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Study of Failure Mode and Static Behavior of Lightweight FRP Truss Bridge Deck System (복합재료 트러스 교량시스템의 정적거동 및 파괴모드에 관한 해석적 연구)

  • Jung, Woo-Young;Lee, Hyung-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.20 no.5
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    • pp.511-520
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    • 2007
  • There is a concern with worldwide deterioration of highway bridges, particularly reinforced concrete. The advantages of fibre reinforced plastic(FRP) composites over conventional materials motivate their use in highway bridges for replacement of structures. Recently, an FRP deck has been installed on a state highway, located in New York State, as an experimental project. In this paper, a systematic approach for analysis of this FRP deck bridge is presented. Multi-step linear numerical analyses have been performed using the finite element method to study the structural behavior and the possible failure mechanism of the FRP deck-superstructure system. Deck's self-weight and ply orientations at the interface between steel girders and FRP deck are considered in this study. From this research, the results of the numerical analyses were corroborated with field test results. Analytical results reveal several potential failure mechanism for the FRP deck and truss bridge system. The results presented in this study may be used to propose engineering design guideline for new and replacement FRP bridge deck structure.

Development of Method for Manufacturing Freeform EPS Forms Using Sloped-LOM Type 3D Printer (Sloped-LOM 방식 3D 프린터를 이용한 비정형 EPS 거푸집 제작 공법 개발)

  • Ahn, Heejae;Lee, Dongyoun;Ji, Woojong;Lee, Woojae;Cho, Hunhee
    • Journal of the Korea Institute of Building Construction
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    • v.20 no.2
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    • pp.171-181
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    • 2020
  • Recently, free-formed construction technology is becoming a new measure of representing technological superiority and sociocultural ingenuity. However, the CNC processing technology utilizing the existing wood and iron form has limitations in terms of the manufacturing time and material cost. Therefore, in this study, the method and process of manufacturing free-formed EPS form using S-LOM-based 3D printing technology were suggested. Furthermore, through the mock-up test, a comparative analysis of the manufacturing time and precision with CNC milling technology was conducted. The results show that S-LOM-based 3D printing technology has reduced manufacturing time about 57.4% compared to CNC milling technology during the free-formed EPS form manufacturing process. In addition, compared to the design drawings, the maximum error value was 20.5mm, proving the applicability of S-LOM-based 3D printing technology. The results of this study are expected to contribute to the improvement of S-LOM method and the activation of S-LOM method by verifying the applicability of S-LOM-based 3D printing technology.

Appraisal Study on Tensile Test Method of Mechanical Properties of FRP Composite Used in Strengthening RC Members (구조보강용 FRP 복합체의 역학적 특성치 분석을 위한 인장시험방법 평가 연구)

  • You, Young-Chan;Choi, Ki-Sun;Kang, In-Seok;Kim, Keung-Hwan
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.12 no.1
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    • pp.73-80
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    • 2008
  • Experimental study has been performed in order to construct the standard test methods and appraisal criteria by investigating the influence of specimen types(property, width, layers) and loading rate on the tensile characteristics of FRP used in strengthening RC structures. The FRP composite tested in this study are the unidirectional CFRP sheet/strip and the bidirectional GFRP sheet. Test variables consist of the various width ranging from 10mm to 25mm and number of CFRP sheets plied up to 5 layers. Test results indicated that maximum tensile strength and minimum coefficient of variation are recorded at each different width according to the fiber types and weaving directions. Also, the average tensile strengths of CFRP sheets are decreased as the number of layer of CFRP sheet are increased.

Shear Characteristics of Elastomeric Bearing Rubber Deteriorated by Accelerated Heat Aging(2): Chloroprene Rubber (가속열 노화로 열화된 탄성받침 고무재료의 전단 특성(2): 합성고무)

  • Sun, Chang-Ho;Kim, Ick-Hyun
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.25 no.6
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    • pp.103-110
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    • 2021
  • Elastomeric bearings composed of flexible rubber materials and steel reinforcement plates are widely used for seismic retrofit of bridges due to their excellent vertical stiffness and flexible lateral stiffness. Especially, it has the advantages of simple construction and low cost. Chloroprene rubber, a type of rubber material, has greater resistance to aging than natural rubber, but its performance is also degraded due to various deterioration factors. Although these aging characteristics are not reflected in the seismic design standards and seismic performance evaluation guidelines, it is reasonable to reflect this when related studies are accumulated. For chloroprene rubber, accelerated heat aging test was performed with variables of heating temperatures and exposure time to analyze shear characteristics. As aging progresses the maximum shear stress and shear strain decrease. Also, the shear stiffness is greatly increased at the same shear strain.

Optimization of Material Extruding Performance to Build a 3D Printed Habitat on the Moon and Mars (달, 화성 3D 프린팅 주거지 건설을 위한 재료 사출기능 최적화 연구)

  • Lee, Jin Young;Lee, Tai Sik
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.39 no.2
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    • pp.345-349
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    • 2019
  • The National Aeronautics and Space Administration (NASA) has long been studying the essential elements of manned planetary exploration and has held several international challenges to encourage the research works related to it. One of them was the NASA Centennial Challenge Programs which started in 2015. Following the second in 2017, the third is currently going on in 2019. Participating "3D-Printed Habitat Challenge", one of the challenges in the second program, this research team designed and developed the 3D printer extruding module for the Lunar Simulant (Korea Hanyang Lunar Simulant-1; KOHLS-1) and the polymer. For optimizing the modul, a cylindrical specimen of ${\varnothing}150{\times}300mm^3$ volume and a specimen of $200{\times}100{\times}650mm^3$ volume were manufactured and their compressive and flexural strengths were tested. The findings can help automatize the space construction in the future.

Structural Characteristics of Pultruded Composite Bridge Deck of Hollow Section (인발성형 중공단면 복합소재 교량 바닥판의 구조적 특성 분석)

  • Lee, Sung Woo;Kim, Byung Suk;Jo, Nam Hoon
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.1A
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    • pp.35-43
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    • 2006
  • In this paper, procedures and research results involved in the development of glass reinforced composite bridge deck of hollow section were presented. Laminate design for the 3 cell deck section was performed. Structural characteristics such as serviceability, strength, failure and stability for DB24 load were analytically studied through the finite element analysis for the composite deck plate girder bridge. Composite deck tube was fabricated with pultrusion and extensive tests such as flexural test, girder-connection test, barrier-connection test, compression fatigue test and flexural fatigue test were carried out to evaluate structural behavior experimentally. Also, field load test was conducted for the demonstration plate girder bridge with composite deck and requirements for the strength and serviceability were reviewed.

Evaluation of Fire Investigation as the Separation Distances for Several Types of Insulation Panels (단열패널 종류별 이격거리에 따른 화재감식 평가)

  • Kim, Jeong-Hun;Kim, Da-Seul
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.4
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    • pp.403-412
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    • 2021
  • Despite strengthening requirements for fire retardancy and applied buildings of insulation panels, the number of fires and influence of damage have increased. In this study, the thermal effects were evaluated as the separation distances, and three types of EPS panel, glass wool panel, and gypsum board panel were then selected. Temperature sensors on the panels were installed vertically from the ground. The fire source on the lamination layer of lumber was ignited by changes in the separation distances (0 cm, 25 cm, 50 cm) from the panels. The test results suggested that the maximum temperature was 349 ℃ in the EPS panel. The inside/outside shape changes were limited by the height of the low and middle positions until the critical point of a 25 cm separation distance. Furthermore, the combustion marks appeared after 500 s on average, and then the EPS panel with a high fire strength showed a broad "U type" pattern, glass wool panel, and gypsum board panel showed medium or narrow "V type" pattern. Therefore, the acquired data can provide valuable information for evaluating the fire risks and verifying fire investigation from buildings composed of these insulation panels.

Permanent Formwork of PLA Filament utilizing 3D Printing Technology (3D 프린팅 기술을 활용한 PLA 필라멘트 비탈형 거푸집 연구)

  • Jeong, Junhyeong;Hyun, Jihun;Jeong, Heesang;Go, Huijae;Lee, Juhee;Ahn, Joseph
    • Korean Journal of Construction Engineering and Management
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    • v.22 no.1
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    • pp.81-89
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    • 2021
  • In recent years, the design of buildings is changing from formal to creative and freeform. Accordingly, the scale of construction technology is changing to architectural design and construction of irregular buildings. Using the FDM method, which is one of the 3D printing technologies, it is possible to manufacture various forms of irregular formwork inexpensively and quickly coMPared to the existing formwork, and it seems to be able to solve the manpower problem. Using a 3D printer, the PLA filament formwork is produced in the form of a cylinder and a rectangular cuboid, and the usability of the PLA filament formwork is confirmed by examining the compression strength test and the degree of deformation and reusability over 28 days of age. Different sizes of additional specimens are also conducted according to the size. As a result of the experiment, it was confirmed that the filament formwork itself has about 3~4MPa strength. As a result of reviewing data through existing linear studies and experiments, it is appropriate to use more than 60% infill, and it is advantageous in terms of strength. As a result of cutting and dismantling the filament formwork, the surface is very clean and there is no damage, so it can be reused.