• Journal of the Korean Society of Hazard Mitigation
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• v.7 no.5
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• pp.27-35
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• 2007

This study presents a non -prismatic beam element for modeling the elastic and inelastic behavior of the steel beam, which has the post-Northridge connections in steel moment frames that are subjected to earthquake ground motions. The elastic stiffness matrix for non-prismatic members with reduced beam section (RES) connection is in the closed-form. The plasticity model is of a discrete type and is composed of a series of nonlinear hinges connected by rigid links. The hardening rules can model the inelastic behavior for monotonic and random cyclic loading, and the effects of local buckling. Verification and calibration of the model are presented in a companion paper.

• Structural Engineering and Mechanics
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• v.5 no.4
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• pp.415-431
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• 1997

Stability equations that evaluate the elastic critical axial load of stepped columns under extreme and intermediate concentrated axial loads in any type of construction with sidesway totally inhibited, partially inhibited and uninhibited are derived in a classical manner. These equations can be utilized in the stability analysis of framed structures (totally braced, partially braced, and unbraced) with stepped columns with rigid, semirigid, and simple connetions. The proposed column classification and the corresponding stability equations overcome the limitations of current methods which are based on a classification of braced and unbraced columns. The proposed stability equations include the effects of: 1) semirigid connections; 2) step variation in the column cross section at the point of application of the intermediate axial load; and 3) lateral and rotational restraints at the intermediate connection and at the column ends. The proposed method consists in determining the eigenvalue of a $2{\times}2$ matrix for a braced column at the two ends and of a $3{\times}3$ matrix for a partially braced or unbraced column. The stability analysis can be carried out directly with the help of a pocket calculator. The proposed method is general and can be extended to multi-stepped columns. Various examples are include to demonstrate the effectiveness of the proposed method and to verify that the calculated results are exact. Definite minimum bracing criteria for single stepped columns is also presented.

• Interaction and multiscale mechanics
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• v.3 no.4
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• pp.365-372
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• 2010

Station is an important building in high-speed railway, and its vibration and noise may significantly affect the comfort of waiting passengers. A coupling vibration model for train-structure system is established to analyze and evaluate the vibration level of a typical waiting hall under dynamic train load. The motion of a four-axle vehicle with two suspension system is modeled in multi-body dynamics with linear springs and dampers employed. The station is modeled as a whole finite element structure which is 113 m in longitudinal and 163.5 m in lateral, and the stiffness of the station foundation is considered. According to the assumptions that both wheel and rail are rigid bodies and keep contact to each other in vertical direction, and the wheel/rail interaction and displacement coordination in horizontal direction is defined by the simplified Kalker creep theory, the vehicle spatial vibration model has 27 degrees-of-freedom. An overall analysis procedure is made of the train moving through the station, by which the dynamic responses of the train and the station are calculated. According to the comparison between analysis and test results, the actual connection status between different parts of the station is estimated and the vibration level of the waiting hall is evaluated.

• Journal of the Korean Society of Safety
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• v.31 no.1
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• pp.74-80
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• 2016

In this paper, structural characteristics for an extradosed prestressed concrete box girder bridge are investigated in terms of selective parameters. These parameters are mainly associated with the structural details of the extradosed bridge and derived from currently available literatures regarding previous design drawings. The analyses have been carried out using general-purpose structural analysis program, RM-Space Frame. The parameters evaluated for the present study represent the most salient features of the extradosed bridge and are as follows; 1) span length ratio(side-span length to center-span length), 2) boundary condition of girder, 3) height of pylon, 4) anchorage location of external cables and 5) girder stiffness. The analytical predictions indicate that span length ratio and pylon height are reasonably adequate in the range of 0.55 to 0.60 and $L_m/8$ to $L_m/12$ respectively for the bridge under consideration. Also, demonstrated is the boundary condition of girder, in which rigid-connection details give more efficiency than the continuous details. In addition, considering structural characteristics of the extradosed bridge, it is desirable that the girder stiffness should be determined by the stress range of external cables rather than bending moment of girder.

• Journal of the Korean Wood Science and Technology
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• v.23 no.2
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• pp.12-18
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• 1995

고도(高度)의 엔지니어링 구조물(構造物)로 경제성이 높은 경량(輕量) 목조(木造)트러스에 사용될 수 있는 소나무(Pinus densiflora) 재(材)에 적용한 20게이지 아연도금 강(鋼) 플레이트 접합부(接合部)의 조합하중(組合荷重) 및 모멘트 성능(性能)을 평가하기 위하여 정밀도를 개선(改善)한 편심가력(偏心加力) 장치(裝置)를 창안하여 실험하고 반강절(半剛節) 접합부의 개념(槪念)과 가상(假想)일 법(法)을 적용한 모형을 유도하여 비선형(非線形) 해석(解析)하였다. 반강절(半剛節) 접합부(接合部)의 개념을 도입하여 저자가 유도한 비선형(非線形) 모형으로 조합하중 하에서의 접합부 거동을 해석한 결과, 금속 플레이트 접합부의 모멘트는 Wolfe 모형에 비하여 정확도가 높은 값으로 계산되었는데, 이는 비선형모형에서 접합부의 반강성(半剛性)에 의한 2차적인 모멘트의 영향을 적절히 고려한 때문으로 판단되었다. 본 연구에서 사용한 실험장치는 조합하중에 대한 금속 플레이트 접합부의 성능을 평가하기 위한 표준시험법(標準試驗法)으로 적용될 수 있을 것이며, 비선형(非線形) 해석방법(解析方法)은 조합하중(組合荷重)및 모멘트 성능(性能)을 예측(豫測)하는데 활용될 수 있다.

• Steel and Composite Structures
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• v.20 no.1
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• pp.107-125
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• 2016

Steel shear wall system has been used in recent years in tall buildings due to its appropriate behavior advantages such as stiffness, high strength, economic feasibility and high energy absorption capability. Coupled steel plate shear walls consist of two steel shear walls that are connected to each other by steel link beam at each floor level. In this article the frames of 3, 10, and 15 of (C-SPSW) floor with rigid connection were considered in three different lengths of 1.25, 2.5 and 3.75 meters and link beams with plastic section modulus of 100% to the panel beam at each floor level and analyzed using three pairs of accelerograms based on nonlinear dynamic analysis through ABAQUS software and then the performance of walls and link beams at base shear, drift, the period of structure, degree of coupling (DC) and dissipated energy evaluated. The results show that the (C-SPSW) system base shear increases with a decrease in the link beam length, and the drift, main period and dissipated energy of structure decreases. Also the link beam length has different effects on parameters of coupling degrees.

• Steel and Composite Structures
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• v.24 no.4
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• pp.425-439
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• 2017

As a thin-walled structure, local joint flexibility (LJF) in a tubular structure is prominent, and it may produce significant effect on the static performance for the overall structure. This study presents a simplified analytical model to analyze the static behavior for a steel tubular structure with LJF. The presented model simplifies a tubular structure into a frame model consisted of beam elements with considering the LJFs at the connections between any two elements. Theoretical equations of the simplified analytical model are deduced. Through comparison with 3-D finite element results of two typical planar tubular structures consisted of T- and Y-joints respectively, the presented method is proved to be accurate. Furthermore, the effect of LJF on the overall performance of the two tubular structures (including the deflection and the internal forces) is also investigated, and it is found from analyses of internal forces and deformation that a rigid connection assumption in a frame model by using beam elements in finite element analysis can provide unsafe and inaccurate estimation.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.10a
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• pp.219-224
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• 2002

This paper aims to derive a mathematical model of the dynamics of handling tasks in robot finger which stable grasping and manipulates a rigid object with some dexterity. Firstly, a set of differential equation describing dynamics of the manipulators and object together with geometric constraint of tight area-contacts is formulated by Lagrange's equation. Secondly, problems of controlling both the internal force and the rotation angle of the grasped object under the constraints of area-contacts of tight area-contacts are discussed. The effect of geometric constraints of area-contacts on motion of the overall system is analyzed and a method of computer simulation for overall system of differential-algebraic equations is presented. Thirdly, simulation results are shown and the effects of geometric constraints of area-contact is discussed. Finally, it is shown that even in the simplest case of dual single D.O.F manipulators there exists a sensory feedback from sensing data of the rotational angle of the object to command inputs to joint actuators and this feedback connection from sensing to action eventually realizes secure grasping of the object, provided that the object is of rectangular shape and motion is confined to a horizontal plane.

• Earthquakes and Structures
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• v.20 no.2
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• pp.201-213
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• 2021

Contrast to the conventional jointed bridge design, integral abutment bridges (IABs) offer some marked advantages like reduced maintenance and enhanced service life of the structure due to elimination of joints in the deck and monolithic construction practices. However, the force transfer mechanism during seismic and thermal movements is a topic of interest owing to rigid connection between superstructure and substructure (piers and abutments). This study attempts to model an existing IAB by including the abutment backfill interaction and soil-foundation interaction effects using Winkler foundation assumption to determine its seismic response. Keeping in view the significance of abutment behavior in an IAB, the probability of damage to the abutment is evaluated using fragility function. Incremental Dynamic Analysis (IDA) approach is used in this regard, wherein, nonlinear time history analyses are conducted on the numerical model using a selected suite of ground motions with increasing intensities until damage to abutment. It is concluded from the fragility analysis results that for a MCE level earthquake in the location of integral bridge, the probability of complete damage to the abutment is minimal.

• Journal of the Korean Society of Food Culture
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• v.25 no.6
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• pp.639-651
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• 2010

This study investigated women's magazines and women's food consumption stories of the 1950/s. That is, it attempted to comprehend the connection between the public and private aspects of food consumption as discussed in the 1950's. The public aspect of culture was investigated using the women's magazine "Yeo-won" which reflected the social and intellectual hegemony of the time. The private aspects of culture were investigated by reviewing the daily life of women though in-depth interviews. Mass media reflected the social and intellectual hegemony and indicated that a cultivated woman who supported western food was a wise mother and a good wife, and that a woman who consumed flour-based food was a reasonable and modern consumer, ahead of her time The admiration for the U.S. and its advanced civilization through free handouts of flour and powdered milk accelerated the consumption of industrialized flour-based foods such as noodles, hardtack, and steamed bread. This lead to the rigid traditional food-eating habits of boiled rice, and side dishes changed to flour-based and processed foods. That is, food represented a cultural identity.