• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.2
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• pp.33-44
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• 2013

Although many studies have been performed for the structural details of orthotropic steel deck, most of them were focused on the trough rib of standard type, but not for orthotropic steel deck with longitudinal rib of open section used at beginning of the deck. In order to investigate the cause of fatigue crack for orthotropic steel deck bridge serviced 31 years with longitudinal rib of open section, in this study, the behavior characteristics of target structural details were analyzed based on measurement data under real traffic condition. Also the typical loading truck passing the target bridges was estimated with the structural analysis detailed, and the stresses and deformation patterns of target structural details were analyzed by performing the detailed structural analysis. Based upon the analysis, retrofitting methods of the fatigue crack were suggested and its validation was examined. From this study, it was clarified that fatigue crack of longitudinal rib with open section were affected with the stress increment by shear deformation in the rib and the occurrence of alternative stress due to moving vehicle. In addition, it was known that it is important to perform fatigue design reflected the local behavior of the structural details.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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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.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1228-1236
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• 2006

In soft ground, There are many case that Bridge Abutment is constructed after soil improvement in order to reduce the Negative Friction and prevent from Lateral Soil movements of Bridge Abutment. That section of Horizontal Subgrade Reaction $Modulus(K_h)$ derivation has much important mean due to Horizontal Stability of Abutment. It is come from behavior of Pile and Soil within depth of $1/\beta$. After Soil Improvement, however, If Bridge Abutment was construction, It's not impossible to carry out Field Investigation After Ground of Improved at design stage. Therefore, It's not able to derivate Horizontal Subgrade Reaction $Modulus(K_h)$. Therefore, in this case of study compare with Field Construction Test Data in order to derivation of Horizontal Subgrade Reaction $Modulus(K_h)$ and Reliability in terms of ground of Bridge Abutment by Sand Compaction Pile(SCP) during design of The 2nd Bridge Connection Road of Incheon International Airport. In this paper determine, Soil Property(The rate of strength increase, $c_u$ so on) and Horizontal Subgrade Reaction $Modulus(K_h)$ after soil improvement at design stage.

• Smart Structures and Systems
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• v.25 no.1
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• pp.23-35
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• 2020

It is important to take into account the thermal behavior in assessing the structural condition of bridges. An effective method of studying the temperature effect of long-span bridges is numerical simulation based on the solar radiation models. This study aims to develop a time-varying solar radiation model which can consider the real-time weather changes, such as a cloud cover. A statistical analysis of the long-term monitoring data is first performed, especially on the temperature data between the south and north anchors of the bridge, to confirm that temperature difference can be used to describe real-time weather changes. Second, a defect in the traditional solar radiation model is detected in the temperature field simulation, whereby the value of the turbidity coefficient t_u is subjective and cannot be used to describe the weather changes in real-time. Therefore, a new solar radiation model with modified turbidity coefficient γ is first established on the temperature difference between the south and north anchors. Third, the temperature data of several days are selected for model validation, with the results showing that the simulated temperature distribution is in good agreement with the measured temperature, while the calculated results by the traditional model had minor errors because the turbidity coefficient t_u is uncertainty. In addition, the vertical and transverse temperature gradient of a typical cross-section and the temperature distribution of the tower are also studied.

• Explosives and Blasting
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• v.11 no.2
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• pp.60-68
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• 1993

The noise and vibration generated by the subway rolling stocks operated along the Seoul Subway Line No.1, 2, 3, and 4 lead to a controversy of pollution problem especially in residential areas. However, there is no data or guide to define the damage or provide adequate protection against such pollutions. The field measurements were made to characterize the noise attenuation due to distance, noise level distribution around the subway track of the aboveground and underground parts of each Line. The assessment criteria and methods are considered in addition to the practical available noise control methods. The noise level measured at Line No. 1 and 3 are less than 60 dB(A) with no pollution problem. Only a part of the aboveground section of Line No.2 and 4 indicates severe noise pollution. The effective boundary of these areas exposed to 70dB (A) noise are within 50m from the track centerline of No.2 line and 25m of No.4 line. The residents file a strong complaints whenever the noise level exceeds the 80dB (A) , and an occasional complaints between 70 to 80 dB(A). The distribution of high level noise of 80 dB(A) occurs within 25m from the track centerline of the overbridge, 12.5m of the short steel bridge, and about loom of the long steel bridge such as Dangsan Bridge. The intermediate noise level of 70 to 80 dB(A) is recorded within 50m from the overbridge, U-type retaining structure, and short steel structure, and 280m from the long steel bridge. The results presented in this paper can be used to understand the characteristics of the noise pollution along the Seoul Subway now In operation, and used as a guide to improve the existing noise pollution problems.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.207-214
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• 2011

Ultra High Performance Concrete (UHPC), which is characterized by its high strength and advanced ductile behavior that is much superior to those of convention concrete, is a useful material to make thinner and longer bridges. The precast segmental construction method utilizing UHPC has been mainly studied because cast-in-place UHPC is very difficult and complicate to be achieved. As a part of those research, the structural performance evaluation of different types of joint connection method for hybrid cable-stayed bridge utilizing UHPC by using nonlinear analyses is performed in this study. The bond stress at joint is obtained by section force analyses for a 600 m cable-stayed bridge deck, and compared with the required bond stress at joint. Analysis results show that the U Type connection and straight type connection resist the highest ultimate load and bond strength, respectively. In addition, all considered joint connection systems satisfy the bond performances at joint required in the final stage of cable-stayed bridge utilizing UHPC.

• Journal of Korean Society of Disaster and Security
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• v.16 no.3
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• pp.17-26
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• 2023

Prestressed Concrete (PSC) girders are divided into pre- and post-tension types as prestressing method, and I- and U-type as cross-sectional shape. There are both advantages and disadvantages depending on each prestressing method and cross-sectional shape, and each method is applied to bridge construction sites. In this study, a new girder design was attempted to develop that overcomes its shortcomings by using the pretension method and U-type cross sectional shape. Its structural performance was verified in this study. Pretension type girders are mainly manufactured in factories because they require a reaction arm and related facilities, and have the disadvantage of being limited in weight and span length for road transportation. In addition, in the case of the U-type cross-section, structural stability is very reliable during construction against overturning, but its own weight is relatively large comparing to I-type, and the post-tension method is mainly applied after on-site production. In this study, a PSC girder manufacturing method using the field pretension was proposed and a span length of 40 m real-scale test specimen was manufactured and verified its structural performance.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.993-999
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• 2008

A girder height limitation is the critical parameter for rapid construction of bridge deck and construction space limitation especially in urban area such as high population area and high density habitats. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder height in order to retain sufficient moment arm between compression force and tensile force. To elaborate this issue, a small U-shaped section with wide flanges can be used as a possible replacement of I-shaped standard girder. This prestressed concrete box girder allows more flexible girder height adjustment rather than standard I-shaped post-tensioned girder plus additional torsion resistance benefits of closed section. A 30m-long, 1.7m-high and 3.63m-wide actual small prestressed concrete box girder is designed and a laboratory test for its static behaviors by applying 6,200kN amount of load in the form of 4-point bending test was performed. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extracting the dynamic characteristics such as natural frequency and damping ratio of this girder, several excitation tests with artificial mechanical exciter with un-symmetric mass are carried out using operational frequency sweep-up. Nonlinear finite element analysis of this 4 point bending test under monotonic static load is investigated and discussed with aids of concrete damaged plasticity formulation using ABAQUS program.

• Steel and Composite Structures
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• v.36 no.5
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• pp.553-568
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• 2020

Steel-concrete composite structures have been extensively used in building, bridges, and other civil engineering infrastructure. Shear stud connectors between steel and concrete are essential in composite members to guarantee the effectiveness of their behavior in terms of strength and deformability. This study focuses on investigating the shear stiffness of headed studs embedded in several types of concrete with wide range of compressive strength, and their effects on the elastic behavior of steel-concrete composite girders were evaluated. Firstly, totally 206 monotonic push-out tests from the literature were reviewed to investigate the shear stiffness of headed studs embedded in various types of concrete (NC, HPC, UHPC etc.). Shear stiffness of studs is defined as the secant stiffness of the load-slip curve at 0.5V_u, and a formulation for predicting defined shear stiffness in elastic state was proposed, indicating that the stud diameter and the elastic modulus of steel and concrete are the main factors. And the shear stiffness predicted by the new formula agree well with test results for studs with a diameter ranging from 10 to 30 mm in the concrete with compressive strength ranging from 22.0 to 200.0MPa. Then, the effects of shear stiffness on the elastic behaviors of composite girders with different sizes and under different loading conditions were analyzed, the equations for calculating the stress and deformation of simply supported composite girders considering the influence of connection's shear stiffness were derived under different loading conditions using classical linear partial-interaction theory. As the increasing of shear stiffness, the stress and deflection at the most unfavorable section under partial connected condition tend to be those under full connected condition, but the approaching speed decreases gradually. Finally, the connector's shear stiffness was recommended for fully connection in composite girders with different dimensions under different loading conditions. The findings from present study may provide a reference for the prediction of shear stiffness for headed studs and the elastic design of steel-concrete composite girder.