• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.1-13
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• 1993

In design of prestressed concrete structures, structural analysis is performed normally several times for selection of adequate sectional dimension and tendon amount. Especially for precast segmental multi-span bridges. time consuming structural analysis process due to time dependent material properties and structural system change could be effectively reduced by use of a reduced-span bridge model. 5-span and 3-span bridges are selected as reduced-span models for the 10-span full bridge to investigate the acceptability in practical design. The analytical results of deflection, total moment, statical moment, and ultimate moment of the reduced span-models are compared with those of the 10-span full bridge. Application of the load factors to structural analysis for ultimate moment calculation in prestressed concrete is reviewed and a rational method is proposed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.2
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• pp.165-179
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• 2007

For the purpose of optimum design of reinforced concrete structures, pre-determined section database of column and beam are constructed and arranged in order of the resisting capacity. Then, regression equations representing the relation between section number and section resisting capacity are derived. In advance, effective optimization algorithms which search optimized solution quickly using direct search method from these database are proposed. In practice, from the fact that engineers conduct member design close to capacity optimization rather than cost optimization, both capacity and cost optimization using proposed algorithms are performed, and the review for the obtained results are followed. Moreover, the investigation for the applicability and effectiveness of the Introduced design procedure is conducted through correlation study for example structures. Because of no restriction in constructing objective functions with very simple optimization processes and fast convergence, the introduced method can effectively be used in the preliminary design stage. Especially, selected solutions from database are directly applicable in practice because these sections already satisfy all the requirements in design codes and practical restrictions.

• Journal of the Korean Wood Science and Technology
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• v.39 no.6
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• pp.521-530
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• 2011

Nowadays, market demand of structural Glulam is growing and diversifying. The durability of Glulam should be significantly considered when they are intended to apply for out-door use such as timber bridge and pergola. This study was aimed to develop the manufacturing process of preservative treated structural Glulam using domestic softwood species. 10 m long structural Glulam were manufactured from domestic pitch pine logs with CuAz-3 preservative treatment. At each manufacturing process, the production yield was evaluated. Finally, bending tests were performed to verify the structural performance of manufactured Glulam. From the results, it was shown that the preservative treatment process hardly influenced on the production yield. But domestic pitch pine was proved to not be suitable for making the preservative treated Glulam due to the large difference of preservative permeability between sapwood and heartwood.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.3
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• pp.75-83
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• 2018

In study, Structural stability was considered when applying the high strength strut method with improved general strut method. considered whether there is sufficient stiffness to so as not buckling to the maximum hypothetical earth pressure. also structure stability of the strut component was reviewed. The high strength strut method is a technique used in place of the general strut method. high strength prefabricated Strut method is a technique that has bolt holes drilled in the upper flange at regular intervals. As a result of the buckling analysis, it was considered that the safety factor increased by about 5 %. also Since the stress generated is below the allowable stress, it is judged that structural stability of the strut is ensured. In particular, the safety factor of axial compressive stress increases about 16 % with use of high strength steel when applying the high strength prefabricated strut method. the high strength strut method is construction method may shorten the construction period and there is no expense to purchase additional materials.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.3
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• pp.71-83
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• 2008

In this paper, the basic principle, the application and the limitation of Infrared thermography technique to detect defects in different kinds of concrete structures are reviewed. Considered are voids beneath the concrete surface with experiments, delamination between concrete surface and fiber reinforced polymer sheet, the deterioration of steel bars in reinforced concrete, surface defects in historical buildings, pavements, bridges, and railway track graves. As a result, we conclude that infrared thermography methods are useful for fast detecting defects; however, they are influenced by environmental factors, specially temperature. Therefore it is recommended to use the infrared thermography technique with other NDT equipments to expect better result.

• 대한공업교육학회지
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• v.31 no.2
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• pp.364-380
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• 2006

This paper presents a procedure for designing command to maneuver flexible structure with very little residual vibration, even in the presence of modeling errors. For the open loop maneuver, the various shaped profiles using multiple step inputs delayed in time are considered for robustness and compared with the responses of rigid body and flexible body in virtue of simulations and experiments. Input shaping generates vibration-reducing shaped commands through convolution of an impulse sequence with the desired command. A flexible model with a cylindrical hub and four symmetric appendages is considered to examine the responses to real plant, and to illustrate the effectiveness of the proposed shapers. The appendages are long and flexible, leading to low frequency vibration under any control action. It is shown by a series of simulation that a properly designed feedback controller with input shaper performs well, as compared with open loop controller with input shaper. The control objective is to achieve a fast settling time of residual vibration to flexible structure and robustness (insensitivity)to plant uncertainty, to eliminate residual vibration.

• Journal of the Korean Society of Hazard Mitigation
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• v.9 no.5
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• pp.69-78
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• 2009

Since the blast vibration induced by explosives of the powder possibly provide damage of the nearby structures adjacent to the tunnel, the stability of the nearby structures should be estimated. In this study, the stability of the tunnel based on the allowable peak particle velocity of the structures as well as allowable stress of the structures presented in the concrete structural design standard was estimated with respect to the stress of the concrete lining and axial force of the rockbolt during the blasting operation at the ground surface of the pre-existing tunnel. The analyses were carried out by using $FLAC^{2D}$ which is one of the programs developed based on the finite difference method. The bending compressive stress and shear stress of the concrete lining and axial force of the rockbolt were rapidly increased when the blasting operation was conducted near the tunnel.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.3
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• pp.196-200
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• 2010

The number of railway tunnels has been increasing rapidly. Although fires in long railway tunnels are rare, the consequences can be devastating. Prior to this study, there were no adequate time-temperature curves for the fire safety assessment of Korean railway tunnels. We studied a standard foreign time-temperature curve for which the heat rate is based on the traffic and the types of vehicles. We then proposed a hydrocarbon curve as a fire design model for railway tunnels in Korea. We examined the implications of this proposed model on railway tunnel structures using numerical analysis.

• Journal of the Korean GEO-environmental Society
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• v.12 no.9
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• pp.5-11
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• 2011

Recently, large and deep excavations are increasing. The damage of adjacent structures due to excavation has steadily increased with increasing construction demand. Especially in urban development and poor conditions, the excavation adjacent to the subway structures has caused a lot of problems. This paper was reviewed that the underground excavation and reinforcement of the status process through a case study on the field. And stability analysis through the case study evaluates applicability for reasonable reinforcement method by numerical analysis. As a result, the strata distribution condition of all 16 sites consisted of landfill from the top and distributed in the order of deposits, weathered soils, weak rock from the bottom. Also, when proceeding the excavation adjacent to structures, the location of site and layer conditions have highly effect on the results of the construction. Therefore, this study was applied reinforcement method to protect damage by excavation. Displacement and settlement were within allowable criterion and hence, stability of structure was analyzed as safe.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.36 no.5
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• pp.347-354
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• 2023

In this study, virtual reality software was developed to support the generation of an analysis model of a Hanok and to increase the use of the completed analysis model. The structural analysis model of the Hanok was generated using midas Gen, a general-purpose structural analysis software. After converting it into a text-based input file, the developed software stores the data necessary for the examination of the analysis model. Then, in the developed virtual reality software, the three-dimensional analysis model of the Hanok can be visualized in various ways and the related data can be shown by selecting a specific member. Through this process, errors in the analysis model can be identified and corrected to build a complete analysis model. The developed software was applied to three Hanok cases to verify its applicability and effectiveness. The software is expected to be used in other fields besides the structural field.