• Proceedings of the KSR Conference
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• 2005.05a
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• pp.115-122
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• 2005

This study analyzed the characteristics of four kinds of bridge rubber pads and suggested how to determine the stiffness the pads. The stiffness of rubber pads can be estimated by a direct static test. In the procedure to estimate the stiffness of a pad, the dead load(preload) of a bridge and live load of a vehicle are considered. The polyurethane rubber pads have larger hardness than natural and chloroprene rubber pads and thus carry larger load bearing capacity. In addition, they showed higher stiffness with the same shape factor than the others and thus are more avaliable as for bridge bearings. Although natural and chloroprene rubber pads are elongated to large deformation in horizontal direction due to vertical loads, polyurethane rubber pads almost do not generate horizontal deformation due to vertical loads regardless to the thickness and hardness of the pads. Therefore, they do not need reinforced plate to restrict horizontal deformation.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.1279-1286
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• 2010

This paper deals with the influence on the dynamic response of I-type girder railway bridge with high-speed electric multiple unit(HEMU) train load. This bridge system which has six I-girder and several cross beams, is modeled with plate and frame elements. And the upper slab is assumed to be fully connected with girders using rigid rinks. Span lengths, types of vehicle and running speeds are selected as parameters for analyses. For more exact analysis, it was adopted that 3-dimensional section of bridge models was produced by the assumed design wheel loads of HEMU vehicle at 200~350 km/hr speeds. Dynamic vertical deflections, dynamic amplification factors and vertical accelerations of bridges having 30 and 35 m span length were investigated and compared with the limit values specified in various national railway bridge specifications.

• 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.

• Smart Structures and Systems
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• v.21 no.5
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• pp.637-652
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• 2018

This paper presents a comparative study of displacement measurement using four sensors that are being used in the field: they are a ring gauge, a laser Doppler vibrometer (LDV), a vision-based displacement measurement system (VDMS), and an optoelectronic displacement meter (ODM). The comparative study was carried out on a brand-new high-speed railroad bridge designed to produce displacements within a couple of millimeters under the loading of a high-speed train. The tests were carried out on a single-span steel plate girder bridge two times with different train loadings: KTX and HEMU. The measured displacement is compared as raw and further discussion was made on the measurement noise, peak displacement, and frequency response of four sensors. The comparisonsare summarized to show the pros and cons of the used sensors in measuring displacement at a typical high-speed railroad bridge.

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.220-223
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• 2000

A method of calculating the natural frequency corresponding to the modes of vibration of beams and tower structures, with irregular cross sections and with arbitrary boundary conditions was developed and reported by Kim, D. H. in 1974. In this paper, the result of application of this method to the three span continuous reinforced concrete bridge with elastic intermediate supports is presented. Such bridge represents either concrete or sandwich type three span bridge on polymeric supports for passive control or on actuators for active control The concrete slab is considered as a special orthotropic plate. The influence of the modulus of the foundation and $D_{22}$, $D_{12}$, $D_{66}$ stiffnesses on the natural frequency is thoroughly studied.

• Wind and Structures
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• v.9 no.1
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• pp.59-74
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• 2006

Vertical stabilizer plates have been found to be an effective aerodynamic measure to improve the aerodynamic stability of bridges either with an open cross section or with a streamlined box cross section in wind tunnel testings and have been adopted in some long span bridges. By taking an open deck II-shaped section and a closed box section as examples, the mechanism of vertical stabilizer plates for improving aerodynamic stability are investigated by using numerical simulation based on Random Vortex Method. It is found that vertical stabilizer plates can increase the amplitude of the heaving motion, and decrease that of the rotational motion of the bridge decks.

• Journal of Korean Society of Steel Construction
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• v.26 no.2
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• pp.105-118
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• 2014

The number of the deteriorated bridge has been sharply increased due to the increase in the bridge service period in Korea. Local corrosion problem of structural member can be occurred according to atmospheric corrosion environments based on the installation location of steel bridges. Especially, in case of the plate girder bridge, corrosion damage is concentrated on the web panel and stiffener at girder end. An asymmetrical shear resistant web section in the plate girder bridge can be caused from the local corrosion of the web panel, because local corrosion is not symmetrically occurred to the bridge. In this study, therefore, the shear buckling strength and behavior of a plate girder with asymmetrically corroded web panel was numerically evaluated using FE analysis, which was considering an aspect ratio and corrosion damage level of web panel. The shear buckling strength reduction of an asymmetrical shear resistant web panel was compared and evaluated according to corroded volume ratio for a web panel and for diagonal tension field of a web panel.

• Steel and Composite Structures
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• v.26 no.5
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• pp.583-594
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• 2018

Although a lot of experimental and analytical investigations have been carried out for steel bridge piers made of SS400 and SM490, the formulas available for SS400 and SM490 are not suitable for evaluating ultimate load and deformation capacities of steel bridge piers made of high strength steel (HSS) SM570. The effect of various parameters is investigated in this paper, including plate width-to-thickness ratio, column slenderness ratio and axial compression force ratio, on the ultimate load and deformation capacities of steel bridge box piers made of SM570 steel subjected to cyclic loading. The elasto-plastic behavior of the steel bridge piers under cyclic loads is simulated through plastic large deformation finite element analysis, in which a modified two-surface model (M2SM) including cyclic hardening is employed to trace the material nonlinearity. An extensive parametric study is conducted to study the influences of structural parameters on the ultimate load and deformation capacities. Based on these analytical investigations, new formulas for predicting ultimate load and deformation capacities of steel bridge piers made of SM570 are proposed. This study extends the ultimate load and deformation capacities evaluation of steel bridge piers from SS400, SM490 steels to SM570 steel, and provides some useful suggestions.

• Smart Structures and Systems
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• v.21 no.2
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• pp.171-185
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• 2018

Maintenance of deteriorated bridge structures has always been one of the challenging issues in developing countries as it is directly related to daily life of people including trade and economy. An effective maintenance strategy is highly dependent on timely inspections on the bridge health condition. This study is intended to investigate an approach for detecting bridge damage for the long-term health monitoring by use of copula theory. Long-term measured data for the seven-span plate-Gerber bridge is investigated. Autoregressive time series models constructed for the observed accelerations taken from the bridge are utilized for the computation of damage indicator for the bridge. The copula model is used to analyze the statistical changes associated with the modal parameters. The changes in the modal parameters with the time are identified by the copula statistical properties. Applicability of the proposed method is also discussed based on a comparison study among other approaches.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.10
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• pp.109-115
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• 2001

The compliance approach to the problem of load sharing between a cracked plate and multiple plate used to bridge the crack. The theory is validated by using calculated stress intensity factors for the multiple load path plate to reduce experimentally observed growth rate to a common base. Calculations are them made on the effect of multiple load path plate width on fatigue crack retardation in order to demonstrate the predictive capability of the technique.