• Journal of the Korean Geotechnical Society
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• v.37 no.11
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• pp.51-60
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• 2021

River scour erodes the soil around the pier, reducing the lateral bearing capacity of the pier and lowering the stability of the structure. In this study, in order to examine the effect of scouring on the stability of the structure, an experiment was performed to measure the natural frequency of the pier according to the excavation of the surrounding ground. Impact vibration test was conducted on the pier with the caisson foundation of the Mangyeonggang Bridge, which is scheduled to be demolished. Accelerometers were attached to the top, center, and bottom of the pier and the acceleration responses were measured by hitting those three points. The experimental results showed that the top hit showed consistent and reasonable results of the acceleration responses according to the hitting position. The measured accelerations were converted to the frequency domain through Fast Fourier Transform (FFT), and then the natural frequency was determined. In addition, to analyze the scour effect on the natural frequency of the pier, the ground around the pier was excavated and the natural frequency change was analyzed. As a result, the natural frequency showed the decreasing tendency according to the excavation depth, but the decrease was small due to the large stiffness of the caisson foundation.

• Structural Engineering and Mechanics
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• v.77 no.3
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• pp.343-354
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• 2021

The frequencies formulas of the bridge are of great importance in the design process since these formulas provide insight dynamic characteristics of the structure, which guides the designers to parametric analyses and the layout of the bridge in conceptual or preliminary design. Continuous rigid frame bridge is popular in the mountainous area. Mostly, this type of bridge was simplified either as a girder or cantilever when calculating the frequency, however, studies showed that the different configuration of the bridge made the problem more complex, and there is no unified fundamental calculation pattern for this kind of bridge. In this study, an empirical frequency equation is proposed as a function of pier's height, stiffness of pier and the weight of the structure. A unified fundamental frequency formula is presented based on the energy principle, then the typical continuous rigid frame bridge is investigated by finite element method (FEM) to study the dynamic characteristics of the structure, and then several key parameters are investigated on the effect of structural frequency. These parameters include the number, position and stiffness of the tie beam. Nonlinear regression analyses are conducted with a comprehensive statistical study from plenty of engineering structures. Finally, the proposed frequency equation is validated by field test results. The results show that the fundamental frequency of the continuous rigid frame bridge increases more than 15% when the tie beams are set, and it increases with the stiffness ratio of tie beam to pier. The results also show that the presented unified fundamental frequency has an error of 4.6% compared with the measured results. The investigation can predicate the approximate longitudinal fundamental frequency of continuous ridged frame bridge, which can provide reference for the seismic response and dynamic impact factor design of the pier.

• Journal of Korea Port Economic Association
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• v.37 no.3
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• pp.105-116
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• 2021

Harbor floating pier is a structure in which one or several floating vessels are connected to have a port function so that ships can be bordered regardless of tide level in places where differences between tidal rocks are severe. There are 233 harbor floating piers in Korea, and 27.5% of harbor floating pier are over 30 years old. Harbor floating piers older than 30 years are potentially at high risk of accidents. However, there is no clear standard for disposal or sale of aging harbor floating pier, and the management regulations on the timing of maintenance inspection and repair are ambiguous. In this study, the AHP model was designed by classifying the problems and improvement factors of harbor floating pier facility operation through interviews with port managers and existing literature studies. The AHP analysis showed that the relative importance of the evaluation factors of the higher class was in the order of improvement of the legal system, improvement of operational management and technical improvement. This study can be used as basic data for improving the operation of Korea harbor floating pier facilities.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.6
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• pp.407-413
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• 2011

Reliability analysis of pile type quaywalls were done by using response surface method. Pier structures have implicit form of limit state function since they are flexible in motion, which is different from gravity type quaywalls. To solve a reliability analysis problem with implicit limit state function, response surface method was applied. Reliability indices of structure under seismic load were found for pier structures Then, they were compared with those found by simulation method. In numerical analysis, both the inclined type and vertical type were analyzed.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.4
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• pp.91-97
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• 2009

The flow is changed by the structure which goes across the river. The structure with debris causes high water level and overflow. The changed flow, which caused by pier and stream characteristics like velocity and slope, was analysed by 2D model. After rainfall, the influences of increased discharge were evaluated. Velocity was simulated in the channel by SMS (Surface water Modeling System) using RMA2, and high velocity values were found in the steep and narrow reach. Highest velocity value around piers was showed in the middle of space between two piers. The increased discharge due to rainfall increases velocity and changes flow contour considerably.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2023.05a
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• pp.106-107
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• 2023

The purpose of this study is to derive priorities for the introduction of smart port technology by utilizing domestic and foreign prior research and AHP analysis to establish an automated pier at Gwangyang Port. In order to establish a hierarchical structure for smart port technology, R& D tasks, roadmaps, and literature related to domestic and foreign smart port technology were investigated to select two first-tier and six second-tier attributes and determine the hierarchical structure. ‥‥(중략)‥‥

• Journal of the Korean Society of Marine Environment & Safety
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• v.22 no.1
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• pp.82-89
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• 2016

In this study, we proposed a pier of pontoon-type, "Very Large Floating Structure" (VLFS), with the length of 500m, breadth of 200 m and height of 2 m in Yeosu domestic port. Since this structure ought to endure wave loads for long periods at sea, it is essential to analyze the wave response characteristics. Direct-method is used to analyze the fluid-structure problem and the coupled motion of equation is used to obtain response results. The structural part is calculated by using finite element method (FEM) and the fluid part is analyzed by using boundary element method (BEM). Dynamic responses caused by the elastic deformation and rigid motion of structure are analyzed by numerical calculation. To investigate response characteristics of the pier in regular waves, several factors such as the wavelength, water depth, wave direction and flexural rigidity of structure are considered. As a result, wave response of pier changed at the point of $L/{\lambda}$ 1.5 and represented the torsional phenomenon according to the various incident waves. And the responses showed increasing tendency as the water depths increase at the incident point in case of $L/{\lambda}=8.0$ and peak point of vertical displacement amplitude moved from side to side as the flexural rigidity of structure changes.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.459-466
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• 2002

In this study magneto-rheological damper, a kind of semi-active device, is used to reduce the response of pier and girder of bridge structure subjected to seismic excitation and as a effective semi-active control method fuzzy control technique considering nonlinear behavior of the damper dynamics. By Numerical simulations of a nine span continuous bridge system subjected to various earthquakes, fuzzy control technique is compared with existing clipped optimal control technique in control performance which reduces displacement of pier and girder simultaneously. In the comparison of the control performance within a control force limit, it is confirmed that presented fuzzy control technique more efficiently reduce the pier and girder displacement than clipped optimal control technique based on optimal control theory.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.745-750
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• 2000

The rigidity of pier is important in the analysis of rail on high speed railway bridges. This study is being performed because of followings. 1) Actual longitudinal stiffness of the structure including substructure should be considered in the calculation of longitudinal stresses in rails. 2) There are many uncertainties in piers and foundations for design. 3) Actual guideline for the design of piers is necessary. 4) Measurement on the rigidity of pier according to the types of pier, foundation and soil-condition is needed. Curve for rigidity will be obtained through this study and applied for actual design as the guideline. Stresses in rails can be estimates accurately. A pair of piers, which consists of pot-bearing for fixed support and pad-bearing for movable support, is loaded by steel frame through steel wire ropes. The responses which are intended to measure in the field test are displacements, forces and tilts on the top of piers.

• Proceedings of the Korea Concrete Institute Conference
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• 2010.05a
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• pp.153-154
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• 2010

For completing an fully optimized and prefabricated substructure system of bridge, developing pier of precast segment PSC which equip the connection structure of shear resistance and precast foundation are conducted previously. Specimens of coping of bridge were developed and customized, and experiments were performed. The result of the experiment through the result from a reliable non-linear analysis program (RCAHEST) were compared and analyzed and evaluated the stability and ultimate behavior of coping of precast pier.