• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.67-78
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• 2004

Soil-steel bridges are made of flexible corrugated steel plates buried in the well-compacted granular soil. One kind of possible collapses of these structures could be initiated by shear or tension failure in the soil cover subjected to vehicle loads. Current design codes provide the requirements for the minimum depth of the soil cover to avoid problems associated with soil cover failures. However, these requirements were developed for short span (less than 7.7 m) structures which are made of unstiffened plates of standard corrugation (150$\times$50 m). Numerical analyses were carried out to investigate the behavior of long span soil steel bridges according to thickness of the soil cover. The span of structures were up to 20 m and deep corrugated plates (381$\times$140 m) were used. The analysis showed that the minimum cover depth of 1.5 m could be sufficient to prevent the soil cover failure in the structures with a span exceeding 10 m. Additional analyses were performed to verify the reinforcement effect of the concrete relieving slab which can be a special feature to reduce the live-load effects. Analyses revealed that the bending moment of the conduit wall with a relieving slab was less than 20% of that without a relieving slab in a case of shallow soil cover conditions.

• Journal of Korean Society of Steel Construction
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• v.18 no.6
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• pp.793-804
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• 2006

Various PSC and steel-concrete composite railway bridges are being developed for short-medium spans with structural and economic efficiency. According to the design concept, the prestressed composite girder bridge has the advantages of being lightweight and having low girder depth, with the capacity for long spans. However, the dynamic behavior under a passing train is one of the critical issues concerning these railway bridges designed with more flexibility. Therefore, it is very important to evaluate the modal parameters before performing dynamic analyses. In this paper, real-scale prestressed composite girders were fabricated as a test model and modal testing was carried out to evaluate modal parameters including natural frequency and modal damping ratio. During the modal testing, a digitally controlled vibration exciter as well as an impact hammer was applied to obtain frequency-response functions, and the modal parameters were also evaluated after the fracture of test models. With application of reliable properties from modal tests, the estimation of dynamic performances of prestressed composite girder railway bridges can be obtained from various parametric studies on dynamic behavior under the passage of a moving train.

• Journal of the Society of Disaster Information
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• v.11 no.1
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• pp.45-54
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• 2015

In the case of railway facilities in cities such as a railway station or a bridge, the significance of design for reducing vibration and noise is getting more significant. The vibration control solution is in need especially for an elevated railway station to block vibration of a train and secondary noise effectively. Even though a vertical vibration isolation device is able to be applied effectively to railway facilities such as elevated railway stations which transfer vibration directly from a train to a structure, the development of the vertical device is much slower than a horizontal vibration isolation device. In this paper, a vibration isolation device using wedge type friction material which is currently developing to reduce train-induced vibration effectively is introduced and test results for verification of dynamic performance is also presented. The vibration test on a concrete structure equipped with the developed vibration isolation device is conducted through which the isolation performance and dynamic properties are verified and needs for improving the performance of the device is identified.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.187-196
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• 2005

Since the allowable bearing capacities of piles in weathered/fractured rock are mainly governed by settlement, the load-displacement behavior of pile should be known accurately. To predict pile head settlement at the design stage, the exact understanding of the load-transfer mechanisms is essential. Therefore, in this research, the load-transfer mechanism of drilled shaft socketed into weathered rock was investigated. For the investigation, five cast-in-place concrete piles with diameters of 1,000 mm were socketed into weathered gneiss. The static axial load tests and the load-transfer measurements were performed to examine the axial resistant behavior of the piles. A comprehensive field/laboratory testing program on weathered rock at the Held test sites was also performed to describe the in situ rock mass conditions quantitatively. And then, the effect of rock mass condition on the load transfer mechanism was investigated. The f-w (side shear resistance-displacement) curve of the pile in moderately weathered rock reached to yielding point at a for millimeter displacements, and after yielding point, the rate of resistance increment dramatically decreased. However, the f-w curve in the highly/completely weathered rock did not show the obvious yielding point, and the resistance gradually increased showing the hyperbolic pattern until relatively high displacement (>15 mm). The q-w (end bearing resistance-displacement) curves showed linear response at least until the base displacement of approximately 10 mm, regardless of rock mass conditions.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.4
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• pp.60-75
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• 2014

The purpose of this study was to look for useful implications in its next application or similar planning by assessing visitors' recognition of International Garden Exposition Suncheon Bay Korea 2013. To do this, blogs acknowledged as powerful communication media in modern information society were used. After searching for blogs related to International Garden Exposition Suncheon Bay Korea in the portal site ranked first in the domestic market share, this study classified 300 cases. This study was able to grasp the consciousness as bloggers gave descriptions of information and impressions and experiences of spaces without making any adjustments. The survey results are as follows: First, Dutch gardens were the most preferred, followed by Korean gardens, Chinese gardens and French gardens; in general, visitors were not satisfied with the national gardens. Inquiry is needed into the method of determining diverse cultural identity rather than a sample garden type through blogs delivering regret regarding the world gardens. Second, the survey results showed that the level of awareness of designers' gardens was low. This study judges that more emphasis should be placed on their roles as places speaking for the original purpose of the garden exposition which introduces gardening art and design through experimental design. Third, it was understood that many bloggers were deeply impressed by ephemeral landscapes like the change in landscape consequent on the elapse of time, distinctive atmosphere, and detailed-landscapes. These aspects are important landscape elements, and those elements should be addressed with weight in a subsequent study. Fourth, the most impressive places are 'Suncheon Lake Garden' and 'Bridge of Dreams', which are establishing themselves as icons of International Garden Exposition Suncheon Bay Korea 2013. However, relatively, public attitude towards the world gardens and designers' gardens are weak. Fifth, bloggers were providing a variety of information like transportation, events schedules, ticket purchasing & prices, discount information, etc. Ticket price was commented on the most, and most of the bloggers thought ticket prices were 'expensive'. This study understands such a phenomenon as a result of the general population's non-establishment of the perception that it's proper to view gardens at visitors' own expense. Generally, bloggers expressed satisfaction with International Garden Exposition Suncheon Bay Korea 2013, but with criticism as well. Their criticism included disappointing matters, to be improved upon and wishes without any distortion, providing meaningful implications deserving reference for similar cases. In this context, a blogger could be called a citizen-reviewer while a blog could be referred to as 'a field of informal discourse' for the public. As a research method of this study, blogs are difficult to interpret as they are subjective and personal, and have limited data analysis through their quantifications; however, blogs as methods of recognition survey are channels for varied, concrete and detailed awareness which are hard to grasp through a questionnaire survey or interviews. This study judges that such an aspect of a blog could be a useful means of grasping and reflecting upon visitors' attitude in future studies.