• Journal of the Computational Structural Engineering Institute of Korea
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• v.28 no.3
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• pp.293-300
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• 2015

In this study, a series of forced vibration testing and ambient vibration measurement were performed at a lowrise masonry-infilled reinforced concrete frame structure before and after seismic retrofit and its dynamic properties were extracted using system identification techniques. Also, analytical models which show similar dynamic properties to the measures ones were constructed. The system identification results showed that damping ratios in x direction along which the dampers were installed has been increased. From the comparison between the analytical models, the effective stiffness of post-installed member and post-reinforced members(shear walls and damper frames) were only 50% of gross sectional stiffness of the members, which indicates that the these members were not fully integrated with the existing structure or members. In addition, support condition of post-installed footing has to be pinned in y direction to match the dynamic properties, which is seemingly caused by the change of fixity of the soil due to the installation of new footing.

• Geotechnical Engineering
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• v.7 no.2
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• pp.67-82
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• 1991

When bridge abutments are constructed on pile foundations in unstable slope, horizontal deflections may be developed in the piles and the abutments due to lateral soil movements arisen from backfills. In most of the above mentioned cases, the piles are situated in a soft layer where lateral earth pressures are developed between the piles and the soils. The undesirable lateral earth pressures decreases the stability of the piles. However, the piles may have a preventive effect against lateral soil movements and improve the stability of the slope. For the stability problem of such slope containing piles in a row, two kinds of analyses for the slope-stability and the pile-stability have to be performed. The whole stability of bridge abutments on pile foundation can be obtained only by the stabilization for both the slope and the piles. A reasonable analytical method for the bridge abutments on pile foundation was established in this study By use of the analytical method for an example, several factors which influence affect the stability of bridge abutment were investigated. Finally, for the bridge abutment subjected to lateral deflections damage, the fixity condition of pile head was investigated.

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.91-98
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• 2012

In this paper, the behavior of offshore wind turbine(OWT) foundation which is modeled by using existing design method and FEM is compared. When the same type of foundation is designed under the same sea and ground condition, the behavior characteristics with each model are compared. As a result, the member forces between apparent fixity and distributed spring type foundation which consider the ground stiffness are not different markedly, while fixed-base type foundation shows relatively lower member forces, which results in smaller safety margin. In other words, considering ground stiffness is reasonable because soil-pile interaction affects significantly on the analysis result. A case study with a monopile shows significant errors between p-y and FEM model at the head and tip of the pile. Also, it shows that the errors at the tip with diameter increase of the pile is larger. Thus, considering ground characteristics and engineering judgment are necessary in practice. A comparison of reliability analysis between tripod and monopile type foundation on the same condition shows larger probability of failure in monopile type and it indicates that the safety margin of monopile type can be lower.