• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.196-197
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• 2021

The underground method can be divided into Top-Down, Semi-Top-Down, Up-Up and Down-Up methods according to the construction order of the upper and lower structures. Among them, the Down-Up method proceeds with the construction of the first floor and its lower floors, and when the foundation is completed, the vertical members of the basement are sequentially completed from the foundation and the above-ground floor is constructed. In this paper, the crack reduction method around the open section of the Down-Up method affected by earth pressure was analyzed and divided into design and construction parts.

• 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.

• Journal of Korean Association for Spatial Structures
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• v.11 no.2
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• pp.129-138
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• 2011

Construction methods for underground structure are classified as bottom-up, up-up, and top-down methods depending on the procedure of construction related to a superstructure. In top-down construction methods, building's main structure is built from the ground level downwards by sequentially alternating ground excavation and structure construction. In the mean time, the main structure is also used as supporting structure for earth-retaining wall, which results in the increased stability of the earth-retaining wall due to the minimized deformation in adjacent structures and surrounding grounds. In addition, the method makes it easy to secure a field for construction work in the downtown area by using each floor slabs as working spaces. However top-down construction method is often avoided since an excavation under the slab has low efficiency and difficult environment for work, and high cost compared with earth anchor method. This paper proposes a combined construction method where semi-open cut is selected as excavation work, slurry as earth -retaining wall and CWS as top-down construction method. In the case study targeted for an actual construction project, the proposed method is compared with existing top-down construction method in terms of economic feasibility, construction period and work efficiency. The proposed construction method results in increased work efficiency in the transportation of earth and sand, and steel frame erection, better quality management in PHD construction, and reduced construction period.

• 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.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.101-109
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• 2019

The purpose of this study is to improve a general Top-Down construction process for superstructure construction period reduction. In a general Top-Down construction sequence, the ground floor slab is set up first. Subsequently, 1st basement level construction including core walls is constructed. Initiation of the ground level superstructure gets waited until then. In this study, removable deck plate installation on the bottom of the core walls of ground level is preceding the concrete casting, therefore, ground level superstructure construction is able to get started earlier. Up to first typical floor concrete casting, total of seventy-two working(calendar) days will be resulted in a reduction from the total construction periods.

• 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.

• 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.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.638-641
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• 2006

In this paper, A calculating cost method of maintenance and repair for bridge which is built up by new construction technique named Up-Down Precast Concrete(UDPSC). After 2000, 109 Bridges which are using UDPSC technique have been built up, 37 bridges's construction work are processing, and 194 designs are presented for construction. Because this technology has developed recently, there are few field data for analyzing the maintenance and repair cost. Therefore, the maintenance and repair cost is computed using Construction and Transportation Ministry's guide line for computation and former research's data.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2006.05a
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• pp.1-4
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• 2006

A down construction method is frequently used in these days to reduce popular discontent and to assure sufficient working space at early stage in downtown area. There are two main problems in the existing down construction method. One is a confliction between frame works and excavation works, and the other is a cold joint in retaining wall which is unavoidable due to a sequence of concrete placement and induces a water leakage. Therefore, a new method is needed to overcome these problems. The CWS (buried wale Continuous Wall System) method was developed by authors. By replacing RC perimeter beam with embedded steel wale, the steel frame works of substructure can be simplified and the water leakage can be prevented using continuous retaining wall. Consequently, the improved duality and reduction of construction period can be obtained from CWS method.

• Journal of Korean Society of Steel Construction
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• v.13 no.4
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• pp.433-441
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• 2001

Thus study presents the basic concepts of 3 span continuous preflex composite beam of bridges by re-up down of supports and analysis relationship of between variables and stress of critical section. Also, it shows the pre-compression effects of re-up down of supports method by presenting the difference of between old section and new section got from new method. This study's new method makes more economic sections to be possible and when the sections designed with the existing method are used in the new method. efficient stress state is accomplished.