• Magazine of the Korea Concrete Institute
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• v.5 no.3
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• pp.187-194
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• 1993

본 논문에서는 유리섬유의 적층수, 유리섬유의 배향각도에 대한 유리섬유 강화 플라스틱(Glass Fiber Reinforced Plastics ; GFRP)의 인장거동 변화를 고찰하고, 이들의 상관관계를 규명하기 위하여 일련의 GFRP 시험체에 대하여 인장실험을 수행하였다. 시험체는 폭12.5mm, 길이 60mm크기로 일정하게 제작하였으며, 시험체에 대하여 인장실험을 수행하였다. 시험체 제작시 유리섬유로 적층수는 14, 22, 30층, 유리섬유의 배향각도는 0$^{\circ}$, 30$^{\circ}$, 45$^{\circ}$로 하였다. 인장실험시 각 시험체의 파괴양상, 극한하중 및 하중변화에 대한 인장변형율을 조사하였고, 이들 결과를 토대로 유리섬유의 적층수와 배향각도에 따른 GFRP의 극한하중, 응력-변형율 선도 및 탄성계수 등을 비교 분석하였다. 한편 본 논문에서는 유리섬유의 적층수, 직경 변화에 따른 GFRP관의 파괴거동을 고찰하기 위하여 4점 재하법에 의한 GFRP관의 휨파괴실험을 수행하였다. 실험에 사용된 시험체는 길이 1200mm로 하였으며, 유리섬유의 적층수를 30, 35, 40층, 관의 직경을 50, 100, 150mm로 하였다. 파괴실험시 각 시험체의 하중변화에 대한 휨 변형율, 중앙점 처짐량 및 항복하중을 측정하였고, 이들 결과를 토대로 유리섬유으 적층수와 관의 직경에 따라 GFRP관의 항복하중 및 파괴에너지를 비교 분석 하였으며, 항복시 파괴에너지를 추정할 수 있는 제안식을 유도하였다.

• Corrosion Science and Technology
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• v.7 no.5
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• pp.265-268
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• 2008

Prestressed Concrete Cylinder Pipe(PCCP) had became one of the dominating kinds of pipes substituting for steel pipes because of its unique feature (high intensity, high pressure and high leakproofness). PCCP was produced firstly by Bonna company in France. By the end of 20th century, there were over 19000 km of this product installed in America. PCCP was introduced from Ameron company by Shandong Eletric Power Pipeline Engineering Company in 1988. As the statistical data in 2002, 700 km of PCCP had been applied in China, and the application trended towards rapid increase.Since prestressing wire would be corroded in environment, Several accidents due to the breakdown of pipe had happened. Consequently the external wall of pipe should be covered with protective coatings. There was a lack of technical study in corrosion and control of PCCP, because PCCP had been applied for a short time in China. in order to ensure the service life of PCCP, we have developed a kind of protective coating for concrete pipe, which had high intensity and anti-corrosive property with convenient applicability. The physical and chemical properties, painting technology and field application of this coating was introduced in the paper, at the same time, the future of external protective coating for PCCP was looked into.

• Steel and Composite Structures
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• v.46 no.6
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• pp.745-757
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• 2023

In order to study the fatigue performance of the flat steel plate-lightweight aggregate concrete hollow composite bridge slab subjected to fatigue load, both static test on two specimens and fatigue test on six specimens were conducted. The effects of the arrangement of the steel pipes, the amplitude of the fatigue load and the upper limit as well as lower limit of fatigue load on failure performance were investigated. Besides, for specimens in fatigue test, strains of the concrete, residual deflection, bending stiffness, residual bearing capacity and dynamic response were analyzed. Test results showed that the specimens failed in the fracture of the bottom flat steel plate regardless of the arrangement of the steel pipes. Moreover, the fatigue loading cycles of composite slab were mainly controlled by the amplitude of the fatigue load, but the influences of upper limit and lower limit of fatigue load on fatigue life was slight. The fatigue life of the composite bridge slabs can be determined by the fatigue strength of bottom flat steel plate, which can be calculated by the method of allowable stress amplitude in steel structure design code.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.869-881
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• 1999

Inchon International Airport Elevated Road Way is located between the Passenger Terminal Building and Transportaion Center which are Inchon International Airport core construction projects. The deck of the bridge is consists of 5-span or 6-span continuous pre-stressed concrete slab. Steel form has been used to enhance the quality of texture on concrete slab. Steel form has been used to enhance the quality of texture on concrete surface, lower surface of deck slab with the two way arch has been manufactured by highly professional manner in order to get an beautiful exterior architectural looks. The prestressed concrete deck slab is mass concrete structures with a high-specified concrete strength and a varying section in the range of 0.95-2.8m thickness. Therefore high risks of thermal cracking occurrence by heat of hydration highly are expected. To resolve such problem, we adopted type 1 cement and pipe cooking method at construction site through mass concrete specimen test and 3-dimensional analysis. For Pipe cooling we used 25mm diameter stainless pipes with wrinkles. Cooling pipe with spacing 50-60cm has been installed. And continuous pipe cooling with cooling water of 15$^{\circ}C$ was conducted for 2days. In present 8 span of all 29 spans construction has been completed. No thermal cracking heat hydration has been observed yet.

• Journal of The Korean Society of Agricultural Engineers
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• v.48 no.7
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• pp.25-31
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• 2006

Permeable polymer concretes can be applied to roads, sidewalks, river embankment, drain pipes, conduits, retaining walls, yards, parking lots, plazas, interlocking blocks, etc. This study was to explore a possibility of using bottom ash as filler and recycled coarse aggregate of industrial by-products for permeable polymer concrete. The tests carried out at $20{\pm}1^{\circ}C$ and $60{\pm}2%$ relative humidity. At 7 days of curing, unit weight, void ratio, compressive and flexural strength and coefficient of permeability ranged between $1,652{\sim}1,828kgf/m^{3},\;15{\sim}29+%,\;18.2{\sim}24.5\;MPa,\;6.4{\sim}8.4\;MPa\;and\;6.8{\times}10^{-2}{\sim}1.7{\times}10^{-1}\;cm/s$, respectively. It was concluded that the bottom ash and recycled coarse .aggregate can be used in the permeable polymer concrete.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.891-896
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• 2000

It is necessary to drill new opening in an existing R.C beam either for service ducts and pipes or the determination of in place concrete strength. Therefore, to simulate in this study, 18-R.C beams were fabricated with circular openings. The major parameters considered are the sizes, location of opening and cut-off stirrup. These beams are tested shear failure and capacity under a point loading. The sizes of opening are changed 0.11, 0.2, 0.3 times of beam-depth and the locations of opening are divided into $X_1$ zone, $X_2$ zone, $X_3$zone. Loads are applied up to failure to observe the cracking initiation and propagation, initial diagonal cracking, midspan deflection. As a result, the sizes of opening with 0.11D and 0.2D in R.C beams without cutoff stirrup are profitable in $X_1$ and $X_3$zone. R.C beams with 0.3D and cutoff stirrup are advantageous in $X_3$zone.

• International Journal of Concrete Structures and Materials
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• v.7 no.4
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• pp.265-271
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• 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.

• Earthquakes and Structures
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• v.22 no.4
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• pp.431-437
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• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Earthquakes and Structures
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• v.22 no.5
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• pp.439-445
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• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.269-274
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• 1999

Various method have been developed for mass concrete structures to reduce the temperature increase of concrete mass due to exothermic hydration reactions of concrete compounds and thereby to avoid thermal cracks. One of the methods widely acceptable for practical use is pipe cooling, in which cooling is achieved by circulating cold water through thin-wall steel pipes embedded in the concrete. A numerical simulation was performed to investigate the effectiveness of pipe cooling. A three-dimensional finite element method was proposed to analyse the transient three-dimensional heat transfer between the hardening concrete and the cooling water in pipe and to predict the stress development during the curing process. The effects of the cement type and content and the environment were taken into consideration by the heat generation rate and the boundary conditions, respectively. In order to test the validity of the numerical simulation, a model RC structure with pipe cooling was constructed and the time-dependent temperature and stress distributions within the structure as well as the variation of the temperature of cooling water along the pipe were measured. The results of the simulation agreed well the experimental measurements. The results of this study have important implications for the optimal design of the cooling pipe layout and for the estimation of thermal stress in order to eliminate thermal cracks.