• Journal of the Korea Concrete Institute
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• v.24 no.6
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• pp.737-744
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• 2012

Hysteretic steel damper has been applied mainly to steel buildings. However, the usage in RC buildings is rapidly increasing recently. In order to apply the steel hysteretic damper in RC buildings, supporting elements of the damper should have sufficient strength and stiffness suitable for transferring damper forces to beams and walls. But due to the inevitable damage in reinforced concrete elements due to cracking, identification of the load transfer mechanism from damper to supporting element and hysteretic characteristics of the supporting element are extremely important in evaluating the damper behavior. Experiments were carried out on connection details between RC walls and supporting elements of the steel plate typed damper such as EaSy damper. The test results showed that fracture patterns of all specimens were almost identical except in the crack number and pattern associated with shear loading condition. Among the specimens, HD-3 shoed a well distributed cracks patterns along with good performance with respect to energy dissipation capacity, stiffness deterioration, and strength degradation.

• Journal of Korean Society of Steel Construction
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• v.24 no.4
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• pp.443-450
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• 2012

In this study, This study investigates the axial load behavior of concrete-filled steel columns using seismic rectangular steel tube with the width-to-thickness and slenderness ratio. Due to cold-roll forming and cold-press forming of steel tube, the flat part and the corner part of the rectangular steel tubes are changed in the material properties compared to SN-steel plate. It was showed the tendency to increase yield strength, tensile strength and upper limit of yield ratio This phenomenon affects the nonlinear behavior after local buckling of the steel tube. Therefore, the coupon test was performed by the processing of rectangular steel tube, in order to assess forming performance. And a total of 6 CFT-columns were tested under monotonic loading condition. Main parameters were the width-thickness ratio and the slenderness ratio.

• Journal of Korean Society of Steel Construction
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• v.16 no.4 s.71
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• pp.463-470
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• 2004

In this study, the bearing pressure distribution and design method of rectangular steel tubular column base plates under concentric loading were investigated. In general, the size and thickness of the baseplate are determined with the assumption that the bearing pressure of the column baseplate is uniformly distributed. When the column is loaded lightly, however, the size of the baseplate becomes smaller, the thickness becomes thinner and the bearing pressure of the baseplate is not distributed evenly. In this study, the distribution of the bearing pressure was investigated using the experimental and analytical methods. Four test specimens of the rectangular steel column baseplate were fabricated and tested. The analysis of the specimens was done using the finite element analysis program ANSYS. The result was that it was appropriate to use the effective width method to design the lightly loaded column baseplate, because the bearing pressure was not distributed evenly and was only concentrated under the column section.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.17-20
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• 2008

This study presents experimental results of Steel-PSC hybrid beams having a rear plate joint with a perfobond rib shear connector between the steel girder and the prestressed concrete girder. Three specimens of 3.9m length(3.6m span length) were tested to evaluate the flexural characteristics of the joint under the condition of the three point loading. Based on load-deflection curves and failure modes of specimens by the experimental test, it is found that the proposed joint with the perfobond rib shear connector shows the higher strength and initial stiffness and the sufficient ductility. Therefore, the suggested perfobond rib shear connector can perform effectively as the joint of the Steel-PSC hybrid structural system.

• Journal of Korean Society of Steel Construction
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• v.28 no.4
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• pp.231-242
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• 2016

Earthquake resistance of RC column-steel beam (RCS) joints with simplified details were studied. Simplified details are necessary for large columns to improve the productivity and constructability. To strengthen the beam-column joint, the effects of transverse beams, studs, and U-cross ties were used. Four 2/3 scale interior RCS connections were tested under cyclic lateral loading. The specimens generally exhibited good deformation capacity exceeding 4.0% story drift ratio after yielding of both beam and beam-column joint. Ultimately, the specimens failed by shear mechanism of the joint panel. The test strengths were compared with the predictions of existing design methods.

• Tunnel and Underground Space
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• v.19 no.2
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• pp.158-166
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• 2009

As a basic study for investigating the development of the stress-induced crack in Hoek-Brown rock, a homogenization technique of elastic cracks is proposed. The onset of crack is monitored by Hoek-Brown empirical criterion, while the orientation of the crack is determined by the critical plane approach. The concept of volume averaging in stress and strain component was invoked to homogenize the representative rock volume which consists of intact rock and cracks. The formulation results in the constitutive relations for the homogenized equivalent anisotropic material. The homogenization model was implemented in the standard FEM code COSMOSM. The numerical uniaxial tests were performed under plane strain condition to check the validity of the propose numerical model. The effect of friction between the loading plate and the rock sample on the mode of deformation and fracturing was examined by assuming two different contact conditions. The numerical simulation revealed that the homogenized model is able to capture the salient features of deformation and fracturing which are observed commonly in the uniaxial compression test.

• Journal of Korean Society of Steel Construction
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• v.16 no.5 s.72
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• pp.695-703
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• 2004

In this paper, the results of monotonic loading analysis with four steel models and one composite model were shown. The effect that moment transfer efficiency of a web and strain concentration at a steel beam-to-column connections was investigated. Analysis results showed that the moment transfer efficiency of the analytical model with box-column was poor when comparing to model with H-column due to out-of-plane deformation of the box-column flange. The presence of scallop, thin plate of box column and floor slabs was also a reason of the decrease of moment transfer efficiency, which would result in a potential fracture of the steel beam-to-column connections. Analytical results were compared with experimental results based on previous test. As a result, the deformation capacity of connections with a box-column or a floor slab decreased due to the poor moment transfer efficiency and the strain concentration of beam flange in the vicinity of the steel beam-to-column connections based on the experimental data.

• Journal of Korean Society of societal Security
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• v.3 no.1
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• pp.33-42
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• 2010

This study predicts the stress history for truss bridge with local damages by using global-local model combination method. For this end, the global structure is modeled by 3D frame elements and the selected local details are modeled by shell elements. Then superposition principle enable the global-local model to be combined interactively. Because the frame model cannot consider the rigidity of gusset plate and the interation of structural members due to the complexity of stress distribution in truss connection. The section modification factors are proposed to calibrate the stiffness of global frame element. The global-local model combination is verified by comparing the numerical results with experimental data obtained from the proof loading test to the operating truss bridge. Furthermore, stress histrories of the truss bridge are generated in the consideration of the rigidity of truss connection with local damage by using the combination method.

• Journal of the Korean Geosynthetics Society
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• v.13 no.2
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• pp.41-47
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• 2014

Various prediction methods for the bearing capacity of helical piles have been introduced with consideration of both the steel shaft and the helix plates attached to the shaft. In this paper, three representative methods, that is, individual bearing method, cylindrical shear method, and torque correlation method are discussed and compared to each other. The prediction methods were verified by comparing with a series of loading test results performed on moderate-size helical piles from the companion paper. As a result, the measured bearing capacity is greater than the bearing capacity predicted by the cylindrical shear method, but smaller than that of the individual bearing method. In addition, the bearing capacity predicted by the torque correlation method is in good agreement with the measured bearing capacity.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.2_2
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• pp.333-340
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• 2023

Environmental regulations are being strengthened worldwide to solve global warming. For this reason, interest in eco-friendly gas fuels such as LNG and hydrogen is continuously increasing. However, when adopting eco-friendly gas fuel, liquefying at a cryogenic temperature is essential to ensure economic feasibility in storage and transportation. Although austenitic stainless steel is typically applied to store cryogenic liquefied gas, structural steel can experience sudden heat shrinkage in the case of leakage in the loading and unloading process of LNG. In severe cases, the phase of the steel may change, so care is required. This study conducted Charpy impact tests on steel material in nine different temperature ranges, from room to cryogenic temperatures, to analyze the effects of cryogenic liquefied gas leaks. As a result of the study, it was not easy to find variations in ductile to brittle transition temperature (DBTT) due to the leakage of cryogenic liquefied gas. Still, the overall impact toughness tended to decrease, and these results were verified through fracture surface analysis. In summary, brittle fracture of the steel plate may occur when a secondary load is applied to steel for hull structural use exposed to a cryogenic environment of -40 ℃ or lower. Therefore, it needs to be considered in the ship design and operating conditions.