• Journal of Navigation and Port Research
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• v.36 no.5
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• pp.339-347
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• 2012

After towing rope connecting a barge to a tug was subdivided into multiple finite elements, then those dynamic models was established using Newton's second law and considering the external force and moment such as tension, drag, Coriolis force, gravity, buoyancy, and impact due to free surface acting on each element. While the previous research on the model of towing rope considered only translation, five-degree-of-freedom equations of motion except roll based on the body-fixed frame were established in this paper. All elements are connected by a spring and a damper, and the stiffness of the spring was set as the equivalent value of the real rope. In order to confirm the established multiple finite element model, various scenarios such as freely falling of towing rope in the air and above the free surface, accelerating of a tug which tows a barge connected by towing rope, and sinusoidal moving of a tug were set up and simulated. As the results, the trajectories of the tug, the barge, and the towing rope showed good tendencies to the ones of real expected situations.

• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.5
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• pp.11-21
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• 2009

Considering that the weight of a biaxial hollow slab system is not increased with an incremental increase in its thickness, and that the flexural stiffness of a biaxial hollow slab is not significantly lower than that of a general solid slab, there has been a growing need for biaxial hollow slab systems, because long span structures are in great demand. In a long span structure, the problem of vibration of floor slabs frequently occurs, and the dynamic characteristics of a biaxial hollow slab system are quite different from the conventional floor systems. Therefore, in this study, the floor vibration of a biaxial hollow slab system subjected to walking load is investigated in comparison with a conventional floor slab system. For the efficiency of time history analysis, an equivalent plate slab model that can precisely represent the dynamic behavior of a biaxial hollow slab system is used. From the analytical results, it was determined that vibration of a biaxial hollow slab system subjected to walking load is evaluated as "office-level vibration," according to the classifications of the architectural institute of Japan and ANSI.

• Journal of the Korean GEO-environmental Society
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• v.23 no.2
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• pp.13-23
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• 2022

The ground-structure interaction of the bridge foundation has been pointed out as a major factor influencing the behavior of the bridge during earthquakes. In this study, the effect of characteristics of ground and bridge foundation on the earthquake vulnerability is investigated. From the pseudo-static analysis, it is confirmed that non-linearity becomes lesser and horizontal load becomes greater when surcharge is considered. It is also found that as the ground worsens and the size of foundation decreases, horizontal load reduces. To derive reasonable structural model for bridge foundation, fragility curve is obtained considering four conditions (fixed condition, equivalent linear condition, non-linear without surchage condition, non-linear with surcharge condition) and compared. Seismic analysis is performed on single pier with Opensees. From the earthquake vulnerability analysis, it is found that shallow foundation can be assumed as fixed condition. In conservative approach, stiffness of spring can be obtained based on Korean highway bridge design code for pile foundation which can consider the ground condition.