• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.3
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• pp.259-266
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• 2011

The transient vibration test and synchronized human excitation is performed for low-rise concrete buildings and their identified natural frequency, damping ratio, and mode shape are compared. Form the identified dynamic parameters, it was found that the damping ratio obtained through the synchronized human excitation test is greater than those obtained from the transient vibration test. However, the mode shapes of the first mode are not significantly different regardless of the test method. Further, the stiffness of the interior brick partition considerably affect the stiffness of the entire building such that the first natural mode of rectangular shaped building occurred in the longitudinal direction rather than transverse direction.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.6
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• pp.617-627
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• 2011

This paper presents the results of analytical simulation of shake-table responses of a 1:5 scale 10-story reinforcement concrete(RC) residential building model by using the PERFORM-3D program. The following conclusion are drawn based on the observation of correlation between experiment and analysis; (1) The analytical model simulated fairly well the global elastic behavior under the excitations representative of the earthquake with the return period of 50 years. Under the design earthquake(DE) and maximum considered earthquake(MCE), this model shows the nonlinear behavior, but does not properly simulate the maximum responses, and stiffness and strength degradation in experiment. The main reason is considered to be the assumption of elastic slab. (2) Although the analytical model in the elastic behavior closely simulated the global behavior, there were considerable differences in the distribution of resistance from the wall portions. (3) Under the MCE, the shear deformation of wall was relatively well simulated with the flexural deformation being overestimated by 10 times that of experiment. This overestimation is presumed to be partially due to the neglection of coupling beams in modeling.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.5
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• pp.361-368
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• 2014

Modal properties for tapered cantilever pipe-type beam is identified by applying the boundary conditions to a general solution for tapered beam. A bending stiffness for cracked beam is constructed based on an energy method for tapered cantilever thin-walled pipe, which has a through-the-thickness crack, subjected to bending. Then the natural frequencies and mode shapes of a tapered cantilever thin-walled cracked pipe are identified. It can be found that the phenomenon of the bending stiffness distribution along the beam length of the cracked beam is quite reasonable, the natural frequencies are decreased as the crack sizes are increased, and the mode shapes are changed due to the crack. This results may be used to the vibration-based crack identification for the tapered cantilever pipe-type tower structures.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.30 no.1
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• pp.17-22
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• 2017

In this study, we designed the metallic reception part of a patch antenna using the phase field design method. The design object function is formulated with the S-parameter value which represent the return loss so that it is targeted to maximize radiation efficiency at a target frequency. The initial model of a patch antenna was designed via the ordinary theory based approach and its performance was enhanced by changing the structural configuration of the metallic part using the phase field design method combined with the double well potential functions. The final shape was proposed by removing the gray scale area along the structural boundary by employing a cut-off method. The proposed shape shows that the radiation efficiency at target frequency is significantly improved compared with the initial patch shape. The finite element analysis and optimization precess was performed using the commercial package COMSOL and Matlab programming.

• Computational Structural Engineering
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• v.7 no.2
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• pp.89-99
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• 1994

The nonlinear dynamic behaviors of guardrail established on the local or high way have been investigated using BARRIER VII program with respect to four design variables such as section type of beams and posts, impact angle, impact velocity and vehicle weight. Computer simulation programs are sophisticated analytical models for analyzing dynamic vehicle/barrier interactions and provide a relatively inexpensive alternative to full scale crash testing. This study has been focused on the structural adequacy, occupant risk, and vehicle trajectory. For this purpose, the maximum defection and impact force have been calculated to design the clear zone and to analyze effect of impact attenuation. Also, the acceleration of vehicle and exit angle after collision have been computed to estimate the occupant risk. From this study, it is suggested that we should strengthen the design criteria of guardrail to prevent from disastrous traffic accidents.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.5
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• pp.405-411
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• 2012

Inside a rotorcraft fuel cell, pipes and components are located for fuel storage and fuel supply into the engine. Utility helicopters, operated in battle fields, fly at lower altitude compared to fixed-wing aircraft and hence are more likely to be exposed to gunfire. Since internal pressure of fluid increases when hit, the effect on LRU due to increase in pressure must taken into account when designing the aircraft for survivability. However, it is costly and time consuming to manufacture a fuel cell for gunfire test, and due to constraints from usage of live ammunition, related data gathered through numerical simulation is needed. In this study, numerical simulation on rotorcraft fuel cell exposed to gunfire was carried out using Autodyn to analyze bullet movement inside the fuel cell after hit, and internal pressure of fluid and equivalent stress on fuel cell assessed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.2
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• pp.177-184
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• 2011

In this paper the nonlinear analysis that include time-dependent characteristics of materials and geometric nonlinearity of elements for the cable-stayed PSC bridges is presented. Analysis models for finite element method were developed based on the flexibility based fiber beam-column model originally proposed by Spacone et al.(1996). The developed analysis model implemented in general purpose object-oriented finite element analysis program named HFC(Cho 2009). The performance of proposed analysis models is evaluated by comparing with the former results of the design data. The deflection of time dependent analysis is larger than time ignored analysis on construction sequences, and the bridge is destructed at a smaller deflection than the time ignored analysis on failure behavior.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.17 no.2
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• pp.215-222
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• 2004

Drift design methods using resizing techniques have been presented as a practical drift control methods of high-rise buildings. Most drift design methods using the resizing techniques have adopted the cross-sectional area as the design variables for all structural members in a structure. However, the cross-sectional area is not always governing sectional property for the structural members, but the governing sectional property of each member is dependent on the characteristics of member forces. In this paper, a drift design method using the sectional property related to the governing displacement participation factor as the design variable of each member is presented and applied to the drift design of 20-story steel frame-shear wall system. It can be noted from example test that drift design method considering member characteristics shows similar or somewhat better results in the view point of structural weights and the accuracy of displacement estimation.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.4
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• pp.365-373
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• 2008

Fiber Reinforced Polymer, FRP has a light weight, a high tensile strength based on design, non-electronic, non-magnetic, and rust-resistant feature, etc and many researches are being conducted recently on FRP in the construction area. Among them, GFRP (Glass Fiber Reinforced Polymer) is excellent in price competitiveness and is widely being used. However, since GFRP has a relative low modulus of elasticity and causes excessive deflection, the section must be large to be used as a structural component and an investigative review must be carried out in design to set the limit for deflection by the use load. Therefore, in order to solve the mentioned technical problems, this study suggested a section of a module form such that application of a large-scale section is possible. Also, to secure the low rigidity of FRP, this study developed a new FRP+ concrete composite girder form that confined the concrete. To identify the structural movement of the developed FRP+ concrete composite girder, shear strength test was carried out.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.16 no.1
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• pp.43-52
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• 2003

The present study is to investigate the ultimate behavior and limit state design of 2-I) R/C structures, with the changing of crack direction, and the yielding of the reinforcing steel bars, and Is to introduce an algorithm for the limit state design and analysis of 2-D R/C structures, directly from the finite element model. For the design of reinforcement in concrete the limit state design equation is incorporated into finite element algorithm to be based on the pointwise elemental ultimate behavior. It is also introduced a simplified nonlinear analysis algorithm for stress-strain relationship of R/C plane stress problem considering the cracking and its rotation in concrete and the yielding of the reinforcing steel bar. The algorithm is incorporated into the nonlinear finite element analysis. The analysis model is compared with the experimental model of R/C shear wall. In a simple design example for a shear wall, the required reinforcement ratios in each finite element is obtained from the limit state design equations.