• Journal of Korean Society of Disaster and Security
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• v.5 no.2
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• pp.71-79
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• 2012

Recently, in the total railroad construction field, the concrete slab track is adapted, not ballast track. Because the ballast track have the characteristics doing the ongoing maintenance and difficult to handle increasing maintenance costs, eventually the concrete slab track is selected as an alternative. However, owing to the hydration heat reactions and temperature affected shrinkage cracks related to concrete itself, a variety of studies to solve maintenance problems related to concrete slab track are underway. This study analysed characteristics of TQI values evaluating the track irregularity, searched the relationship between crack progress and TQI, and then evaluated of the correlation between the two values. Through this method, there is a need to complete the problems of the current method, only TQI is the main decision making tool in track maintenance, and also the need for the development of evaluation index considering the crack.

• Journal of the Korean Society for Railway
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• v.20 no.5
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• pp.637-648
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• 2017

In this paper, the effects of initial built-in deformation and temperature deformation on the stress distribution of discontinuous precast concrete track slab under train load were examined. According to the results, when train load is put on a precast concrete slab with initial built-in deformation and deformation due to temperature gradient, the maximum tensile stresses develop at the upper side of slab in the slab center, edge center and corner of shear pocket; the stress distribution is different from that of the case under train load only. Therefore, to accurately predict the actual weak points and failure modes, one should calculate the stress under train load considering the initial built-in and temperature deformation of the slab.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.4
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• pp.81-90
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• 2022

In this study, for one-way concrete slabs, the flexural strength, deflection, and crack width according to the amount of reinforcing bars were compared for the cases of using steel reinforcing bars and CFRP reinforcing bars. Critical performance dominating the flexural design was investigated and how to design the CFRP-reinforced concrete slab with efficiency was also discussed. It was found that CFRP-reinforced concrete slabs could achieve greater design flexural strength with the same amount of reinforcing bars compared to those using steel rebar, while deflection and crack width were relatively much larger. In concrete slabs using CFRP reinforcing bars, it was confirmed that the maximum crack width acts as a dominant factor in the design. For more efficient flexural design, it is necessary to mitigate the allowable crack width to 0.7 mm and to apply smaller diameter reinforcing bars to control the crack width.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.125-132
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• 2006

In the present study, in order to elucidate the vibration characteristics of track and train body according to the type of track in tunnel, the vibration accelerations of the track and the KTX train body have been measured in tunnels of Kyong-Bu high-speed railway(HSR) lines, and the frequency analysis of the measured data has been performed. From this, the vibration characteristics of the track components such as rail, sleeper, ballast and slab, the tunnel lining and the vehicle body according to the type of track are investigated and their relation is analyzed. The test results show that the vibration of rail and vehicle body rapidly increases at 80Hz in tunnel, and that is much higher in the tunnel on which the concrete slab track is placed. According to the results of the present study, rail supporting stiffness can variate the vibration characteristics of the total system including the vehicle, and therefore the correlation between the vibration of vehicle should be taken into account to determine the supporting stiffness of the slab track.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.37-38
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• 2010

The deflection of RC half slabs with rids was much smaller than that of the conventional RC half slabs. In this study, the deflection of RC half slabs with rids was calculated by using a FE method and a elastic analysis. The deflections predicted by the FE method and the elastic analysis predicted the deflection measured by tested slabs with reasonable agreement.

• Journal of the Korea Concrete Institute
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• v.22 no.3
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• pp.345-356
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• 2010

An alternative design method for interior flat plate-column connections subjected to punching shear and unbalanced moment was developed. Since the slab-column connections are severely damaged by flexural cracking before punching shear failure, punching shear was assumed to be resisted mainly by the compression zone of the slab critical section. Considering the interaction with the flexural moment of the slab, the punching shear strength of the compression zone was evaluated based on the material failure criteria of concrete subjected to multiple stresses. The punching shear strength was also used to evaluate the unbalanced moment capacity of the slab-column connections. For verification, the proposed strength model was applied to existing test specimens subjected to direct punching shear or combined punching shear and unbalanced moment. The results showed that the proposed method predicted the strengths of the test specimens better than current design methods in ACI 318 and Eurocode 2.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.19 no.1 s.71
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• pp.15-25
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• 2006

The researches on the early-aged concrete hydration process and the techniques for the early-aged concrete crack control mainly have been focused and developed on the massive concretes in both experimental and numerical studies. However, those researches for relatively thin members such as the upper slab of the reinforced concrete rahmen bridge have nearly been attempted. In this study, a designing technique for crack controlling in the thin members of the early-aged reinforced concrete rahmen bridges based on measured temperature history, strength revelation model and sinkage model is proposed. A method of calculating the reinforcing bar area for crack controlling is also proposed and it is found that the distributing bars under the design loads become the main reinforcing bars in the temperature stress analysis of the early-aged reinforced concrete rahmen bridges. It is shown that the proposed analysis technique is able to use the design of crack control for the early-aged reinforced concrete rahmen bridge.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.1
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• pp.126-133
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• 2017

This paper presents the shear capacities of hollow slab with plate and octagonal pillar type hollow sphere. Recently, the interest in precast hollow slab system for buildings is growing up according to the demand for high quality control and the increase in slab thickness. A hollow slab system is widely known as one of the effective slab system which can reduce self-weight of slab. However, hollow slabs are vulnerable to the deterioration in the shear strength due to the decrease of concrete at slab web which resists shear. Especially, in case of precast hollow slabs, it has joint surface between precast concrete slab modules along transverse axis of slab, and shear failure, that is caused by cracks at joints, has to be prevented. Therefore, in this study, shear capacity of the I-slab system is evaluated by 3-points-supported shear test along the longitudinal and transverse axis of slab specimen. Test results showed that I-slab had enough shear strength compared to theoretical shear strength even if it included the joint surfaces.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.129-139
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• 2015

Concrete-Face Rock-Fill Dams (CFRDs) are rock-fill dams with watertight-concrete slabs on its upstream slope instead of its central earth cores. The design for CFRDs are still largely empirical and typically based on past experiences. This paper presents a description of the concrete face slabs and leakage behaviors of two post-constructed CFRDs based on the data gathered through instrumentation during the initial impoundment. The results show that the strain on the concrete face slab and the horizontal displacements of the vertical slab joints are slightly affected by both the seasonal temperature change and water loading during the initial impoundment. The deformation of perimetric joints are less affected by the temperature change, however it is significantly affected by the water loading during the initial impoundment. The leakage rate is significantly affected by the hydrostatic load and the deformation of the perimetric joints.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.1
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• pp.37-45
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• 2013

In this study, the resistance of various reinforced concrete (RC) slabs subjected to contact detonation was assessed. In order to enhance the blast resistance, fibers and external FRP sheets were reinforced to RC slabs. In the experiment, the $2,000{\times}1,000{\times}100mm$ sized RC slabs were fabricated using normal concrete (NC), steel fiber reinforced concrete (SFRC), polyvinyl alcohol fiber reinforced cementitious composite (PVA FRCC), and ultra-high performance cementitious composites (UHPCC). The damage levels of RC slabs subjected to contact detonation were evaluated by measuring the diameter and depth of crater, spall and breach. The experimental results were compared to the analyzed data using LS-DYNA program and three different prediction equations. The diameter and depth of crater, spall and breach were able to be predicted using LS-DYNA program approximately. The damage process of RC slabs under blast load was also well expressed. Three prediction equations suggested by other researchers had limitations to apply in terms of empirical approaches, therefore it needs further research to set more analytical considerations.