• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.653-660
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• 2004

To increase the efficiency of the urban areas, pipe section steel piers, which have relatively small sections, must be constructed. Since smaller sections mean decreased load capacity, longitudinal stiffeners were applied to the pipe section steel piers to increase their load capacity. Increased load capacity through longitudinal stiffeners, however, could not yet be confirmed. Therefore, the effect of longitudinal stiffeners on the load capacity of pipe section steel piers still needs to be studied. In this paper, the effect of the number of longitudinal stiffeners on the load capacity of steel piers was determined by carrying out elastic plastic FE analysis on material and geometric non-linearity. In addition, comparative analyses of the parameters of the width, the thickness of longitudinal stiffeners, and the slenderness ratio of steel piers were carried out to determine the effects of longitudinal stiffeners.

• Journal of Korean Society of Steel Construction
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• v.14 no.4
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• pp.471-479
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• 2002

In this paper, 18 square CFT columns filled with high-strength concrete were tested under concentric or eccentric axial loading. Two parameters of the experimental program included the buckling length-section depth ratio ($L_K$/D) and the eccentricity of the appled compressive load (e). In additon, mechanical properties such as the compressive concrete strength and compressive and tensile steel strength were measured and incorporated into the material models for the stress-strain relationships of concrete and steel. This model was used in an elasto-plastic analysis in order to predict the behavior of the slender CFT columns. Observtions of the failure mode during the tests under axial loadig were also presented. The strengths obtained from the analysis. Recommendations for Design, and Constructions of CFT structures were presented, as verified by the experimental results.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.58-68
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• 2014

Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct and require larger amount of transverse steels. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of columns of the oblong cross-section and flared column. The experimental study for octagonal oblong cross-section was carried out by the flared columns test in strong axis. The lateral confinement method using proposed oblong hoop detail showed satisfactory performance of lateral confinement. Therefore it can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency.

• Journal of the Korea institute for structural maintenance and inspection
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• v.19 no.6
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• pp.1-9
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• 2015

Transverse steel bars are used in the plastic hinge zone of columns to insure adequate confinement, prevention of longitudinal bar buckling and ductile behavior. Fabrication and placement of rectangular hoops and cross-ties in columns are difficult to construct. Details of reinforcement for rectangular section require a lot of rectangular hoops and cross-ties. In this paper, to solve these problems, the new lateral confinement method using oblong hoop is proposed for the transverse confinement of the flared column. It can be the alternative for oblong cross-section and flared column with improved workability and cost-efficiency. The final objectives of this study are to suggest appropriate oblong hoop details and to provide quantitative reference data and tendency for seismic performance or damage assessment based on the drift levels such as residual deformation, elastic strain energy. This paper describes factors of seismic performance such as ultimate displacement/drift ratio, displacement ductility, response modification factor, equivalent viscous damping ratio and effective stiffness.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.4
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• pp.363-370
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• 2009

We simulated large deformation and inelastic behavior of API-X80 steel linepipes using nonlinear finite element method. Gurson-Tvergaard-Needleman(GTN) model is employed for the development of the constitutive model of the steel. The GTN model is implemented in the form of the user-supplied material subroutine(UMAT) for the commercial software of ABAQUS. To calibrate the model parameters, we simulated the behavior of the uniaxial tension test using ABAQUS equipped with the developed GTN model. Using the set of the model parameters, we were able to capture the characteristics of the plastic buckling of API-X80 steel linepipes.

• Steel and Composite Structures
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• v.34 no.1
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• pp.107-122
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• 2020

Moment resisting stub columns (MRSCs) have increasingly adopted in special moment-resisting frame (SMF) systems in steel building structures, especially in Asian countries. The MRSCs typically provide a lower deformation capacity compared to shear-panel stub columns, a limited post-yield stiffness, and severe strength degradation as adopting slender webs. A new MRSC design with cored configuration, consisting of a core-segment and two side-segments using different steel grades, has been proposed in the study to improve the demerits mentioned above. Several full-scale components of the cored MRSC were experimentally investigated focusing on the hysteretic performance of plastic hinges at the ends. The effects of the depths of the core-segment and the adopted reduced column section details on the hysteretic behavior of the components were examined. The measured hysteretic responses verified that the cored MRSC enabled to provide early yielding, great ductility and energy dissipation, enhanced post-yield stiffness and limited strength degradation due to local buckling of flanges. A parametric study upon the dimensions of the cored MRSC was then conducted using numerical discrete model validated by the measured responses. Finally, a set of model equations were established based on the results of the parametric analysis to accurately estimate strength backbone curves of the cored MRSCs under increasing-amplitude cyclic loadings.

• Journal of the Earthquake Engineering Society of Korea
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• v.10 no.3 s.49
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• pp.149-158
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• 2006

The reduced beam section (RBS) steel moment connection has performed well in past numerous tests. However there still remain several design issues that should be further examined. One such issue on RBS connection performance is the panel zone strength. Although a significant amount of test data are available, a specific recommendation for a desirable range of panel zone strength versus beam strength has yet to be proposed. In this paper, the effects of panel zone strength on the cyclic performance of RBS connection are investigated based on the available test database from comprehensive independent testing programs. A criterion for a balanced panel zone strength that assures sufficient plastic rotation capacity while reducing the amount of beam buckling is proposed. Numerical studies to supplement the test results are then presented based on the validated finite element analysis. Satisfactory numerical simulation achieved in this study also indicates that numerical analysis based on quality finite element modeling can supplement or replace, at least in part, the costly full-scale cyclic testing of steel moment connections.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.92-105
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• 2000

A study for the structural strength evaluation on the slender doubler plate has been performed through the systematic evaluation process. In order to estimate the proper static strength of doubler plate subjected to the longitudinal in-plane compression, elasto-plastic large deflection analysis is introduced including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed based on their results. Also, in order to compare the doubler structure with the original strength of main plate without doubler, a simple formula for the evaluation of the equivalent flat plate thickness is derived based on the additional series analysis of flat plate structure. Using this derived equation, the thickness change of a equivalent flat plate is analyzed according to the variation of various design parameters of doubler plate and some design guides are suggested in order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent flat plate formula and the developed buckling strength formulas by author et al. is discovered and these relations are formulated for the future development of simple strength evaluation formula of doubler plate structure.

• Design & Manufacturing
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• v.17 no.1
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• pp.48-55
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• 2023

In this study, on the structure simulation for manufacturing a high strength/light weight 48V battery housing for a mild hybrid vehicle was conducted. Compression analysis was performed in accordance with the international safety standards(ECE R100) for existing battery housings. The effect of plastic materials on compressive strength was analyzed. Three models of truss, honeycomb and grid rib for the battery housing were designed and the strength characteristics of the proposed models were analyzed through nonlinear buckling analysis. The effects of the previous existing rib, double-sided grid rib, double-sided honeycomb rib and double-sided grid rib with a subtractive draft for the upper cover on the compressive strength in each axial direction were examined. It was confirmed that the truss rib reinforcement of the battery housing was very effective compared to the existing model and it was also confirmed that the rib of the upper cover had no significant effect. In the results of individual 3-axis compression analysis, the compression load in the lateral long axis direction was the least and this result was found to be very important to achieve the overall goal in designing the battery housing. To reduce the weight of the presented battery housing model, the cell molding method was applied. It was confirmed that it was very effective in reducing injection pressure, clamping force and weight.

• Earthquakes and Structures
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• v.26 no.1
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• pp.77-86
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• 2024

To investigate the seismic performance of steel pipe-aeolian sand recycled concrete columns, this study designed and produced five specimens. Low-cycle repeated load tests were conducted while maintaining a constant axial compression ratio. The experiment aimed to examine the impact of different aeolian sand replacement rates on the seismic performance of these columns. The test results revealed that the mechanical failure modes of the steel pipe-recycled concrete column and the steel pipe-aeolian sand recycled concrete column were similar. Plastic hinges formed and developed at the column foot, and severe local buckling occurred at the bottom of the steel pipe. Interestingly, the bulging height of the damaged steel pipe was reduced for the specimen mixed with an appropriate amount of wind-deposited sand under the same lateral displacement. The hysteresis curves of all five specimens tested were relatively full, with no significant pinching phenomenon observed. Moreover, compared to steel tube-recycled concrete columns, the steel tube-aeolian sand recycled concrete columns exhibited improved seismic energy dissipation capacity and ductility. However, it was noted that as the aeolian sand replacement rate increased, the bearing capacity of the specimen increased first and then decreased. The seismic performance of the specimen was relatively optimal when the aeolian sand replacement rate was 30%. Upon analysis and comparison, the damage analysis model based on stiffness and energy consumption showed good agreement with the test results and proved suitable for evaluating the damage degree of steel pipe-wind-sand recycled concrete structures.