• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 봄 학술발표회 논문집(I)
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• pp.251-256
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• 1999

In the preliminary design stage of Prestressed Concrete (PSC) Box Girder Bridges, the design factors(including depth, thickness of web, and jacking force) decided by inexperience designer could heavily affect the final design factors. So there is a possibility that the design ends up with an excessively wasteful design. To aim at an economical design with preventing an excessive design, the optimal design program has been developed by using ADS optimal program and SPCFRAME(PSC Bridge analysis program) in these studies. The optimal design program automatically calculates economically optimized design studies. The optimal design program automatically calculates economically optimized design factors by introducing the optimal design techniques of PSC box girder bridge design. The objective function for optimal design is material cost of box girder and constrained functions are constituted with design specifications and workability. The optimal design techniques used the Sequential Unconstraint Minimization Technique (SUMT) with performing the optimal design program. In this study, We designed unprismatic section bridge and prismatic section bridge in the same design condition by optimal design program developed in this study. By analyzing the results we suggested the practical form of tendon's layout comparing the optimal desingns on the basis of each tendon's layout.

• Computers and Concrete
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• 제21권3호
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• pp.269-278
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• 2018

In this paper, two methods M1 and M2 to determine long-term deflection through finite element analyses including the effect of creep and relaxation are proposed and demonstrated for a PSC box-girder. In both the methods, the effect of creep is accounted by different models from international standards viz., ACI-209R-92, CEB MC 90-99, B3 and GL2000. In M1, prestress losses due to creep and relaxation and age adjusted effective modulus are estimated through different models and have been used in finite element (FE) analyses for individual time steps. In M2, effects of creep and relaxation are implemented through the features of FE program and the time dependent analyses are carried out in single step. Variations in time-dependent strains, prestress losses, stresses and deflections of the PSC box-girder bridge through M1 and M2 are studied. For the PSC girder camber obtained from both M1 and M2 are lesser than simple bending theory based calculations, this shows that the camber is overestimated by simple bending theory which may lead to non-conservative design. It is also observed that stresses obtained from FEM for bottom fibre are lesser than the stresses obtained from bending theory at transfer for the PSC girder which may lead to non-conservative estimates.

• 한국철도학회논문집
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• 제9권2호
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• pp.137-144
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• 2006

The Extradosed PSC bridge is one of the best alternates which not only covers the longer span than PSC box girder and also performs the role of landmark facility with much cheaper cost than cable stayed bridge. Since the cable-stayed long span bridge is more flexible than general medium span bridges and railway bridges can be experienced resonance phenomenon by repeated equidistant axle loading of the train, it is inevitable to consider the dynamic behavior on impact, deflection and so on. In the present study, the dynamic behavior of an Extradosed PSC railway bridge subjected to moving train forces is analyzed. As well as trains which operate in conventional railway tines, KTX train is also considered. For the estimation of dynamic performances of the Extradosed PSC bridge, vertical deflection, accelerations of the slab, end rotation of the girder and impact on pylons and cables are discussed.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2011년도 춘계학술대회 논문집
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• pp.680-689
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• 2011

A dynamic analysis procedure is developed to provide a comprehensive estimation of the dynamic response spectrum for locomotive's wheels running over a Pre-Stressed Concrete (PSC) box girder bridge on the Korea high speed railway. The wheel force spectrum with the bridge behavior are analyzed as the dynamic procedure for various running speeds (50~450km/h). The high-speed railway locomotive (KTX) is used as 38-degree of freedom system. Three displacements(vertical, lateral, and longitudinal) and three rotational components (pitching, rolling, and yawing). For one car-body and two bogies as well as five movements except pitching rotation components for four wheel axes forces are considered in the 38-degree of freedom model. Three dimensional frame element is used to model of the PSC box girder bridges, simply supported span length of 40m. The irregulation of rail-way is derived using the exponential spectrum density function under assumption of twelve level tracks conditions based on the normal probability procedure. The dynamic responses of bridge passing through the railway locomotive with high-speed analyzed by Newmark-${\beta}$ method and Runge-Kutta method are compared and contrasted considering the developed models of bridge, track and locomotive comprehensively. The dynamic analyses of wheel forces by Runge-Kutta method which are able to analyze the forces with high frequency running on the bridge and ground rail-way are conducted. Additionally, wheel forces spectrum and three rotational components of vehicle body for three typical running speeds is also presented.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 춘계학술대회 논문집
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• pp.1168-1173
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• 2004

Bridges and tunnels mainly compose the structural system of Kyung-bu high-speed railway in Korea and the prestressed concrete box girder bridges are applied for the most part of bridge structures. Precast full span construction method was practiced in the construction of many prestressed concrete box girder bridges in Kyung-bu high speed railway for the high quality, great construction speed, low construction cost and construction safety. However, there have been no application of this method in continuous bridges until now. Therefore, a new advanced precast full span construction method is developed using pre-tensioning for precast and post-tensioning in alternating the simple span into a continuous bridge system. since the high-speed railway trains can cause dynamic problems in a continuous bridge. This study shows the structural behavior and the construction process of the new advance method.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2004년도 추계학술대회 논문집
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• pp.934-939
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• 2004

The Korea high-speed rail, based on the French design. It also implements new concept to increase the strength of bridge deck by adding an impact factor (dynamic intensity factor) in static load. In order to assure the dynamic stability, SYSTRA and Jeseph Penzien, a professor in CEC (the US) conducted a dynamic stability review on design phase. Analyzing the review results, they developed design criteria for dynamic behavior. This study deal with operating PSC box GIRDER equipped with measurement equipment or measured data of Seoul $\∼$ Taejeon, P.S.C BOX GIRDER bridge and steel comsition bridge equipped with measurement equipment based on structual knowledge about configuration of measuring sensor, response analysis of structure when train runs was performed by using measured data of PSC box girder to directly compare with design criteria. moreover, the dynamic stability with comparison of high-speed rail construction criteria was reviewed and analyzed based on historical records.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2010년도 추계 학술발표회
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• pp.569-579
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• 2010

Tolerable vertical displacement of a bridge is dependent on the superstructure-type, slope, span, and etc.. In the design stage, however, resultant force of cross section is examined supposed that the settlement is 1 cm at the bearing point. And the 1cm is sometimes considered as if the criteria of allowable foundation settlement. It is needed to establish the criteria of the tolerable displacement for the small and middle bridges which are widely used in domestic area. The design data of domestic bridges including expressway bridges were collected and analyzed according to the types of superstructures and foundations. And numerical simulations were conducted for RC rigid frame bridges, PSC girder bridges, IPC girder bridges, PSC box girder bridges, and steel box girder bridges to examine the tolerable displacements.

• International Journal of Concrete Structures and Materials
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• 제10권sup3호
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• pp.1-17
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• 2016

Recently, advanced transit systems are being constructed to reduce traffic congestions in metropolitan areas. For these projects, curved bridges with various curvatures are required. Many curved bridges in the past were constructed using aesthetically unpleasant straight beams with curved slabs or expensive curved steel box girders with curved slabs. Therefore, many recent studies have been performed to develop less expensive and very safe precast prestressed concrete (PSC) curved girder. One method of reducing the construction cost of a PSC curved girder is to use a reusable formwork that can easily be adjusted to change the curvature and length of a girder. A reusable and curvature/dimension adjustable formwork called Multi-tasking formwork is developed for constructing efficient precast PSC curved girders. With the Multi-tasking formwork, two 40 m precast PSC box girders with different curvatures were constructed to build a two-girder curved bridge for a static flexural test to evaluate its safety and serviceability performance. The static flexural test results showed that the initial cracking load was 1400 kN, exceeding the design cracking load of 450 kN. Also, the code allowed deflection of 50 mm occurred at a load of 1800 kN, verifying the safety and serviceability of the precast PSC curved bridge constructed using the multi-tasking formwork.

• 대한토목학회논문집
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• 제29권3A호
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• pp.243-250
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• 2009

이 연구의 목적은 PSC 거더교를 통상적인 경간 이상으로 장경간화할 수 있는 기법들을 고찰하고, 각 기법이 경간에 미치는 영향을 평가하는 체계적인 방법론을 제안하는 것이다. 전편 논문에서는 평가에 필요한 그래프를 구성하는 기본적인 수식들을 유도한 바 있다. 여기에서는 이러한 방법론을 PSC 거더교 예제에 적용하여 각 장경간화 기법들이 미치는 영향을 정량적으로 분석하였다. 제안된 도식적인 방법은 각 기법이 장경간화에 기여하는 이유를 일목요연하게 파악할 수 있고, 더 나아가 장경간화를 위한 개선점을 용이하게 도출할 수 있는 장점이 있음을 보였다. 분석 결과 여러가지 기법들 중 특히 거더의 고강도화, 바닥판 합성 전 2차 긴장을 실시하는 다단계 긴장 기법, Decked PSC 거더 기법 등이 장경간화에 크게 기여하는 것으로 나타났다. 장경간 거더의 증가된 자중에 대처할 수 있는 시공성 및 경제성만 뒷받침된다면 PSC 거더교도 기존 박스거더교의 영역인 50~70 m 경간까지 충분히 설계 및 시공될 수 있을 것으로 기대된다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2006년도 춘계학술발표회 논문집(I)
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• pp.538-541
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• 2006

PSC(Prestressed Concrete) box girder bridges have been widely applied in Korea. A number of these bridges have been built by the segmental construction method in the longitudinal direction and(or) vertically along the cross-sectional depth with MSS(Moving Scaffolding System). An actual 2-span continuous PSC box girder bridge of Kyeongbu high speed railway was selected and instrumented with 96 vibrating wire embedded type strain gauges and 2 thermocouples. The long-term behavior of the bridge was monitored through two major points located at mid-span of the first span and at the internal support. Data collection started just after the casting of the first segment (U section). Concrete strain and temperature data were gathered regularly by a data logger (CR10) during 600 days under and after construction. According to this measurement, the parabolic longitudinal strain distribution in the top slab at mid-span is shown. And also, the same distribution at the interior support is shown. The compressive strains at the cantilever region are larger than at the web position and the internal part in the top slab. Strain difference largely happened during the early construction period.