• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.1
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• pp.59-67
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• 2014

A dynamic analysis is carried out to provide an evaluation method of running safety for a PSC box bridge located on the Gyung-Bu high speed railway. The numerical models of bridge and train vehicle are developed in detail with corresponding interaction system. Three dimensional skeleton element model of PSC box bridge and 38-degree-of-freedom of vehicle are adopted from the existing properties of KTX bridge and train vehicle. Analysed three direction rotations of vehicle on the bridge and ground tracks are compared for running speeds up to 500 km/h with 10 km/h constant increments. The comparison of the rotations will be an improved evaluation method of Running Safety in stead of the existing standard method.

• Journal of the Korea institute for structural maintenance and inspection
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• v.10 no.4
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• pp.175-184
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• 2006

Two methods of the nonlinear static pushover analysis have been presented for the performance-based seismic design and evaluation of MDOF continuous bridges. Guidelines for buildings presented in FEMA-273 applying the Displacement Coefficient Method (DCM) and in ATC applying the Capacity Spectrum Method(CSM) have been modified for MDOF bridges. Two methods are compared with the time- history analysis. The lateral load distribution pattern for seismic loads has been examined in the static pushover analysis. The force-based fiber frame finite element has been implemented in the modeling of reinforced concrete piers.

• Magazine of the Korea Concrete Institute
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• v.8 no.3
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• pp.209-218
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• 1996

The purpose of the present study is to explore the effects of local reinforced type and to suggest reliable failure mechanism and the design criteria on the anchorage zones of the precast prestressed concrete bridges. To accomplish these objectives, a comprehensive experimental and analytical study has been conducted. From this study, the cracking and ultimate load capacities for spirally reinforced anchorage zone are found to be larger than those for orthogonal reinforced anchorage zone. This indicate the effectiveness of spiral reinforcement in controlling the cracking. And realistic failure mechanism and design criteria of prestressed anchorage zones based on the present study are suggested.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.161-162
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• 2010

In this study, the impact load on concrete compression member was considered to assess the quantitative damage index. The case study was carried out using the LS-DYNA, on explicit finite element analysis program. The parameters for the case study were impact load angle, slenderness ratio, etc. Using the analysis results, the performance based design method for impact load was developed using Bayesian probabilistic method, which can be applied to reinforced concrete column design for impact loads.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2A
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• pp.113-120
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• 2010

The use of Concrete filled circular hollow steel section (CFCHS) members in bridge design is a relatively new concept. The most important part of the design and durability of such structures is the design and the construction of the joints. In the design of recently constructed steel-concrete composite bridges using CFCHS truss girders for the main load carrying structure, the fatigue verification of the tubular spatial truss joints was a main issue. Welded CFCHS joints are very sensitive to fatigue because the geometric discontinuities of the welds lead to a high stress concentration. New research done on the fatigue behaviour of such joints has focused on CFCHS N-joints, directly welded, with finite element analysis method. A commercial software, ABAQUS, is adopted to perform the finite element analysis on the N-joints. This paper is main focused on these topics, including hot spot stress.

• Magazine of the Korea Concrete Institute
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• v.10 no.6
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• pp.149-159
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• 1998

The reasonable prediction of time-dependent deformation of prestressed concrete(PSC) box girder bridges is very important for accurate construction as well as good serviceability. The long-term behavior is mostly influenced by the probabilistic characteristic of creep and shrinkage. This paper presents a method of statistical analysis and sensitivity analysis of creep and shrinkage effects in PSC box been taken into account - model uncertainty, parameter variation and environmental condition. The statistical and sensitivity analyses are performed by using the numerical simulation of Latin Hypercube sampling. For each sample, the time-dependent structural analysis is performed to produce response data, which are then statistically analyzed. The probabilistic prediction of the confidence limits on long-term effects of creep and shrinkage is then expressed. Three measure are examined to quantify the sensitivity of the outputs of each of the input variables. These are rank correlation coefficient(RCC), partical rank correlation coefficient(PRCC) and standardiozed rank regression coefficient(SRRC) computed on the ranks of the observations. Three creep and shrinkage models - i. e., ACI model. CEB-FIP model and the model in Korea Highway Bridge Specification - are studied. The creep model uncertainy factor and the relative humidity appear to be the most dominant factors with regard to the model output uncertainty.

• Journal of the Korea Concrete Institute
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• v.15 no.4
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• pp.606-614
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• 2003

The major cause of deterioration for the concrete bridge decks exposed to de-icing chemicals would be chloride-induced reinforcement corrosion. Thus, in this paper, in order to predict time to corrosion for concrete bridge decks in the urban area, chloride concentration was measured with depth from the surface. A frequency analysis on surface chloride concentration and chloride diffusion coefficient of concrete bridge deck equals 0.192, 29.828 in the scale parameter and 7.899, 1.983 in the shape parameter of gamma distribution. The average value of surface chloride concentration equals 1.5 kg/㎥ and condenses from 1 to 2 kg/㎥ in the level of probability 70%. From the probabilistic results, it is confirmed that 26mm of minimum cover depth in order to target 20 years over is calculated. The countermeasure strategy to extend the service life of concrete bridge deck exposed to de-icing chemicals would be an effective method to increase cover depth and to place high performance concrete, which could lead to reduce the chloride diffusion coefficient and distribution range.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.21 no.1
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• pp.91-101
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• 2008

Structural analysis models to develop live load distribution factors of simply supported prestressed concrete I-girder bridge should have the precision of the analysis results as well as modeling simplicity. This is due to the numerous frequency of structural analysis needed while developing live load distribution factors. In this study, an appropriate structural analysis model is selected by comparing previous researchs studies and models used in practical design. Also, the influence by the flexural stiffness of barrier and diaphragm on the live load distribution had been analyzed through comparing the numerical analysis and experimental tests. As a result, the model that the eccentric girder and the barrier and diaphragm are connected to the deck plate was appropriate in satisfying both accuracy and simplicity for structural analysis of simply supported prestressed concrete I-girder bridge. However, the barrier was analyzed to have insignificant influence on the live load distribution in spite of its variation of stiffness. The eccentric diaphragm showed little influence at 25% or higher of flexural stiffness. From the results, a model that the girder is rigidly connected to the deck plate in consideration of the eccentricity, the barrier is ignored and the whole section of diaphragm is supposed to be valid without eccentricity is decided as the most appropriate structural model to develop the live load distribution factors of simply supported prestressed concrete I-girder bridge in this study.

• Proceedings of the Korea Concrete Institute Conference
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• 2009.05a
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• pp.245-246
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• 2009

This paper presents the development of lightweight aggregate self-consolidating concrete using lightweight aggregates. Lightweight concrete is known for its advantage of reducing the self-weight of the structures, reducing the areas of sectional members as well as making the construction convenient. Thus the construction cost can be saved when applied to structures such as long-span bridge and high rise building. Therefore experimental tests were performed as such mechanical properties and carbonation of self-consolidating concrete using lightweight aggregates.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.1065-1068
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• 2008

Marine bridges are readily deteriorated due to the exposure to marine environment. The concrete deterioration occurred by corrosion of steel in concrete is mainly relevant to chloride in seawater. Chloride ions penetrate through porous concrete, and then reach to the reinforcing steel, and finally corroded them. The corrosion by-products(rusts) increase the volume as much as 6 to 10 times of origin steel. this creates expanding pressure and tensile stress, which cause the structures cracking and spalling. Sometimes the rebar corrosion is accelerated, and then collapsed catastrophically. In order to prevent corrosion damage, it is important to understand well regarding the reason of concrete corrosion, the quantification of its damage, and protection method/system to stop or to mitigate the corrosion. In this study, slab specimens were fabricated to evaluate the effect of cathodic protection which was simulated to marine bridges, and/or port structures. Zn-mesh sacrificial anode has been applied as a chathodic protection system and accelerated test conditions, i.e. temperature and salt concentration have been used in this study.