• Steel and Composite Structures
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• 제34권4호
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• pp.547-559
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• 2020

Buckling restrained braces (BRBs) were developed as an enhanced alternative to conventional braces by restraining their global buckling, thus allowing development of a stable quasi-symmetric hysteretic response. A wider adoption of buckling restrained braced frames is precluded due to proprietary character of most BRBs and the code requirement for experimental qualification. To overcome these problems, BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were developed and experimentally tested in view of prequalification. The first part of this paper presents the results of the experimental program which included sub-assemblage tests on ten full-scale BRBs and uniaxial tests on components materials (steel and concrete). Two different solutions of the core were investigated: milled from a plate and fabricated from a square steel profile. The strength of the buckling restraining mechanism was also investigated. The influence of gravity loading on the unsymmetrical deformations in the two plastic segments of the core was assessed, and the response of the bolted connections was evaluated. The cyclic response of BRBs was evaluated with respect to a set of performance parameters, and recommendations for design were given.

• Steel and Composite Structures
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• 제34권4호
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• pp.561-580
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• 2020

Buckling restrained braces (BRBs) were developed as an enhanced alternative to conventional braces by restraining their global buckling, thus allowing development of a stable quasi-symmetric hysteretic response. A wider adoption of buckling restrained braced frames is precluded due to proprietary character of most BRBs and the code requirement for experimental qualification. To overcome these problems, BRBs with capacities corresponding to typical steel multi-storey buildings in Romania were developed and experimentally tested in view of prequalification. In the second part of this paper, a complex nonlinear numerical model for the tested BRBs was developed in the finite element environment Abaqus. The calibration of the numerical model was performed at both component (material models: steel, concrete, unbonding material) and member levels (loading, geometrical imperfections). Geometrically and materially nonlinear analyses including imperfections were performed on buckling restrained braces models under cyclic loading. The calibrated models were further used to perform a parametric study aiming at assessing the influence of the strength of the buckling restraining mechanism, concrete class of the infill material, mechanical properties of steel used for the core, self-weight loading, and frame effect on the cyclic response of buckling restrained braces.

• 한국건설관리학회논문집
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• 제12권6호
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• pp.3-13
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• 2011

안전한 현장을 구축하기 위한 수급자의 노력에도 불구하고 건설업은 여전히 위험한 산업으로 인식되고 있다. 특히, 여러 항목 중에서도 노무자의 재해율은 건설현장에서 중대하게 고려되는 관리대상이다. 따라서 현재까지 진행된 건설 분야 안전에 관한 연구는 건설현장의 안전관리수준 개선에 초점을 두고 있으며, 과정보다는 결과를 평가하는 방식의 개발에 집중되었다. 그러나, 재해율을 낮추기 위한 수급자의 적극적인 노력을 이끌어내기 위해서는 입찰단계에서부터 재해율과 함께 안전관리수준이 평가되어야 한다. 본 연구에서는 현장의 사고결과만을 평가하는 기존의 안전관리평가의 한계점을 극복하고 수급자의 자발적인 재해예방 활동을 강화하기 위하여, 안전관리수준을 평가하는 체크리스트와 입찰단계에서 재해율과 재해예방노력을 동시에 평가할 수 있는 안전경영지수를 제안하였다. 개발된 안전경영지수를 활용하여 재해율과 안전관리수준을 동시에 평가할 수 있었으며, 지수의 효용성을 검증하기 위해서 32개의 수급자를 대상으로 실시되었던 입찰참가자격사전심사(Prequalification, 이하 PQ) 프로세스에 적용하였다. 적용 결과, 수급자의 점수가 세분화 되고, 순위가 변경되는 등 PQ 결과에 있어서 변별력이 발생하였다. 개발된 안전경영지수를 입찰단계 평가에 적용한다면, 수급자는 사고 예방을 위해서 더욱 노력할 것이며, 발주자는 입찰단계에서 변별력있는 평가항목으로 활용할 수 있을 것이다.

• 한국철도학회논문집
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• 제8권5호
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• pp.460-469
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• 2005

Turnkey contract system is an effective ordering system for the ordering organizations that technical engineers are insufficient for their construction projects. It is possible to reduce project duration and to improve project quality in an integrated contract system between design and construction. However, owners can have a difficulty caused from unitary responsibility system. This study analyzes present situation and problems of turnkey contract system including railway projects. The result includes various methods for improving the system based on the analysis of bid price and selection procedure.

• 국제학술발표논문집
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• The 2th International Conference on Construction Engineering and Project Management
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• pp.830-836
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• 2007

This paper is concerned with identifying the importance of the pre-qualification factors used in selecting contractors and also in determining the importance of various criteria used for the award of contract. The study was carried out through questionnaire survey administered to a population of 60 respondents in consultancy and client's organisation. The data analysis included a statistical comparison of means and interpretation. The result of this study showed that experience of the contractor is the most important prequalification factor while technical expertise is the most important criteria in the award of contract. The result of this study will enable clients, consultants and contractors to lay emphasis on the influencing factors in terms of pre-qualification and award of contract.

• Steel and Composite Structures
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• 제25권3호
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• pp.271-286
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• 2017

The use of Hollow Structural Sections (HSS) provides an alternative for steel buildings in seismic zones, with the advantage over WF columns that the HSS columns have similar resistance along both axes and enhanced performance under flexure, compression and torsion with respect to other columns sections. The HSS columns have shown satisfactory performance under seismic loads, such as observed in buildings with steel moment frames in the Honshu earthquake (2011). The purpose of this research is to propose a new moment connection, EP-HSS ("End-plate to Hollow Structural Section"), using a wide flange beam and HSS column where the end plate falls outside the range of prequalification established in the ANSI/AISC 358-10 Specification, as an alternative to the traditional configuration of steel moment frames established in current codes. The connection was researched through analytical, numerical (FEM), and experimental studies. The results showed that the EP-HSS allowed the development of inelastic action on the beam only, avoiding stress concentrations in the column and developing significant energy dissipation. The experiments followed the qualification protocols established in the ANSI/AISC 341-10 Specification satisfying the required performance for highly ductile connections in seismic zones, thereby ensuring satisfactory performance under seismic actions without brittle failure mechanisms.

• 한국주거학회논문집
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• 제21권6호
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• pp.71-80
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• 2010

The purpose of this study is to classify defects of the residential building by analyzing the defect specified by prequalification of residential building reconstruction and to suggest the solution of the problem which can be arisen during each stage of plan, construction and maintenance. By sorting the main defects which is specified by pre-qualification of residential building reconstruction for three years from August 2006 to August 2009 into 4 catagories and analyzing the cause of the defects, we draw the way of maintenance to prevent the defects and make pleasant residential environment. The reason for the frequent defects from residential building is mainly deterioration. It occured on the finishing more than on the structure, which means that residents can find defects easier on the finishing than the structure and clear the demand for repair. The result of analyzing of pre-qualification of residential building reconstruction is that the defects mostly caused small, masonry constructed and lower apartment. The apartment which is not into legal right for maintenance naturally have more defects than the others. In conclusion, it is necessary to establish a law of obligation duty of the maintenance of small apartment.

• 한국건설관리학회논문집
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• 제5권3호
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• pp.55-62
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• 2004

본 연구는 유능한 민간투자 사업시행자를 선정하기 위한 절차모델을 제안한 것이다. 국내$\cdot$외 문헌과 기존 방식 및 제도에 대한 검토$\cdot$분석을 통하여 국내 민간투자 사업시행자 선정 절차의 현황과 문제점을 파악하였다. 적격심사 및 협상절차의 불합리, 사업 참여주체 간 의사소통$\cdot$정보교환 기회 부족 등 문제점을 도출하였으며, 각각의 문제점들에 대한 대안을 모색하였다. 면담조사 및 설문조사$\cdot$분석을 통하여 국내 실정에 적합한 대안을 설정하고 기존의 절차를 혁신한 새로운 사업시행자 선정모델을 제안하였다. 사전자격심사(PQ)제도의 시행, 사업계획 평가 및 협상 절차의 개선, 민간의 창의와 효율성 도입, 의사소통 및 정보교환의 활성화를 촉진할 수 있는 내용을 선정절차에 포함하였다. 또한 전체 사업시행자 선정이 객관적이고 투명한 환경에서 이루어 질 수 있도록 사업시행자 선정 Team의 구성$\cdot$운영을 제안하였다.