• Journal of the Korean Society for Advanced Composite Structures
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• v.6 no.1
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• pp.45-50
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• 2015

This study performed a finite element crash analysis of support structures made of various composite materials for road facilities. The effects of different material properties of composites for various parameters are studied using the finite element commercial package for this study. In this study, the existing finite element analysis of composite post structures using the LS-DYNA program is further extended to compare dynamic behaviors against car crash of the structures made of various composite materials. The several numerical examples show the comparison of the nonlinear dynamic effects for different materials.

• KCI Concrete Journal
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• v.11 no.3
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• pp.115-126
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• 1999

An analytical method based on the nonlinear layered finite element method is developed to simulate an overall load-deflection behavior of strengthened beams. The developed model distinguishes itself by its capability to trace residual flexural behavior of a beam after the fracture of brittle strengthening materials at peak load. The model. which uses a rather advanced numerical technique for iterative convergence to equilibrium, can be regarded as superior to the two models based on load control and displacement control The model predictions were compared with the experimental results and it was observed that there was good agreement between them.

• Computers and Concrete
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• v.15 no.2
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• pp.259-277
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• 2015

The lack of experimental studies on the mechanical behavior of reinforced concrete (RC) haunched beams leads to difficulties in statistical and reliability analyses. This study performs stochastic and reliability analyses of the ultimate shear capacity of RC haunched beams based on nonlinear finite element analysis. The main aim of this study is to investigate the influence of uncertainty in material properties and geometry parameters on the mechanical performance and shear capacity of RC haunched beams. Firstly, 65 experimentally tested RC haunched beams and prismatic beams are analyzed via deterministic nonlinear finite element method by a special program (ATENA) to verify the efficiency of utilized numerical models, the shear capacity and the crack pattern. The accuracy of nonlinear finite element analyses is verified by comparing the results of nonlinear finite element and experiments and both results are found to be in a good agreement. Afterwards, stochastic analyses are performed for each beam where the RC material properties and geometry parameters are assigned to take probabilistic values using an advanced simulating procedure. As a result of stochastic analysis, statistical parameters are determined. The statistical parameters are obtained for resistance bias factor and the coefficient of variation which were found to be equal to 1.053 and 0.137 respectively. Finally, reliability analyses are accomplished using the limit state functions of ACI-318 and ASCE-7 depending on the calculated statistical parameters. The results show that the RC haunched beams have higher sensitivity and riskiness than the RC prismatic beams.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.11
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• pp.1078-1088
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• 2012

Recently, the vibration and structure-borne noise induced by passing trains are of great concerns, and the floating slab track is highlighted as one of most efficient alternatives to reduce the railway vibration. However, due to the non-linearity and viscosity of rubber spring used in the floating slab track, its dynamic behavior is very complex. In this study, therefore, to simulate the dynamic behavior of floating slab track with a better accuracy, a nonlinear viscoelastic rubber spring model that can be incorporated in commercial finite element analysis codes has been proposed. This model is composed of a combination of elastic spring element, friction element and viscous element, and termed the "generalized friction viscoelastic model(GFVM)". Also, in this study, the method to determine the model parameters of GFVM based on Berg's 5-parameter model was presented. The results of the finite element analysis with this rubber spring model exhibit very good correlation with the test results of a laboratory mock-up test, and the feasibility of GFVM has been verified.

• Structural Engineering and Mechanics
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• v.89 no.4
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• pp.399-409
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• 2024

Assessment of existing concrete bridges is a challenge for owners. It has greater economic impact when compared to designing new bridges. When using conventional linear analyses, judgment of the engineer is required to understand the behavior of redundant structures after the first element in the structural system reaches its ultimate capacity. The alternative is to use a predictive tool such as advanced nonlinear finite element analyses (ANFEA) to assess the overall structural behavior. This paper proposes a new reliability framework for the assessment of existing bridge structures using ANFEA. A general framework defined in previous works, accounting for material uncertainties and concrete model performance, is adapted to the context of the assessment of existing bridges. A "shifted" reliability problem is defined under the assumption of quasi-deterministic dead load effects. The overall exercise is viewed as a progressive pushover analysis up to structural failure, where the actual safety index is compared at each event to a target reliability index.

• Computers and Concrete
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• v.3 no.2_3
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• pp.123-144
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• 2006

Reinforced concrete corbels are structural elements widely used in practical engineering. The complex response of these elements is described in design codes in a simplified manner. These formulations are not sufficient to show the real behavior, which, however, is an essential prerequisite for the manufacturing of numerous elements. Therefore, a deterministic and probabilistic study has been performed, which is described in this contribution. Real complex structures have been modeled by means of the finite element method supported primarily by experimental works. The main objective of this study was the detection of uncertainties effects and safety margins not captured by traditional codes. This aim could be fulfilled by statistical considerations applied to the investigated structures. The probabilistic study is based on advanced Monte Carlo simulation techniques and sophisticated nonlinear finite element formulations.

• Journal of the Korean Society for Advanced Composite Structures
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• v.1 no.4
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• pp.28-34
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• 2010

W e performed a geometrical nonlinear dynamic analysis of laminated skew plates made of advanced composite materials (ACM ) based on the first-order shear deformation plate theory (FSDT). The Newmark method and Newton-Raphson iteration are used for the nonlinear dynamic solution. The effects of skew 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 and skew plates, and the new results reported in this paper show the significant interactions between the skew angle and layup sequence in the skew laminate. Key observation points are discussed and a brief design guideline is given.

• Structural Engineering and Mechanics
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• v.62 no.1
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• pp.33-42
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• 2017

We present in this paper a finite element formulation for nonlinear torsional analysis of 3D beams with arbitrary composite cross-sections. Since the proposed formulation employs a continuum mechanics based beam element with kinematics enriched by the extended St. Venant solutions, it can precisely account higher order warping effect and its 3D couplings. We propose a numerical procedure to calculate the extended St. Venant equation and the twisting center of an arbitrary composite cross-section simultaneously. The accuracy and efficiency of the proposed formulation are thoroughly investigated through representative numerical examples.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 1994.10a
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• pp.55-63
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• 1994

The analysis of superplastic sheet forming process is studied by the use of the finite element method using a convected coordinate system and a skew boundary condition. In the formulation, the large inelastic behavior of the superplastic material is described as incompressible, nonlinear, viscous flow. The formulation is then approximated to the finite dimensional space with the use of membrane elements, which results in algebraic linear equations. In addition to the finite element formulation, a pressure cycle control algorithm is combined in the analysis for optimization of the forming time, which deals with the maximization of the strain rate sensitivity, the protection of the thickness reduction, the consistency of the desired strain rate and improvement of formability.

• Computers and Concrete
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• v.13 no.1
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• pp.1-16
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• 2014

To evaluate the behavior of the advanced unbonded pre-stressed concrete containment vessel (UPCCV) for one typical China nuclear power plant under Japan's March 11 earthquake, five nonlinear time history analysis and a nonlinear static analysis of a 1:10 scale UPCCV structure have been carried out with MSC.MARC finite element program. Comparisons between the analytical and experimental results demonstrated that the developed finite element model can predict the earthquake behavior of the UPCCV with fair accuracy. The responses of the 1:10 scale UPCCV subjected to the 11 March 2011 Japan earthquakes recorded at the MYG003 station with the peak ground acceleration (PGA) of 781 gal and at the MYG013 station with the PGA of 982 gal were predicted by the dynamic analysis. Finally, a static analysis was performed to seek the ultimate load carrying capacity for the 1:10 scale UPCCV.