• Ocean Systems Engineering
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• 제4권3호
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• pp.215-241
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• 2014

Steel catenary riser (SCR) is a popular/economical solution for the oil/gas production in deep and ultra-deep water. The behavioral characteristics of SCR have a high correlation with the motion of floating production facility at its survival and operational environments. When large motions of surface floaters occur, such as FPSO in 100-yr storm case, they can cause unacceptable negative tension on SCR near TDZ (touch down zone) and the corresponding elastic deflection can be large due to local dynamic buckling. The generation, propagation, and decay of the elastic wave are also affected by SCR and seabed soil interaction effects. The temporary local dynamic buckling vanishes with the recovery of tension on SCR with the upheaval motion of surface floater. Unlike larger-scale, an-order-of-magnitude longer period global buckling driven by heat and pressure variations in subsea pipelines, the sub-critical local dynamic buckling of SCR is motion-driven and short cycled, which, however, can lead to permanent structural damage when the resulting stress is greatly amplified beyond the elastic limit. The phenomenon is extensively investigated in this paper by using the vessel-mooring-riser coupled dynamic analysis program. It is found that the moment of large downward heave motion at the farthest-horizontal-offset position is the most dangerous for the local dynamic buckling.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1988년도 가을 학술발표회 논문집
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• pp.36-42
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• 1988

In this study, a formulation of the idealized plate element based upon the idealized structural unit method(ISUM) firstly proposed by Ueda et．al is made in an attempt to analyze the geometric nonlinear behaviour up to the buckling strength of thin-walled long structures like box-column structure including the coupling effect between local and global buckling. An application to the example box-column is also performed and it is found that the present method gives reliable results with consuming very short computing times and therefore is very useful for evaluation of the buckling strength of thin-walled long structures.

• Steel and Composite Structures
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• 제35권3호
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• pp.405-413
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• 2020

Current study on the buckling analysis of steel plate in composite structures normally focuses on applying finite element method to derive the buckling stress. However, it is time consuming, computationally complicated and tedious for general use in design by civil engineers. Therefore, in this study an analytical study is conducted to predict the buckling behavior of steel plates in composite structures. Hand calculation method was proposed based on energy principle. Novel buckling shapes with biquadratic functions along both loaded and unloaded direction were proposed to satisfy the boundary condition. Explicit solutions for predicting the critical local buckling stress of steel plate is obtained based on the Rayleigh-Ritz approach. The obtained results are compared with both experimental and numerical data. Good agreement has been achieved. Furthermore, the influences of key factors such as aspect ratio, width to thickness ratio, and elastic restraint stiffness on the local buckling performance are comprehensively discussed.

• 한국공간구조학회논문집
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• 제15권3호
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• pp.43-49
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• 2015

A single-layerd steel lattice roof, which has 50m span, was constructed. In order to figure out the realistic buckling load level, the structural analysis of this roof structure was performed especially by local snow load. Due to the characteristics of application of snow load, the load combinations of snow should be considered not only global area but also local part so that the critical buckling load could be observed as easy as possible. Geometrical imperfection was simulated to consider inaccurate shape of structure. And then nonlinear analysis were performed. Finally, this paper could investigate that the local snow load with geometrical imperfection decreased the level of buckling load significantly.

• 대한기계학회논문집A
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• 제27권12호
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• pp.2011-2018
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• 2003

To analyze the bending collapse behavior of an aluminum square tube beam under a bending load, a finite element simulation for the four-point bending test has been performed. Using an aluminum tube beam specimen partly inserted with two steel bars, the local buckling deformation near the center of the tube beam was induced. The maximum bending load and the bending collapse behavior obtained from the numerical simulation were in good agreement with experimental results. Using a combination of the four-point bending test and its finite element simulation, analysis of the local buckling and the accompanied bending collapse behavior of aluminum tube beam could be quantitative accomplished.

• 대한기계학회논문집
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• 제19권8호
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• pp.1889-1900
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• 1995

In this study, a large deflection analysis of a plane frame composed of a thin-walled tube in investigated. When bent, a thin-walled tube is usually controlled by local buckling and subsequent bending collapse of the section. So load resistance reaches the yield level in a thin-walled rectangular tube. This relationship can be divided into three regimes : elastic, post-buckling and crippling. In this paper, this relationship is theoretically presented to be capable of describing nonlinearities and a stiffness matrix is derived by introducing a compound beam-spring element. A numerical analysis uses a constant incremental energy method and the solution is obtained by modifying stiffness matrix at elastic/inelastic stage. This analytical results, load-deflection paths show a good agreement with the test results.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 춘계학술대회논문집A
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• pp.254-260
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• 2000

The spacer grid is one of the main structural components in fuel assembly, which supports the fuel rods, guides cooling water, and protects the fuel assembly from the external impact load such as earthquakes. The nonlinear dynamic impact analysis is conducted by using the finite element code ABAQUS/Explicit. Boundary condition for dynamic analysis is well applied to the test condition. Simulation results also similarly predict the local buckling phenomena. In addition to the buckling parameter, the local buckling cause is examined by both simulation and test method. It is found to correspond well with the test results. Impact tests are also carried out for some specimens of the spacer grid in order to compare the results between the test and the simulation. This test is accomplished by a free fall dummy weight onto the specimen. From this test, only the uppermost and lowermost layers of the multi-cell are buckled, which implies the local buckling at the weakest point of the grid structure.

• Structural Engineering and Mechanics
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• 제10권4호
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• pp.371-392
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• 2000

Application of "advanced analysis" methods suitable for non-linear analysis and design of steel frame structures permits direct and accurate determination of ultimate system strengths, without resort to simplified elastic methods of analysis and semi-empirical specification equations. However, the application of advanced analysis methods has previously been restricted to steel frames comprising only compact sections that are not influenced by the effects of local buckling. A concentrated plasticity method suitable for practical advanced analysis of steel frame structures comprising non-compact sections is presented in this paper. The pseudo plastic zone method implicitly accounts for the effects of gradual cross-sectional yielding, longitudinal spread of plasticity, initial geometric imperfections, residual stresses, and local buckling. The accuracy and precision of the method for the analysis of steel frames comprising non-compact sections is established by comparison with a comprehensive range of analytical benchmark frame solutions. The pseudo plastic zone method is shown to be more accurate and precise than the conventional individual member design methods based on elastic analysis and specification equations.

• 한국방재학회 논문집
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• 제10권2호
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• pp.1-5
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• 2010

유리온실에 효과적으로 적용할 수 있는 보는 최대한 가벼운 중량을 유지하면서, 요구되는 휨모멘트 강도와 좌굴 강도를 만족시켜야 한다. 이 연구에서는 유리온실의 보 및 기둥 부재로 최근에 제안된 트러스웹을 가진 보의 실무적인 적용성을 확립하기 위해서 휨거동과 좌굴거동을 해석적으로 분석하였다. 이 결과를 바탕으로 횡좌굴 및 국부좌굴을 고려한 부재설계 프로세스를 제시하였다. 또한 유한요소 해석결과를 바탕으로 횡좌굴 혹은 국부좌굴을 지연시킴으로서 단면성능을 향상시킬 수 있는 개선안을 제시하였다.

• Structural Engineering and Mechanics
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• 제72권5호
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• pp.569-583
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• 2019

Tubular steel sections are widespread all over the world because of their strength and aesthetic appearance. Tubular steel members may exhibit local buckling such as elephant foot or overall buckling under extreme compression load. Recently, external bonding of fiber reinforced polymers (FRP) sheets for strengthening these members has been explored through experimental research. This paper presents three-dimensional nonlinear finite element analysis (FEA) to investigate the structural behavior of strengthening tubular steel members with FRP against local and overall buckling phenomena. Out-of-roundness and out-of-straightness imperfections were introduced to the numerical models to simulate the elephant foot and overall buckling, respectively. The nonlinear analysis preferences such as the integration scheme of the shell elements, the algorithm for solution of nonlinear equations, the loading procedure, the bisection limits for the load increments, and the convergence criteria were set, appropriately enough, to successfully track the sophisticated buckling deformations. The agreement between the results of both the presented FEA and the experimental research was evident. The FEA results demonstrated the power of the presented rigorous FEA in monitoring the plastic strain distribution and the buckling phenomena (initiation and propagation). Consequently, the buckling process was interpreted for each mode (elephant foot and overall) into three sequential stages. Furthermore, the influence of FRP layers on the nonlinear analysis preferences and the results was presented.