• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.93-108
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• 2022

Real-time hybrid simulation (RTHS) was applied to investigate the train-bridge interaction of a high-speed railway system, where the railway bridge was selected as the numerical substructure, and the train was physically tested. The interaction between the two substructures was reproduced by a servo-hydraulic shaking table. To accurately reproduce the high-frequency interaction responses ranging from 10-25Hz using the hydraulic shaking table with an inherent delay of 6-50ms, an adaptive time series (ATS) compensation algorithm combined with the linear quadratic Gaussian (LQG) was proposed and implemented in the RTHS. Testing cases considering different train speeds, track irregularities, bridge girder cross-sections, and track settlements featuring a wide range of frequency contents were conducted. The performance of the proposed ATS+LQG delay compensation method was compared to the ATS method and RTHS without any compensation in terms of residual time delays and root mean square errors between commands and responses. The effectiveness of the ATS+LQG method to compensate time delay in RTHS with high-frequency responses was demonstrated and the proposed ATS+LQG method outperformed the ATS method in yielding more accurate responses with less residual time delays.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.123-128
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• 2018

Girder bridges and slab bridges are equipped with a system consisting of a flexible joint unit, support, inverted T shaped abutment, and a separate connecting slab structure. These systems have problems such as an increase in cost due to frequent breakage of the expansion joints and a decrease in durability due to a structure with low moment redistribution. To improve these problems, propose Inegral and Semi-Integral Hybrid Slab Bridge and examine the safety through structural analysis. As a result of the review, Inegral and Semi-Integral Hybrid Slab Bridge was the section stiffness is small. but it is confirmed that the structural safety, ductility and flexibility are higher than existing bridges because the moment redistribution and the force transmission are surely performed.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2009.04a
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• pp.110-113
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• 2009

본 연구에서는 무선센서노드을 이용하여 강판형 철도교량의 전형적인 손상유형인 거더부의 휨강성 저하와 지점부의 볼트풀림을 효과적으로 모니터링할 수 있는 하이브리드 모니터링 기법을 제안하였다. 이를 위해 다음과 같은 연구가 수행되었다. 첫째, 본 연구진에 의해 개발된 가속도 및 임피던스기반 무선센서노드를 간략하게 소개하였다. 둘째, 가속도 및 임피던스 신호를 이용하여 효과적인 손상모니터링이 가능한 기법들을 선정하였다. 마지막으로, 개발된 가속도 및 임피던스기반 무선센서노드를 모형 강판형 철도교에 설치하고, 일련의 손상 시나리오에 따른 하이브리드 모니터링을 수행하여 무선센서노드 및 모니터링 기법의 성능을 평가하였다.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.123-124
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• 2009

This research is a part of the comprehensive research project to develop the optimized UHPC precast deck system applying to durable and cost-effective hybrid cable stayed bridge. Longitudinally prestressed ribbed section is proposed to make the best use of a advantage of the ultra high performance concrete and the design concept is presented to decide the sectional property.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1470-1477
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• 2010

In 2004, Korea has become the world's fifth-express train states, Honam high-speed railroad which goes down another line with existing Kyoungbu high-speed railroad is divided 19 construction sectors, its total length is 230.9 km and it will be constructed by 2017. This site is located in Jeollabukdo Jeong-eup district along 9.38 km. There are three representative bridges. ;One is the PSC box girder bridge, another is the Extradosed bridge, and the other is the three continuous spans half-through hybrid arch bridge. This paper shows a planning and design of these bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10b
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• pp.845-850
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• 2000

This paper presents the results of tests performed on the transfer girders which have been generally used between upper walls and lower frames in the hybrid structures. The 8 specimens were designed using (1) ACI method, (2) strut-tie model, and (3) X-type shear reinforcement cage. The capacities of the specimens are in general larger than the design values except the one designed according to strut-tie model. The reason for this difference seems to be due to the arbitrary allocation of transferred shear force to the path of direct compression strut and the path of indirect strut and tie. The failure modes turn out toe be (1) shear failure at critical shear zone, (2) compressive concrete crushing in the diagonal strut in the shear zone of transfer girder, and (3) compressive concrete crushing in the corner of upper wall.

• Proceedings of the Korea Concrete Institute Conference
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• 2005.05a
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• pp.411-414
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• 2005

This paper presents how to design and construct the Il-sun bridge, the first PSC box girder bridge with Corrugated Steel Web(CSW) in Korea, including 3D analysis results according to construction steps. Also, the 3D analysis for the beams with CSW was performed for the purpose of verifying the role of the flange plate. As the results of this analysis, it is founded that the flange plate plays a role to resist the flexural strength in the nonlinear region. In the near future, we are plan to carry out the load test for these beams with CSW.

• Structural Engineering and Mechanics
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• v.45 no.6
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• pp.779-802
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• 2013

In this paper, adaptive neuro-fuzzy inference system (ANFIS) and artificial neural networks (ANNs) techniques are developed and applied to identify damage in a model steel girder bridge using dynamic parameters. The required data in the form of natural frequencies are obtained from experimental modal analysis. A comparative study is made using the ANNs and ANFIS techniques and results showed that both ANFIS and ANN present good predictions. However the proposed ANFIS architecture using hybrid learning algorithm was found to perform better than the multilayer feedforward ANN which learns using the backpropagation algorithm. This paper also highlights the concept of ANNs and ANFIS followed by the detail presentation of the experimental modal analysis for natural frequencies extraction.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.3A
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• pp.277-286
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• 2010

Derrick or caterpillar crane is generally used for the long-span/cable-stayed bridge construction by pre-cast segment lifting from over-land or water transportation. The heavy weight of them, however, could make defects on unstable under-construction structure and, furthermore a method of conventional segment transportation is also able to occur additional time and cost. In this study, in order to improve conventional construction method, the newly developed derrick crane is mainly considered. It could be not only eccentrically loadable on constructing girder but having rotatable boom for segment transportation from back-side. A series of construction stage using developed derrick crane is defined and also its numerical analysis is conducted. To reflect load characteristics of developed derrick crane on construction stage analysis, on/out of service load is separately calculated by considering vertical/lateral rotation range of boom and it is loaded on 4 fixed positions of crane. The derrick crane on this study could be time and cost saving solution for cable-stayed bridge construction and also make contributions to construction load reduction in its process.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.415-426
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• 2013

Condition assessment and monitoring of bridges is critical for safe passenger travel, public transportation, and efficient freight. In monitoring, displacement measurement capability is important to keep track of performance of bridge, in part or as whole. One of the most important parts of a bridge is the expansion joint, which accommodates continuous cyclic thermal expansion of the whole bridge. Though expansion joint is critical for bridge performance, its inspection and monitoring has not been considered significantly because the monitoring requires long-term data using cost intensive equipment. Recently, a wireless smart sensor network (WSSN) has drawn significant attention for transportation infrastructure monitoring because of its merits in low cost, easy installation, and versatile on-board computation capability. In this paper, a rapid wireless displacement monitoring system, wireless hybrid sensor (WHS), has been developed to monitor displacement of expansion joints of bridges. The WHS has been calibrated for both static and dynamic displacement measurement in laboratory environment, and deployed on an in-service highway bridge to demonstrate rapid expansion joint monitoring. The test-bed is a continuous steel girder bridge, the Founders Bridge, in East Hartford, Connecticut. Using the WHS system, the static and dynamic displacement of the expansion joint has been measured. The short-term displacement trend in terms of temperature is calculated. With the WHS system, approximately 6% of the time has been spent for installation, and 94% of time for the measurement showing strong potential of the developed system for rapid displacement monitoring.