• International Journal of Highway Engineering
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• v.17 no.2
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• pp.13-20
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• 2015

PURPOSES: This paper describes the expansion caused by the alkali-aggregate reaction (AAR) in concrete pavement currently in service. It also discusses the effects of joints installed to release the stress induced by the AAR expansion. METHODS: The expansion effect on concrete pavement was verified by a visual inspection and long-term measurement of the joint width of a cut-section. The behaviors of 16 newly installed joints were monitored as part of the investigation and long-term monitoring was carried out for three years after cutting. RESULTS: The behavior of a bridge was affected when AAR occurred in the connected pavement. The newly installed joints shrank in the longitudinal direction of the bridge after cutting. The width of the joints decreased over the six months after cutting. A large portion of the joint width (8.5cm) was found to have closed nine months after cutting. It had ultimately shrunk by about 92 percent when the final measurement was taken. CONCLUSIONS : The expansion of the pavement due to AAR was quantitatively described by visual inspection and the long-term monitoring of the newly cut joints. However, the width of the new joints decreased over the six to nine months after cutting. Additional research should be conducted to determine a means of controlling the expansion due to AAR in the pavement.

• Structural Engineering and Mechanics
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• v.17 no.2
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• pp.215-244
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• 2004

There is an ever-increasing demand for assessment of earthquake effects on transportation structures, emphasised by the crippling consequences of recent earthquakes hitting developed countries reliant on road transportation. In this work, vulnerability functions for RC bridges are derived analytically using advanced material characterisation, high quality earthquake records and adaptive inelastic dynamic analysis techniques. Four limit states are employed, all based on deformational quantities, in line with recent development of deformation-based seismic assessment. The analytically-derived vulnerability functions are then compared to a data set comprising observational damage data from the Northridge (California 1994) and Hyogo-ken Nanbu (Kobe 1995) earthquakes. The good agreement gives some confidence in the derived formulation that is recommended for use in seismic risk assessment. Furthermore, by varying the dimensions of the prototype bridge used in the study, and the span lengths supported by piers, three more bridges are obtained with different overstrength ratios (ratio of design-to-available base shear). The process of derivation of vulnerability functions is repeated and the ensuing relationships compared. The results point towards the feasibility of deriving scaling factors that may be used to obtain the set of vulnerability functions for a bridge with the knowledge of a 'generic' function and the overstrength ratio. It is demonstrated that this simple procedure gives satisfactory results for the case considered and may be used in the future to facilitate the process of deriving analytical vulnerability functions for classes of bridges once a generic relationship is established.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.111-122
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• 1994

In this study, an algorithm which can be applied to the optimum design of simple steel plate girders was developed, and efficient optimization strategies for the solution of algorithm were found out. The optimum design algorithm consists of 3-levels of optimization. In the first and second levels of optimization, the absolute maximum bending moment and shearing force are extracted and in the third level of optimization, the optimum cross section of steel plate girder is determined. For the optimum design of cross section, the objective function is formulated as the total area of cross section and constraints are derived in consideration of the various stresses and the minimum dimension of flange and web based on the part of steel bridge in the Korea standard code of road bridge. Sequential unconstrained minimization technique using the exterior penalty function method(SUMT-EP), sequential linear programming(SLP) and sequential quadratic programming (SQP) are proved to be efficient and robust strategies for the optimum design of simple plate girder cross section. From the reliable point of view, SLP is the most efficient and robust strategy and SQP is the most efficient one from the viewpoint of converguency and computing time.

• Journal of the Korean Society of Safety
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• v.29 no.3
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• pp.72-78
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• 2014

The minimum thickness of long-span deck slab is proposed by checking the limit state according to the Korean highway bridge design code(limit state design). Both minimizing thickness and ensuring safety of deck slab are important design factors to increase a competitive price of the long span deck slabs. The required thicknesses for satisfying flexural capacity, preventing punching shear failure and limiting deflection were calculated by considering KL-510 load model which has increased total load compared to DB 24 from 432 kN to 510 kN. The results of the required thickness for various limit states were compared to propose the minimum thickness as a function of span length of deck slabs. The proposed minimum thickness is influenced by satisfying flexural capacity and limiting deflection. It turns out to be similar compared to the results of the previous study by ultimate strength design method even if the live load model was increased in total weights.

• Journal of People, Plants, and Environment
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• v.24 no.1
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• pp.85-94
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• 2021

Background and objective: This study examined, compared, and analyzed the tree vitality of the trees growing on the artificial ground of Seoullo 7017 that transformed the overpass that was to be demolished into a "sky garden" using portable tree pots. Methods: Based on the summer season when the metabolic activity of plants is most active, this study measured the cambial electrical resistance in four directions(east, west, south and north), using the Shigometer (model OZ-93, Osmose) and compared the location and analysis of pots according to their means and standard errors. Results: Meanwhile, according to the analysis, vitality was relatively superior in pots with a big diameter, trees planted individually than in groups, trees of the ramp section rather than the bridge section, and in the southwest direction of the cambium. Conclusion: This study revealed the improper condition of the planting plan and implementation on the site, where various species of trees are displayed in a poor environment. Despite the significant assessment of the vitality of various trees introduced within Seoullo 7017 for the first time, this study is limited in that the data used were measured only once in summer. In this regard, it raised the need for continuous interest in and monitoring of a special plant environment and development of proper maintenance and management techniques, along with follow-up research on seasonal and temperature conditions, soil moisture and root development conditions to supplement this research.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.4
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• pp.187-194
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• 2008

Recently, the constructions of widening bridges or new bridges are often undergoing as a part of road widening because traffic volumes are rapidly increasing caused by fast-growing population and urbanization. But in general, there is no rational decision process and specification to justify the validity of the bridge widening. Moreover, there are also numerous events including various uncertainties involved in widening bridges. In this paper, therefore, a decision making model is proposed for widening bridges using decision tree based on quantitative LCC analysis considering a variety of uncertainties for the rational and practical approach to a quantitative decision making for alternatives.

• Korean Journal of Environment and Ecology
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• v.25 no.5
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• pp.649-657
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• 2011

This study had targeted the Manjong Junction~Hongchun interchange section of Jungang highway in order to analyze the efficiency and improvement of the highway wild-life fences. Being analyzed wild-life fence as an effective facility for the prevention of road-kill, it had founded that the wild animals did not jump over even the two layer guardrail, concrete barrier and noise barrier, fence for rock fall. For the section with high road-kill decrease effect after installing the wild-life fence, the effect was higher at wild-life fence with the height of 1.0m where the door had not been installed and the well connected points of road facility than the area with fence height of 1.5m. The road-kill decrease effect was also high at the well managed areas even if the door has not been installed. Also, road-kill had occurred by concentrating around the end of wild-life fence after installing the fence, Moreover road-kill had also occurred around the cutting section. The door of wild-life fence had higher amount of road-kill occurrence as the installation interval was closer. it was analyzed that the door management has a lot of effect on road-kill decrease. The fence for rock fall, two layer guardrail and concrete barrier having the effect of wild-life fence installed on the road would have to be installed by connecting with wild-life fences through proper facility improvement. Although the door should not be installed if possible, it should be installed as automatic door or gravity door to prevent the door from leaving the door open. An escape route has to be formed for the prompt escape away from the road for the animals entered through the ending section of the fence. The eco-corridor has to be made by restoring the soil layer of dual purpose eco-corridor forming a planting area. Also, the dead body after the accident has to be disposed to the outer section of the road immediately in order to prevent the secondary road-kill by the predator from the road-kill. The fence has to be installed as 500m or longer in both ways, in other words 1,000m or longer, from the targeted spot of minimum accident prevention while connecting up to the bridge or box culvert, etc that are next road facilities if possible to guide wild animals safely to the eco-corridor.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.401-404
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• 2008

Bridges are exposed to very severe environment and experience, as service life increased, elevated traffic load and traffic flow, in addition to natural disasters. In comparing to other road structures, bridges may cause more significant damage, such as human-involved accidents, to the society in the event of collapse. A certain level of service shall be necessarily secured to assure the minimum safety of users. The cost for manage and preserve bridges will increase gradually and more restrictions will be loaded to efficiently distribute the limited resources, such as monetary budget and human resource etc. In order to enhance performance and serviceability of bridges with the limited resource, asset management technique has been applied into the bridge management system, which capitalizes the road infrastructures including bridges and assess them in accordance with the government finance report. In the application of asset management, there must be a tool for assess the performance of bridges and this study introduces the basic information on the definition and role of performance measures for asset management for bridges.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.869-881
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• 1999

Inchon International Airport Elevated Road Way is located between the Passenger Terminal Building and Transportaion Center which are Inchon International Airport core construction projects. The deck of the bridge is consists of 5-span or 6-span continuous pre-stressed concrete slab. Steel form has been used to enhance the quality of texture on concrete slab. Steel form has been used to enhance the quality of texture on concrete surface, lower surface of deck slab with the two way arch has been manufactured by highly professional manner in order to get an beautiful exterior architectural looks. The prestressed concrete deck slab is mass concrete structures with a high-specified concrete strength and a varying section in the range of 0.95-2.8m thickness. Therefore high risks of thermal cracking occurrence by heat of hydration highly are expected. To resolve such problem, we adopted type 1 cement and pipe cooking method at construction site through mass concrete specimen test and 3-dimensional analysis. For Pipe cooling we used 25mm diameter stainless pipes with wrinkles. Cooling pipe with spacing 50-60cm has been installed. And continuous pipe cooling with cooling water of 15$^{\circ}C$ was conducted for 2days. In present 8 span of all 29 spans construction has been completed. No thermal cracking heat hydration has been observed yet.

• Journal of the Korea Institute of Military Science and Technology
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• v.20 no.2
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• pp.279-288
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• 2017

The Material Transportation Capability Analysis Method in North Korea includes adversary's activities such as destruction of bridge which is one kind of choke points in the road network and surprise attack against resupply march unit. Also, the amount of damage on choke points in the road network and repair time depending on repair unit commitment must be reflected. In this study, a scenario encompassing plausible resupply transportation circumstances while counterattacking into NK will be established. Then, based on such scenario, a simulation model will be established and the result of simulation will be compared to the results of numeric example which has been used in the ROK Army. We demonstrate, through a certain Corps operation area, that the Scenario-based Simulation Model results predict the performance of resupply operation very well. Therefore, it makes sustainment planners and commanders do activities which is suitable for battlefield and should be used in the real situation. It is also a stochastic model.