• Structural Engineering and Mechanics
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• v.66 no.4
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• pp.515-529
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• 2018

Multiple hazards (multihazard) conditions may cause significant risk to structures that are originally designed for individual hazard scenarios. Such a multihazard condition arises when an earthquake strikes to a bridge pre-exposed to scour at foundations due to flood events. This study estimates the impact spectrum of flood-induced scour on seismic vulnerability of bridges. Characteristic river-crossing highway bridges are formed based on the information obtained from bridge inventories. These bridges are analyzed under earthquake-only and the abovementioned multihazard conditions, and bridge fragility curves are developed at component and system levels. Research outcome shows that bridges having pile shafts as foundation elements are protected from any additional seismic vulnerability due to the presence of scour. However, occurrence of floods can increase seismic fragility of bridges at lower damage states due to the adverse impact of scour on bridge components at superstructure level. These findings facilitate bridge design under the stated multihazard condition.

• International Journal of Contents
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• v.14 no.3
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• pp.17-26
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• 2018

To ensure safety of bridges, it is critical to inspect and assess physical and functional conditions regularly. Presently, most highway bridges in the U.S. are inspected visually. However, this method of inspection is often influenced by the bridge inspector's knowledge and experience. So, reliability and accuracy of inspection results may be problematic. To solve such problems, an extensive number of robotics systems and image processing techniques for bridge inspection methods have been proposed. These robotics systems and image processing techniques are used to measure various bridge conditions, such as apparent damage, displacement and dynamic characteristics. This paper provides a comprehensive review of robotics systems and image processing technologies used in bridge inspection.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.04a
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• pp.671-676
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• 1999

Because of relatively heavy dead weight of concrete itself and unavoidable heat of massive concrete in bridge piers, circular hollow columns are widely used in Korean highway bridges. Since the occurrence of 1995 Kobe earthquake, there have been much concerns about seismic design for various infrastructures, inclusive of bridge structures. It is, however, understood that there are not much research works for nonlinear behavior of circular hollow columns subjected to earthquake motions. The ultimate of this experimental research is investigate nonlinear behavior of circular hollow reinforced concrete bridge piers under the quasi-static cyclic load, and then to enhance their ductility by strengthening the plastic hinge region with glassfiber sheets. It is concluded from quasi-static tests for 7 bridge piers that energy dissipation capacity and curvatures for a given displacement ductility factor $\{\mu}=frac{\Delta}{\Delta_y}$are about 20% higher for the seismically designed columns and about 70% higher for the retrofitted piers than the nonseismically designed columns in a conventional way.

• Computers and Concrete
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• v.1 no.3
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• pp.355-369
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• 2004

This paper presents a study of four finite element techniques that can be used to model slabon-beam highway bridges. The feasibility and correctness of each modeling technique are examined by applying them to a prestressed concrete I-beam bridge and a prestressed concrete box-beam bridge. Other issues related to bridge modeling such as torsional constant, support conditions, and quality control check are studied in detail and discussed in the paper. It is found that, under truck loading, the bending stress distribution in a beam section depends on the modeling technique being utilized. It is observed that the behavior of the bridge superstructure can be better represented when accounting for composite behavior between the supporting beams and slab.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.09a
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• pp.197-204
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• 2002

The resent earthquakes in worldwide have caused extensive damage to highway reinforced concrete bridge piers. It has been observed in the Korean Peninsula that the number of minor or low earthquake motions have increased year by year. Since the concern about the earthquake hazards is increased, the objective of this research is to evaluate the damage of reinforced concrete bridge piers subjected to probable earthquake motions. Experimental investigation was conducted to study the seismic performance of the full-scale specimens in size D=1.2m H=4.8m, which were constructed with different longitudinal lap splice and loading pattern, through the quasi-static test and the pseudo-dynamic test. It is thought that this result could contribute to establish the retrofit decision-making and disaster planning of reinforced concrete bridge piers in earthquake regions. And it could be also possible to quantify the damage of reinforced concrete bridge piers under cyclic loading

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.187-193
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• 2001

The object of this research is to evaluate the seismic performance of existing circular reinforced concrete bridge piers by the Quasi-static test. Existing reinforced concrete bridge piers, which were non-seismical]y designed in accordance with the conventional provisions of Korea Highway Design Specification, are needed to rating evaluate seismic performance fur probable earthquake motions in future by developing a seismic analysis computer program with estimation algorithm. This study has been performed to verify the effect of lap spliced longitudinal steel, confinement steel type and confinement steel ratio for the seismic behavior of reinforced concrete bridge piers. Quasi-static test has been done to investigate the physical seismic performance of RC bridge piers, such as displacement ductility, energy absorption, strength degradation etc.

• Journal of the Korean Society for Railway
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• v.8 no.2
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• pp.137-144
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• 2005

The possibility of resonance exists always in railway bridges unlike highway bridges because railway bridges are loaded repeatedly by specific trains which has equidistant wheel loads. Resonance phenomenon of the bridge can be broken out when exciting frequencies by tram determined from the speed and effective beating internal coincides with natural frequencies of the bridge Excessive fluctuations of dynamic displacements and accelerations by resonance cause unpleasant passenger comfort and instability of railway structures. On the other hand, resonance suppression phenomenon that all the previous loads which pass through the bridge sum to zero can be occurred. In case we apply this resonance suppression properly, design of stable railway bridge from dynamics point of view can be made. In the present study, most dominant beating internal of conventional trams will be find. A(ter that. specific span length of the bridge which derives resonance suppression can be selected for railway bridges which accomplishes superior dynamic behavior.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.331-338
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• 2001

The soil-steel bridges which were introduced in Korea recently are widely used instead of underpasses of highway or small bridges. This bridge is a kind of flexible buried conduit which sustain the applied load by the interaction with the backfill soil. The 6.25m din. round soil-steel bridge was instrumented so as to investigate the behavior of load sustenance, The axial forces and moments at the 7 locations around the metallic shell were calculated from the measurement of strains during backfilling. The maximum axial force and moment were compared with those of various design predictions. Finally, the stability of bridge was evaluated.

• Wind and Structures
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• v.31 no.5
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• pp.459-472
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• 2020

This study focused on the non-synoptic, tornado-like wind-induced effects on flexible horizontal structures that are extremely sensitive to winds. More specifically, the nonuniform, intensive vertical wind-velocity and transient natures of tornado events and their effects on the global behavior of a long-span bridge were investigated. In addition to the static part in the modeling of tornado-like wind-induced loads, the motion-induced effects were modeled using the semi-empirical model with a two-dimensional (2-D) indicial response function. Both nonlinear wind-induced static analysis and linear aeroelastic analysis in the time domain were conducted based on a 3-D finite-element model to investigate the bridge performance under the most unfavorable tornado pattern considering wind-structure interactions. The results from the present study highlighted the important effects due to abovementioned tornado natures (i.e., nonuniform, intensive vertical wind-velocity and transient features) on the long-span bridge, and hence may facilitate more appropriate wind design of flexible horizontal structures in the tornado-prone areas.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 1998.04a
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• pp.115-122
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• 1998

Earthquake damage civil engineering structures every year in the world and bridges are no exception. Bridge structures have proven to be vulnerable to earthquake, sustaining damage to substructure and foundation and being totally destroys as superstructures collapse from their supporting elements. The poor seismic performance of bridge structures is surprising in view of the substantial advance made in design and construction for vertical load. Recently, bridge spans have been pushed further than before, alignment has become increasingly complex and aesthetic requirement have been become more demanding. To reduce the seismic force and to improve the safety of the advanced bridges, the bridge bearings which are the substructures and foundations and their connections to the superstructure become more important and critical elements. Therefore, the functions about seismic devices to be using as bridge bearing are discussed.