• Proceedings of the KSR Conference
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• 2004.06a
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• pp.955-960
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• 2004

In this study, three dimensional FE analysis of concrete slab track has been performed in order to develop the realistic design of precast concrete slab track. The precast slab track system including the precast concrete slab panel and the grout layer is modeled using the three dimensional solid element with crack softening effect. The input load is computed from the one dimensional beam element model constituting the rail and several discrete springs. To investigate the effect of the longitudinal connection of slab panels, two different systems-continuous and discrete systems - are modeled. The analytical results show that the stresses of both the slab panel and the grout layer are in the range of linear elastic, and, at the interface between two adjacent panels, the primary stresses of the grout layer of the discrete system are higher than those of the continuous system. However, The overall stress levels of the grout layer are very low relative to the strength of th grout.

• Proceedings of the KSR Conference
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• 2003.10b
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• pp.104-110
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• 2003

Precast concrete slab track has been already turned out to be more efficient than cast-in place concrete slab track in view of the easiness of construction and the quality control of concrete. Thus, there is a great need to bring in the precast slab track system. In order to develop the realistic precast slab track system that is well conformed to our circumstances, the performance criteria of slab track, and the state-of-the art of precast slab track systems that are used in other countries are briefly discussed here.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.397-400
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• 2004

This research aims to estimate the shear strength of the composition of prestressed hollow-core slab and steel beam. The shear strength of prestressed hollow-core slab combined with the steel beam decreases, as the beam deflection increases to a considerable extent. Existing studies on the shear strength of prestressed hollow-core slab are mostly limited to 265mrn- and larger thickness slab on concrete beam. This study investigates the slab of 100mm-thickness combined with steel beam instead of concrete beam. Five shear connector methods are proposed and the shear strength is estimated with or without the beam deflection for each composition method, respectively. Finally the reduction coefficient $(\beta)$ for the transverse shear stress$(\tau_{zx})$, which is critical for the failure of prestressed hollow-core slab, is proposed.

• Journal of the Korea Concrete Institute
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• v.12 no.6
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• pp.109-117
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• 2000

CFRD(Concrete Faced Rockfill Dam) face slab concrete has a much capability to occur crack due to drying shrinkage, plastic shrinkage and bad compaction etc. Because of these cracks of concrete induce structural problem and decrease durability of dam, it is need to reduce crack of face slab concrete. This is an experimental study to analyze the influence factors on crack properties of CFRD face slab concrete. For this purpose, various mix proportion of CFRD face slab concrete and concrete using PPF(polypropylene fiber0 and fly ash was selected. And tests for drying shrinkage, bonding strength, water permeability and plastic shrinkage were performed, and then CFRD D and PPC of those mix proportion were placed in CFRD field. According to test results, it was found that the bonding strength of C1(compact sufficiently) was higher about 10~20% than that of C2(compact insufficiently). And the engineering properties of PPC(concrete using PPF) and FAC(concrete using fly ash) were better than those of the others ; the permeability of PPC and FAC after 8 weeks curing was little lower than that of CFRD D, and plastic shrinkage crack of PPC and FAC was lower 40~60% than crack of CFRD D.

• Journal of the Korea Concrete Institute
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• v.19 no.2
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• pp.209-216
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• 2007

This study reports on the structural characteristics of slab-column connections using fiber-reinforced ultra-high-strength concrete (UHSC). Compression tests were performed on two slab-column and four isolated column specimens. In the column load tests, slab loads were also applied on the slab-column specimens so that the actual confinement condition at the slab-column joint was considered. The main parameter investigated was the "puddling" of fiber-reinforced UHSC. This paper also investigates the effects of some parameters, such as confinement of slab concrete, steel fibers, and concrete strength of the joint, related to the ability of the slab-column specimens and isolated column specimens without the surrounding slab to transmit axial loads from the UHSC columns through slab-column connections. Furthermore, the ACI Code (2005) and the CSA Standard (2004) are compared to the experimental results. The beneficial effects of the puddling of fiber-reinforced UHSC on the transmission of column loads through slab-column connections are demonstrated.

• Structural Engineering and Mechanics
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• v.74 no.5
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• pp.589-600
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• 2020

The bonding interface of the concrete slab track and cement-asphalt mortar layer plays an important role in transferring load and restraining the track slab's deformation for slab track structures without concrete bollards in high-speed railway. However, the interfacial bond-slip behavior is seldom considered in the structural analysis; no credible constitutive model has been presented until now. Elaborating the field tests of concrete to cement-asphalt mortar interface subjected to longitudinal and transverse shear loads, this paper revealed its bond capacity and failure characteristics. Interfacial fractures all happen on the contact surface of the concrete track slab and mortar-layer in the experiments. Aiming at this failure mechanism, an interfacial mechanical model that employed the bilinear local bond-slip law was established. Then, the interfacial shear stresses of different loading stages and the load-displacement response were derived. By ensuring that the theoretical load-displacement curve is consistent with the experiment result, an interfacial bond-slip constitutive model including its the corresponding parameters was proposed in this paper. Additionally, a finite element model was used to validate this constitutive model further. The constitutive model presented in this paper can be used to describe the real interfacial bonding effect of slab track structures with similar materials under shear loads.

• Proceedings of the Korea Concrete Institute Conference
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• 2002.10a
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• pp.637-640
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• 2002

The deterioration of RC deck slabs has been a serious problem and high portion of budget has been a spent for repair and strengthening of deck slab. The concrete deck slabs are subject to direct application of vehicle loading and accumulation of fatigue damage. Besides, various environmental causes. In this paper, an probabilistic study is carried out to predict exact load effects and structural capacity of deck slab during its service life, and estimate an appropriate remaining life of deck slab. To achieve this purpose the live load model is developed using by influence line including deterioration of deck slab, and deterioration model of bridge deck slab is developed. In addition, the fatigue life of reinforced concrete deck slabs considering corrosion of reinforcement are estimated based on experimental formula. This study will help rational decisions for the management and repair of reinforced concrete deck slabs.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.409-414
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• 1998

In this paper, we present the results of finite element analyses pertaining to the mechanical behavior of simply supported skew concrete slab bridges. To investigate the bending behavior of skew concrete slab three skewed slabs are modelled with different plate aspect ratios. In each modelled skew plate, skew angles are varied from 0$^{\circ}$to 45$^{\circ}$ by 5$^{\circ}$interval. It is found that the support reactions at the obtuse corner are remarkably higher than the other support reactions. In the design of skew slab bridge bearings, the capacity of bearing installed at the obtuse corner should be very high or otherwise the spacing between the bearings at this corner must be adjusted appropriately to resist extra high reactions.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.689-692
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• 2006

The crack of concrete induced by the heat of hydration is a serious problem, particularly in massive concrete structures. In order to control the temperature crack of massive concrete, the selection of appropriate materials like low heat cement, mixture materials, etc. is essential. In tills study, mix proportion using low heat portland cement and lime stone powder was designed and the best mix proportion, B-1, was selected. When bottom slab of the #219 LNG tank in Incheon was constructed, concrete temperature was measured. And thermal stress was analyzed about bottom slab of the LNG tank. As results of the thermal analysis, crack index was 1.60 in bottom slab and satisfied with construction specifications(over 1.0).

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.781-786
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• 1999

One of the major causes of concrete pavement deterioration is the loss of support due to erosion and pumping of subbase and subgrade. In this study, procedures for the detection of voids under concrete pavement slab are presented using nondestructive test method such as FWD(Falling Weight Deflectometer) and GPR(Ground Penetration Radar). The deflection responses of concrete slab obtained in FWD field test are analysed for determining the presence of void. Also, reflection responses in GPR test are interpreted. It was concluded that these procedures are available for detecting the viods under concrete pavement slab.