• Title/Summary/Keyword: Dynamic Displacement Sensitivity

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Applicaion of Sensitivity Formulation to Analyze the Dynamic Response due to the Excitation Force for the Undamped Vibration of Cantilever Beam (외팔보의 비감쇠 진동시 가진력에 의한 동적 반응의 민감도 정식화 및 해석)

  • Yun, Seong-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.11
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    • pp.29-34
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    • 2020
  • In this study, a sensitivity formulation was applied to analyze the dynamic response due to the effect of the excitation force for the undamped vibration of the cantilever beam. The theoretically fundamental formulations were derived considering an eigenvalue problem and its modal analysis to govern the second order algebraic differential equation in terms of the change in the modal coordinate with respect to the design parameters. A representative physical quantity pertaining to the dynamic response, that is, the rate of change in the dynamic displacement, was observed by changing the design variables, such as the cross-sectional area of the beam. The numerical results were obtained at various locations, considering the application of the external forces and observation of the dynamic displacement. When the detection position was closer to the free end of the cantilever beam, the sensitivity of the dynamic displacement was higher, as predicted through the oscillating motion of the beam. The presented findings can provide guidance to compute the dynamic sensitivity for a flexibly connected structure under dynamic excitations.

Sensitivity Analysis of Dynamic Response by Change in Excitation Force and Cross-sectional Shape for Damped Vibration of Cantilever Beam (가진력과 단면형상 변화에 따른 외팔보 감쇠 진동의 민감도 해석)

  • Yun, Seong-Ho
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.20 no.8
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    • pp.11-17
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    • 2021
  • This paper describes the time rate of change of dynamic response of a cantilever beam inserted with a damping element, such as bonding, which is excited under a general force at various locations. A sensitivity analysis was performed in a finite element model to show that two types of second-order algebraic governing equations were used to predict the rate of change of dynamic displacement: one is related to the modal coordinate linked to a physical coordinate, and the other to the design parameter of the time rate of change of displacement. The sensitivity differential equation formulation includes more complicated terms compared with that of the undamped cantilever beam. The sensitivities of the dynamic response were observed by changing the location of the excitation force, displacement extraction, and cross-sectional area of the beam. The analytical results obtained by this suggested theory showed a relatively good agreement when compared with those obtained using the commercial finite element program. The suggested analysis procedure enables the prediction of the response sensitivity for any finite element model of the dynamic system.

Sensitivity Analysis of Rockfill Parameters Influencing Crest Displacements of CFRD Subjected to Earthquake Loading (지진하중을 받는 필댐 정부변위에 영향을 미치는 입력물성에 대한 민감도 분석)

  • Ha, Ik-Soo;Shin, Dong-Hoon
    • Proceedings of the Earthquake Engineering Society of Korea Conference
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    • 2006.03a
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    • pp.351-357
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    • 2006
  • In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of Concrete-Faced Rockfill Dam(CFRD) subjected to earthquake loading was carried out. The purpose of this study is to indicate the most important input parameter and to show the quantitative variation of displacement at the crest of CFR type dam during earthquake loading with this input parameter. From the sensitivity analysis, it was found that the crest displacement of CFR type dam subjected to dynamic loading was absolutely affected by the shear modulus of rockfill material and the effect of friction angle of it was negligible. This relative difference of sensitivity was more outstanding in case of crest settlement than in case of crest horizontal displacement. Also, it was found that the extent of effect of shear modulus on the displacement at the crest of CFRD due to dynamic loading decreased as maximum amplitude of input acceleration increased.

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Dynamic Sensitivity Analysis For Lateral Drift Control Of Frame-Shear Wall Structures (골조-전단벽 구조물의 횡변위제어를 위한 동적 민감도 해석)

  • Lee, Han-Joo;Kim, Ji-Youn;Han, Seung-Baek;Nam, Kyung-Yun;Kim, Ho-Soo
    • Proceedings of the Computational Structural Engineering Institute Conference
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    • 2007.04a
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    • pp.571-576
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    • 2007
  • This study presents stiffness-based optimal design to control quantitatively lateral drift of frame-shear wall structures subject to seismic loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also, the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. The 12 story frame-shear wall structural models is considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

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Quantitative Lateral Drift Control of RC Tall Frameworks using Dynamic Displacement Sensitivity Analysis (동적 변위민감도 해석을 이용한 고층 RC 골조구조물의 정량적인 횡변위 제어 방안)

  • Lee, Han-Joo;Kim, Ho-Soo
    • Journal of Korean Association for Spatial Structures
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    • v.6 no.3 s.21
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    • pp.103-110
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    • 2006
  • This study presents a technique to control quantitatively lateral drift of RC tall frameworks subject to lateral loads. To this end, lateral drift constraints are established by introducing approximation concept that preserves the generality of the mathematical programming and can efficiently solve large scale problems. Also the relationships of sectional properties are established to reduce the number of design variables and resizing technique of member is developed under the 'constant-shape' assumption. Specifically, the methodology of dynamic displacement sensitivity analysis is developed to formulate the approximated lateral displacement constraints. Three types of 10 and 50 story RC framework models are considered to illustrate the features of dynamic stiffness-based optimal design technique proposed in this study.

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Sensitivity Analysis on Rockfill Material Parameters Influencing Crest Displacement of Concrete-Faced Rockfill Dam (콘크리트 표면차수벽형 석괴댐 정상부 변위에 영향을 미치는 입력물성에 대한 민감도분석)

  • Ha, Ik-Soo;Seo, Min-Woo;Shin, Dong-Hoon
    • Proceedings of the Korean Geotechical Society Conference
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    • 2006.03a
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    • pp.846-853
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    • 2006
  • In this study, quantitative sensitivity analysis on rockfill material influencing the dam crest displacement of Concrete-Faced Rockfill Dam(CFRD) was carried out. The purpose of this study is to indicate the most important input parameter and to show the quantitative variation of displacement at the crest of CFR type dam with this input parameter. The rockfill material properties for parametric study were obtained from the results of large scale triaxial tests on 34 rockfill materials in the 22 different sites. From the statistical analysis on these data, some statistical characteristics of rockfill material properties such as property range, distribution characteristics, and correlation between the properties were investigated. based on these characteristics, 27 property combinations were constituted by Latin Hypercube sampling method. Dam crest displacements after construction, impounding, and earthquake loading were evaluated by static and dynamic numerical analysis on each combination. From the sensitivity analysis, it was found that the crest displacement of CFR type dam was absolutely affected by the shear modulus of rockfill material and the effect of friction angle of it was negligible. This relative difference of sensitivity was more outstanding in case of crest settlement than in case of crest horizontal displacement. Also, it was found that the settlement and horizontal displacement of dam crest logarithmically decreased as the shear modulus increased and the difference between the maximum value and the minimum vale amounted to about 9.5 times in case of settlement and about 10 times in case of horizontal displacement.

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State-space formulation for simultaneous identification of both damage and input force from response sensitivity

  • Lu, Z.R.;Huang, M.;Liu, J.K.
    • Smart Structures and Systems
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    • v.8 no.2
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    • pp.157-172
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    • 2011
  • A new method for both local damage(s) identification and input excitation force identification of beam structures is presented using the dynamic response sensitivity-based finite element model updating method. The state-space approach is used to calculate both the structural dynamic responses and the responses sensitivities with respect to structural physical parameters such as elemental flexural rigidity and with respect to the force parameters as well. The sensitivities of displacement and acceleration responses with respect to structural physical parameters are calculated in time domain and compared to those by using Newmark method in the forward analysis. In the inverse analysis, both the input excitation force and the local damage are identified from only several acceleration measurements. Local damages and the input excitation force are identified in a gradient-based model updating method based on dynamic response sensitivity. Both computation simulations and the laboratory work illustrate the effectiveness and robustness of the proposed method.

Structural Damage Detection Method Using Sensitivity Matrices (민감도행렬을 사용한 구조물의 손상추정법)

  • 윤정방;김두기
    • Computational Structural Engineering
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    • v.9 no.4
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    • pp.117-126
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    • 1996
  • Damage detection methods using structural tests can be divided into two methods, i.e., static and dynamic. The static methods which use the stiffness properties of the structure are simpler than the dynamic methods. However, static approaches are very sensitive to the displacement measurement noises and modeling errors. The dynamic methods also have limitations in acquiring the natural frequencies and mode shapes of the high frequencies. In this study, a method for the structural damage assessment using sensitivity matrices is developed, in which the drawbacks of the static and dynamic methods can be compensated. Based on the measurement data for the static displacements and dynamic modal properties, the damage locations and the degree of damage are determined using the presented sensitivity matrix method. The efficiency of the proposed method has been examined through numerical simulation studies on truss type structures.

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Nonlinear Dynamic Response Structural Optimization of an Automobile Frontal Structure Using Equivalent Static Loads (등가정하중법을 이용한 차량 전면 구조물의 비선형 동적 반응 구조최적설계)

  • Yoon, Shic;Jeong, Seong-Beom;Park, Gyung-Jin
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.1156-1161
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    • 2008
  • Nonlinear dynamic analysis is generally used in automobile crash analysis and structural optimization considering crashworthiness uses the results of nonlinear dynamic analysis. Automobile crash optimization has high nonlinearity and difficulty in calculating sensitivity. Recently the equivalent static load (ESL) method has been proposed in order to overcome these difficulties. The ESL is the static load set generating the same displacement field as the nonlinear dynamic displacement field at each time step in dynamic analysis. From various researches regarding the ESL method, it has been proved that the ESL method is fairly useful. The ESL method can mathematically optimize a crash optimization problem through nonlinear analysis and well developed static optimization. The ESL is applied to nonlinear dynamic structural optimization of the automobile frontal impact problem. An automobile bumper is optimized. The mass of the structure is minimized while some constraints are satisfied.

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A Study on the Seismic Resistance of Fill-dams by Newmark-type Deformation Analysis (Newmark 기반 변형해석에 의한 필댐의 내진저항성 연구)

  • Park, Dong Soon
    • Journal of the Earthquake Engineering Society of Korea
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    • v.18 no.4
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    • pp.161-170
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    • 2014
  • Newmark-type deformation analysis has rarely been done in Korea due to the popularity of simple pseudo-static limit equilibrium analysis and detailed time-history FE/FD dynamic analysis. However, the Korean seismic dam design code updated in 2011 prescribes Newmark-type deformation analysis as a major dynamic analysis method for the seismic evaluation of fill dams. In addition, a design PGA for dynamic analysis is significantly increased in the code. This paper aims to study the seismic evaluation of four existing large fill dams through advanced FEM/Newmark-type deformation analyses for the artificial earthquake time histories with the design PGA of 0.22g. Dynamic soil properties obtained from in-situ geo-physical surveys are applied as input parameters. For the FEM/Newmark analyses, sensitivity analyses are performed to study the effects of input PGA and $G_{max}$ of shell zone on the Newmark deformation. As a result, in terms of deformation, four fill dams are proved to be reasonably safe under the PGA of 0.22g with yield coefficients of 0.136 to 0.187, which are highly resistant for extreme events. Sensitivity analysis as a function of PGA shows that $PGA_{30cm}$ (a limiting PGA to cause the 30 cm of Newmark permanent displacement on the critical slip surface) is a good indicator for seismic safety check. CFRD shows a higher seismic resistance than ECRD. Another sensitivity analysis shows that $G_{max}$ per depth does not significantly affect the site response characteristics, however lower $G_{max}$ profile causes larger Newmark deformation. Through this study, it is proved that the amplification of ground motion within the sliding mass and the location of critical slip surface are the dominant factors governing permanent displacements.