• Title/Summary/Keyword: top-down

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A Study on the Construction Process Management of the Top-Down Construction Method (Top-Down 공사의 공정관리 방법 연구)

  • Kang Hyun-Jung;Rhim Hong-Chul;Lee Ghang;Yun Dae-Jung;Kim Sang-Il
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.05a
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    • pp.133-136
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    • 2006
  • The top-down construction method is an excavation and substructure construction method by excavating earth and building slabs from the ground level to the bottom of a building. The top-down method can be categorized into several types by its process and other technical details. Some of commonly used top-down methods in Korea today are S.O.G., N.S.T.D., and S.P.S. Among these, one method is chosen depending on construction field conditions, cost, construction time and so on. This study explores several factors that may affect the selection of a top-down method. This paper reports preliminary survey results with 54 top-down construction experts and comparison results of 5 top-down construction sites.

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A Study on the Sub-elements of the Top-down Construction Method Selection Model using Weighting Factor in Downtown Area (가중치 분석을 통한 도심지 Top-Down 공사에서의 공법요소 선정 모델 개발에 관한 연구)

  • Park, Chang-Wook;Moon, Seung-Yun;Yun, Seok-Heon
    • Journal of the Korea Institute of Building Construction
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    • v.8 no.4
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    • pp.61-69
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    • 2008
  • The size of the construction projects become huge and complex, and the depth of excavation for the underground structures become deeper. Also the working area is not enough for loading materials and temporary facilities. This is the most case of recent construction projects in downtown area. Top-down is the most useful method for this kind of construction projects. Top-down construction method consists of supporting method, retaining wall type, foundation type and construction direction such as up-down or up-up. construction managers have to select sub-elements for top-down construction method in planning phase. This study is to suggest the sub-elements selection model for the top-down construction method, and the case study is conducted for evaluating this model.

Numerical Approach to Evaluate the Behavior of Concrete Panel Considering Construction Method (수치해석을 이용한 시공방법에 따른 판넬식 옹벽의 거동 분석에 관한 연구)

  • Junhee, Kang;Hoki, Ban
    • Journal of the Korean GEO-environmental Society
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    • v.23 no.12
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    • pp.17-23
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    • 2022
  • This paper analyze the precast panel retaining wall's safety factor changes based on the numerical analysis using PLAXIS 2D software. Numerical analysis conditions include construction method, nail and panel fixing method, backfill material compaction conditions, rainfall conditions. The classification according to the construction method of the precast panel retaining wall includes the top-down and bottom-up methods. The difference between the top-down and bottom-up methods is the presence or absence backfill material and the ground excavation method. The top-down method involves vertically excavating the ground and attaching the panel using mortar, but in the bottom-up method, the ground is vertically excavated and harden the backfill material. As a result of numerical analysis, the top-down method secured a higher safety factor in all cases except the rainfall conditions.

Characteristics and Case Analysis of Top-Down Construction in China (중국 Top-Down 공법의 특징과 시공사례 분석)

  • Fang, Guang-Xiu;Rhim, Hong-Chul;Lee, Hai-Chool;Song, Jee-Yun
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2009.05b
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    • pp.41-44
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    • 2009
  • Top-Down construction is becoming a popular construction method in China as there is a growing need for building high-rise structures in crowded urban areas. This paper deals with the explanation and analysis of characteristics of Top-Down construction in China. In China, usually construction site is relatively large or sometimes huge compared to that in Korea. Thus, as the high-rise portion of the building needs to be constructed first and fast, island method is used at the center p망t of the building. In the meanwhile, the remaining area of the building is constructed using Top-Down method to provide working area for equipments and workers. Also, the case studies of construction examples are provided in this paper. The purpose of this paper is to promote international understanding and interaction between neighborhood countries for the utilization of Top-Down construction.

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Load Carrying Capacity of Top Down Prefounded Columns on Different Excavation Schedule (굴착순서에 따른 Top Down 선기둥 지지력 산정)

  • Rhim, Hong-Chul;Hwang, Hee-Sun
    • Journal of the Korea Institute of Building Construction
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    • v.6 no.4 s.22
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    • pp.45-52
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    • 2006
  • Top Down method is more widely used in downtown construction, recently. As underground construction constitutes a significant portion of the total construction cost and time in Top Down construction, it is important to develop a construction method to reduce the time required in underground works. The purpose of this study is to analyze load carrying capacity of Top Down prefounded columns on different excavation schedule. When several floors are excavated, the valid buckling length of prefounded column is increased and allowable buckling stress is decreased. The result shows that all columns are safe in buckling down to B3 story whether 2 or 3 stories are excavated. However, several columns are not safe from B4 story when 2 or 3 stories are excavated straightly. With these results, a process can be designed that the first three stories in the basement are excavated, and then excavate B4 story after placing concrete on B1 and B2 floor.

Non-destructive Inspection of Top Down construction Joints of Column in SRC Structure using Radar and Thermography Method (적외선법과 레이더법에 의한 콘크리트 역타시공 이음부위의 충진상태 평가시험)

  • 박석균;임영수;차은용;김명모
    • Proceedings of the Korea Concrete Institute Conference
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    • 2000.04a
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    • pp.799-804
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    • 2000
  • The joint treatment of concrete is one of the technical problems in top down construction method. Joints created wit the top down construction result in serous weakness from the aspects of both structural and water-barrier function. Several case studies for the insepction of top down construction joints of column in SRC structure using radar and infrared thermography method. The advantages and limitations of these methods for non-destructive inspection in top own construction joints are investigated.

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Top-Down Method of Deep Basement Construction in Urban Area : a Comparison of Numerical Analysis and Field observation Data (도심지 지하굴착에 적용된 Top-Down 공법의 수치해석과 실측비교)

  • 김학문
    • Proceedings of the Korean Geotechical Society Conference
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    • 1991.10a
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    • pp.312-331
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    • 1991
  • Top-down Method of basement construction technique has been applied for building of the deep basement car park the close proximity of priceless historic buildings in LONDON. Numerical analysis for the prediction of ground movement of the surrounding buildings was performed in order to compare the field data at the various stages of excavation and support. The predicted results from the elasto-plastic analytical method were compared with the observed data and the agreement is very satisfactory. It may be concluded that the system of diaphragm wall supported by the permanent base slabs (Top-Down Method) was proved to be the most effective technique in terms of reducing any critical damage to the surrounding buildings.

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Opened Slab Based on Top-Down Method (개방형 슬래브를 이용한 지하 역타공법)

  • Jeon, Keum-Seok;Goh, Soo-Jin;Yom, Kyong-Soo;Rhim, Hong-Chul;Choi, Lin
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2006.11a
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    • pp.9-12
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    • 2006
  • In recent years, construction site has developed lots of new methods and materials for Time-Cost Trade-off and improving constructability. In the case of underground construction, especially, there are many restrictions and difficulties. Shortening of the construction time in construction of underground, we use top-down method in undergroud wall. A open slab has been designed for the purpose of overcoming a weak point of former top-down method. This study based on open slab on the under ground top-down method, to more improve constructability, to introduce the effect and the performance of top-down method.

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Analysis of Cases Using Top-Down Construction Method Under Various Site Condition (현장 조건에 따른 Top-Down 공법 사례분석에 관한 연구)

  • Shin, Hyun-Jung;Shin, Kyoo-Chul
    • Proceedings of the Korean Institute of Building Construction Conference
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    • 2011.05a
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    • pp.197-199
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    • 2011
  • To utilize the Top-Down construction method, it is required to analyse building area, floors, and soil conditions to choose the three basic elements of retaining wall, base column, and floor structure. The purpose of this research is to compare the methods of Top-Down with other construction methods. The research method is to analyse the project conditions of Top-Down project cases. The aim is to develop a method of selecting alternatives, considering construction characteristics, work schedule, supporting methods, foundation types.

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A Case Study on the Top-Down Methods Performed in the Excavation Works of Domestic Downtown (국내 도심지 굴착공사에 적용된 Top-Down 공법의 시공사례 연구)

  • Chung, Jeeseung;Park, Sukk
    • Journal of the Korean GEO-environmental Society
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    • v.18 no.2
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    • pp.5-19
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    • 2017
  • Underground excavation for building construction in Korea is changing from conventional support method (Strut, Ground anchor) to inside permanent support method by stability, economic, circumstances around excavation and etc. This study was selected the sites of Top-down, New Top-down, S.P.S, S.T.D and B.R.D in general use. This study was compared and analyzed a construction cost and period between aforementioned methods and conventional support method. Also, this study was confirmed the stability of temporary retaining wall by analysis for measurement data under construction. As a result, this study can grasp that most improved permanent support method is excellent in economic and constructability than conventional support method in case of deep excavation and rapid appearance of bedrock.