• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.163-171
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• 2006

The behaviors and design procedures of building excavation plane in innovative prestressed support (IPS) system are presented in this paper. Determination procedure for initial pretension in IPS wale subjected to design earth pressure is derived. The computer analysis model under uniform and non-uniform earth pressure is constructed using beam element for the IPS wale, tension-only element for cable, and compression-only element for soil. Axial forces and bending moments of IPS wale under initial pretension and design earth pressure are calculated. The combined stresses due to these axial force and bending moment are calculated and safety condition of building excavation plane is investigated.

• Journal of Korean Society of Steel Construction
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• v.21 no.5
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• pp.483-492
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• 2009

In this study, nonlinear analysis of steel plane frame was performed using the refined plastic hinge method of advanced analysis techniques. In deterioration of stiffness in plastic zone, influences by flexural bending, residual stress, geometrical non-linearity, and semi-rigid connection are considered. And also, further reduced tangent modulus was used for geometrical non-linearity, top and seat angle were chosen for semi-rigid connection. Furthermore, 3 parameter power model was used for moment-rotation behaviour of beam to column connection. The loading conditions are combined with axial and lateral force and the inverse triangle distribution of lateral and eight type of analytical models were used in analysis. The results of analyses were compared with semi-rigid and rigid connection on behaviour of numerical analysis models. And also, the behaviors of frame with changes of semi-rigidity were analyzed by using the results obtained from MIIDAS-GENw.

• Journal of Korean Society of Steel Construction
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• v.11 no.4 s.41
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• pp.397-407
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• 1999

In this paper, the fatigue safety in the suspension bridge is investigated by using nominal and variable stress, respectively. The technique on structural modeling and the fatigue evaluation using nominal stress are mainly dealt with in this paper. To make the finite element analysis model reflecting the actual structural behavior of the suspension bridge with cross frame, the parametric study is carried out. In this study, the influence of supporting condition. the difference of the results of 2- and 3-D analysis and the number of cross frames modelled in are considered. The nominal stress under the real traffic flow of the bridge is calculated by the combination of the stresses due to the unit DB-24 loading. The nominal stresses for details under consideration are compared with allowable stress ranges specified in the codes and the results are discussed.

• Journal of the Korean Geotechnical Society
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• v.18 no.1
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• pp.41-48
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• 2002

Anisotropy of stiffness, from extremely small strains to post-failure strains, of isotropically consolidated air-pluviated sands in plane strain compression was studied by using the newly developed instrumentation fur small strain measurements, Seven types of sand of world-wide origins were tested, which have been extensively used for research purposes. Stress-strain relationships for a wide range of strain from about 0.0001% to the peak were obtained by measuring axial and lateral strains locally free from the effects of bedding and membrane penetration errors at the specimen boundaries. The result showed that the relationship between the principal stress ratio and the principal strain increment ratio was constant, being rarely affected by the over-consolidation ratio and the confining pressure. Although in the small strain the anisotropy hardly affected the relationship between the principal stress ratio and the principal strain increment ratio, the K value around the peak varied according to the $\delta$ value. In general, Rowe\`s stress-dilatancy equation works fairly well from the small strain to the peak.

• Journal of the Korean Geotechnical Society
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• v.36 no.4
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• pp.5-15
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• 2020

This paper proposes a revised Modified Cam Clay type failure surface based on the critical state theory. In the plane of the mean effective and von Mises stresses, the original Modified Cam Clay model has an elliptic failure surface which leads the critical-state mean effective stress to be always half of the pre-consolidation mean effective stress without hardening and evolution rules. This feature does not agree with the real mechanical response of clay. In this study, the preconsolidation mean effective stress only reflects the consolidation history of the clay whereas the critical state mean effective stress only relies on the currenct void ratio of clay. Therefore, the proposed failure surface has a distorted elliptic shape without any fixed ratio between the preconsolidation and critical state mean effective stresses. Numerical simulations for various clays using failure surfaces as yield surface provide mechanical responses similar to the experimental data.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.29 no.4A
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• pp.267-279
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• 2009

A numerical model that can simulate the nonlinear behavior of ultra high strength fiber reinforced concrete (UHSFRC) structures subjected to monotonic loading is introduced. The material properties of UHSFRC, such as compressive and tensile strength or elastic modulus, are different from normal strength reinforced concrete. The uniaxial compressive stress-strain relationship of UHSFRC is designed on the basis of experimental result, and the equivalent uniaxial stress-strain relationship is introduced for proper estimation of UHSFRC structures. The steel is uniformly distributed over the concrete matrix with particular orientation angle. In advance, this paper introduces a numerical model that can simulate the tension-stiffening behavior of tension part of the axial member on the basis of the bond-slip relationship. The reaction of steel fiber is considered for the numerical model after cracks of the concrete matrix with steel fibers are formed. Finally, the introduced numerical model is validated by comparison with test results for idealized UHSFRC beams.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.3
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• pp.115-121
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• 2001

In micro automation technology, the concurrent realization of a high resolution and a large operating rage has been achieved by a dual actuator, usually called by piggy-back system, conventionally. But, because of its manufacturing cost, the complexity of control, and the limit of overall bandwidth, the contract-free and single servo actuators have been suggested with specific applications. In this paper, we suggest a novel non-contact surface actuator suing combination of the Lorentz force and the magnetized force, and discuss the actuating principles including an analytical approach. Differently from the existing planar system, an operating range of the suggested system can be expanded by an additional attachment of active elements. Therefore, it is estimated to be suitable for the next-generation moving system.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.11
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• pp.2871-2882
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• 1994

Two kinds of 4-node plane stress/strain finite elements are presented in this work. They are derived from the modified Hellinger-Reissner variational principle so as to employ the internal incompatible displacement and independent stress fields, or the incompatible displacement and strain fields. The introduced incompatible functions are selected to satisfy the constant strain condition. The elements are evaluated on several problems of bending and material incompressibility with regular and distorted elements. The results show that the new elements perform excellently in the calculation of deformation and stresses.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.1
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• pp.187-194
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• 2001

The objective of this study is to develop a model for the grinding process for predicting the temperature, thermal stress and thermal deformation. The thermal load during grinding is modeled as uniformly distributed, 2D heat source moving across the surface of elastic half space, which is insulated or subjected to convective cooling. That non-dimensional temperature distribution, non-dimensional longitudinal stress distribution and non-dimensional thermal deformation distribution are calculated with non-dimensional heat source half width and non-dimensional heat transfer coefficient. Finite element models are developed to simulate moving heat source, which is modeled as uniformly or triangularly distributed, the FEM simulation is compared with numerical solution.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.12 no.3
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• pp.457-464
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• 1999

The object of this study is form finding, stress-strain analysis and cutting pattern analysis of membrane structures under the following assumptions : (1) material is linearly elastic (2) stress state is plane stress. The cable and membrane structures undergo large deformation because of its highly flexibility, therefore, we must take account of its geometric nonlinearity. The analysis procedure is consisted of three steps considering geometric nonlinearity unlike any other structures. First step is the form finding analysis to determine the initial equilibrium shape. Second step is the stress-strain analysis to investigate the behaviors of structures under various external loads. Once a stationary shape has been fount a cutting pattern based on the form finding analysis may be generated for manufacturing procedure. In this paper, form finding, stress-strain analysis and cutting pattern analysis is carried out for applying to Seoguipo worldcup soccer stadium roof structures and optimal cutting pattern analysis technique is proposed.