• Journal of the Korean Society for Railway
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• v.13 no.2
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• pp.186-193
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• 2010

Track system and periodic live load are characteristics of railway bridges. In the design and construction of railway bridge, periodic live load increases the importance of dynamic behavior. And It is well known that behavior of railway bridge may be affected by track system in real bridge. Through experimental study, static and dynamic behaviors were investigated. Deflection and stress due to bending moment were measured, the location of neutral axis of each section, natural frequency, damping ratio were analyzed for each three track systems - girder only, installed ballast track system and installed concrete slab track system. According to measured values for the each type of track system, concrete track system increases the stiffness of bridge by 50%, and ballast system does by 7%, dynamic responses of structure change linearly with the magnitude of load and location of neutral axis of each sections varies with each track system. Damping ratio is almost equal without and with track. Therefore, the effects of track system on the integral behaviors of railway bridge can not be ignored in the design of bridge, especially in the case of concrete slab track system. So study of the quantitative analysis method for effects of track system must be performed.

• Journal of the Korea Concrete Institute
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• v.19 no.5
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• pp.569-575
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• 2007

The repair of concrete surfaces does not normally take into account structural tolerance for longer service lift and better capabilities of concrete structures. In particular, the repair of surface spelling completes as mortar is applied, which does not display additional structural performances. The use of crimped wire mesh for better construction and fracture resistance, however, expects to have some reinforcement effects. Particularly, it is also expected that the repair of bottom part in structures built between bridges like irrigation structures results in the increase of flexural resistance. Therefore, this study is intended to perform the repair using crimp wire mesh and examine strength depending on the repair section and depth. For this, a slab with 150 mm in depth, 3,000 mm in length and 600 mm in width and total 8 objects to experiment such as upper part, upper whole, bottom part, bottom whole and crimp wire mesh reinforced are manufactured to perform flexural performance. The results of the analysis show that yield strength and failure load increase as the depth of repair materials in the experiment reinforced with crimp wire mesh get bigger. In the same condition, repair of bottom part is able to increase internal force of bending force. Besides, the results show that partial repair of structures under bending force cannot produce flexural performance. Consequently, the repair method with crimp wire mesh results in the increase of flexural resistance.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.3
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• pp.119-129
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• 2018

The Ministry of Land, Transport and Maritime Affairs has promulgated the mandatory design of BIM for road projects of more than 50 billion won by 2020 under the Basic Plan for the Sixth Construction Technology Promotion. As a result, major public clients are attempting to implement BIMs that are appropriate to the situation of each institution. On the other hand, it is difficult to design and construct a proper BIM and accumulate BIM information of the ordering organization because the technical guidelines and standard classification system that can perform BIM effectively have not been presented sufficiently. The characteristics of the road should be managed systematically, e.g., atypical objects, such as earthworks, which are constantly changing along a line; large objects, such as bridges and tunnels; and facilities, such as signs and soundproof walls. To achieve this, a multitude of standard systems should be developed and disseminated, but there have been insufficient studies on practical methods. To solve this problem, this study developed a BIM standard object classification system in the road sector to meet the international standard, accommodate a multi-dimensional information system, and provide a more effective BIM standard information environment that can be utilized easily by practitioners.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.683-692
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• 2020

A joint displacement resistance evaluation method for selecting waterproofing materials in railway bridge decks is proposed. The displacement range for an evaluation is determined by finite element method (FEM) analysis of a load case based on an existing high-speed PSC Girder Box railroad bridge structure. The FEM analysis results were used to calculate the minimum joint displacement range to be applied during testing (approximately 1.5 mm). For the evaluation, four commonly used waterproofing membrane types, cementitious slurry coating (CSC), polyurethane coating system (PCS), self-adhesive asphalt sheet (SAS), and composite asphalt sheet (CAS), were tested, with five specimens of each membrane type. The joint displacement width range conditions, including the minimum displacement range obtained from FEM analysis, were set to be the incrementing interval, from 1.5, 3.0, 4.5, and 6.0 mm. The proposal for the evaluation criteria and the specimen test results demonstrated how the evaluation method is important for the sustainability of high-speed railway bridges.

• Journal of the Korea Concrete Institute
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• v.21 no.6
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• pp.681-688
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• 2009

The railroad bridges have been usually experienced by vibration and impact in service state. With this reason, it is important that the effective strengthening capacity should be considered to resist the kind of service loading. In this study, NSM strengthening technique is recommended for the concrete railroad bridge because of its better effective resistance for dynamic loading condition and strengthening cost than the conventional externally bonded strengthening using fiber sheet. However, to widely apply NSM method for the concrete railroad bridge, it needs that the strengthening ratio has to be reasonably evaluated with geometrical and material uncertainties, especially for the concrete bridge under long-term service state without the apparent design history and detail information such as concrete compressive strength, reinforcing ratio, railroad characteristics. The purpose of this study is to propose the critical strengthening ratio of CFRP plate for the targeted concrete railroad bridge with uncertainties of deterioration of the structures. To do this, Monte Carlo Simulation (MCS) for geometrical and material uncertainties have been applied so that this approach may bring the reasonable strengthening ratio of CFRP plate considering probabilistic uncertainties for the targeted concrete railroad bridge. Finally, the critical strengthening ratio of NSM strengthened by CFRP plate is calculated by using the limit state function based on the target reliability index of 3.5.

• Journal of the Korea Concrete Institute
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• v.28 no.2
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• pp.177-185
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• 2016

This paper concerns the flexural behavior of steel fiber-reinforced ultra-high-performance concrete (UHPC) beams with compressive strength of 150 MPa. It presents experimental research results of hybrid steel fiber-reinforced UHPC beams with steel fiber content of 1.5% by volume and steel reinforcement ratio of less than 0.02. This study aims at investigating of compressive and tensile behavior of UHPC to perform a reasonable prediction for flexural capacity of UHPC beams. Tensile behavior modeling was performed using load-crack mouth opening displacement relationship obtained from bending test. The experimental results show that steel fiber-reinforced UHPC is in favor of cracking resistance and ductility of beams. The ductility indices range from 1.6 to 3.0, which means high ductility of hybrid steel fiber-reinforced UHPC. Test results and numerical analysis results for the moment-curvature relationship are compared. Though the numerical analysis results for the bending capacity of the UHPC beam without rebar is larger than test result, the overall comparative results show that the bending capacity of steel fiber-reinforced UHPC beams with compressive strength of 150 MPa can be predicted by using the established method in this paper.

• Journal of architectural history
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• v.19 no.1
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• pp.91-104
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• 2010

Korea's stone buildings are varied in their types such as stone pagodas, stone lanterns, stone bridges, stoneworks, etc. These account for more than 30% over the entire cultural properties, but research achievements are lacking compared to wooden buildings. Accordingly, this study aims to identify the shape, role and transition of Tapgu, which had been used to set up boundary at a stone pagoda, one of the stone buildings. The 20th stone pagodas, which have relative accuracy in its forming year, have been studied around national treasure or treasure between 7th century and 9th century. There are a lot of different opinions about the role and meaning of Tapgu, and at this writer's option, Tapgu is defined as follows: First, each structure plays a different role. A structure to pass the load in the upper part to the ground can be seen as a stair or a pedestal, but a structure to form double foundations can be considered as Tapgu. Second, Tapgu can be used to divide areas with stones or stepping stones. As a result, the shape, role and transition of Tapgu is as follows: Firstly, when it comes to its shape, Tapgu includes flagstone type, belt type, double foundation type, compound type. Flagstone type had been used to set up boundary at stone pagodas by using foundation stone, belt type by keeping apart from stone pagodas, and double foundation stone by installing dual foundation stones. Secondly, Tapgu is considered to set up boundary in the case of flagstone and plate stone, and acts like a structure which can prevent surrounding area of stone pagoda from coming up while being stuck around stone pagodas. Belt type was installed only for the purpose of forming boundary. At the bottom, double foundation stone had been used to pass the load in the upper part to the ground in the same way as the foundation stone in the upper part, and the boundaries were set varying the size. Thirdly, when it comes to the transition of Tapgu, flagstone type of boundary stone had been installed in the 7th century, and belt type of boundary stone had been mainly installed in the 8th century. And double foundation stone had been installed in the 9th century. Comprehensively, flagstone type and belt type had been made around the 7th and 8th century when Tapgu was regarded important and stone pagoda started to be built. At the turn to the 9th century, the role of Tapgu had been increasingly losing in the construction of stone pagoda, and foundation stone started to appear.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.189-198
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• 2011

Although high strength bolts with tensile strength of 1,000 MPa are mainly used in steel structure construction sites throughout the world, new high strength bolts are required owing to the installation of continuous long-span bridges resulting from the development and distribution of high strength steel and ultra-thick steel plates. Currently, high strength bolts with tensile strength of 1,300 MPa are being used. However, as they tend to place a large load on a small section of space, a high strength bolt of high structural performance and screw thread shape with less stress concentration is thought to be more effective. This study conducted analyses in order to develop an improved screw thread shape relative to the KS screw thread shape. A new screw thread shape with less stress concentration and effective load distribution at the time of fastening bolts and nuts was provided upon analysis of the characteristics of screw thread shape. Additionally, in an experimental study, the structural performance of high strength bolts with tensile strength of 1,300 MPa was investigated. The results revealed that the new screw thread shape was more effective than the existing screw thread shape in terms of structural performance and mitigating the stress concentration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.3A
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• pp.207-214
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• 2011

Ultra High Performance Concrete (UHPC), which is characterized by its high strength and advanced ductile behavior that is much superior to those of convention concrete, is a useful material to make thinner and longer bridges. The precast segmental construction method utilizing UHPC has been mainly studied because cast-in-place UHPC is very difficult and complicate to be achieved. As a part of those research, the structural performance evaluation of different types of joint connection method for hybrid cable-stayed bridge utilizing UHPC by using nonlinear analyses is performed in this study. The bond stress at joint is obtained by section force analyses for a 600 m cable-stayed bridge deck, and compared with the required bond stress at joint. Analysis results show that the U Type connection and straight type connection resist the highest ultimate load and bond strength, respectively. In addition, all considered joint connection systems satisfy the bond performances at joint required in the final stage of cable-stayed bridge utilizing UHPC.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.1
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• pp.85-91
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• 2020

The descendants of Jang, Chang-woo(張昌雨) reconstructed the Mangwijung (晩歸亭), which is currently located at Seha-dong, Seo-gu, Gangju Metropolitan City, in the context of succeeding the work of their ancestor. This study investigated the management viewpoint of Mangwijung that has been altered in going through the reconstruction and repairs processes, and examined the chronological history for a landscape of the Mangwijung Garden. First, in the Mangwijung Garden, three gazebos such as Mangwijung, Seubhyanggag(襲香閣) and Mukamjeongsa(墨庵精舍) stand in a row with three bridges between each of them in the middle of a wide pond. This is a group of gazebos that is a quite unique structure. Second, Hyowoodang(孝友堂) Jang, Chang-woo (張昌雨) built Mangwijung as a role of thatched cottage in order to teach younger students and enjoy the arts in his later life. The Mangwijung was reconstructed by the descendants of Jang, Chang-woo at the collapsed place later on in order to commemorate the achievements of their ancestor. By the way, it was revealed that the management of Mangwijung has been altered during the process of reconstruction. Third, when comparing the current appearance with those depicted in the 8 scenic views(八景) by Jang, Chang-woo and the literary works of his descendants, it was confirmed that the landscape and shape of the pond were damaged due to a road expansion caused by a construction of Seubhyanggag and Mukamjeongsa as well as an advancement of the city. Fourth, it is speculated that the pond of Mangwijung Garden is probably a spring not a reservoir to store the water stream that flows in.