• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.1
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• pp.101-113
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• 2013

This paper intends to develop mechanical analysis models that are able to predict complete nonlinear behavior in the bolted connector subjected to cyclic loads. In addition, experimental data which were obtained from loading tests performed on the T-stub connections are utilized to validate the accuracy of analytical prediction and the adequacy of numerical modeling. The behavior of connection components including tension bolt uplift, bending of the T-stub flange, stem elongation, relative slip deformation, and bolt bearing are simulated by the multi-linear stiffness models obtained from the observation of their individual force-deformation mechanisms in the connection. The component springs, which involve the stiffness properties, are implemented into the simplified joint element in order to numerically generate the behavior of full-scale connections with considerable accuracy. The analytical model predictions are evaluated against the experimental tests in terms of stiffness, strength, and deformation. Finally, it can be concluded that the mechanical models proposed in this study have the satisfactory potential to estimate stiffness response and strength capacity at failure.

• The Journal of Engineering Geology
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• v.29 no.4
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• pp.451-460
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• 2019

In this study, a complex behavior connector is proposed to overcome the problems that may occur when small pile pipe and micro pile is used as a friction pile concept in the lower foundation of an oil sand plant where a piloti foundation is used. The individual settlement and heaving of piles were connected in one group to allow the composite behavior. This study performed to analyze the load carrying capacity to identify a complex behavior. In addition, the shape of the composite behavior connector was examined to apply the advantages of pile-group and piled raft foundations to oil sand plants. A scale model was constructed to measure the behavior of the load. The stability and weakness of the device were selected to determine the shape of the connector using the scale model testing.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.7
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• pp.9-16
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• 2017

To improve concrete-filled tube (CFT) columns, an octagonal concrete-filled tube (OCFT) column was developed. Because the OCFT column requires a small boring diameter, the OCFT column is suitable for Top-Down construction method. In this study, the compression performance of OCFT column to be used as Top-Down pile foundation was verified using centrifuge equipment. Under 12 g centrifugal acceleration, the bearing capacities of the pile foundations of OCFT and H-shaped sections were tested. When the pile foundations were embedded in soil of full depth, 45 % of the design strength, which was assumed to be the construction load, was supported by the OCFT and H-shaped sections in the elastic states. When the pile foundations were embedded in soil of half depth, the buckling of the pile foundations was not investigated. After the loading test, the rock at the bottom of pile foundation, which had a strength of 3.5 MPa, was not damaged due to 45 % of the design strength.

• Journal of the Earthquake Engineering Society of Korea
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• v.3 no.3
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• pp.75-86
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• 1999

An analysis model is developed to evaluate the dynamic responses of a bridge system under seismic excitations, in which pounding actions between girders are considered in addition to other phenomena such as nonlinear pier motion, rotational and translational motions of foundations. The model also considers the abutment and restrainers connecting adjacent girders to prevent the unseating failures. Using the developed model, the longitudinal dynamic behaviors of a bridge system are examined for various peak ground accelerations, and the effects of the applied restrainers are investigated. It is found that the restrainers reduce the relative displacement with the shorter clearance length as well as the higher stiffness of the restrainers for moderate excitations. However, in the region with strong excitations the restrainers may yield due to the large relative displacement. Therefore, the extension of support length in addition to restrainers may need to prevent the unseating failure more effectively.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.2
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• pp.87-94
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• 1998

Behavioral characteristics of shallow circular arches with dynamic loading and different end conditions are analysed. Geometric nonlinearity is modelled using Lagrangian description of the motion. The finite element analysis procedure is used to solve the dynamic equation of motion, and the Newmark method is adopted in the approximation of time integration. The behavior of arches is analysed using the buckling criterion and non-dimensional time, load and shape parameters which Humphreys suggested. But a new deflection-ratio formula including the effect of horizontal displacement plus vertical displacement is presented to apply for the non-symmetric buckling problems. Through the model analysis, it's confirmed that fix-ended arches have higher buckling stability than hinge-ended arches, and arches with the same shape parameter have the same deflection ratio at the same time parameter when loaded with the same parametric load.

• Journal of the Korean Geotechnical Society
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• v.19 no.5
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• pp.15-26
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• 2003

Urban excavation requires highly reliable prediction technique for the design and construction of earth retaining structure in order to protect adjacent structures around deep excavation. Application of the pre-loading of bracing for deep excavation has been reported, and the known beneficial effects are not fully understood and recognized by many practitioners. Model tests have been carried out to evaluate the efficiency of pre-loading system in reducing ground settlement as well as prediction of structural damage around excavation in sand. The test results revealed that the applied pre-loading of 50% and 70% showed about 20% of reduction in horizontal wall displacement and 30∼40% reduction in ground settlement. Also, bracing forces and earth pressure distribution behind the wall have been monitored during pre-loading at various excavation stages.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.13 no.4
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• pp.437-448
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• 2000

In this study, a numerical analysis method for soil-pile interaction in frequency domain problem is presented. The total soil-pile interaction system is divided into two parts so called near field and far field. In the near field, beam elements are used lot a pile and plain strain finite elements for soil. In the far field, dynamic fundamental solution for multi-layered half planes based on boundary element formulation is adopted lot soil. These two fields are coupled using FE-BE coupling technique. In order to verify the proposed soil-pile interaction analysis, the dynamic responses of pile on multi-layered half planes are simulated and the results are compared with the experimental results. Also, various numerical analyses of piles considering different conditions of soil-pile interaction system are performed to examine the dynamic behavior of the system. It has been found that the developed method which satisfies the radiation conditions of multi-layered half planes can be applied to various structure systems effectively in frequency domain.

• Journal of the Korean Geosynthetics Society
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• v.10 no.1
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• pp.43-51
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• 2011

Pile-supported embankment is one of the reinforcing methods to minimize damage due to the severe subsidence and lateral flow when soft clay ground is supported with embankment. pile-supported embankment mainly penetrates soft ground into the bearing stratum in order to support surcharge load which minimizes the subsidence and lateral flow due to the surcharge load. The aim of this research is to review quantitatively reinforcing effect of pile-supported embankment which is installed in soft clay ground. From the model test, it reproduced the ground movement with regard to the non-reinforced and reinforcing embankment-pile and also analyzed stabilizing effects of lateral flow due to the pile-supported embankment. With regard to the case of installing pile-supported embankment, its were analyzed stabilizing effects of lateral flow in cases of quick-load and slow-load to make different surcharge load.

• Journal of the Korean Geosynthetics Society
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• v.19 no.1
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• pp.55-63
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• 2020

In this study, a scaled model test of the shaking table and a seismic analysis considering effective stresses were performed to reveal the dynamic behavior characteristics of box structures deep located in multi-layered soils upon seismic loading. The input seismic wave was operated below the ground using five seismic waves, including long period wave (Hachinohe), short period wave (Ofunato), artificial wave and real earthquakes that occurred in Gyeong-ju and Po-hang. As a result of model test and numerical analysis, the vertical displacement of box structures upon seismic loading was greater than that of horizontal direction, and it was confirmed that an increase of excess pore water pressure below the foundation ground caused a displacement. In addition, behavior of the ground and structures during artificial seismic wave appeared to be larger than real earthquake wave.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.5
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• pp.237-242
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• 2016

This paper introduces a method of measuring the displacement of a cable-stayed bridge using digital image processing (DIP). The validity of the DIP technique was confirmed by comparing the results with those obtained using a displacement meter and ANSYS analysis. The normalized cross-correlation (NCC) coefficient was used. 100 kgf and 200 kgf loading experiments were carried out, which showed that when the displacement is large, the reliability of the DIP technique is increased. That is, when the load was increased from 100 kgf to 200kgf, it decreased from 31% to 14% compared to the ANSYS results and from 14% to 4% compared to the displacement meter results. Therefore, the image processing method is able to measure the displacement sufficiently accurately.