• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 추계 학술발표회
• /
• pp.683-690
• /
• 2008

Steel-concrete composite columns are popular for superstructures of bridges, and the outside steel attached to the shaft increases the shaft resistance due to confining concrete. In this study, lateral resistance of steel-concrete composite drilled shafts was evaluated quantitatively based on numerical analysis when steel casings are used as structural elements like composite columns. Ultimate lateral resistance of composite drilled shafts with various diameters was numerically calculated through 3D finite element analysis. For that, elasto-plastic model with perfectly plasticity is involved to capture the ultimate load. A commercial FEM program, MIDAS-GTS, is used in this study. Real field conditions of the West Coast, Korea were considered to set up the ground conditions and pile lengths required for this parametric studies. Detailed characteristics of the stress and displacement distributions are evaluated for better understanding the mechanisms of the composite shaft behavior.

• 한국건축시공학회지
• /
• 제9권2호
• /
• pp.31-38
• /
• 2009

In today's construction industry, buildings have been more complicated and higher, the demands of steel works have been increasingly concerned, which makes the schedule planning and management more significant. However, in actual construction sites, management is more based on a manager's construction experience than productivity data accumulated in previous projects. Moreover, most of the existing studies also featured a theoretical approach rather than an analysis of data straightforwardly collected in sites. In this study, a steel-erection site was visited to collect productivity data. The study found that there were significant disparities between aboveground work productivity and underground work; one tower crane operated work and two tower crane operated; and work productivity conducted in clear weather condition, cloud and rainy. However, the productivities of 'first node on ground' and 'second node on ground' were estimated similar. The productivity data collected and factors affecting the productivity will help managers to plan and control their similar steel-erection works. This study will also be beneficial for those performing related studies.

• 한국건축시공학회지
• /
• 제12권6호
• /
• pp.636-647
• /
• 2012

Construction projects have become so large, complicated and incredibly high-tech that process management is currently considered one of the most important issues. Unlike typical manufacturing industries, most major construction activities are performed in the open air and thus are exposed to various environmental factors. Many studies have been conducted with the goal of establishing efficient techniques and tools for overcoming these limitations. Productivity analysis and prediction, one of the related research subjects, must be considered when evaluating approaches to reducing construction duration and costs. The aim of this research is to present a quantified impact analysis of construction delay factors on construction productivity of a steel staircase system, which has been widely applied to high rise building construction. It is also expected to improve the process by managing the factors, ultimately achieving an improvement in construction productivity. To achieve the research objectives, this paper analyzed different delay factors affecting construction duration by means of multiple regression analysis focusing on steel staircase systems, which have critical effects on the preceding and subsequent processes in structure construction. Statistical analysis on the multiple linear regression model indicated that the environment, labor and material delay factors were statistically significant, with 0.293, 0.491, and 0.203 as the respective quantified impacts on productivity.

• International Journal of Concrete Structures and Materials
• /
• 제7권1호
• /
• pp.51-59
• /
• 2013

The use of light-gauge steel framing in low-rise commercial and industrial building construction has experienced a significant increase in recent years. In such construction, the wall framing is an assembly of cold-formed steel (CFS) studs held between top and bottom CFS tracks. Current construction methods utilize heavy hot-rolled steel sections, such as steel angles or hollow structural section tubes, to transfer the load from the end seats of the floor joist and/or from the load-bearing wall studs of the stories above to the supporting load-bearing wall below. The use of hot rolled steel elements results in significant increase in construction cost and time. Such heavy steel elements would be unnecessary if the concrete slab thickening on top of the CFS wall can be made to act compositely with the CFS track. Composite action can be achieved by attaching stand-off screws to the track and encapsulating the screw shank in the deck concrete. A series of experimental studies were performed on full-scale test specimens representing concrete/CFS flexural elements under gravity loads. The studies were designed to investigate the structural performance of concrete/CFS simple beams and concrete/CFS continuous headers. The results indicate that concrete/CFS composite flexural elements are feasible and their structural behavior can be modeled with reasonable accuracy.

• International Journal of Quality Innovation
• /
• 제9권1호
• /
• pp.68-93
• /
• 2008

The steel bars account for a high percentage of material costs for the current construction projects. At the present time, most of the construction projects for the factories of thin-film transistor liquid crystal display (TFT-LCD) complete the transactions of steel bars when the suppliers ship the steel bars to the temporary storage/processing sites. This paper applies the buy-in concept in the Theory of Constraint (TOC) on the supply chain of steel bars. In this study, suppliers are required to establish warehouses at the construction sites and complete the transactions when the formed and processed steel bars are shipped into the factory sites. The aim is to find a win-win solution to meet with the expectations from constructors as they hope that there is no need to build up inventories but supply is ready at any time. Also, this paper compares and analyzes the traditional supply/inventory model of steel bars and the Demand-Pull (D-P) model under the TOC framework. It is proved that Vendor Management Inventory (VMI) in the D-P model is able to more effectively manage steel bars as a material.

• Steel and Composite Structures
• /
• 제20권5호
• /
• pp.999-1022
• /
• 2016

The use of Carbon Fiber Reinforced Polymer (CFRP) to strengthen steel structures has attracted the attention of researchers greatly. Previous studies demonstrated bonding of CFRP plates to the steel sections has been a successful method to increase the mechanical properties. However, the main limitation to popular use of steel/CFRP strengthening system is the concern on durability of bonding between steel and CFRP in various environmental conditions. The paper evaluates the performance of I-section steel beams strengthened with pultruded CFRP plate on the bottom flange after exposure to diverse conditions including natural tropical climate, wet/dry cycles, plain water, salt water and acidic solution. Four-point bending tests were performed at specific intervals and the mechanical properties were compared to the control beam. Besides, the ductility of the strengthened beams and distribution of shear stress in adhesive layer were investigated thoroughly. The study found the adhesive layer was the critical part and the performance of the system related directly to its behavior. The highest strength degradation was observed for the beams immersed in salt water around 18% after 8 months exposure. Besides, the ductility of all strengthened beams increased after exposure. A theoretical procedure was employed to model the degradation of epoxy adhesive.

• 한국건설관리학회논문집
• /
• 제8권3호
• /
• pp.87-96
• /
• 2007

최근 국 내외 건설 환경은 대형화, 전문화, 다양화되고 있다. 이러한 건설 환경의 변화로 인하여 강구조물 프로젝트의 수요가 점차 증가하고 있으며 강구조물 공사의 효율적 품질관리의 중요성은 더욱 부각되고 있다. 강구조물 공사는 다수의 협력업체와 수많은 공종에 따른 많은 기술력을 요구하는 공사이기 때문에 다양한 리스크와 불확실 요인을 내포하고 있다. 하지만 현재 강구조물 공사의 리스크 대응 및 관리는 과학적이고 체계적 인 방법으로 진행되는 것 보다 공사자의 직감과 경험에 의존한 방법으로 진행되고 있다. 강구조물 공사의 리스크 요인을 파악하고 대응방안을 세우는 것은 강구조물 공사의 품질관리 성패를 좌우한다고 할 수 있다. 따라서 본 연구는 강구조물 공사의 과학적이고, 체계적인 리스크 관리를 위하여 전문가들의 설문조사를 실시하고 계층적 분석법(Analysis Hierarchy Process : 이하 AHP)을 통하여 리스크 중요도와 분석된 리스크 요인의 대응방안을 제시함으로써 강구조물 공사의 품질관리 체계를 정립하고자 한다.

• 국제학술발표논문집
• /
• The 8th International Conference on Construction Engineering and Project Management
• /
• pp.30-37
• /
• 2020

In the building construction, the steel-frame work occupies an important position in terms of structure, cost and quality. Especially in Japan, steel frames have traditionally been the main structure of many buildings. For steel-frame works in such positions, this paper investigates an existing steel fabricator to clarify the actual conditions of design decision making process and management method in steel production process. This study focuses on a steel fabricator (Company M in the following sentences), whose main market is Japan and which has facilities in Thailand, China, and Japan. Company M uses QR codes to control the production status of products, and exchanges all information between inside and outside the company via specialized departments in the form of documents. The authors have already analyzed the relationship between production lead time and defect rate based on actual project data at Architectural Institute of Japan in 2016. In 2019, we expressed the process from the confirmation of the design information of the current steel frame to the production by WBS, and clarified the relationship between the production lead time and steel frame product quality structurally. In this paper, the authors reoport the progress of the survey conducted so far, the positioning of the collected data, and the future survey policy.

• 한국건설관리학회논문집
• /
• 제7권1호
• /
• pp.64-72
• /
• 2006

철골공사 참여자들은 문서를 통해 다른 참여주체와 다양한 정보를 교환한다. 현재의 철골공사 업무체계는 다단계 도급의 형태를 가지고 있어서 참여주체들 간에 문서를 통하여 신속하게 정보를 교환하는데 있어 많은 어려움을 가지고 있다. 따라서 여러 주체가 관련된 설계변경과 같은 문제점이 발생했을 경우 업무처리에 많은 기간이 소요되며 관련 주체들 간의 협의가 불충분해질 우려가 있다 본 연구에서는 현재의 철골공사 설계변경 업무프로세스를 체계화하였으며, 철골공사 참여자들이 신속하고 정확하게 설계변경 업무를 처리함으로써 성공적인 철골공사 관리가 가능하도록 하기 위하여 현행의 설계변경 업무 프로세스에 XML을 적용하여 프로세스를 개선하고, XML지반 철골공사 업무지원시스템(XCOS)을 개발하였다.

• 한국강구조학회 논문집
• /
• 제22권1호
• /
• pp.55-65
• /
• 2010

공공 건설공사에서 공사 단계별 합리적인 공사비를 산정하는 것은 국가 예산의 효율적 확보 및 집행 등에 있어 매우 중요한 요소이다. 일반적으로 공사예정가격은 대상 구조물의 설계 종료시점에서 산출된다. 그러므로 대상 구조물의 구체적인 상세 단면이 주어지지 않은 기획단계 및 설계초기단계에서 교량 구조물에 대한 단순 정보만을 가지고 개략공사비를 추정하는 것은 상당히 어려운 문제일 것으로 생각된다. 본 연구에서는 선행연구에서의 61개의 강박스거더교 공사비 분석에 의해 효율적이고 적절한 기획단계 및 설계초기단계의의 개략공사비 산정 모델의 제시 및 타당성을 검증하고자 한다. 연구결과, 본 연구에서 제시된 공사비 산정 모델에 의해 얻어진 추정공사비는 기존에 사용된 방법과 비교할 때 매우 높은 신뢰도를 갖는 것을 알 수 있었다.