• Title/Summary/Keyword: Stable structural behavior

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Application of Energy-Dissipating Sacrificial Device(EDSD) for Enhancing Seismic Performance of Bridges (교량의 내진성능 향상을 위한 희생부재형 에너지소산장치(EDSD)의 적용에 관한 연구)

  • Kim, Sang-Hyo;Cho, Kwang-Yil;Kim, Hae-Young
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2006.03a
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    • pp.445-452
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    • 2006
  • A new Energy-Dissipating Sacrificial Device(EDSD) is proposed, which can effectively dissipate the energy stored in the structures during seismic actions. A mathematical 3-D bridge models and analysis techniques are developed to represent the non-linear behavior of the EDSD, various seismic responses of a sample bridge with the EDSD are analyzed in terms of energy, member forces and deformation using the developed analysis method. And the EDSD is tested and certified it's behavior and stability to apply on exiting bridges. The EDSD can be able to dissipate a large amount of energy and therefore it can prevent the pier's excessive forces under seismic excitations and EDSD and its connected members are also stable. Additionally, the method and guidelines of an optimum EDSD design are proposed in terms of installation method and decision of number of EDSD. The Proposed EDSD under seismic excitations can significantly decrease the excessive storing energy in the bridge structures and reduce the relative displacements of each superstructure to the ground. The EDSD is also found to function as a structural fuse under strong ground motions, sacrificing itself to absorb the excessive energy. Consequently, economical enhancement of the seismic performance of bridges can be achieved by employing the newly developed energy dissipation sacrificial device(EDSD).

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Experimental Study on Seismic Performance Enhancement of Exposed Column-base Plate Strong-axis Connections for Small-Sized Steel Buildings (소규모 철골조건축물 강축방향 노출형 주각부의 내진성능 향상을 위한 실험 연구)

  • You, Young-Chan
    • Journal of the Architectural Institute of Korea Structure & Construction
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    • v.34 no.12
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    • pp.11-20
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    • 2018
  • The purpose of this study is to investigate the seismic performance of exposed column-base plate strong-axis connections for small-sized steel buildings. Even though the seismic design for small-sized buildings became mandatory since Dec.2017, the arbitrary connection details in steel structure have been applied at the construction site, which is considered to be very insufficient to secure structural safety and stability considering the increased seismic risk. Therefore, a series of experimental test programs had been carried out to develop enhanced connection details in order to ensue the adequate seismic safety of small buildings. The hysteretic behavior of the exposed column-base plate connections commonly used in Korea seem to be very pure poor due to the "Rocking" phenomena between anchor plate and concrete by the residual plastic deformation of anchor bolts. A series of hysteretic tests were conducted to find the solution to overcome the "Rocking" phenomena of the exposed column-base plate connections, finally the stable seismic behavior was obtained by uisng at least 8 anchor bolts with good bonding strength to the protptype specimen.

Experimental and numerical study of a proposed steel brace with a localized fuse

  • Parsa, Elham;Ghazi, Mohammad;Farahbod, Farhang
    • Structural Engineering and Mechanics
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    • v.84 no.2
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    • pp.269-283
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    • 2022
  • In this paper, a particular type of all-steel HSS brace members with a locally reduced cross-sectional area was experimentally and numerically investigated. The brace member was strengthened against local buckling with inner and outer boxes in the reduced area. Four single-span braced frames were tested under cyclic lateral loadings. Specimens included a simple steel frame with a conventional box-shaped brace and three other all-steel reduced section buckling-restrained braces. After conducting the experimental program, numerical models of the proposed brace were developed and verified with experimental results. Then the length of the proposed fuse was increased and its effect on the cyclic behavior of the brace was investigated numerically. Eventually, the brace was detailed with a fuse-to-brace length of 30%, as well as the cross-sectional area of the fuse-to-brace of 30%, and the cyclic behavior of the system was studied numerically. The study showed that the proposed brace is stable up to a 2% drift ratio, and the plastic cumulative deformation requirement of AISC (2016) is easily achieved. The proposed brace has sufficient ductility and stability and is lighter, as well as easier to be fabricated, compared to the conventional mortar-filled BRB and all-steel BRB.

Nonlinear inelastic analysis of steel-concrete composite beam-columns using the stability functions

  • Park, Jung-Woong;Kim, Seung-Eock
    • Structural Engineering and Mechanics
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    • v.30 no.6
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    • pp.763-785
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    • 2008
  • In this study, a flexibility-based finite element method considering geometric and material nonlinearities is developed for analyzing steel-concrete frame structures. The stability functions obtained from the exact buckling solution of the beam-column subjected to end moments are used to accurately capture the second-order effects. The proposed method uses the force interpolation functions, including a moment magnification due to the axial force and lateral displacement. Thus, only one element per a physical member can account for the interaction between the bending moment and the axial force in a rational way. The proposed method applies the Newton method based on the load control and uses the secant stiffness method, which is computationally both efficient and stable. According to the evaluation result of this study, the proposed method consistently well predicts the nonlinear inelastic behavior of steel-concrete composite frames and gives good efficiency.

An Effect of $O_2/Ar$ Ratio on the Characteristics of RF Magnetron Sputtered $BaTiO_3$ Thin Film (RF Magnetron Sputtering법으로 $BaTiO_3$ 박막 증착시 $O_2/Ar$비가 박막의 특성에 미치는 영향)

  • 안재민;최덕균;김영호
    • Journal of the Korean Ceramic Society
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    • v.31 no.8
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    • pp.886-892
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    • 1994
  • Structural and electrical properties of BaTiO3 thin films deposited on Pt/SiO2/Si substrates by RF magnetron sputtering method have been investigated. Crystallization behavior and electrical properties were studied for the films deposited under various sputtering gas compositions (Ar+O2 gas mixture) and substrate temperatures. All the films deposited above 50$0^{\circ}C$ were all crystallized and their preferred orientation changed from (001) to (111) with the addition of oxygen gas. The dielectric constant of films deposited in pure argon was about 110 and showed little dependence on the substrate temperature. But that was increased as the ratio of O2/Ar increased and its substrate temperature dependence was discernible. The highest dielectric constant reached to 550. In addition, the films deposited in mixed gas showed stable dielectric properties against the frequency and temperature.

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Electrochemical Properties of PPy/CNT Electrodes Prepared by Chemical Process for Ultracapacitor

  • Shin, Jeong-Gyun;Park, Soo-Gil
    • Journal of the Korean Electrochemical Society
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    • v.10 no.2
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    • pp.141-144
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    • 2007
  • Polypyrrole(PPy) was composite with MWNT to attain cycle stable by chemical method. We have been considered PPy is the ideal material for high energy density electrochemical capacitor due to pseudo capacitor reaction. In this study we found that increase in cycle life due to composite MWNT. Also PPy/MWNT composite material have resulted larger capacitance and exhibits better electrochemical behavior. The structural feature was investigated by using SEM and TEM. The PPy/CNT composite is not only a promising ultracapacitor material for energy storages but also has a good possibility because of its great capacitive properties, simple preparation and low cost.

The Vacuum Pressure Effects on Electrochromic Properties of Tungsten Oxide Thin Films by Electron Beam Evaporation (전자비임에 의해 제작된 WO$_3$ 박막의 전기적착색 특성에 대한 진공도의 효과)

  • 이길동
    • Proceedings of the Korea Society for Energy Engineering kosee Conference
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    • 1995.05a
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    • pp.41-44
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    • 1995
  • The electrochromic WO$_3$ thin films were prepared by using an electron - beam evaporation technique. The influence of the electron - beam evaporation conditions. especially the vacuum pressure, and resistance of ITO substrate on the structural and electrochromic properties of the investigated film was presented. This films showed electrochromic behavior in an aqueous electrolyte of 1 M H$_2$SO$_4$. Among these WO$_3$ thin films, films prepared at a vacuum pressure of 10$^{-4}$ mbar were found to be most stable in terms of cycling durability. The chemical stability of film against dissolution in the aqueous solution was also shown to depend on the quantity of water in the film.

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Characteristics and electrochemical performance of Metal Oxide/MWNTs/nano-composites for ultra capacitor (울트라 커패시터용 Metal Oxide/MWNTs의 특성과 전기화학적 성능)

  • Shin, Jeong-Gyun;Park, Soo-Gil
    • Proceedings of the KIEE Conference
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    • 2007.07a
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    • pp.1365-1366
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    • 2007
  • Cobalt oxide was composite with MWNT to attain cycle stable by chemical method. We have been considered CoOx is the ideal material for high energy density electrochemical capacitor due to pseudo capacitor reaction. In this study we found that decrease in resistance due to composite MWNT. Also CoOx/MWNT composite material have resulted larger capacitance and exhibits better electrochemical behavior. The structural feature was investigated by using SEM. The CoOx/MWNT composite is not only a promising ultracapacitor material for energy storages but also has a good possibility because of its great capacitive properties, simple preparation and low cost.

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Redox Property of Vanadium Oxide and Its Behavior in Cataltic Oxidation

  • 김영호;이호인
    • Bulletin of the Korean Chemical Society
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    • v.20 no.12
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    • pp.1457-1463
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    • 1999
  • Structure and their redox property of the vanadium oxides prepared by decomposing NH₄VO₃ at various temperatures were studied by XRD, SEM, XPS, and temperature programmed reduction/temperature programmed oxidation (TPR/TPO) experiment. All TPR profiles have two sharp peaks in the temperature range 650-750℃, and the area ratio of the two sharp peaks changed from sample to sample. There were three redox steps in TPR/TPO profiles. The oxidation proceeded in the reverse order of the reduction process, and both the reactions proceeded via quite a stable intermediates. The changes of the morphological factor $(I_{(101)}/I_{(010)})$, the ratio of $O_{1S}$ peak area (O$_{1S}$( α)/O$_{1S}$( β)) in the XPS results, and the ratio of hydrogen consumption in TPR profiles with various vanadium oxides showed the distinct relationship between the structural property and their redox property of vanadium oxides. The change of the specific yield of phthalic anhydride with various vanadium oxides showed a very similar trend to those of the peak area ratio in TPR profiles, which meant that the first reduction step related to the partial oxidation of o-xylene on the vanadium oxide catalyst.

Experimental Study on Double Skin Composite Walls Subjected to Cyclic Loading (주기하중을 받는 이중강판합성벽의 실험연구)

  • Eom, Tae Sung;Park, Hong Gun;Kim, Jin Ho;Chang, In Hwa
    • Journal of Korean Society of Steel Construction
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    • v.20 no.2
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    • pp.289-301
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    • 2008
  • Double skin composite (DSC) wall is a structural wall that is filed with concrete between two steel plate skins connected by tie bars. This type of wall was developed to enhance the structural performance of wall, to reduce wall thickness, and to enhance constructibility, eliminating the use of formwork and re-bars. In this study, cyclic tests were performed to investigate the inelastic behavior and earthquake resistance of isolated and coupled DSC walls with rectangular and T-shapedcross-sections. The DSC walls showed stable cyclic behaviors, exhibiting excellent energy dissipation capacity. The te st specimens failed by the tensile fracture of welded joints at the wall base and coupling beam and by the severe local buckling of the steel plate. The deformation capacity of the walls varied with the connection details at the wall base and their cross-sectional shapes. The specimens with well-detailed connections at the wall base showed relatively god deformation capacity ranging from 2.0% to 3.7% drift ratio. The load-carrying capacities of the isolated and coupled wall specimens were evaluated considering their inelastic behavior. The results were compared with the test results.