• Title, Summary, Keyword: seismic behavior

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Multilevel performance-based procedure applied to moderate seismic zones in Europe

  • Catalan, Ariel;Foti, Dora
    • Earthquakes and Structures
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    • v.8 no.1
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    • pp.57-76
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    • 2015
  • The Performance-based Earthquake Engineering (PBEE) concept implies the definition of multiple target performance levels of damage which are expected to be achieved (or not exceeded), when the structure is subjected to earthquake ground motion of specified intensity. These levels are associates to different return period (RP) of earthquakes and structural behaviors quantified with adopted factors or indexes of control. In this work an 8-level PBEE study is carried out, finding different curves for control index or Engineering Demand Parameters (EDP) of levels that assess the structural behavior. The results and the curves for each index of control allow to deduce the structural behavior at an a priori unspecified RP. A general methodology is proposed that takes into account a possible optimization process in the PBEE field. Finally, an application to 8-level seismic performance assessment to structure in a Spanish seismic zone permits deducing that its behavior is deficient for high seismic levels (RP > 475 years). The application of the methodology to a low-to-moderate seismic zone case proves to be a good tool of structural seismic design, applying a more sophisticated although simple PBEE formulation.

Temperature effect on seismic behavior of transmission tower-line system equipped with SMA-TMD

  • Tian, Li;Liu, Juncai;Qiu, Canxing;Rong, Kunjie
    • Smart Structures and Systems
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    • v.24 no.1
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    • pp.1-14
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    • 2019
  • Transmission tower-line system is one of most critical lifeline systems to cities. However, it is found that the transmission tower-line system is prone to be damaged by earthquakes in past decades. To mitigate seismic demands, this study introduces a tuned-mass damper (TMD) using superelastic shape memory alloy (SMA) spring for the system. In addition, considering the dynamic characteristics of both tower-line system and SMA are affected by temperature change. Particular attention is paid on the effect of temperature variation on seismic behavior. In doing so, the SMA-TMD is installed into the system, and its properties are optimized through parametric analyses. The considered temperature range is from -40 to $40^{\circ}C$. The seismic control effect of using SMA-TMD is investigated under the considered temperatures. Interested seismic performance indices include peak displacement and peak acceleration at the tower top and the height-wise deformation. Parametric analyses on seismic intensity and frequency ratio were carried out as well. This study indicates that the nonlinear behavior of SMA-TMD is critical to the control effect, and proper tuning before application is advisable. Seismic demand mitigation is always achieved in this wide temperature range, and the control effect is increased at high temperatures.

Seismic response analysis of embankment dams under decomposed earthquakes

  • Nasiri, Fatemeh;Javdanian, Hamed;Heidari, Ali
    • Geomechanics and Engineering
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    • v.21 no.1
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    • pp.35-51
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    • 2020
  • In this study, the seismic response analysis of embankment dams was investigated through numerical modeling. The seismic behavior of dams under main earthquake records and wavelet-based records were studied. Earthquake records were decomposed using de-noising method (DNM) and down-sampling method (DSM) up to five levels. In decomposition process, low and high frequencies of the main earthquake record were separated into two signals. Acceleration response, spectral acceleration, and Fourier amplitude spectrum at the crest of embankment dams under different decomposition levels were evaluated. The seismic behavior under main and decomposed earthquake records was compared. The results indicate an acceptable agreement between the seismic responses of embankment dams under wavelet-based decomposed records and main earthquake motions. Dynamic analyses show that the DNM-based decomposed earthquake records have a better performance compared to DSM-based records. DNM-based records up to level 4 and DSM-based records up to level 2 have a high accuracy in assessment of seismic behavior of embankment dams. The periods corresponding to the maximum values of acceleration spectra and the frequencies corresponding to the maximum values of Fourier amplitude spectra of embankment dam crest under main and decomposed records are in good agreement. The results demonstrate that the main earthquake records can be replaced by wavelet-based decomposed records in seismic analysis of embankment dams.

Dynamic Behavior of Curved Bridges under Seismic Loading (지진하중을 받는 곡선교량의 동적거동)

  • Park, Nam-Hoi;Yoon, Ki-Yong;Kang, Young-Jong
    • Journal of the Korean Society of Hazard Mitigation
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    • v.5 no.3
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    • pp.11-21
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    • 2005
  • This study is performed to understand complex behavior and to investigate the rational analysis methods for seismic design of the curved bridges. To analyze the curved bridges for the seismic loadings, it is used that the finite element analysis program has the 7-dof curved beam and straight beam element. The free vibration characteristics of the curved bridges are compared with the straight bridges that have span length same as the average arc length of inside and outside girder of those. For the same case, the dynamic behavior is compared under seismic loadings. It is found that regular bridges classified by AASHTO are analyzed as if those were straight. To investigate the dynamic behavior of general curved bridges under seismic loading, the seismic loading directions and the subtended angle of curved bridges are varied.

Seismic performance and design method of PRC coupling beam-hybrid coupled shear wall system

  • Tian, Jianbo;Wang, Youchun;Jian, Zheng;Li, Shen;Liu, Yunhe
    • Earthquakes and Structures
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    • v.16 no.1
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    • pp.83-96
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    • 2019
  • The seismic behavior of PRC coupling beam-hybrid coupled shear wall system is analyzed by using the finite element software ABAQUS. The stress distribution of steel plate, reinforcing bar in coupling beam, reinforcing bar in slab and concrete is investigated. Meanwhile, the plastic hinges developing law of this hybrid coupled shear wall system is also studied. Further, the effect of coupling ratio, section dimensions of coupling beam, aspect ratio of single shear wall, total height of structure and the role of slab on the seismic behavior of the new structural system. A fitting formula of plate characteristic values for PRC coupling beams based on different displacement requirements is proposed through the experimental date regression analysis of PRC coupling beams at home and abroad. The seismic behavior control method for PRC coupling beam-hybrid coupled shear wall system is proposed based on the continuous connection method and through controlling the coupling ratio, the roof displacement, story drift angle of hybrid coupled shear wall system, displacement ductility of coupling beam.

Piecewise exact solution for analysis of base-isolated structures under earthquakes

  • Tsai, C.S.;Chiang, Tsu-Cheng;Chen, Bo-Jen;Chen, Kuei-Chi
    • Structural Engineering and Mechanics
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    • v.19 no.4
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    • pp.381-399
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    • 2005
  • Base isolation technologies have been proven to be very efficient in protecting structures from seismic hazards during experimental and theoretical studies. In recent years, there have been more and more engineering applications using base isolators to upgrade the seismic resistibility of structures. Optimum design of the base isolator can lessen the undesirable seismic hazard with the most efficiency. Hence, tracing the nonlinear behavior of the base isolator with good accuracy is important in the engineering profession. In order to predict the nonlinear behavior of base isolated structures precisely, hundreds even thousands of degrees-of-freedom and iterative algorithm are required for nonlinear time history analysis. In view of this, a simple and feasible exact formulation without any iteration has been proposed in this study to calculate the seismic responses of structures with base isolators. Comparison between the experimental results from shaking table tests conducted at National Center for Research on Earthquake Engineering in Taiwan and the analytical results show that the proposed method can accurately simulate the seismic behavior of base isolated structures with elastomeric bearings. Furthermore, it is also shown that the proposed method can predict the nonlinear behavior of the VCFPS isolated structure with accuracy as compared to that from the nonlinear finite element program. Therefore, the proposed concept can be used as a simple and practical tool for engineering professions for designing the elastomeric bearing as well as sliding bearing.

Seismic Performance of Concrete-Filled Steel Piers Part II: Pseudo-Dynamic Test and Residual Seismic Capacity (강합성교각의 내진성능평가 Part II: 유사동적실험 및 잔류내진성능 평가)

  • 조창빈;서진환;장승필
    • Journal of the Earthquake Engineering Society of Korea
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    • v.6 no.2
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    • pp.21-28
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    • 2002
  • Ductile behavior and strength of concrete-filled steel(CFS) piers was supported by many quasi-static cyclic loading tests. This test method, however, only estimates the member′s deformation capacity under escalating and repetitive displacement and ignores dynamic and random aspects of an earthquake load. Therefore, to understand complete seismic behavior of the structure against an earthquake, dynamic tests such as shaking table test and pseudo-dynamic tests are required as well as quasi-static tests. In this paper, following "Seismic Performance of Concrete-Filled Steel Piers Part I : Quasi-Static Cyclic Loadint Test", the seismic behavior of CFS and steel piers designed for I-Soo overpass in Seoul in investigated by the pseudo-dynamic test. In addition, the residual strength of both piers after an earthquake is estimated by the quasi-static test. The results show that both piers have satisfactory ductility and strength against well-known EI Centro earthquake although the CFS pier has better strength and energy dissipation than the steel pier.

Effect of Physical Shape on Seismic Performance of URM Structures (비보강 조적식 구조의 형상에 따른 내진성능 평가 해석)

  • Park, Joonam
    • Journal of the Earthquake Engineering Society of Korea
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    • v.20 no.5
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    • pp.277-283
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    • 2016
  • Unreinforced masonry (URM) buildings are known to be highly vulnerable to seismic loadings. Although significant physical variation may exist for URM buildings that fall into a same structural category, a single set of fragility curves is typically used as a representation of the seismic vulnerability of the URM structures. This study investigates the effect of physical variation of URM structures on their seismic performance level. Variables that describe the physical variation of the structure are defined based on the inventory analysis. Seismic behavior of the structures is then monitored by changing the variables to investigate the effect of each variable. The analysis results show that among the variables considered the seismic performance of URM building depends on the variation of the width, the aspect ratio, and the number of story. The need for further research on the modeling of the connections between the walls and diaphragms and the torsional effect is also addressed.

Seismic Assessment and Performance of Nonstructural Components Affected by Structural Modeling

  • Hur, Jieun;Althoff, Eric;Sezen, Halil;Denning, Richard;Aldemir, Tunc
    • Nuclear Engineering and Technology
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    • v.49 no.2
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    • pp.387-394
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    • 2017
  • Seismic probabilistic risk assessment (SPRA) requires a large number of simulations to evaluate the seismic vulnerability of structural and nonstructural components in nuclear power plants. The effect of structural modeling and analysis assumptions on dynamic analysis of 3D and simplified 2D stick models of auxiliary buildings and the attached nonstructural components is investigated. Dynamic characteristics and seismic performance of building models are also evaluated, as well as the computational accuracy of the models. The presented results provide a better understanding of the dynamic behavior and seismic performance of auxiliary buildings. The results also help to quantify the impact of uncertainties associated with modeling and analysis of simplified numerical models of structural and nonstructural components subjected to seismic shaking on the predicted seismic failure probabilities of these systems.

Nonlinear Behavior Characteristics and Seismic Performance of the Existing RC Piers without Seismic Detailing (비내진 상세 기존 RC 교각의 비선형 거동특성 및 내진성능)

  • 김재관
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • pp.327-334
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    • 2000
  • The seismic performance evaluation of the existing non-seismic detailed RC piers has risen as urgent task for rational and cost-effective seismic retrofitting works as well as development of new seismic design concept. The scale model test has been conducted to investigate nonlinear behavior characteristics and the seismic performance of existing piers with lap-spliced longitudinal reinforcements in the plastic hinge zone which are of the solid circular and the hollow rectangular section. The lap splice in this zone is found to cause premature bond failure. The experimental results show very poor seismic performance of circular section pier but relatively large ductility of the rectangular one.

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