• Title, Summary, Keyword: acceleration response

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Seismic response of steel reinforced concrete spatial frame with irregular section columns under earthquake excitation

  • Xue, Jianyang;Zhou, Chaofeng;Liu, Zuqiang;Qi, Liangjie
    • Earthquakes and Structures
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    • v.14 no.4
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    • pp.337-347
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    • 2018
  • This paper presents some shaking table tests conducted on a 1/4-scaled model with 5-story steel reinforced concrete (SRC) spatial frame with irregular section columns under a series of base excitations with gradually increasing acceleration peaks. The test frame was subjected to a sequence of seismic simulation tests including 10 white noise vibrations and 51 seismic simulations. Each seismic simulation was associated with a different level of seismic disaster. Dynamic characteristic, strain response, acceleration response, displacement response, base shear and hysteretic behavior were analyzed. The test results demonstrate that at the end of the loading process, the failure mechanism of SRC frame with irregular section columns is the beam-hinged failure mechanism, which satisfies the seismic code of "strong column-weak beam". With the increase of acceleration peaks, accumulated damage of the frame increases gradually, which induces that the intrinsic frequency decreases whereas the damping ratio increases, and the peaks of acceleration and displacement occur later. During the loading process, torsion deformation appears and the base shear grows fast firstly and then slowly. The hysteretic curves are symmetric and plump, which shows a good capacity of energy dissipation. In summary, SRC frame with irregular section columns can satisfy the seismic requirements of "no collapse under seldom earthquake", which indicates that this structural system is suitable for the construction in the high seismic intensity zone.

Dynamic Analysis of Ground Motion During Earthquake in the Bangkok Area (지진시 방콕지역의 지반운동에 대한 동력학적 연구)

  • 김상환
    • Geotechnical Engineering
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    • v.1 no.1
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    • pp.13-20
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    • 1985
  • In this paper, earthquake response of the Bangkok area in Thailand was analyzed in terms of the acceleration response spectrum and maximum acceleration of the computed surface motions. The program SHAKE was employed to analyse the ground motion. With increasing the maximum acceleration and predominant period of given base rock motion, the computed maximum ground surface acceleration increases. but converges on a maximum value of about 0.39. The characteristics of earthquake response spectrum in the Bangkok area are also discussed and illustrated.

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Dynamic analysis Ground using 2-D FEM (차량하중에 의한 주변지반의 진동해석)

  • 황성춘;강보순;심형섭;오병헌;박성진
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.642-647
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    • 2001
  • Dynamic response of ground due to train loads is analyzed. A numerical procedure based on finite element method is used to solve two-dimensional ground response. Dynamic train loads assumed in analysis is the point acceleration on train rail with magnitude of 2330 gal and thickness of surface of soil layer assumed is 60cm. In order to consider the effect of acceleration point, dynamic responses such as response acceleration and displacement are computed as a function of distance from acceleration point on rail. In addition, simple methods which reduce dynamic effects on ground are also proposed.

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Structural health monitoring-based dynamic behavior evaluation of a long-span high-speed railway bridge

  • Mei, D.P.
    • Smart Structures and Systems
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    • v.20 no.2
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    • pp.197-205
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    • 2017
  • The dynamic performance of railway bridges under high-speed trains draws the attention of bridge engineers. The vibration issue for long-span bridges under high-speed trains is still not well understood due to lack of validations through structural health monitoring (SHM) data. This paper investigates the correlation between bridge acceleration and train speed based on structural dynamics theory and SHM system from three foci. Firstly, the calculated formula of acceleration response under a series of moving load is deduced for the situation that train length is near the length of the bridge span, the correlation between train speed and acceleration amplitude is analyzed. Secondly, the correlation scatterplots of the speed-acceleration is presented and discussed based on the transverse and vertical acceleration response data of Dashengguan Yangtze River Bridge SHM system. Thirdly, the warning indexes of the bridge performance for correlation scatterplots of speed-acceleration are established. The main conclusions are: (1) The resonance between trains and the bridge is unlikely to happen for long-span bridge, but a multimodal correlation curve between train speed and acceleration amplitude exists after the resonance speed; (2) Based on SHM data, multimodal correlation scatterplots of speed-acceleration exist and they have similar trends with the calculated formula; (3) An envelope line of polylines can be used as early warning indicators of the changes of bridge performance due to the changes of slope of envelope line and peak speed of amplitude. This work also gives several suggestions which lay a foundation for the better design, maintenance and long-term monitoring of a long-span high-speed bridge.

Vibration Analysis on the Ground by 2D FEM (2차원 유한요소법을 이용한 지반의 진동에 대한 동적응답해석)

  • 황성춘;박춘식;정성교
    • Proceedings of the Korean Geotechical Society Conference
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    • pp.365-370
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    • 1999
  • In this paper, dynamic response analysis on the ground movement applied traffic load by 2D finite element procedure has been studied. In particular, The paper deal with pointing acceleration method that applied AFIMEX Code as like 2D-FLUSH using equivalent linear method. As the result, it is found that dynamic response analysis by pointing acceleration method expressed ground movement by traffic load exactly.

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Estimation of Displacements Using the Transformed Response in Time and Frequency Domain

  • Jung, Beom-Seok
    • International Journal of Ocean Engineering and Technology Speciallssue:Selected Papers
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    • v.6 no.1
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    • pp.44-50
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    • 2003
  • If the accelerometers are used in measuring the response, the absolute values of the velocity and displacement are not usually obtainable because their initial values are not accounted for in the integration of the acceleration response. A new dynamic response conversion algorithm of both the time domain and the frequency domain is proposed for the problem in estimating the displacement data by defining the transformed responses. In this algorithm, the displacement response can be obtained from the measured acceleration records by integration without requiring the knowledge of the initial velocity and displacement information. The applicability of the technique is tested by an example problem using the real bridge's superstructure under several cases of moving load. In the response conversion procedure of the frequency domain, the identified response according to the frequency can be estimated by changing over the limits of integration. If the reliability of the identified responses is ensured, it is expected that the proposed method for estimating the impact factor can be useful in the bridge's dynamic test. This method can be useful in those practical cases when the direct measurement of the displacement is difficult as in the dynamic studies of huge structure.

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Acceleration Variation of Surrounding Ground according to distance from Strip-Type Crushed Stone Foundation (쇄석 띠기초와의 거리에 따른 주변지반의 가속도 변화)

  • Son, Su-Won;Son, Tae-Ik;Kim, Soo-Bong;Kim, Jin-Man
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.20 no.1
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    • pp.217-223
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    • 2019
  • In this study, the acceleration changes of the surrounding ground when crushed stones were installed in a strip-type were analyzed using the 1-G shaking table test. The ground was constructed from clay, and the foundation was installed using crushed stone of strip-type form. The response acceleration and response spectrum for various input seismic motions were analyzed. The change in acceleration was examined according to the adjacent distance to the strip-type crushed stone foundation. In the Hachinohe seismic motion results, there was no significant decrease in acceleration, but the maximum response acceleration for the two seismic motions was inversely proportional to the distance from the crushed stone foundation. As a result of the response spectrum analysis, the attenuation period in the long period and the short period input wave were different from each other, and the change in response spectrum affected the maximum acceleration value. As the distance from the crushed stone foundation was increased, the attenuation was larger in the period between 0.08 and 0.5 sec in the Hachinohe seismic motion, the attenuation was larger in the period of less than 0.2 seconds in the Northridge seismic motion.

A Study On Arbitrary Artificial Earthquake Acceleration Generation -Based On Design Response Spectrum of Arbitrary Damping Value- (임의의 인공지진 가속도 발생에 관한 연구 -설계응답 스펙트럼에 기초하여 -)

  • 우운택;김영문;노재선
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • pp.5-10
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    • 1989
  • In this study, the basic concept of design response spectrum is briefly revi-ewed. To generate the artificial earthquake acceleration, the method of superpo-sition of cosine waves is used. Theoretical developments using F.F.T. and spect-ral density function are compared. The amplitude was derived by use of the peak factor and the phase angle is d-erived by use of Monte Carlo simulation. To smoothen the match, the calculated pseudo velocity respon-se spectrum is compared with input pseudo velocity response spectrum at a set of control frequencies. With the modified spectral density function, a new acceleration and pseudo velocity response spectrum are generat-ed.

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Probabilistic Analysis of Liquefaction Cyclic Stress Ratio Considering Soil Variability (지반변동성을 고려한 액상화 진동전단응력비의 확률론적 해석)

  • Heo, Joon
    • Journal of The Korean Society of Agricultural Engineers
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    • v.60 no.2
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    • pp.95-101
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    • 2018
  • The objective of this study is to evaluate the liquefaction cyclic shear stress ratio considering the soil uncertainty. In this study, the probabilistic ground response analysis and the cyclic shear stress ratio analysis for the liquefaction potential evaluation are performed considering the soil variability. The statistical properties of input ground parameters were analyzed to investigate the parameters affecting the seismic response analysis. The Probabilistic analysis was carried out by Monte Carlo Simulation method. The ground response analysis was performed considering the soil variability and the probability distribution characteristics of the ground acceleration. The probability distribution of the peak ground acceleration by seismic characteristics was presented. The differences of liquefaction shear stress ratio results according to soil variability were compared and analyzed. The maximum acceleration of the ground by the deterministic method was analyzed to be overestimation of the ground amplification phenomenon. Also, the shear stress ratio was overestimated.

Design-oriented acceleration response spectrum for ground vibrations caused by collapse of large-scale cooling towers in NPPs

  • Lin, Feng;Jiang, Wenming
    • Nuclear Engineering and Technology
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    • v.50 no.8
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    • pp.1402-1411
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    • 2018
  • Nuclear-related facilities can be detrimentally affected by ground vibrations due to the collapse of adjacent cooling towers in nuclear power plants. To reduce this hazard risk, a design-oriented acceleration response spectrum (ARS) was proposed to predict the dynamic responses of nuclear-related facilities subjected to ground vibrations. For this purpose, 20 computational cases were performed based on cooling tower-soil numerical models developed in previous studies. This resulted in about 2664 ground vibration records to build a basic database and five complementary databases with consideration of primary factors that influence ground vibrations. Afterwards, these databases were applied to generate the design-oriented ARS using a response spectrum analysis approach. The proposed design-oriented ARS covers a wide range of natural periods up to 6 s and consists of an ascending portion, a plateau, and two connected descending portions. Spectral parameters were formulated based on statistical analysis. The spectrum was verified by comparing the representative acceleration magnitudes obtained from the design-oriented ARS with those from computational cases using cooling tower-soil numerical models with reasonable consistency.