• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.61-62
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• 2010

This paper provides an analysis using statistical method on the basis of database (DB) of bridge inspection reports performed by KISTEC from 1995 to 2007. Measured impact factors of total 36 railway bridges were classified by the span length, type of bridges and natural frequency. The fundamental frequency and the impact factors of inspected bridge are compared with formulas specified in both domestic and foreign railway bridge design codes.

• The Journal of the Convergence on Culture Technology
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• v.6 no.3
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• pp.443-448
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• 2020

In this study, field measurements were performed to analyze the effects of train types (AREX, AREX Express, KTX, KTX-Sancheon) and train speeds on the dynamic behavior of the direct fixation track structure on Yeongjong grand bridge by bridge type (truss bridge, suspension bridge). Based on field measurement results, the track impact factor and train running stability (coefficient of derailment, Rate of wheel load reduction, lateral displacement of rail head) are compared with domestic and foreign standards and regulations to influence the dynamic behavior of direct fixation track. As a result, the differences in the dynamic behavior of the direct fixation tracks by the type of bridges of Yeongjong bridge are not significant, but it was analyzed that these were more directly affected by the magnitude of the train load. Therefore, it is necessary to establish the reinforcement plan of the direct fixation track structure on Yeongjong grand bridge in consideration of the increase of the track impact factor and dynamic track force.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.1A
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• pp.45-52
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• 2010

This study pointed on the dynamic impact of AGT (Automated Guide-way Transit) bridge, due to concrete rail prominence. An experiment was done with 30 m P.S.C. bridge in AGT test line in Kyungsan. An artificial prominence with 10 mm hight, was installed at the mid span of concrete rail. And computer simulation was executed for the artificial prominence. As an experiment result, in the case of with prominence, bridge acceleration responses are increased 50% at the speed range of 20 km/h-60 km/h, and bridge displacement responses increased slightly. With these results, the prominence of concrete rail can be induce excess impact and vibration. And the computer program simulated much the same as experiments. So this program can be used for AGT bridge design and formulate the standard of concrete rail management.

• Structural Engineering and Mechanics
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• v.58 no.2
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• pp.199-216
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• 2016

A large number of bridges were built several decades ago, and most of which have gradually suffered serious deteriorations or damage due to the increasing traffic loads, environmental effects, and inadequate maintenance. However, very few studies were conducted to investigate the vibration behaviors of a damaged bridge under moving vehicles. In this paper, the vibration behaviors of such vehicle-bridge system are investigated in details, in which the effects of the concrete cracks and bridge surface roughness are particularly considered. Specifically, two vehicle models are introduced, i.e., a simplified four degree-of-freedoms (DOFs) vehicle model and a more complex seven DOFs vehicle model, respectively. The bridges are modeled in two types, including a single-span uniform beam and a full scale reinforced concrete high-pier bridge, respectively. The crack zone in the reinforced concrete bridge is considered by a damage function. The bridge and vehicle coupled equations are established by combining the equations of motion of both the bridge and vehicles using the displacement relationship and interaction force relationship at the contact points between the tires and bridge. The numerical simulations and verifications show that the proposed modeling method can rationally simulate the vibration behaviors of the damaged bridge under moving vehicles; the effect of cracks on the impact factors is very small and can be neglected for the bridge with none roughness, however, the effect of cracks on the impact factors is very significant and cannot be neglected for the bridge with roughness.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.113-120
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• 2010

Recently, various evaluations concerning structural stability under construction step and completely constructed step have been executed during a Long-span Arch Bridge designing procedure. However, the breakage of cable-hangers of arched bridge in unexpected accident or periodic cable-replacement has not been considered. Therefore, the purpose of this study is that analyzing structural safety of arched bridge when the cable-hangers being fractured by that reasons. Dynamic analysis are performed by idealizing impact load to three types of impact functions as fracturing the cables. Consequently, when the hangers are fractured, the maximum tensile force by dynamic analysis is larger than those by static analysis. Therefore, the dynamic analysis is demanded to accurately obtain the responses for the structural stability with a realistic impact loading model in the breakage and replacement of cable hangers of long-span arched bride. Moreover, the analysis method and results in this study can be used to basic criteria in design.

• Structural Engineering and Mechanics
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• v.71 no.4
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• pp.391-405
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• 2019

Compared to the ambient vibration test mainly identifying the structural modal parameters, such as frequency, damping and mode shapes, the impact testing, which benefits from measuring both impacting forces and structural responses, has the merit to identify not only the structural modal parameters but also more detailed structural parameters, in particular flexibility. However, in traditional impact tests, an impacting hammer or artificial excitation device is employed, which restricts the efficiency of tests on various bridge structures. To resolve this problem, we propose a new method whereby a moving vehicle is taken as a continuous exciter and develop a corresponding flexibility identification theory, in which the continuous wheel forces induced by the moving vehicle is considered as structural input and the acceleration response of the bridge as the output, thus a structural flexibility matrix can be identified and then structural deflections of the bridge under arbitrary static loads can be predicted. The proposed method is more convenient, time-saving and cost-effective compared with traditional impact tests. However, because the proposed test produces a spatially continuous force while classical impact forces are spatially discrete, a new flexibility identification theory is required, and a novel structural identification method involving with equivalent load distribution, the enhanced Frequency Response Function (eFRFs) construction and modal scaling factor identification is proposed to make use of the continuous excitation force to identify the basic modal parameters as well as the structural flexibility. Laboratory and numerical examples are given, which validate the effectiveness of the proposed method. Furthermore, parametric analysis including road roughness, vehicle speed, vehicle weight, vehicle's stiffness and damping are conducted and the results obtained demonstrate that the developed method has strong robustness except that the relative error increases with the increase of measurement noise.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.511-516
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• 2007

Rubber wheeled AGT(Automated Guide-way Transit) system is a prominence transportation system for urban area, because of its low construction cost and management, low noise and vibration and fine exterior view. AGT system uses concrete tracks. Concrete can be easily damaged by the impact, change of temperature and external loads. The fault of concrete track is harmful not only to riding quality but also to bridge. Therefore, in this study, the effects of railway prominence to the bridge are surveyed by experimental method. The experiment was executed for PSC bridge at AGT test line in Kyungsan. And the test results for 5mm, 10mm prominence and without prominence are compared and investigated, according to the vehicle speed.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1093-1098
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• 2007

In designing the high-speed railroad track, it is important to utilize appropriate track components to maintain uniform stiffness and ensure track alignment within the tolerance set for that system. In this regard, continuous welded rails (CWRs) were introduced to the Korean railways. Yet the installation of CWRs can result in an adverse impact due to the track/structure interaction on bridge sections yielding variations in the stiffness at the expansion joints. It may also impose additional axial force, generate excessive stress or deflection on track, and loosen the ballast at the ends as a bridge deck contracts or expands owing to a thermally-induced dynamic response. The risk is even greater in a long bridge deck, resulting in track longitudinal irregularities, deteriorating passenger's comfort, and increasing maintenance efforts. This study evaluates the performance of ZLR and their impact on track longitudinal irregularities through the track measuring results on a test section installed the ZLR in order to minimize the thermally-induced responses and the maintenance efforts for the high speed railway bridges.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1999.10a
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• pp.193-202
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• 1999

effect of pounding and friction between oscillators upon global response behaviors of a bridge system under seismic excitations are examined in this study. For convenience an idealized mechanical model is proposed which still retains the dynamic characteristics of bridge motions using multiple oscillators, Each oscillator is consisting of four degrees-of-freedom to implement the pounding between the adjacent oscillators and friction at movable supports, The impact element and bi-linear model are utilized for pounding and friction at movable supports. The impact element and bi-linear model are utilized for pounding and friction respectively. Also the effects of abutments are investigated by adding the addition oscillators consisting of two degrees-of-freedom. The effects of pounding and frictions are determined using the proposed model and the effect of the abutment is also verified, It is found that both pounding and friction affect the bridge responses significantly while the first pounding occurs between the abutment and the nearby oscillator.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.69-76
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• 2020

Bridges which are components of road network consume large amounts of resources such as concrete and steel materials, which have large environmental impacts during construction. This causes a great environmental burden. In order to reduce the environmental impact caused by the construction of the bridge, the environmental impact should be reviewed based on reasonable data in the early design stage. The purpose of this study is to provide basic data for LCA-based environmental impact assessment in the process of selecting bridge type in the early design stage. For this purpose, design data for four types of PSC bridges (general PSC girder, IPC girder, e-Beam, DR girder) were collected and LCA was performed to analyze the basic unit value and impact factors of environmental load. The results of the analysis showed that the environmental impact of IPC girder was the smallest, and the environmental impact of e-Beam was 133.7% higher than that of IPC girder. In addition, concrete, reinforcement, PC strand, square timber, sheath pipe, and steel plate were derived as the main factors that generate 98.5% of the overall environmental impact of PSC girder.