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Pohang, South Korea

Lee Y.,Seoyeong Engineering | Lee E.-T.,Chung - Ang University
International Journal of Concrete Structures and Materials | Year: 2013

Prestressed concrete cylindrical pipe (PCCP) has been widely used for the distribution of water in communal, industrial, and agricultural systems for a long time. However, as it deteriorates, structural failures have been experienced. Replacing the entire existing PCCP with partial damages is not an economical method. Currently, as a cost effective repairing method, a new approach using fiber reinforced polymer (FRP) has been applied. A new design procedure of this method was proposed considering various kinds of loading condition. However, it is not easy to apply this method for design purpose due to its complex procedures. The objective of this study is to provide a new design criteria and process for PCCP rehabilitation with FRP. Through this method, the appropriate quantities of FRP layers will be decided after examining of limit states of deteriorated PCCP. For this purpose, two deterioration conditions are assumed; fully deteriorated and partially deteriorated. Different limit states for each case are applied to decide the quantities of attached FRP. The concept of "margin of safety" is used to judge whether the design results are within the optimal ranges to satisfy all limit states. © 2013 The Author(s). Source


Lee Y.,Seoyeong Engineering | Lee E.-T.,Chung - Ang University
KSCE Journal of Civil Engineering | Year: 2015

Prestressed concrete cylinder pipe is widely used for water distribution but structural failures have happened due to deterioration and a significant amount of money has been spent every year for repair and replacement. As the robot technique with fiber reinforced polymer to rehabilitate is being developed, a need for a new analysis method that can tell how many layers are required for a certain deterioration level has arisen. Currently, no analytical tool is available for this purpose. In this study, an analysis procedure is proposed to predict the pressure and the radial displacement relation and the bursting capacity of prestressed concrete cylinder pipes under internal loading. The finite element method is used to validate the proposed method. It is found that the debond of prestressing wire, the number of the reinforcing layers, and the layer attachment angle are important factors to pipe capacity. © 2015, Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg. Source


Lee Y.,Seoyeong Engineering | Feng M.Q.,Columbia University | Lee E.-T.,Chung - Ang University
KSCE Journal of Civil Engineering | Year: 2014

The deflection of the buried pipe is a function of the load on the pipe, and also the load on the pipe is a function of the deflection. It is a typical soil-pipe interaction. The vertical deflection of buried pipe with the soil properties has been relatively well studied, however, there is no proper and practical guideline on the horizontal deflection of buried pipe considering the soil-pipe interaction. In practice, the horizontal deflection is considered as the same as the vertical deflection and it provides unnecessary conservative design. In this study, the deflection of buried prestressed concrete cylinder pipe is measured using a selected soil model. A finite element model is built to reflect the soil properties, as well as the backfill and in-situ condition. An equation for horizontal deflection of buried pipe considering soil-pipe interaction is proposed. © 2014, Korean Society of Civil Engineers and Springer-Verlag Berlin Heidelberg. Source


Byeon S.,Innovation International | Koo B.,Seoyeong Engineering | Jang D.,Incheon National University | Baeck S.,Incheon National University
Sustainability (Switzerland) | Year: 2016

The spread of urbanization drives problems which distort the urban water cycle as a formof flood disaster and pollutant loads. When it comes to pollution, a lack of information on theload and characteristics of pollutants has led to insufficient reduction measures. Thus, this studydiscusses filtration by different types of filter media as an initial treatment to reduce pollutant loads.This study examined the effectiveness of the filtration method with different types of filter to controlmicro-particles from rainfall runoff water. The particle size and characteristics of pollutants wereinvestigated. In addition, the characteristics of filter media in the filtration process, such as headloss, treatment efficiency, and changes in particle size distribution were also analyzed by lab-scaleexperiments. This study suggested the best filtration material to treat surface wash-off pollutantsbased on the results of various experiments on the treatment of real samples collected from roadsand combined sewers. The results and discussions shown in this study may be useful as basicinformation for appropriate design and operating parameters of filtering facilities to control rainfallrunoff pollutants caused by urban storms. © 2016 by the authors. Source


Shin J.-H.,Konkuk University | Moon H.-G.,Konkuk University | Chae S.-E.,Seoyeong Engineering
Tunnelling and Underground Space Technology | Year: 2011

In urban areas, it is common to excavate rocks adjacent to existing tunnels. Excavation of rock ground is commonly carried out using the drill and blast method which may cause blast-induced damages to the existing tunnels. In this case securing the safety of the existing tunnels is one of the main issues, and the possible effects need to be evaluated. Empirical approaches using the velocity formulae are frequently adopted to evaluate the influence of the blast-induced vibration. This method cannot, however, appropriately consider various influencing factors on vibration and basically needs to be validated using the trial blast in the field. In this paper, attempts to identify the effect of blast-induced vibration on the immediately adjacent tunnels are made, and a preliminary guideline for evaluating the protection zone for the blast vibration is proposed. A numerical method is adopted for the dynamic modeling of a tunnel in soft rock. A two-dimensional blast load is evaluated by modifying the detonation pressure formula based on the results of field tests. Tunnel behavior due to the blast-induced vibration is investigated in terms of particle velocity, displacement, and stress of the linings. A guideline for the blast protection zone is proposed based on a parametric study on blast location, tunnel depth, and the amount of explosives. © 2010 Elsevier Ltd. Source

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