Advanced analysis can predict the combined nonlinear effects of connection, geometry, and material on the behavior and strength of semi-rigid frames. The Kishi-Chen power model was used to describe the nonlinear behavior of semi-rigid connections. Geometric nonlinearity was determined using stability functions. On the other hand, material nonlinearity was determined using the Column Research Council (CRC) tangent modulus and parabolic function. The direct search method proposed by Choi and Kim was used as optimization technique. The member with the largest unit value evaluated using the LRFD interaction equation was replaced one by one with an adjacent larger member selected from the database. The objective function was assumed as the weight of steel frame, with the constraint functions accounting for load-carrying capacities, deflections. inter-story drifts, and ductility requirement. Member sizes determined by the proposed method were compared with those derived using the conventional LRFD method.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.5A
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• pp.361-367
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• 2011

This study introduces an elastic parabolic cable element for initial shaping analysis of cable-supported structures. First, an elastic catenary cable theory is shortly summarized by deriving the compatibility condition and the tangent stiffness matrices of the elastic catenary cable element. Next, the force-deformation relations and the tangent stiffness matrices of the elastic parabolic cable elements are derived and discussed under the assumption that sag configuration under self-weights is small. In addition the equivalent cable tension is defined in the chord-wise direction. Finally, to demonstrate the accuracy of the elastic parabolic cable element, nonlinear relationships of nominal cable tension-chord length and nominal cable tension-tangential stiffness for a single element are presented and compared with results using an elastic catenary cable theory as the slope is varied.

• Journal of Korean Association for Spatial Structures
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• v.10 no.2
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• pp.61-68
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• 2010

The collapsing accidents of pipe greenhouses in the farmhouse have been increased duo to heavy snow load. However, the study on exact structure analysis to prevent the collapse of pipe greenhouses is rare and the damage of the farmhouse is annually repeated. The method of existing structure analysis is basically made of linear elastic analysis based on the micro displacement. But the actual stiffness of the pipe greenhouse is significantly weaker than the stiffness of buildings and the load acting on the greenhouses gets to become relatively bigger. It means that the geometry shape of greenhouses changes so that the relation of strain-displacement gets to indicate a nonlinear behavior. Therefore, this study is performed to evaluate the structural safety so as to prevent the collapse of pipe greenhouses, which are the single-span greenhouse(farmhouse guidance shape, G) and multi-span greenhouse(farmhouse supply shape, 1-2W), by performing the large-displacement analysis considering nonlinear effects.

• Journal of the Society of Naval Architects of Korea
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• v.29 no.4
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• pp.227-233
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• 1992

To study the large displacement and large rotation problems, geometrically nonlinear formulation of eccentric degenerated beam element has been developed, where the restrictions of infinitesimal rotation increments are removed and the incremental equations are derived using the Taylor series expansion of the displacement function at time t+dt. The geometrically nonlinear analyses are carried out for the cases of cantilever, square frame, shallow arch and 45-degree bend beam and all of them are compared with each of the other results published. The element developed in the present research can be efficiently utilized for analysis of the nonlinear behaviours of structures when displacements and rotations are large.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.8 no.2
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• pp.185-196
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• 1988

In this study, a method of nonlinear dynamic analysis of suspension bridges subjected to random wind loads is pre.sented. The nonlinearity considered is the one due to the interaction between the motion of the bridge girder and the tertsion variation of the main cables. The equation of motion is formulated using a continuum approach. The coupling between the vertical and torsional motions are included in the analysis. The equation of motion is solved by using the mode superposition method. The analysis is carried out in the frequency domain utilizing the stochastic linearization technique on to the modal equations. In the linearization procedure, the nonlinear terms are approximated as linear ones with constant terms. The verification of the method has been performed on a case with four modal degrees of freedom. Example analyses are carried out on two suspension bridges for various wind speeds and wind force parameters. Numerical results indicate that, by including the nonlinearity into the analysis, the dynamic responses of the bridges, particularly in the vertical direction, change considerably.

• Journal of Korean Society of Steel Construction
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• v.14 no.1
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• pp.13-21
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• 2002

In this paper, 3-D frame design using refined plastic-hinge analysis accounting for local buckling is developed. This analysis accounts for material and geometric nonlinearities of the structural system and its component members. Moreover, the problem associated with conventional refined plastic-hinge analyses, which do not consider the degradation of the flexural strength caused by local buckling, is overcome. Efficient ways of assessing steel frame behavior including gradual yielding associated with residual stresses and flexure, second-order effect, and geometric imperfections are presented. In this study, a model consisting of the width-thickness ratio is used to account for local buckling. The proposed analysis is verified by the comparison of the LRFD results. A case study shows that local buckling is a very crucial element to be considered in second-order plastic-hinge analysis. The proposed analysis is shown to be an efficient, reliable tool ready to be implemented into design practice.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.489-497
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• 2002

Nonlinear behavior and large deformation cannot be analyzed using techniques based on linear theory. Nonetheless, they are emerging as gradually huge and complex structures. In addition, the optimum design of structure is necessary in the development of high-performance computation and numerical methods. as well as stricter design-criterion. Therefore, the structural problems in engineering that are limited to the linear region must be extended to the nonlinear region. Likewise, structural behavior must be accurately analyzed. In turn, this requires considering the expected problems beforehand. Only then can an efficient, economical, and optimized structure be designed. This paper presents the solution of the geometrical nonlinear problem of anisotropic cylindrical shell. The characteristics of the geometrical nonlinear behavior of anisotropic circular cylindrical shells may vary according to several causes. e.g., change of fibers, curvature in the circumferential direction, subtended angle, aspect, etc. Parametric studies were conducted to determine the effect of factors on the large deflection behavior of laminated shells, with interesting observations.

• Computational Structural Engineering
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• v.8 no.3
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• pp.79-89
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• 1995

Two-element plate concept is incorporated into the buckling problem in order to simplify the nonlinear distribution of stress through the thickness of plate. Finite element formulations and programs based upon the Reissner functional and the modified Reissner functional using two-element plate concept are developed for buckling analysis of plates under axial compression. The two programs have been applied to obtain the linear elastic buckling behavior of axially compressed flat plates. Excellent agreement of linear elastic-solution results with exact or approximate solutions of other authors for the same boundary conditions proves the validity of the finite element method using two-element plate theory.