• Journal of Korea Water Resources Association
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• v.32 no.1
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• pp.49-59
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• 1999

In order to understand the present situation of bridge scouring and to provide the fundamental information for bridge design, in-situ measured data is analyzed for bridge scours at small and medium streams in the heartland of Korea. The physical parameters affecting the bridge scouring such as flow depth, velocity, pier length and width, scouring depth, and the angle between flow and pier are extensively surveyed and measured. According to the locality and the pier type data are classified to analyze. With these data, some important factors for the scour depth such as flow depth, angle and Froude number are investigated and applied to existing formulas proposed by many researchers. In addition, the computational results are compared with the measured and some of the applicable formulas in this region are recommended.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.03a
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• pp.38-47
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• 2009

Scour means the erosion of bed material by flow change when a bridge is constructed in a stream. Scour is one of the critical factors of a bridge failure. There are several methods for the monitoring of scour near bridge foundations; Sounding rods, Magnetic sliding collar System, Sonar system, underwater camera system and so on. In general, Sonar system is preferred due to its convenience and good accuracy. In this study, the new scour monitoring system was developed using profiling sonar sensor. The new system can measure a line profile of a seabed and has small size due to the effectively designed data logger. The performance of the new scour monitoring system was evaluated at a bridge pier in tidal environment. The measured local scour depths were discussed with the result of the empirical formulas; CSU, Froehlich, Laursen and Neill.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1A
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• pp.1-9
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• 2006

An analysis of the annual frequency of collapse(AF) is performed for each bridge pier exposed to ship collision. From this analysis, the impact lateral resistance can be determined for each pier. The bridge pier impact resistance is selected using a probability-based analysis procedure in which the predicted annual frequency of bridge collapse, AF, from the ship collision risk assessment is compared to an acceptance criterion. The analysis procedure is an iterative process in which a trial impact resistance is selected for a bridge component and a computed AF is compared to the acceptance criterion, and revisions to the analysis variables are made as necessary to achieve compliance. The distribution of the AF acceptance criterion among the exposed piers is generally based on the designer's judgment. In this study, the acceptance criterion is allocated to each pier using allocation weights based on the previous predictions. To determine the design impact lateral resistance of bridge components such pylon and pier, the numerical analysis is performed iteratively with the analysis variable of impact resistance ratio of pylon to pier. The design impact lateral resistance can vary greatly among the components of the same bridge, depending upon the waterway geometry, available water depth, bridge geometry, and vessel traffic characteristics. More researches on the allocation model of AF and the determination of impact resistance are required.

• Earthquakes and Structures
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• v.16 no.4
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• pp.391-399
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• 2019

Residual deformation of high-speed railway bridge piers is cumulative under repeated earthquakes, and influences the safety and ride comfort of high-speed trains. This paper investigates the effects of the peak ground acceleration, longitudinal reinforcement ratio, and axial compression ratio on the cumulative deformation through finite element analysis. A simply-supported beam bridge pier model is established using nonlinear beam-column elements in OpenSees, and validated against a shaking table test. Repeated earthquakes were input in the model. The results show that the cumulative deformation of the bridge piers under repeated earthquakes increases with the peak ground acceleration and the axial compression ratio, and decreases with the longitudinal reinforcement ratio.

• 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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• 2001.11a
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• pp.1097-1102
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• 2001

Seismic safety of continuous span concrete bridge can be enhanced by distributing a large seismic lateral load to each supporting pier. A new viscoelastic device called Shock Transmission Unit(STU), which is a simple cylinder-piston assembly packed with a so-called silicone putty compound, enables the lateral seismic load to be transmitted to the pier by installation of the device to movable bearings of the bridge. The seismic safety of concrete bridges having the STU depends on not only safety of the bridges globally but also safety of anchor systems which anchors the STU to concrete pier. An experimental investigation is performed to study the behavior of cast-in-place anchor and post-installed anchor subjected to shear load statically and cyclically according to different edge distance, embedment length, and anchor spacing. Finally, the experimental results are compared with results by design methods of ACI and CCD, and results by FEM analysis.

• Korean Journal of Hydrosciences
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• v.2
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• pp.39-59
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• 1991

Scour at bridge pier is a complicated three-dimensional problem involving interaction of fluld force on movable aid nonuniformily distributed sand grains. Although several analytical solution approaches, experimental research and field investigations for scout at piers have been conducted, no comprehensive and universally acceptable solution is so far available. Even though many methods and equations for predicting scour at piers are available in the literature, hydraulic and/or bridge design engineers are often at a loss over which method or equation is applicable for the specific bridge sites. To provide better understanding about scour phenomena and better predicting of scour at piers, intensive research is conducted through comprehensive review of published literature. Based on the research the state-of-the-art of pier scour prediction for design application is provided as a design guide for practicing engineers in this field. Recommendations for applying aggradation and degradation, contraction scour, and local scour prediction methods or equations are suggested. It is hoped that this paper may provide good information for the prediction of scour at piers.

• Structural Engineering and Mechanics
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• v.24 no.3
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• pp.355-374
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• 2006

Thin walled steel bridge-piers/columns are vulnerable to damage, when subjected to earthquake excitations. Local buckling, global buckling or interaction between local and global buckling usually is the cause of this damage, which results in significant strength reduction of the member. In this study new innovative design concepts, "thin-walled corrugated steel columns" and "thin-walled cellular steel columns" are presented, which allow the column to undergo large plastic deformations without significant strength reduction; hence dissipate energy under cyclic loading. It is shown that, compared with the conventional designs, circular and stiffened box sections, these new innovative concepts might results in cost-effective designs, with improved buckling and ductility properties. Using a finite element model, that takes the non-linear material properties into consideration, it is shown that the corrugations will act like longitudinal stiffeners that are supporting each other, thus improving the buckling behavior and allowing for reduction of the overall wall thickness of the column.

• Journal of the Korean Society of Hazard Mitigation
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• v.5 no.2 s.17
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• pp.29-35
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• 2005

In Korea more than ninety bridges are collapsed every year by flood, which causes the scour of pier foundation. Researches on the quantitative assessment method to assess the integrity of bridge against scour have not been organized systematically in the bridge design practice and maintenance area. In this study, dynamic characteristics assessment experiments are carried out as an emergency inspection method to assess the integrity of the pier foundation for scour after a flood. According to the dynamic characteristics assessment experiment, which simulates foundation scour of the spread footing pier, foundation scour can be evaluated by the first mode natural frequency of the pier.

• Journal of the Korean Society of Hazard Mitigation
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• v.1 no.1 s.1
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• pp.81-90
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• 2001

This paper presents the results of the parametric study on the longitudinal behavior of 2-span continuous railway bridge. To perform the main objective of this paper, the effects of pier shaft stiffness, pier height, the size of pier foundation, and the bearing stiffness on the longitudinal behavior of the bridges are studied. Within the limits of this study, the research result has revealed that the variation of the fixed pier is more effective than that of the moved pier. In addition, the control of the hearing stiffness is much less expensive than that of any other parameters.