• Title, Summary, Keyword: OpenSees

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SEISMIC ISOLATION OF NUCLEAR POWER PLANTS

  • Whittaker, Andrew S.;Kumar, Manish;Kumar, Manish
    • Nuclear Engineering and Technology
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    • v.46 no.5
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    • pp.569-580
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    • 2014
  • Seismic isolation is a viable strategy for protecting safety-related nuclear structures from the effects of moderate to severe earthquake shaking. Although seismic isolation has been deployed in nuclear structures in France and South Africa, it has not seen widespread use because of limited new build nuclear construction in the past 30 years and a lack of guidelines, codes and standards for the analysis, design and construction of isolation systems specific to nuclear structures. The funding by the United States Nuclear Regulatory Commission of a research project to the Lawrence Berkeley National Laboratory and MCEER/University at Buffalo facilitated the writing of a soon-to-be-published NUREG on seismic isolation. Funding of MCEER by the National Science Foundation led to research products that provide the technical basis for a new section in ASCE Standard 4 on the seismic isolation of safety-related nuclear facilities. The performance expectations identified in the NUREG and ASCE 4 for seismic isolation systems, and superstructures and substructures are described in the paper. Robust numerical models capable of capturing isolator behaviors under extreme loadings, which have been verified and validated following ASME protocols, and implemented in the open source code OpenSees, are introduced.

Experimental study and modelling of CFRP-confined damaged and undamaged square RC columns under cyclic loading

  • Su, Li;Li, Xiaoran;Wang, Yuanfeng
    • Steel and Composite Structures
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    • v.21 no.2
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    • pp.411-427
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    • 2016
  • While the cyclic behaviour of fiber-reinforced polymer (FRP)-confined columns is studied rather extensively, the cyclic response especially the energy dissipation of FRP-confined damaged and undamaged square RC columns is not yet fully understood. In this paper, an experimental and numerical investigation was conducted to study the cyclic behavior of two different types of Carbon FRP (CFRP)-confined square RC columns: strengthened and repaired. The main variables investigated are initial damage, confinement of CFRP, longitudinal steel reinforcement ratio. The experimental results show that lower initial damage, added confinement with CFRP and longitudinal reinforcement enhance the ductility, energy dissipation capacity and strength of the columns, decrease the stiffness and strength degradation rates of all CFRP-confined square RC columns. Two hysteretic constitutive models were developed for confined damaged and undamaged concrete and cast into the non-linear beam-column fiber-based models in the software Open System for Earthquake Engineering Simulation (OpenSees) to analyze the cyclic behavior of CFRP-confined damaged and undamaged columns. The results of the numerical models are in good agreement with the experiments.

The Countermeasure for improvement of Construction Safety Management (건설 안전관리의 현황과 발전방향 - 건설공사 관리의 개선방안)

  • 박무일
    • Journal of the Korean Professional Engineers Association
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    • v.34 no.3
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    • pp.33-40
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    • 2001
  • Predict-Plan-Do is the main point to settle Safety management well, but we have neither Predict nor Plan. So just like the system of English CDM is necessary to be adapted in construction work which makes them work in full responsibility by clarifying the responsibility located step by step from planning to designing & constructing-To adapt this system needs more money for Safety than now, but this system makes companies earn maximum confidence & profit by accident prevention. Furthermore leads the nation and the society to earn large profit, then open the road to Welfare State. If you sees only the things such as money, profit, etc before your eyes, no more safety remains. That means no more respect of persons and no more welfare state.

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Development of Progressive Collapse Analysis Program considering Dynamic Effects (동적효과를 고려한 연쇄붕괴해석 프로그램의 개발)

  • Kim, Jin-Koo;Park, Jun-Hee;An, Da-Woon;Kim, Hyun-Su
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.771-776
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    • 2007
  • Widespread propagation of failure can be triggered by localized damage to a structure because of fires, impact and explosion etc. In this paper, the progressive collapse analysis program is developed to automatically check the failed members and construct the modified structural model at each step. OpenSees, that is widely used in many research groups, was used for the developed progressive collapse analysis control program. The control program developed in this study automatically computes the damage indices of all the structural members and performance a progressive collapse analysis after the first failed member is selected. Using the developed program, we compared the progressive collapse behaviors of the example structures considering dynamic effects or not, and the difference of progressive collapse mechanism according to the modeling method of the failed members.

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Constitutive models of concrete structures subjected to seismic shear

  • Laskar, Arghadeep;Lu, Liang;Qin, Feng;Mo, Y.L.;Hsu, Thomas T.C.;Lu, Xilin;Fan, Feng
    • Earthquakes and Structures
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    • v.7 no.5
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    • pp.627-645
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    • 2014
  • Using OpenSees as a framework, constitutive models of reinforced, prestressed and prestressed steel fiber concrete found by the panel tests have been implemented into a finite element program called Simulation of Concrete Structures (SCS) to predict the seismic behavior of shear-critical reinforced and prestressed concrete structures. The developed finite element program was validated by tests on prestressed steel fiber concrete beams under monotonic loading, post tensioned precast concrete column under reversed cyclic loading, framed shear walls under reversed cyclic loading or shaking table excitations, and a seven-story wall building under shake table excitations. The comparison of analytical results with test outcomes indicates good agreement.

Cumulative deformation of high-speed railway bridge pier under repeated earthquakes

  • Gou, Hongye;Leng, Dan;Bao, Yi;Pu, Qianhui
    • Earthquakes and Structures
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    • v.16 no.4
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    • pp.391-399
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    • 2019
  • Residual deformation of high-speed railway bridge piers is cumulative under repeated earthquakes, and influences the safety and ride comfort of high-speed trains. This paper investigates the effects of the peak ground acceleration, longitudinal reinforcement ratio, and axial compression ratio on the cumulative deformation through finite element analysis. A simply-supported beam bridge pier model is established using nonlinear beam-column elements in OpenSees, and validated against a shaking table test. Repeated earthquakes were input in the model. The results show that the cumulative deformation of the bridge piers under repeated earthquakes increases with the peak ground acceleration and the axial compression ratio, and decreases with the longitudinal reinforcement ratio.

Nonlinear static and dynamic behavior of reinforced concrete steel-braced frames

  • Eskandari, Reyhaneh;Vafaei, Davoud;Vafaei, Javid;Shemshadian, Mohammad Ebrahim
    • Earthquakes and Structures
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    • v.12 no.2
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    • pp.191-200
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    • 2017
  • In this paper, the seismic performance of reinforced concrete braced frames (RC-BF) under far- and near-fault motions was investigated. Four-, eight-, 12- and 16-story RC-BFs were designed on the basis of a code-design method for a high risk seismic zone. Nonlinear static and dynamic analyses of the frames have been performed using OpenSees software. To consider diverse characteristics of near-fault motions, records with forward-directivity and fling-step effects were employed. From the results obtained in the analytical study it is concluded that the used design method was reasonable and the mean maximum drift of the frames under all ground motion sets were in acceptable range. For intermediate- and high-rise buildings the near-fault motions imposed higher demands than far-faults.

Reliability analysis of double-layer domes with stochastic geometric imperfections

  • Gordini, Mehrdad;Habibi, Mohammad Reza;Sheidaii, Mohammad Reza;Tahamouliroudsari, Mehrzad
    • Advances in Computational Design
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    • v.2 no.2
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    • pp.133-146
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    • 2017
  • This study aimed to investigate the effect of initial member length an imperfection in the load carrying capacity of double-layer domes space structures. First, for the member length imperfection of each member, a random number is generated from a normal distribution. Thereupon, the amount of the imperfection randomly varies from one member to another. Afterwards, based on the Push Down analysis, the collapse behavior and the ultimate capacity of the considered structure is determined using nonlinear analysis performed by the OpenSees software and this procedure is repeated numerous times by Monte Carlo simulation method. Finally, the reliability of structures is determined. The results show that the collapse behavior of double-layer domes space structures is highly sensitive to the random distribution of initial imperfections.

RTS test study and numerical simulation of mechanical properties of HDR bearings

  • Peng, Tianbo;Wu, Yicheng
    • Earthquakes and Structures
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    • v.13 no.3
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    • pp.299-307
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    • 2017
  • High Damping Rubber bearings (HDR bearings) have been used in the seismic design of bridge structures widely in China. In earthquakes, structural natural periods will be extended, seismic energy will be dissipated by this kind of bearing. Previously, cyclic loading method was used mainly for test studies on mechanical properties of HDR bearings, which cannot simulate real seismic responses. In this paper, Real-Time Substructure (RTS) test study on mechanical properties of HDR bearings was conducted and it was found that the loading rate effect was not negligible. Then the influence of peak acceleration of ground motion was studied. At last test results were compared with a numerical simulation in the OpenSees software framework with the Kikuchi model. It is found that the Kikuchi model can simulate real mechanical properties of HDR bearings in earthquakes accurately.

Fragility characteristics of skewed concrete bridges accounting for ground motion directionality

  • Jeon, Jong-Su;Choi, Eunsoo;Noh, Myung-Hyun
    • Structural Engineering and Mechanics
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    • v.63 no.5
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    • pp.647-657
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    • 2017
  • To achieve this goal, two four-span concrete box-girder bridges with typical configurations of California highway bridges are selected as representative bridges: an integral abutment bridge and a seat-type abutment bridge. A detailed numerical model of the representative bridges is created in OpenSees to perform dynamic analyses. To examine the effect of earthquake incidence angle on the fragility of skewed bridges, the representative bridge models are modified with different skew angles. Dynamic analyses for all bridge models are performed for all earthquake incidence angles examined. Simulated results are used to develop demand models and component and system fragility curves for the skewed bridges. The fragility characteristics are compared with regard to earthquake incidence angle. The results suggest that the earthquake incidence angle more significantly affects the seismic demand and fragilities of the integral abutment bridge than the skewed abutment bridge. Finally, a recommendation to account for the randomness due to the ground motion directionality in the fragility assessment is made in the absence of the predetermined earthquake incidence angle.