• Computational Structural Engineering
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• v.1 no.1
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• pp.87-94
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• 1988

The linerization method as one of the recursive quadratic programming method is applied for the optimal design of a large-scale structure supported by Pshenichny's proof of global convergence of the algorithm and convergence rate estimates. The linearization method transforms all constants of the design problem into an equivalent linearized constraint and employs the active-set strategy. This results in substantial computational savings by reducing the number of sate and adjoint to be solved at every design iteration. The illustrative example of plates with beams supported by columns is the typical one of a large-scale structure to give successful optimum solutions with satisfactory convergence criteria. Hopefully, the method may be applicable to all classes of optimization problems.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.23 no.5
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• pp.517-524
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• 2010

In this paper the progressive collapse resisting capacity of steel moment frames with viscous dampers was evaluated by nonlinear dynamic analysis. The effects of dampers installed in steel beam-column sub-assemblages with varying natural period and yield strength were evaluated after sudden removal of a column. According to the parametric study the vertical displacement general decreased as the damping ratio of the system increased, and the dampers were effective both in elastic and elasto-plastic systems. The nonlinear dynamic analysis results of the 15-story analysis models showed that the decrease in vertical deflection of the structure with 9m span length, which showed larger deflection, was more predominant than that of the structure with 6m span length.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.5
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• pp.465-474
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• 2008

The real-time hybrid testing method(RT-HYTEM) is a structural testing technique in which the numerical integration of the equation of motion for a numerical substructure and the physical testing for an experimental substructure are performed simultaneously in real-time. This study presents the quantitative evaluation of the seismic performance of a building structure installed with an passive and semi-active MR damper by using RT-HYTEM. The building model that was identified from the force-vibration testing results of a real-scaled 5-story building is used as the numerical substructure, and an MR damper corresponding to an experimental substructure is physically tested by using the universal testing machine(UTM). The RT-HYTEM implemented in this study is validated because the real-time hybrid testing results obtained by application of sinusoidal and earthquake excitations and the corresponding analytical results obtained by using the Bouc-Wen model as the control force of the MR damper respect to input currents were in good agreement. Also for preliminary study, some semi-active control algorithms were applied to the MR damper in order to control the structural responses optimally. Comparing between the test results of semi-active control using RT-HYTEM and numerical analysis results show that the RT-HYTEM is more resonable than numerical analysis to evaluate the performance of semi-active control algorithms.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.32 no.6
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• pp.56-63
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• 2004

In this study, dynamic aeroelastic analyses of the canard with oscillating flap are conducted considering the effect of aerodynamic compressibility. The canard model considered herein is an all-movable type with a pitching axis on a canard-rotor-wing aircraft which was considered as one of the major UAV candidates under developing in Korea. The equivalent structural model is constructed based on the initial design data by the Korea smart UAV development center. Both the frequency and the time-domain aeroelastic analyses have been applied to practically conduct parametric studies on the effects of equivalent torsional stiffness. In the case of all-movable control surface with oscillating flap, the equivalent rotational stiffness of the pitch axes are important design parameters. The parametric results for the aeroelastic instability are practically presented.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.5
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• pp.445-452
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• 2017

The wing leading edge skin in this research is an essential structural factor for improving wings' aeromechanical functions, protecting the interior elements of the wings from external damage including birds, and navigating planes safely. The study compared and reviewed models manufactured for optimal light-weight wings of composite UAVs. It compared and investigated displacement forms of torsion loads through finite element analysis using MSC. Patran/Nastran. By confirming the improvement of light-weighting performance according to lamination type, thickness change and shape through torsion strength tests of each model, the research suggested the optimal light-weight wing leading edge skin for small composite UAVs.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.319-325
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• 2021

The 2011 East Japan Earthquake caused accidents at a number of nuclear power plants in Fukushima, highlighting the need for a study on the seismic safety of multiple NPP (Nuclear Power Plant) units. In the case of nuclear power plants built on a site that shows a similar seismic response, there is at least a correlation between the seismic damage of structures, systems, and components (SSCs) of nuclear power plants. In this study, a probabilistic seismic safety assessment was performed for the loss of essential power events of twin units. To derive an appropriate seismic damage correlation coefficient, a probabilistic seismic response analysis was performed. Using the external event mensuration system program, we analyzed the seismic fragility and seismic risk by composing a failure tree of multiple loss of essential power events. Additionally, a comparative analysis was performed considering the seismic damage correlation between SSCs as completely independent and completely dependent.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.3
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• pp.277-283
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• 2016

A high-precision force-feedback 3-axes accelerometer developed in Korea has been investigated and studied for the verification of feasibility in the computational analysis and health monitoring of civil infrastructures. Through a series of experiment, the nonlinearity, bandwidth, low-frequency signal measurement accuracy and bias characteristics of the accelerometer has been thoroughly compared to those of two accelerometers produced by two market leaders in domestic and global accelerometer market. The experiment results shows that the overall measurement performance of the accelerometer has superiority over the performance of the two accelerometers from global market leader companies. Especially, the accelerometer shows a better low-frequency signal measurement accuracy and constant bias characteristic, which are mostly required in the computational analysis and the long-term health monitoring of large-scale civil infrastructures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.6
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• pp.769-778
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• 2007

In this paper, excitation systems using linear mass shaker (LMS) and active tuned mass damper (ATMD) are presented in order to simulate the wind induced responses of a building structure. The actuator force for the excitation systems is calculated by using the inverse transfer function of a target structural response to the actuator. Filter and envelop function are used such that the error between the wind and actuator induced responses is minimized by preventing the actuator from exciting unexpected modal response and initial transient response. The analyses results from a 76-story benchmark building problem in which wind load obtained by wind tunnel test is given, indicate that the excitation system installed at a specific floor can approximately embody the structural responses induced by the wind load applied to each floor of the structure. The excitation system designed by the proposed method can be effectively used for evaluating the wind response characteristics of a practical building structure and for obtaining an accurate analytical model of the building under wind load.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.1
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• pp.39-50
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• 2007

This paper presents 3D infinite elements for the elastodynamic problem with multi-layered half-space. Five different types of infinite elements are formulated by using approximate expressions of multiple wave components for the wave function in multi-layered soil media. They are horizontal, horizontal-corner, vortical, vertical-corner and vertical-horizontal-comer infinite elements. The elements can effectively be used for simulating wane radiation problems with multiple wave components. Numerical example analyses are presented for rigid disk, square footings and embedded footing on homogeneous and layered half-space. The numerical results show the effectiveness of the proposed infinite elements.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.5
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• pp.485-490
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• 2015

This paper presents development of a geometrically nonlinear triangular planar element including rotational degrees of freedom, based on the co-rotational(CR) formulation. The CR formulation is one of the efficient geometrically nonlinear formulations and it is based on the assumptions on small strain and large rotation. In this paper, modified CR formulation is suggested for the developemnt of a triangular planar element. The present development is validated regarding the static and time transient problems. The present results are compared with the results predicted by the previous researchers and those obtained by the existing commercial software.