• 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.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.05a
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• pp.339-340
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• 2023

Steel construction is one of the commonly used methods in building construction due to its efficiency in terms of time and cost. In particular, the top-down method using steel frames is widely used in the construction of underground structures in urban areas to shorten the construction period. However, there is currently no standardized cost estimation for subway steel frame construction in Korea, causing difficulties in determining the expected cost. In this study, we aim to provide basic data for establishing a cost estimation standard for subway steel frame construction through on-site surveys of subway steel frame construction commonly used in urban areas.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.27-30
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• 2008

For the purpose of developing economical and time-efficient formwork for Top-down construction, a Non-Supporting Form System has been proposed. The system is consisted of two parts: a hanging part to support a steel frame and a section of concrete slab, and the other hanging part to lower the steel frame. In this paper, the proposed system is compared to two existing systems of Non Supporting Top-down Method and Bracket Supported R/C Downward Method. It is expected that this system can be used in Top-down construction with further development.

• 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 Korea Concrete Institute Conference
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• 2008.04a
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• pp.957-960
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• 2008

The purpose of this study is to explore a safe, advanced, and environment-friendly demolition equipments and their operation methods. As an initial achievement, the capacity of the existing equipments have been evaluated through technical discussions and demonstrations with some experts in the related industry. From these evaluations, it was concluded that a haptic based remote control with force feed-back mechanism and sensor fusion functions would be the most appropriate to the demolition equipments. Therefore, a novel haptic device that is adequately designed for the demolition equipments is proposed in this paper. Top-down demolition method is also proposed, which is very effective in the demolition of high-rise buildings.

• 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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• 2018.05a
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• pp.279-280
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• 2018

The waterproofing material can be roughly divided into a coating material and a sheet waterproofing material. In the case of coating waterproofing materials, sheet waterproofing materials, which are easy to use in terms of workability and quality control, have been recently used because of their incomplete use of coating thickness, long curing time and poor blending due to in situ blending. However, in the case of the sheet waterproofing material, since the sheet overlapping portion is inevitably generated, various defects (breakage due to the behavior) are frequently observed. Therefore, it is imperative to establish fundamental measures to minimize this.