• Steel and Composite Structures
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• 제25권2호
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• pp.245-255
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• 2017

The performance of an Industrialised Building System (IBS) consists of prefabricated reinforced concrete components, is greatly affected by the behaviour of the connection between beam and columns. The structural characteristics parameters of a beam-to-column connection like rotational stiffness, strength and ductility can be explained by load-rotation relationship of a full scale H-subframe under gravitational load. Furthermore, the connection's degree of rigidity directly influences the behaviour of the whole frame. In this research, rotational behaviour of a patented innovative beam-to-column connection with unique benefits like easy installation, no wet work, no welding work at assembly site, using a hybrid behaviour of steel and concrete, easy replacement ability, and compatibility with architecture was investigated. The proposed IBS beam-to-column connection includes precast concrete components with embedded steel end connectors. Two full-scale H-subframes constructed with a new IBS and conventional cast in-situ reinforced concrete system beam-to-column connections were tested under incremental static loading. In this paper, load-rotation relationship and ratio of the rigidity of IBS beam-to-column connection are studied and compared with conventional monolithic reinforced concrete connection. It is concluded that this new IBS beam-to-column connection benefits from more rotational ductility than the conventional reinforced concrete connection. Furthermore, the semi-rigid IBS connection rigidity ratio is about 44% of a full rigid connection.

• Structural Engineering and Mechanics
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• 제71권3호
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• pp.233-244
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• 2019

Steel jacketing technique is a retrofitting method often employed for static and seismic strengthening of existing reinforced concrete columns. When no continuity is given to angle chords as they cross the floor, the jacket is considered "indirectly loaded", which means that the load acting on the column is transferred partially to the external jacket through interface shear stresses. The evaluation of load transfer mechanism between core and jacket is not straightforward to be modeled, due to the absence of knowledge of a proper constitutive law of the concrete-to-steel interface and to the difficulties in taking into account the mechanical nonlinearities of materials. This paper presents an incremental analytical/numerical approach for evaluating the compressive response of RC columns strengthened with indirectly loaded jackets. The approach allows calculating shear stresses at the interface between core and jacket and predicting the axial capacity of retrofitted columns. A proper constitutive law is proposed for modelling the interaction between the steel and the concrete. Based on plasticity rules and the non-linear behaviour of materials, the column is divided into portions. After a detailed parametric analysis, comparisons are finally made by theoretical predictions and experimental results available in the literature, showing a good agreement.

• Structural Engineering and Mechanics
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• 제6권2호
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• pp.125-141
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• 1998

Recent test results of steel moment connections repaired with a haunch on the bottom side of the beam have been shown to be a very promising solution to enhancing the seismic performance of steel moment-resisting frames. Yet, little is known about the effects of using such a repair scheme on the global seismic response of structures. When haunches are incorporated in a steel moment frame, the response prediction is complicated by the presence of "dual" panel zones. To investigate the effects of a repair on seismic performance, a case study was conducted for a 13-story steel frame damaged during the 1994 Northridge earthquake. It was assumed that only those locations with reported damage would be repaired with haunches. A new analytical modeling technique for the dual panel zone developed by the author was incorporated in the analysis. Modeling the dual panel zone was among the most significant consideration in the analyses. Both the inelastic static and dynamic analyses did not indicate detrimental side effects resulting from the repair. As a result of the increased strength in dual panel zones, yielding in these locations were eliminated and larger plastic rotation demand occurred in the beams next to the shallow end of the haunches. Nevertheless, the beam plastic rotation demand produced by the Sylmar record of 1994 Northridge earthquake was still limited to 0.017 radians. The repair resulted in a minor increase in earthquake energy input. In the original structure, the panel zones should dissipate about 80% (for the Oxnard record) and 70% (for the Sylmar record) of the absorbed energy, assuming no brittle failure of moment connections. After repair, the energy dissipated in the panel zones and beams were about equal.

• 대한건축학회연합논문집
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• 제20권6호
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• pp.41-46
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• 2018

The context of innovation in which we evolve today, subtracts us in a spacial reality and virtuality (digital) that aimed less and less to interact with natural processes which could converge to new possible relationships in the world. We constantly live in presence of fluctuations and imperceptible natural energies (wind, solar radiation, etc.) defined by flows, their own physicality, which remains without being virtual, elusive. This study first outlines how these energies already exploited within the framework of production, could be thought as interactive of our habitat's space dimension, as a prolongation of a physical and material environment built by men and for men, giving rise to new social, cultural dynamics, and making natural complexity of our space vivid, comprehensible with new visual and physical clues. In recent days, where lifestyles are changing, architecture no longer needs to limit its scope of creation to only built structures. Based on a deeper understanding of human and through new potential advanced technologies (kinetic system, etc), it is time to fundamentally diagnose what environments or devices contribute to our lives. Architecture becomes ${\ll}interface{\gg}$, step up its fundamental role, and newly defines the sturdy image and tectonics of existing environment, establishing a stance to search for a new typology. In the end, building will show two simultaneous and distinctive connections related to its physical existence: reality in its function and irreductibility, in its ability to forge new dynamic connections with its environment, hybridizing the spatial dimension to a new form of physicality, adaptive and incessantly flexible in the dimension time, becoming a vessel for ever changing contemporary lifestyles.

• 산경연구논집
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• 제10권9호
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• pp.7-17
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• 2019

Purpose - In recent years, the bilateral political relationship between Vietnam and India was upgraded to strategic and comprehensive partnership. Thus, the purpose of this paper is to analyze current relations and prospects of the Vietnam-India trade. Research design, data and methodology - The data was mainly based on World Integrated Trade Solution (WITS) and Foreign Investment Agency of Vietnam Ministry of Planning and Investment (FIA) from 2010-2018. The relationship of the two countries has showed growth in all sectors, including trade cooperation. This paper focused on assessing the current relations of trade cooperation of the two countries and then andlyzed the prospects of trade cooperation in the next period. Result - The Indian Government's strategy shifted from "Look East" policy to "Look East" action by the end of 2015. Vietnam is a partner and a pillar of India's Look East policy (Muni, 2011). The governments of both countries should further strengthen exchanges and trade connections in order to provide cooperation opportunities for investors and businesses of the two countries. Conclusion - The paper discusses and gives an overview of the current status of the trade relations of Vietnam and India as well as lucidating the opportunities and challenges for two countries in the future.

• Structural Engineering and Mechanics
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• 제18권2호
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• pp.247-262
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• 2004

In the earlier application of the spline finite strip method(FSM), the uniform B3-spline functions were used in the longitudinal direction while the conventional interpolation functions were used in the transverse direction to construct the displacement filed in a strip. To overcome the shortcoming of the uniform B3-spline, non-periodic B-spline was developed as the displacement function. The use of non-periodic B3-spline function requires no tangential vectors at both ends to interpolate the geometry of shell and the Kronecker delta property is also satisfied at the end boundaries. Recently, non-periodic spline FSM which was modified to have a multiple knots at the boundary was developed for the shell analysis and applied to the analysis of bridges. In the formulation of a non-symmetric spline finite strip method, the concepts of non-periodic B3-spline and a stress-resultant finite strip with drilling degrees of freedom for a shell are used. The introduction of non-symmetrically spaced knots in the longitudinal direction allows the selective local refinement to improve the accuracy of solution at the connections or at the location of concentrated load. A number of numerical tests were performed to prove the accuracy and efficiency of the present study.

• 환경영향평가
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• 제21권1호
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• pp.185-199
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• 2012

Ecotourism has been attracting much attention as an example industry that can vitalize local economy markets and preserve natural resources. Implementation of 'Ecotourism Designation System' is under consideration to provide ecotourism products that can both emphasize the original meanings of ecotourism and ensure stronger trust from customers than ever before. This research introduced the direction, principles, subjects, and assessment indicators by subjects in terms of implementing the system and proposed fundamentals for both designation assignment and score calculation. In the face of implementing such a system in Korea, the investigation sought subjects whose target areas and programs are in need of examination. For assessment criteria by subjects, six assessment indicators were selected in the end for ecotourism sites, including: (1) the value of natural/ecological preservation (2) facility's ecological design (3) understanding both the environment and local culture (4) systems connecting local communities for cooperation (5) long/short term preservation and maintenance strategies/plans (6) willingness to further develop ecotourism and cooperative platform. In addition, seven assessment indicators were selected for program assignments, including: (1) the value of natural/ecological preservation (2) minimization of environmental effects (3) expansion of environmental understanding (4) sharing the local culture (5) vitalizing local connections and economical activities among communities (6) securing and maintaining professionality among human resources (7) odds of continuation, creativity, and aptness to improve programs. After considering the pros and cons of both categorizing system and yes/no system, implementation of categorizing system for the short term and yes/no for the long term were suggested, followed by additional suggestions of a score calculation system for each system. The official implementation of the 'Ecotourism Designation System' is scheduled for launch in 2013 after the trial operation in 2012. The assessment indicators and fundamentals suggested in this research, considering judgment, must be improved via systematic and practical methods through the trial operation.

• 한국구조물진단유지관리공학회 논문집
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• 제22권5호
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• pp.55-63
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• 2018

최근에 오스테나이트와 페라이트의 조직을 갖는 듀플렉스계 스테인리스강이 개발되었고 오스테나이트계 스테인리스강에 비해 고강도, 응력부식균열에 대한 고내식성과 재료비절감으로 다양한 산업분야에서 사용량이 증가되고 있다. 그러나, 현재 스테인리스강은 한국 건축구조기준에 구조용재료로 지정되어 있지 않고 구조설계기준도 마련되어 있지 않는 실정이다. 이 연구에서는 2행 1열 듀플렉스계 스테인리스강(STS329FLD) 볼트접합부에 대한 구조적 성능을 조사하기 위한 실험적 연구를 수행하였다. 주요변수는 전단접합형태(일면전단과 이면전단)과 하중방향 연단거리이다. 종국파단형태는 전형적인 블록전단파단, 인장파단과 면외변형이 관찰되었다. 일면전단 접합부에서 면외변형발생으로 최대 20%까지 내력저하가 발생되었다. 실험최대내력은 현행설계기준 AISC/AISI/KBC, EC3와 AIJ 및 기존연구자에 의한 제안된 식에 의한 예측내력과 비교하였다. 면외변형이 발생하지 않은 접합부에 대해서 실제 전단파단단면을 고려한 Clement & The의 식에 의한 예측내력이 실험내력에 가장 근접했고 면외변형을 동반한 접합부에 대해서는 면외변형을 고려해 제안한 Kim & Lim식에 의해서 과대평가하는 것으로 나타났다.

• Steel and Composite Structures
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• 제26권3호
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• pp.329-345
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• 2018

This paper systematically investigated the mechanical performance of the weak-axis cover-plate connection, including a beam end monotonic loading test and a column top cyclic loading test, and a series of parametric studies for exterior and interior joints under cyclic loading using a nonlinear finite element analysis program ABAQUS, focusing on the influences of the shape of top cover-plate, the length and thickness of the cover-plate, the thickness of the skin plate, and the steel material grade. Results showed that the strains at both edges of the beam flange were greater than the middle's, thus it is necessary to take some technical methods to ensure the construction quality of the beam flange groove weld. The plastic rotation of the exterior joint can satisfy the requirement of FEMA-267 (1995) of 0.03 rad, while only one side connection of interior joint satisfied ANSI/AISC 341-10 under the column top cyclic loading. Changing the shape or the thickness or the length of the cover-plate did not significantly affect the mechanical behaviors of frame joints no matter in exterior joints or interior joints. The length and thickness of the cover-plate recommended by FEMA 267 (1995) is also suitable to the weak-axis cover-plate joint. The minimum skin plate thickness and a design procedure for the weak-axis cover-plate connections were proposed finally.

• 대한수학교육학회지:수학교육학연구
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• 제23권2호
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• pp.213-235
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• 2013

본 연구는 수학과목 학습이 부진하고, 특히 함수식과 그래프의 관계에 대한 이해가 부족한 특성화 고등학생들을 대상으로 학생들에게 친숙한 엑셀 프로그램을 사용하여 지도한 효과를 살펴보았다. 엑셀의 식, 표, 그래프를 한 화면에 담을 수 있는 기능과 스크롤바를 이용하여 그래프를 움직이는 기능이 주로 사용되었다. 함수개념을 과정관점과 대상관점으로 나누고, 함수 표상을 표, 식, 그래프로 나누었을 때 학생들이 지도를 통하여 표상 내에서 또는 관점 간 유연한 전환이 일어나는 것을 목표로 지도하였고 긍정적인 효과가 나타났다. 실험은 특성화 고등학교 2학년 학생 5명을 대상으로 5일간 컴퓨터실에서 실시되었다. 학생들에 대한 진단평가를 토대로 중학교 수준의 함수와 그래프를 엑셀을 이용해서 지도하였다. 학생들에게는 엑셀파일이 제공되었고, 학생들은 수업 중에 실제 조작해보고 조작결과를 배포된 활동지에 적고 함께 토론하는 방식으로 수업을 진행하였다.