• Journal of Korean Society of Steel Construction
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• v.11 no.2 s.39
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• pp.213-222
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• 1999

Elastic-plastic methods have been used for the better prediction of the actual behavior of continuous-composite plate girder bridges in the overload and maximum load analysis. The structural evaluation using ALFD(Alternate Load Factor Design) uses the elastic-plastic analysis. The plastic rotations that remain after the load is removed can be occurred by the yielding locations of the maximum moment section. This situation can occur due to the residual stresses even if the moment is below the theoretical yield moment. The local yielding causes positive automoments that assure elastic behavior under subsequent overloads. In this study, the automoments at the piers occurred due to the unit plastic rotations and other locations were calculated by the conjugate-beam method and three-moment equation, using the nine design span with progressively smaller pier sections. The automoments were determined by the developed computer programs in this study in which the moments and plastic rotations from the continuity and moment-inelastic rotation relationships must be equal. And also the ratings of 3-span continuous composite plate girder bridges with non-compact section were carried out according to the Korean Highway Bridge Specification.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1174-1187
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• 2007

Monorail System has many advantages compared with other Urban Lightweight Transit Systems, such as the friendliness of the vehicle's appearance, slenderness of the bridge structures, it's low construction cost and short construction period. So, lots of city governments have reviewed or proposed the Monorail System as the attractive alternative system. And recently, Daegu Metropolitan City Government have chosen the Monorail System for the Urban Railroad Line 3. According to these trends on Urban Lightweight Transit Systems, this paper has introduced the outline of the planning and design of Monorail Bridges. At first, trends of overseas Monorail Bridges have been reviewed and the principal design criteria adopted in the basic design of the Urban Railroad Line 3 for Daegu have been introduced. And next, the methods of planning, design, fabrication of the guideway beams which are made of PSC Beam or Steel Beam have been explained. We hope this paper be helpful for the Engineers who are interested in the Monorail Bridges.

• Journal of Korean Society of Steel Construction
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• v.23 no.1
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• pp.13-27
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• 2011

This paper presents an investigation of the structural stability of cable-stayed bridges, using geometric nonlinear finite-element analysis and considering various geometric nonlinearities, such as the sag effect of the cables, the beam-column effect of the girder and mast, and the large displacement effect. In this analytic research, a nonlinear frame element and a nonlinear equivalent truss element were used to model the girder, mast, and cable member. The live-load cases that were considered in this research were assumed based on the traffic loads. To perform reasonable analytic research, initial shape analyses in the dead-load case were performed before live-load analysis. In this study, the geometric nonlinear responses of the cable-stayed bridges with different cable arrangement types were compared. After that, parametric studies on the characteristics of the structural stability in critical live-load cases were performed considering various geometric parameters, such as the cable arrangement type, the stiffness ratios of the girder and mast, the area of the cables, and the number of cables. Through this parametric study, the effect of geometric shapes on the structural stability of cable-stayed bridges was investigated.

• Structural Monitoring and Maintenance
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• v.1 no.3
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• pp.249-271
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• 2014

This paper presents a unique study of Structural Health Monitoring (SHM) for the maintenance decision making about a real life movable bridge. The mechanical components of movable bridges are maintained on a scheduled basis. However, it is desired to have a condition-based maintenance by taking advantage of SHM. The main objective is to track the operation of a gearbox and a rack-pinion/open gear assembly, which are critical parts of bascule type movable bridges. Maintenance needs that may lead to major damage to these components needs to be identified and diagnosed timely since an early detection of faults may help avoid unexpected bridge closures or costly repairs. The fault prediction of the gearbox and rack-pinion/open gear is carried out using two types of Artificial Neural Networks (ANNs): 1) Multi-Layer Perceptron Neural Networks (MLP-NNs) and 2) Fuzzy Neural Networks (FNNs). Monitoring data is collected during regular opening and closing of the bridge as well as during artificially induced reversible damage conditions. Several statistical parameters are extracted from the time-domain vibration signals as characteristic features to be fed to the ANNs for constructing the MLP-NNs and FNNs independently. The required training and testing sets are obtained by processing the acceleration data for both damaged and undamaged condition of the aforementioned mechanical components. The performances of the developed ANNs are first evaluated using unseen test sets. Second, the selected networks are used for long-term condition evaluation of the rack-pinion/open gear of the movable bridge. It is shown that the vibration monitoring data with selected statistical parameters and particular network architectures give successful results to predict the undamaged and damaged condition of the bridge. It is also observed that the MLP-NNs performed better than the FNNs in the presented case. The successful results indicate that ANNs are promising tools for maintenance monitoring of movable bridge components and it is also shown that the ANN results can be employed in simple approach for day-to-day operation and maintenance of movable bridges.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2006.11a
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• pp.680-685
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• 2006

Bridges are an integral part of Transportation that is always open to traffic.To effectively manage bridges today, more needs to be done to assess the day-to-day condition and behavior of bridges, and the deterioration rates of their components, so that efficient and proactive measures can be taken. Conventional methods consumemore time and they lack flexibility to reach all locations in high convoluted structures which most bridges offer. Instead, this work uses a new concept of robot, termed as Bridge inspecting robot, which, as its name suggests, possesses superior ability to flex, reach, and approach all points on the bridge. This study also provides economical feasibility model for the same and a comparison with existing bridge inspection and automated inspection work. Finally, we have uncovered few issues and did not analyze some information because of limitation to data.

• Journal of Korean Society of Steel Construction
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• v.9 no.4 s.33
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• pp.501-513
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• 1997

The general behavior of curved girder including the warping effects is formulated by series of differential equations postulated by Vlasov. In order to determine the maximum shear force, the maximum bending moment, the maximum pure torsion, the maximum warping torsion, and the maximum bimoment for the curved girder grid bridges, it is important to find the location of live load applied to the curved girder grid bridges, so that the influence line can be estimated. In this paper, the influence line of shear force, bending moment, pure torsion, warping torsion, and bimoment due to unit vertical load and unit torsional moment for curved I-girder grid bridges are obtained by using the finite difference method.

• Korean Journal of Construction Engineering and Management
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• v.12 no.2
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• pp.101-110
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• 2011

Because bridges can cause more significant damage than other infrastructure a certain level of safety shall necessarily be secured for users. As most of bridges' service life become 20-30 years there will be a dramatic increase in the maintenance and repair cost but the budget and human resource will be limited. Asset management technique can help the efficiency in maintenance and budget management with the limited resource. For its application, there must be a way to evaluate how bridges provide service to users. The level of service can be quantified by a performance measure. This study introduces performance measures and an evaluation process for the determination of level of service. The evaluation results will be used as a fundamental information in the determination of maintenance/repair/management targets and in the decision making process of the bridge asset management.

• Journal of the Architectural Institute of Korea Structure & Construction
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• v.35 no.6
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• pp.153-164
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• 2019

The presence of thermal bridges in a building envelope cause additional heat loss which increases the heating energy. Given that a higher building insulation performance is required in these cases, the heat loss via thermal bridges is a high proportion of the total heat energy consumption of a building. For the dry exterior insulation system that uses mullions and transoms to fix insulation and exterior materials such as stone and metal sheet, the occurrence of thermal bridges at mullions and transoms is one of the main reasons for heat loss. In this study, a dry exterior insulation system using the truss insulation frame (TIF) was proposed as an alternative to metal mullions. To evaluate the building envelope performance, structural, air-leakage, water-leakage, fire-resistance, thermal, and condensation risk tests were conducted. In addition, the annual energy consumption associated with heating and cooling was calculated, including the linear thermal transmittance of the thermal bridges. As a result, the dry exterior insulation system using TIF achieved the allowable value for all tests. It was also determined that the annual heating load of a building was reduced by 36.7 % when the TIF dry exterior insulation system was used, relative to the dry exterior insulation system using steel pipes without additional insulations.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2005.04a
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• pp.704-711
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• 2005

Recently Life Cycle Cost Analysis for civil infrastructures such as pavements, bridges, and dams has been emphasized However, so far, there are few systems available for life cycle cost analysis of bridges at design stage. Therefore, the objective of this paper is to develop a user-friendly life-cycle cost analysis system for LCC-effective optimal design decision making at design stage. The program is based on the proposed LCC model, formulation, analysis modules and systematic procedure that suit Korean construction conditions. It is expected that the developed system can be effectively utilized for more LCC-effective design of bridges. It is applied to an actual bridge design project in order to demonstrate its effectiveness and applicability.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.439-446
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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.