• Journal of the Korean GEO-environmental Society
• /
• v.21 no.12
• /
• pp.5-10
• /
• 2020

In this study, the evolution of soil engineering property values according to excavation was analyzed through the inverse analysis for the OO deep excavation site located in Incheon. The stiffness of the ground was updated by comparing the horizontal wall deformation of the excavation support wall calculated by the finite element analysis at each stage of excavation and the value measured using an inclinometer. The updated stiffness was used to predict the response of the excavation support wall in the next excavation step. The finite element analysis method using the Hardening Soil model was used, and the stratum where the excavation support wall is located was selected as the stratum for the inverse analysis. The inverse analysis results showed that the stiffness value at the stiffness value at the initial stage of excavation is larger than the stiffness used in the original design. As the excavation proceeds, the stiffness calculated through the second inverse analysis was found to decrease compared to the value derived by the first inverse analysis. Therefore, it can be stated that the deformation of the excavation support wall can be accurately calculated through finite element analysis when an appropriate stiffness value is input according to the excavation stage.

• Journal of the Korean Society for Railway
• /
• v.14 no.4
• /
• pp.333-340
• /
• 2011

The purpose of this paper is to develop two kinds of finite element models for the heavy deformable obstacle defined in grade crossing collision scenario of the Europe TSI and the Korean rolling stock safety regulations and to apply the crashworthiness evaluation for the Korean high-speed EMU with the FE model. The numerical models of the heavy obstacle were changed from a past rigid one to a current deformable one whose stiffness requirement should be verified by a collision simulation defined in the regulations. Through several trial simulations, two types of numerical models for the heavy obstacle were developed, which satisfied physical properties specifies in the regulations. One is a solid-type obstacle with uniform density and the other is a shell-type. With the obstacles developed in this study, the grade crossing collision scenario for Korean high-speed EMU was simulated and evaluated for the two-type obstacle models. From the simulation results, the shell and solid-type obstacles showed quite different behaviors after collision, and the shell type model gave more severe results.

• Composites Research
• /
• v.17 no.2
• /
• pp.9-14
• /
• 2004

In this study, analytical investigations on the flexural behavior of FRP reinforced concrete slab were discussed. In the derivation of analytic solution, the FRP reinforced concrete slab was modeled as a structural orthotropic plate. To determine the flexural rigidities of an orthotropic plate model, the elastic equivalence method was employed. In the finite element analysis, the approximate method to determine the rigidity matrix of orthotropic plate element was also suggested using the elastic equivalence method. The results obtained by the analytical solution and the finite element analysis were compared with that of experiment.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.10 no.3
• /
• pp.106-114
• /
• 2006

This study proposed the applicability of inverse stiffness method on the seismic design for steel frame with buckling restrained braces and the design results were compared with former research's. The concept of this method is simple and efficient. Furthermore it is able to reflect the high mode's effect and control the ductility factors of each story individually. Design results using the proposed method showed that according to increase of the given target drift, the areas of brace generally decreased but partially increased in some stories of the tall structure with very large ductility. And the post yield stiffness ratio's variation had more effect on the design results in the small post yield stiffness ratio.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 1998.04a
• /
• pp.194-199
• /
• 1998

축어긋남이 있는 회전체-볼베어링계에 대한 동적모델을 이용하여, 각축어긋남에 의한 2x 축진동현상을 조사하였다. 이때 유효베어링강성계수를 정의하여 축어긋남과 불균형량에 의해 발생되는 강성계수의 평균과 동기 변화성분을 운동방정식에 도입하였다. 수치해석과 실험결과는 각축어긋남에 의한 바나나 형태의 선회궤적이 회전체계 임계속도의 1/2이 도는 속도영역에서 뚜렷이 나타나는 것을 보여주었다.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1997.05b
• /
• pp.520-525
• /
• 1997

액체금속로의 안전성과 경제성을 향상시키는데 중요한 요소로 부각된 면진설계기술을 개발하기 위하여 고감쇠 면진베어링의 축소모델을 제작하고, 성능확인을 위한 다양한 시험을 실시하였다. 면진베어링의 성능을 나타내는 전단강성, 감쇠특성, 항복하중특성값, 전단변형능력 등에 대한 시험결과 전단강성은 목표값에 비하여 작았지만 감쇠값과 전단변형은 목표값에 근접하였다. 이를 이용한 면진 원자로건물의 지진응답을 분석한 결과 면진베어링은 건물의 지진응답 가속도를 대폭 줄여주는 것으로 나타났다.

• Journal of the Korean GEO-environmental Society
• /
• v.18 no.8
• /
• pp.5-15
• /
• 2017

To perform an integrated load analysis carried out to evaluate the stability evaluation of wind turbine generators, the six degree-of-freedom stiffness matrix of foundation, which describes relationships between loads and displacement, is needed. Since the foundation stiffness should accurately reflect the shape of foundation and the condition of soil, it is necessary to calculate the stiffness of the bucket foundation that considers the elasto-plastic behavior of the soil. In this study, finite element analyses were performed for a range of soils and shapes of bucket foundations to estimate the foundation stiffness. Normalized stiffness curves are developed from respective numerical simulations. Proposed results are considered to be useful because they can be directly applied in the design.

• Journal of the Korea Concrete Institute
• /
• v.20 no.2
• /
• pp.213-219
• /
• 2008

The purpose of this study is to propose frame analysis method for flat plate slabs having edge beam under lateral loads. Flat plate system is defined as the system only with slab of uniform thickness and column. However, the slab system generally incorporate edge beams at exterior connection in actual design. ACI 318 (2005) allows three methods for conducting flat plate system analysis subjected to lateral loads. There are the finite element method (FEM), the equivalent frame method (EFM), and the effective beam width method (EBWM). Among methods, the EBWM enables us to analyze practically by substituting the actual slab to beam element. In this model, the beam element has a thickness equal to that of the slab, and effective beam width equal to some fraction of the slab transverse width. However, the established EBWM was generally proposed for variables of geometry or stiffness reduction factor and seldom proposed for the effect of edge beams. This study verifies that, in the case of flat plate system having edge beams at exterior connections, the lateral stiffness is considerably larger than without edge beams. Therefore it need to analysis method for considered the effect of edge beams. In this study, an analysis model is proposed for the flat plate system having edge beams under lateral loads by considering the effect of edge beams. To verify the accuracy of proposed model, this study compared results of the proposed EBWM with results of FEM of flat plate systems having edge beams under lateral loads. Also, the proposed approach is compared with experimental results of former research.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.26 no.4
• /
• pp.65-72
• /
• 2022

Recently, damage to buildings due to earthquakes in Korea occurred mainly in school buildings and Piloti-type multi-family houses, highlighting the need for seismic retrofit for buildings of the same type. In the early days of the seismic retrofit project for school facilities, various patented methods using dampers as a ductile seismic retrofit method were applied without sufficient verification procedures. However, in 「School Facility Seismic Performance Evaluation and Retrofit Manual, 2021」, when the patented method is applied, it must be applied through a separate strict verification procedure, and instead, the strength/stiffness retrofit method was induced as a general method. In practice,when evaluating seismic performance for retrofit by infilled steel frame with brace, the analysis model is constructed by directly connecting only the steel brace to the existing RC member. However, if the frame is removed from the analysis model of the infilled steel frame with brace, the force reduction occurring on the existing RC member near the retrofit is considered to be very large, and this is judged to affect the review of whether to retrofit the foundation or not. Therefore, in this study, preliminary analysis with variables such as whether or not steel frame is taken into account and frame link method for the analysis model of RC school building retrofitted by infilled steel frame with brace and nonlinear analysis for actual 3-story school building was performed, and basic data for rational analysis model setting were presented by comparing preliminary analysis and pushover analysis results for each variable.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.3
• /
• pp.159-181
• /
• 2012

The segment lining which consists of segments and joints are main component of shield tunnel. There are a number of methods that are being used in design which compute the sectional forces of a ring of segment lining. The traditional design methods which do not consider the effect of joints have been commonly used for design procedure without a specific verification of structural analysis. This paper presents the result of a comparative study for analytical and numerical models of the shield tunnel segment lining. For the traditional methods, the elastic equation method and the Duddeck & Erdmann method were considered. The ring-beam and the continuum analysis model were also considered as the numerical model.