• Title/Summary/Keyword: response displacement method

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Direct Control of Displacement Using Displacement and Resistance Force Contribution Factor (변위 및 내력기여도계수를 이용한 정량적 변위 제어)

  • Kim, Young-Min;Kim, Chee-Kyeong
    • Journal of Korean Association for Spatial Structures
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    • v.5 no.3 s.17
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    • pp.91-100
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    • 2005
  • The paper presents a direct method for the diplacement control and stiffness redesign using displacement and response force contribution factors. At first, these two kinds of factors are derived and the relationship between them is examined. An equation to evaluate the change of displacement according to the change of each member stiffness is proposed. For the statically determinate structures, the proposed equation gives the exact solution with no approximation. But it has some error in case of statically indeterminate structures because the redistribution of response forces is neglected in the equation. However, the equation may be very useful even for statically indeterminate structures because it provides the relationship between the member stiffness and the global displacement. The proposed method is expected to be useful for the displacement control of large space or hi-rise building structures where the stiffness design governs the design result.

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Blast Analysis of Single Degree of Freedom Plant Structures Considering Static Displacement (정적변위를 고려한 플랜트 구조물의 단자유도 폭발 해석)

  • Lee, Jae-Kyoon;Lee, Seung-Hoon;Kim, Han-Soo
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.35 no.5
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    • pp.317-324
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    • 2022
  • In this paper, an analysis method that considers the initial static displacement of structural members using an equivalent single-degree-of-freedom system is presented. Newmark's dynamic analysis algorithm was improved to consider the effect of the initial static displacements of structural members. The effect of the initial static displacement on the maximum response according to the assumed duration of the blast load and natural period of the member was investigated. The effects of positive and negative static displacements on the maximum dynamic responses of structural members subjected to a positively applied blast load were also studied. Modified response charts for the shock-type and pressure-type waves are presented so that static displacements can easily be considered. Using a design example, we demonstrate the significance of the modified response chart that considers the static displacement. Based on the results of this study, the maximum response of a the structural member can be easily obtained whilst considering its initial static displacement. The modified response chart presented in this study can be used for the structural design of plants and military facilities.

Ductility-based seismic design of precast concrete large panel buildings

  • Astarlioglu, Serdar;Memari, Ali M.;Scanlon, Andrew
    • Structural Engineering and Mechanics
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    • v.10 no.4
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    • pp.405-426
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    • 2000
  • Two approximate methods based on mechanism analysis suitable for seismic assessment/design of structural concrete are reviewed. The methods involve use of equal energy concept or equal displacement concept along with appropriate patterns of inelastic deformations to relate structure's maximum lateral displacement to member and plastic deformations. One of these methods (Clough's method), defined here as a ductility-based approach, is examined in detail and a modification for its improvement is suggested. The modification is based on estimation of maximum inelastic displacement using inelastic design response spectra (IDRS) as an alternative to using equal energy concept. The IDRS for demand displacement ductilities are developed for a single degree of freedom model subjected to several accelerograms as functions of response modification factor (R), damping ratios, and strain hardening. The suggested revised methodology involves estimation of R as the ratio of elastic strength demand to code level demand, and determination of design base shear using $R_{design}{\leq}R$ and maximum displacement, determination of plastic displacement using IDRS and subsequent local plastic deformations. The methodology is demonstrated for the case of a 10-story precast wall panel building.

Hazard-Consistent Ground Displacement Estimation for Seismic Input of Underground Utility Tunnels in Korea (국내 재해도에 상응하는 공동구의 지반변위 산정)

  • Kim, Dae-Hwan;Lim, Youngwoo;Chung, Yon-Ha;Lee, Hyerin
    • Journal of the Korean Geotechnical Society
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    • v.37 no.12
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    • pp.7-23
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    • 2021
  • Underground utility tunnels, which contribute to supply of electricity, communication, water and heat, are critical lifelines of an urban area. In case service is discontinued or functional disruption happens, there will be a huge socio-economic impact. For the improved seismic design and evaluation of underground structures, this study proposes a ground displacement measure when the site is subjected to a scenario earthquake based on hazard-consistent source spectra and site amplification/attenuation. This measure provides a rational estimation of ground displacement and can be an alternative to existing response displacement methods.

Frequency response of rectangular plates with free-edge openings and carlings subjected to point excitation force and enforced displacement at boundaries

  • Cho, Dae Seung;Kim, Byung Hee;Kim, Jin-Hyeong;Vladimir, Nikola;Choi, Tae Muk
    • International Journal of Naval Architecture and Ocean Engineering
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    • v.8 no.2
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    • pp.117-126
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    • 2016
  • In this paper, a numerical procedure for the natural vibration analysis of plates with openings and carlings based on the assumed mode method is extended to assess their forced response. Firstly, natural response of plates with openings and carlings is calculated from the eigenvalue equation derived by using Lagrange's equation of motion. Secondly, the mode superposition method is applied to determine frequency response. Mindlin theory is adopted for plate modelling and the effect of openings is taken into account by subtracting their potential and kinetic energies from the corresponding plate energies. Natural and frequency response of plates with openings and carlings subjected to point excitation force and enforced acceleration at boundaries, respectively, is analysed by using developed in-house code. For the validation of the developed method and the code, extensive numerical results, related to plates with different opening shape, carlings and boundary conditions, are compared with numerical data from the relevant literature and with finite element solutions obtained by general finite element tool.

An absolute displacement approach for modeling of sliding structures

  • Krishnamoorthy, A.
    • Structural Engineering and Mechanics
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    • v.29 no.6
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    • pp.659-671
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    • 2008
  • A procedure to analyse the space frame structure fixed at base as well as resting on sliding bearing using total or absolute displacement in dynamic equation is developed. In the present method, the effect of ground acceleration is not considered as equivalent force. Instead, the ground acceleration is considered as a known value in the acceleration vector at degree of freedom corresponding to base of the structure when the structure is in non-sliding phase. When the structure is in sliding phase, only a force equal to the maximum frictional resistance is applied at base. Also, in this method, the stiffness matrix, mass matrix and the damping matrix will not change when the structure enters from one phase to another. The results obtained from the present method using absolute displacement approach are compared with the results obtained from the analysis of structure using relative displacement approach. The applicability of the analysis is also demonstrated to obtain the response of the structure resting on sliding bearing with restoring force device.

Conservativeness of Response Displacement Method used in Seismic Response Analysis of Power Cable Tunnels (전력구의 지진응답해석법에 사용되는 응답변위법의 보수성 평가)

  • Lim, Jae-Sung;Yang, Dae-Seung;Hwang, Kyeong-Min;Kim, Jae-Min
    • Journal of the Computational Structural Engineering Institute of Korea
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    • v.34 no.4
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    • pp.243-254
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    • 2021
  • In this study, the conservatism of the response displacement method (RDM) for the seismic response analysis of box-shaped power cable tunnels was evaluated. A total of 50 examples were used considering the cross-sections of 25 power cable tunnels and two soil conditions for each power cable tunnel. The following three methods were applied for the analysis by the RDM: (1) single cosine method, (2) double cosine method, and (3) dynamic free-field analysis method. A refined dynamic analysis method considering soil-structure interaction (SSI) was employed to compare the conservatism of the RDM. The double cosine method demonstrated the most conservative result, while the dynamic free-field analysis method yielded the least deviation. The soil stiffness reduction factor, C, for the double cosine method was recommended to be 0.9 and 0.7 for the operational performance and collapse prevention levels, respectively, to ensure a probability of at least 80% that the member force by the RDM is larger than that of dynamic SSI analysis.

Seismic response of smart nanocomposite cylindrical shell conveying fluid flow using HDQ-Newmark methods

  • Zamani, Abbas;Kolahchi, Reza;Bidgoli, Mahmood Rabani
    • Computers and Concrete
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    • v.20 no.6
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    • pp.671-682
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    • 2017
  • In this research, seismic response of pipes is examined by applying nanotechnology and piezoelectric materials. For this purpose, a pipe is considered which is reinforced by carbon nanotubes (CNTs) and covered with a piezoelectric layer. The structure is subjected to the dynamic loads caused by earthquake and the governing equations of the system are derived using mathematical model via cylindrical shell element and Mindlin theory. Navier-Stokes equation is employed to calculate the force due to the fluid in the pipe. Mori-Tanaka approach is used to estimate the equivalent material properties of the nanocomposite and to consider the effect of the CNTs agglomeration on the scismic response of the structure. Moreover, the dynamic displacement of the structure is extracted using harmonic differential quadrature method (HDQM) and Newmark method. The main goal of this research is the analysis of the seismic response using piezoelectric layer and nanotechnology. The results indicate that reinforcing the pipeline by CNTs leads to a reduction in the displacement of the structure during an earthquake. Also the negative voltage applied to the piezoelectric layer reduces the dynamic displacement.

Evaluation of Seismic Performance of Mixed Building Structures by using the Nonlinear Displacement Mode Method (비선형 변위모드법을 적용한 복합구조물의 내진성능평가)

  • 김부식;송호산
    • Journal of the Earthquake Engineering Society of Korea
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    • v.7 no.6
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    • pp.71-80
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    • 2003
  • Though a nonlinear time history analysis may be provided to estimate more exactly the seismic performance of building structure, approximation methods are still needed in the aspect of practicality and simplicity, In converting a multi-story structure to an equivalent SDOF system, the mode vectors of the multi-story structure are assumed as the mode shape in elastic state regardless of elastic or elastic-plastic state. However, the characteristics of displacement mode are also changed after the yielding made in the structural elements, because the structure becomes inelastic in each incremental load step. In this research, a method of converting MDOF system to ESDOF system is presented by using nonlinear displacement mode considering the mode change of structures after the yielding. Also, the accuracy and efficiency of the method of the nonlinear displacement mode method of the estimate of seismic response of Mixed Building Structures were examined by comparing the displacements of the roof level of the multi-story building structures estimated from this converted displacement response of ESDOF with the displacement of the roof level through the nonlinear dynamic analysis of the multi-story building structures subjected to an actual earthquake excitation.

The relationship between time-varying eccentricity of load with the corner lateral displacement response of steel structure during an earthquake

  • Takin, Kambiz;Hashemi, Behrokh H.;Nekooei, Masoud
    • Steel and Composite Structures
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    • v.20 no.4
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    • pp.801-812
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    • 2016
  • In an actual design, none of the structures with shear behaviors will be designed for torsional moments. Any failure or damages to roofs, infills, shear walls, and braces caused by an earthquake, will inevitably result in relocation of center of mass and rigidity of the structure. With these changes, the dynamic characteristics of structure could be changed during an earthquake at any moment. The main objective of this paper is to obtain the relationship between time-varying eccentricity of load and corner lateral displacement. In this study, various methods have been used to determine the structural response for time-varying lateral corner displacement. As will be seen below, some of the structural calculation methods result in a significant deviation from the actual results, although these methods include the interaction effects of modes. Controlling the lateral displacement of structure can be performed in different ways such as, passive dampers, friction dampers, semi-active systems including the MR damper and active Systems. Selecting and locating these control systems is very important to bring the maximum safety with minimum cost into the structure. According to this study will be show the relation between the corner lateral displacements of structure and time-varying eccentricity by different kind of methods during an earthquake. This study will show that the response of the structure at the corners due to an earthquake can be very destructive and because of changing the eccentricity of load, calculating the maximum possible response of system can be carried out by this method. Finally, some kind of systems must be used for controlling these displacements. The results shows that, the CQC, DSC and exact methods is comply each other but the results of Vanmark method is not comfortable for these kind of buildings.