• Steel and Composite Structures
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• v.34 no.4
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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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• v.34 no.4
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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.

• Korean Journal of Construction Engineering and Management
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• v.12 no.6
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• pp.3-13
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• 2011

The construction industry is still the most risky industry and labor accident is a significant management factor on construction site. Safety management has been studied for improving the safety performance on construction sites. However, Almost all of them have been considered on the site safety management for the contractors and evaluation of accident rate. To resolve the limitation of current research, this study is focused on considering accident result and effort by performing the evaluation of safety level of the head office and site in construction companies. By studying the research about a safety management and interviewing with specialists in safety management, 7 items were selected and weighted based on the KOSHA18001 List. Consequently, The checklist was developed to evaluate safety performance management in construction company and Safety Management Index was suggested to coordinate 1) the score of results in accident rate and 2) the effort to evaluate a safety performance management. Safety Management Index is more helpful to evaluate the safety management results and effort. As a result of considering the score of the accident rate and the safety performance management, the outcome of prequalification was changed. Using this index, contractors will attempt to prevent accidents and owners will be able to discriminate individual differences in bidding process.

• Journal of the Korean Society for Railway
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• v.8 no.5
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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.

• International conference on construction engineering and project management
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• 2007.03a
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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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• v.25 no.3
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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.

• Journal of the Korean housing association
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• v.21 no.6
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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.

• Korean Journal of Construction Engineering and Management
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• v.5 no.3 s.19
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• pp.55-62
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• 2004

The purpose of this study is to suggest a systematic procedural model for selecting competent project promoter. The proposed model was made by comparing domestic regulations and procedures with foreign nations', and through interviews with experts and literatures survey. The summaries of this paper are as follows. The current promoter selection procedure was evaluated by reviewing relevant papers, regulations and existing model. Some obstructions which hinder PPI project activation were identified, those are inadequacy of promoter qualification and negotiation process, lack of communication between parties, etc. Some alternatives which remove major obstructions are embodied in the model. The suggested model is comprised of PQ(prequalification), two phased evaluation for the technical proposals which include alternate, communication meeting, etc. To manage the overall procedure well, an involvement of professional "project promoter selection team" would be highly recommended. They will participate in each evaluation stage with full activities, and provide government with some technical materials for selecting promoter as coordinator.