• Title/Summary/Keyword: Seismic Response Coefficient

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Seismic Response Analysis of the Center-Core Rockfill Dam (중심코아령사력댐의 지진응답해석)

  • 오병현;임정열;이종옥
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.09a
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    • pp.139-146
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    • 2001
  • The seismic safety analysis were performed for the center-core rockfill dam(CCRD) The static and pseudo-static FEM analysis using seismic coefficient Method, and dynamic FEM analysis using Hachinohe earthquake wave(0.12g) were used for the seismic safety of CCRD. The results of seismic analysis were that the factor of safety of down slope was 1.5, horizontal displacement is about 14.3cm, and vertical displacement is 3.3cm at dam creast. The model dam did not show any seismic stability problems for 0.12g. And much more research is still necessary in seismic safety of CCRD.

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Seismic Response Analysis of a Two-Mass Rack System Considering Frictional Behavior (마찰거동을 고려한 이중질량시스템의 지진응답해석)

  • Park, Kwan-Soon;Ok, Seung-Yong;Lee, Jeeho
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.31 no.6
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    • pp.347-352
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    • 2018
  • This study proposes seismic response analysis technique of a two-mass rack system which sustains heavy loads with frictional behavioral characteristics. In order to deal with the nonlinear frictional characteristics of the mass on the rack system, the equations of motion of the system has been derived and the appropriate numerical simulation technique has been developed. In order to examine the seismic performance of the proposed system, we consider two parameters that are expected to have great influence on the seismic performance of the system. One is the ratio of the two masses of the load and the rack structure, and the other is the friction coefficient between rack and loaded mass. A number of numerical simulations of the seismic response of structures with various natural frequencies for both parameters have been performed in order to investigate the seismic safety of the rack structures. From the simulated results. it is observed that the maximum displacement of the rack system tends to decrease drastically as the natural frequency of the structure increases regardless of the two parameters of mass ratio and friction coefficient. The proposed study provides important reference data to guarantee the seismic safety of the rack system by considering nonlinear frictional behavior of the loaded mass.

Performance Evaluation of IRB System Using Seismic Isolation Test (내진시험을 통한 IRB 시스템의 성능 평가)

  • Park, Young-Gee;Ha, Sung Hoon;Woo, Jae Kwan;Choi, Seung-Bok;Kim, Hyun
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2013.04a
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    • pp.401-406
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    • 2013
  • This paper presents experimental evaluation of IRE (isolation roller bearing) seismic isolation device. From the combination of base isolation on the IRE system displacement response spectrum and acceleration response spectrum, the compressive strength and the coefficient of friction experiments. Also the IRE system is evaluated by environment test according to KS standards. Both the resonance and seismic experiments using a combination of the IRE and Natural Rubber Bearing (NRB) are performed in order to analyze the seismic isolation of the IRE system dynamic characteristics. For the given load and exciting frequency, the resonant frequency becomes lower, but the resonant magnification remains to be same. However, it is shown that when we consider the IRE only, the vibration on the table with the horizontal movement and the independent horizontal displacement due to the rolling motion of the plate and roller are significantly reduced. This result verifies that the proposed optimal design method of the IRE system is very effective.

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Probabilistic analysis of peak response to nonstationary seismic excitations

  • Wang, S.S.;Hong, H.P.
    • Structural Engineering and Mechanics
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    • v.20 no.5
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    • pp.527-542
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    • 2005
  • The main objective of this study is to examine the accuracy of the complete quadratic combination (CQC) rule with the modal responses defined by the ordinates of the uniform hazard spectra (UHS) to evaluate the peak responses of the multi-degree-of-freedom (MDOF) systems subjected to nonstationary seismic excitations. For the probabilistic analysis of the peak responses, it is considered that the seismic excitations can be modeled using evolutionary power spectra density functions with uncertain model parameters. More specifically, a seismological model and the Kanai-Tajimi model with the boxcar or the exponential modulating functions were used to define the evolutionary power spectral density functions in this study. A set of UHS was obtained based on the probabilistic analysis of transient responses of single-degree-of-freedom systems subjected to the seismic excitations. The results of probabilistic analysis of the peak responses of MDOF systems were obtained, and compared with the peak responses calculated by using the CQC rule with the modal responses given by the UHS. The comparison seemed to indicate that the use of the CQC rule with the commonly employed correlation coefficient and the peak modal responses from the UHS could lead to significant under- or over-estimation when contributions from each of the modes are similarly significant.

Seismic response control of benchmark highway bridge using variable dampers

  • Madhekar, S.N.;Jangid, R.S.
    • Smart Structures and Systems
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    • v.6 no.8
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    • pp.953-974
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    • 2010
  • The performance of variable dampers for seismic protection of the benchmark highway bridge (phase I) under six real earthquake ground motions is presented. A simplified lumped mass finite-element model of the 91/5 highway bridge in Southern California is used for the investigation. A variable damper, developed from magnetorheological (MR) damper is used as a semi-active control device and its effectiveness with friction force schemes is investigated. A velocity-dependent damping model of variable damper is used. The effects of friction damping of the variable damper on the seismic response of the bridge are examined by taking different values of friction force, step-coefficient and transitional velocity of the damper. The seismic responses with variable dampers are compared with the corresponding uncontrolled case, and controlled by alternate sample control strategies. The results of investigation clearly indicate that the base shear, base moment and mid-span displacement are substantially reduced. In particular, the reduction in the bearing displacement is quite significant. The friction and the two-step friction force schemes of variable damper are found to be quite effective in reducing the peak response quantities of the bridge to a level similar to or better than that of the sample passive, semi-active and active controllers.

Development of Machine Learning Based Seismic Response Prediction Model for Shear Wall Structure considering Aging Deteriorations (경년열화를 고려한 전단벽 구조물의 기계학습 기반 지진응답 예측모델 개발)

  • Kim, Hyun-Su;Kim, Yukyung;Lee, So Yeon;Jang, Jun Su
    • Journal of Korean Association for Spatial Structures
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    • v.24 no.2
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    • pp.83-90
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    • 2024
  • Machine learning is widely applied to various engineering fields. In structural engineering area, machine learning is generally used to predict structural responses of building structures. The aging deterioration of reinforced concrete structure affects its structural behavior. Therefore, the aging deterioration of R.C. structure should be consider to exactly predict seismic responses of the structure. In this study, the machine learning based seismic response prediction model was developed. To this end, four machine learning algorithms were employed and prediction performance of each algorithm was compared. A 3-story coupled shear wall structure was selected as an example structure for numerical simulation. Artificial ground motions were generated based on domestic site characteristics. Elastic modulus, damping ratio and density were changed to considering concrete degradation due to chloride penetration and carbonation, etc. Various intensity measures were used input parameters of the training database. Performance evaluation was performed using metrics like root mean square error, mean square error, mean absolute error, and coefficient of determination. The optimization of hyperparameters was achieved through k-fold cross-validation and grid search techniques. The analysis results show that neural networks and extreme gradient boosting algorithms present good prediction performance.

Feasibility Study of Seismic Probabilistic Risk Assessment for Multi-unit NPP with Seismic Failure Correlation (다수기의 확률론적 지진안전성 평가를 위한 지진손상 상관계수의 적용)

  • Eem, Seunghyun;Kwag, Shinyoung;Choi, In-Kil
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.34 no.5
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    • pp.319-325
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    • 2021
  • The 2011 East Japan Earthquake caused accidents at a number of nuclear power plants in Fukushima, highlighting the need for a study on the seismic safety of multiple NPP (Nuclear Power Plant) units. In the case of nuclear power plants built on a site that shows a similar seismic response, there is at least a correlation between the seismic damage of structures, systems, and components (SSCs) of nuclear power plants. In this study, a probabilistic seismic safety assessment was performed for the loss of essential power events of twin units. To derive an appropriate seismic damage correlation coefficient, a probabilistic seismic response analysis was performed. Using the external event mensuration system program, we analyzed the seismic fragility and seismic risk by composing a failure tree of multiple loss of essential power events. Additionally, a comparative analysis was performed considering the seismic damage correlation between SSCs as completely independent and completely dependent.

Effect on Coefficient of Subgrade Reaction on Dynamic responses of Buried Pipelines (지중매설관로의 동적응답에 미치는 지반반력계수의 영향)

  • Jeong, Jin-Ho;Lee, Kwang-Yeol;Kang, Hyo-Sub
    • Journal of Power System Engineering
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    • v.21 no.2
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    • pp.83-88
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    • 2017
  • We have examined the effect of values of subgrade reaction coefficient on the dynamic responses(displacement and strain responses) of the buried concrete pipeline of which the end boundary condition is the fixed ends. We have carried out the dynamic analysis of mode superposition method with representative values of coefficient of subgrade reaction applicable to the classified rock masses. We have found that the effect of subgrade reaction coefficient on the dynamic responses of the pipeline appears noticeable for the seismic waves having relatively high frequency and low apparent propagation velocity.

Seismic Response Analysis of the Concrete Face Rockfill Dam (콘크리트표면차수벽령 석괴댐의 지진응답해석)

  • 오병현;임정열;이종옥
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2001.09a
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    • pp.147-154
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    • 2001
  • In this study, comprehensive seismic performance analysis were performed for the concrete face rockfill dam(CFRD) designed seismic coefficient method(0. 10g). The static and pseudo-static FEM analysis, limited equilibrium method and dynamic FEM analysis were used for the dam safety analysis. The results of the seismic analysis were that the minimum factor of safety of down slope was 1.2 and horizontal displacement increased 8cm and vertical displacement increased 1.2cm at dam crest rather than those of static condition. The model dam did not show any serious tai lure in seismic stabi1ity for 0.13g. And much more research is still necessary in seismic safety of CFRD.

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Seismic Fragility of I-Shape Curved Steel Girder Bridge using Machine Learning Method (머신러닝 기반 I형 곡선 거더 단경간 교량 지진 취약도 분석)

  • Juntai Jeon;Bu-Seog Ju;Ho-Young Son
    • Journal of the Society of Disaster Information
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    • v.18 no.4
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    • pp.899-907
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    • 2022
  • Purpose: Although many studies on seismic fragility analysis of general bridges have been conducted using machine learning methods, studies on curved bridge structures are insignificant. Therefore, the purpose of this study is to analyze the seismic fragility of bridges with I-shaped curved girders based on the machine learning method considering the material property and geometric uncertainties. Method: Material properties and pier height were considered as uncertainty parameters. Parameters were sampled using the Latin hypercube technique and time history analysis was performed considering the seismic uncertainty. Machine learning data was created by applying artificial neural network and response surface analysis method to the original data. Finally, earthquake fragility analysis was performed using original data and learning data. Result: Parameters were sampled using the Latin hypercube technique, and a total of 160 time history analyzes were performed considering the uncertainty of the earthquake. The analysis result and the predicted value obtained through machine learning were compared, and the coefficient of determination was compared to compare the similarity between the two values. The coefficient of determination of the response surface method was 0.737, which was relatively similar to the observed value. The seismic fragility curve also showed that the predicted value through the response surface method was similar to the observed value. Conclusion: In this study, when the observed value through the finite element analysis and the predicted value through the machine learning method were compared, it was found that the response surface method predicted a result similar to the observed value. However, both machine learning methods were found to underestimate the observed values.