• Journal of Korean Society of Steel Construction
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• v.27 no.4
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• pp.371-376
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• 2015

This study was conducted for the torsional behavior of catwalk system which is a temporary structure on a suspension bridge. The torsional deformation of the catwalk structure has a significant effect on the workability and safety of workers during main cable erection. For this reason, the torsional deformation of catwalk is controlled to be acceptable levels below by adjusting the cross bridge interval in design stage. This study analyzed the effect of separation between cross bridge associated with twist safety of catwalk system. For the analytical approach, a detailed analysis model was created including cross bridge. Both wind load within the wind velocity range that allows the construction and eccentric load of Prefabricated Parallel Wire Strand were analyzed by analysis model. Result of study shows that separation between cross bridges has a significant effect on the torsional behavior of the catwalk.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.4
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• pp.61-68
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• 2017

Bridge decks are members that rapidly deteriorated due to various environmental factors such as heavy vehicle and deicing salt, etc. As the lifespan of bridges built in Korea increases, it is expected that the demand for replacing the deteriorated bridge decks will increase. In other countries, Accelerated Bridge Construction technology using precast decks is already actively being used as a countermeasure for replacement demand of deteriorated bridge decks. In this study, bridge decks deterioration models are proposed by collecting and analysing the condition index data of domestic bridge decks. Also, the future replacement demands of deteriorated bridge decks in terms of replacement time and replacement scale are predicted.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.895-898
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• 2008

This research paper intends to investigate and review the new technology of patent registration trend for the most recent domestic retaining wall and bridge abutment, and to apply the technology appropriately to the actual retaining wall and bridge abutment construction. Investigated new technological patents for retaining wall include pre-fabricated PC retaining wall construction method that reduces section force with prestressed PS steel bars, pre-fabricated Coupler-Tension retaining wall, clay reinforced retaining wall block for road, earth reinforced retaining wall block that induces uniform settlement, and etc. Investigated new technologies for abutment are abutment construction method that uses sheet pile, monolithic bridge with complex abutments, construction method for abutment bridge, earth reinforced abutment structure and etc.

• Wind and Structures
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• v.35 no.3
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• pp.177-191
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• 2022

Trains emerging on a streamlined bridge-girder may have salient interference effects on the aerodynamic properties of the bridge. The present paper aims at investigating these interferences by wind tunnel measurements, covering surface pressure distributions, near wake profiles, and flow visualizations. Experimental results show that the above interferences can be categorized into two primary effects, i.e., an additional angle of attack (AoA) and an enhancement in flow separation. The additional AoA effect is demonstrated by the upward-moved stagnation point of the oncoming flow, the up-shifted global symmetrical axis of flow around the bridge-girder, and the clockwise-deflected orientation of flow approaching the bridge-girder. Due to this additional AoA effect, the two critical AoAs, where flow around the bridge-girder transits from trailing-edge vortex shedding (TEVS) to impinging leading-edge vortices (ILEV) and from ILEV to leading-edge vortex shedding (LEVS) of the bridge-girder are increased by 4° with respect to the same bridge-girder without trains. On the other hand, the underlying flow physics of the enhancement in flow separation is the large-scale vortices shedding from trains instead of TEVS, ILEV, and LEVS governed the upper half bridge-girder without trains in different ranges of AoA. Because of this enhancement, the mean lift and moment force coefficients, all the three fluctuating force coefficients (drag, lift, and moment), and the aerodynamic span-wise correlation of the bridge-girder are more significant than those without trains.

• Journal of Korean Society of Steel Construction
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• v.23 no.5
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• pp.557-568
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• 2011

To effectively come up with and secure a national budget, it is very important to estimate the reasonable construction cost of each step in public construction projects. In this study, the approximate construction cost of a steel box girder bridge in the early stages of the project, on which available information is limited, was proposed using case-based reasoning. In addition, construction cost estimation models were used for existing sample design models, and the accuracy of the estimation model for the presented cost was verified. The analysis results showed that the error rate was comparatively stable. Therefore, it is expected that construction cost estimation will be effectively suggested in the country's budget preparation.

• Journal of the Korean Society of Industry Convergence
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• v.7 no.4
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• pp.433-441
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• 2004

This paper presents a strategy for the quality assurance of the continuous preflex composite girder bridge through the camber management of the girder during construction. The construction stages which require welding, balanced preflexion loads at the ends, etc. may cause unexpected large deformation to the preflex girder. Furthermore, these defects can be detected by measurements and analyses of the girder behavior which is sometimes time consuming. In the present study, preflex girder's camber data at equally spaced nodes in each construction stage are obtained and analyzed for the quality control of thee span continuous preflex girder composite bridge.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2018.11a
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• pp.10-11
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• 2018

Internal Insulation system is applied to the most apartment building in Korea. However due to the importance of building energy enhanced the interest of the exernal insulation system. The extermal insulation system has better thermal performance because the thermal bridge through the structure are rarely formed. But the thermal bridge around the window decrease the thermal performance of the envelope system. Therefore the technology for reducing the thermal bridge around window improves energy efficiency of the building. In order to this it is necessary to minimize the thermal bridge around window of building. In this study it is aimed to minimize the thermal bridge around the window of building. It was confirmed that the use of thermal bridge barrier imporved the heat transfer rate by 64% or more and the condensation reduction phenomenon by 42% or more compared with the exist technology. These thermal bridge barrier will be used as the main technology to improve the energy efficiency of building.

• Journal of the Earthquake Engineering Society of Korea
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• v.20 no.1
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• pp.33-43
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• 2016

This study investigates the performance of hollow precast segmental bridge columns with reinforcement details for material quantity reduction. The proposed triangular reinforcement details are economically feasible and rational, and facilitate shorter construction periods. The precast segmental bridge columns provides an alternative to current cast-in-place systems. We tested a model of hollow precast segmental bridge columns under a constant axial load and a quasi-static, cyclically reversed horizontal load. We used a computer program, Reinforced Concrete Analysis in Higher Evaluation System Technology (RCAHEST), for analysis of reinforced concrete structures. The used numerical method gives a realistic prediction of performance throughout the loading cycles for hollow precast segmental bridge column specimens investigated. As a result, proposed reinforcement details for material quantity reduction was equal to existing reinforcement details in terms of required performance.

• Wind and Structures
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• v.28 no.2
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• pp.99-110
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• 2019

Vortex-Induced-Vibration (VIV) is one kind of the wind-induced vibrations, which may occur in the construction and operation period of bridges. This phenomenon can bring negative effects to the traffic safety or can cause bridge fatigue damage and should be eliminated or controlled within safe amplitudes.In the current VIV studies, one available mitigation countermeasure, the horizontal flow-isolating plate, shows satisfactory performance particularly in PI shaped bridge deck type. Details of the wind tunnel test are firstly presented to give an overall description of this appendage and its control effect. Then, the computational-fluid-dynamics(CFD) method is introduced to investigate the control mechanism, using two-dimensional Large-Eddy-Simulation to reproduce the VIV process. The Reynolds number of the cases involved in this paper ranges from $1{\times}10^5$ to $3{\times}10^5$, using the width of bridge deck as reference length. A field-filter technique and detailed analysis on wall pressure are used to give an intuitive demonstration of the changes brought by the horizontal flow-isolating plate. Results show that this aerodynamic appendage is equally effective in suppressing vertical and torsional VIV, indicating inspiring application prospect in similar PI shaped bridge decks.

• Structural Engineering and Mechanics
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• v.47 no.1
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• pp.59-73
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• 2013

The Xiaolan channel super large bridge is unique in style and with greatest span in the world with a total length of 7686.57 m. The main bridge with spans arranged as 100m+220m+100m is a combined structure composed of prestressed concrete V-shape rigid frame and concrete-filled steel tubular flexible arch. First of all, the author compiles APDL command flow program by using the unit birth-death technique and establishes simulation calculation model in the whole construction process. The creep characteristics of concrete are also taken into account. The force ratio of the suspender, arch and beam is discussed. The authors conduct studies on the three-plate webs's rule of shear stress distribution, the box girder's longitudinal bending normal stress on every construction stage, meanwhile the distribution law of longitudinal bending normal stress and transverse bending normal stress of completed bridge's box girder. Results show that, as a new combined bridge, it is featured by: Girder and arch resist forces together; Moment effects of the structure are mainly presented as compressed arch and tensioned girder; The bridge type brings the girder and arch on resisting forces into full play; Great in vertical stiffness and slender in appearance.