• Title/Summary/Keyword: 변위계수법

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Development of Performance-Based Seismic Design of RC Column Retrofitted By FRP Jacket using Direct Displacement-Based Design (직접변위기반설계법에 의한 철근콘크리트 기둥의 FRP 피복보강 내진성능설계법의 개발)

  • Cho, Chang-Geun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.11 no.2 s.54
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    • pp.105-113
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    • 2007
  • In the current research, an algorithm of performance-based seismic retrofit design of reinforced concrete columns using FRP jacket has been proposed. For exact prediction of the nonlinear flexural analysis or FRP composite RC members, multiaxial constitutive laws of concrete and composite materials have been presented. For seismic retrofit design, an algorithm of direct displacement-based design method (DDM) proposed by Chopra and Goel (2001) has been newly applied to determine the design thickness of FRP jacket in seismic retrofit of reinforced concrete columns. To compare with the displacement coefficient method (DCM), the DDM gives an accurate prediction of the target displacement in highly nonlinear region, since the DCM uses the elastic stiffness before reaching the yield load as the effective stiffness but the DDM uses the secant stiffness.

Development of the Drift Design Method of High-rise Buildings using Weight Control Factors (중량 조절계수를 이용한 고층 건물 변위설계법 개발)

  • Park, Hyo Seon;Seo, Ji Hyun
    • Journal of Korean Society of Steel Construction
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    • v.17 no.3 s.76
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    • pp.285-294
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    • 2005
  • Drift design is one of the core techniques in the structural design of high-rise buildings and resizing technique is regarded as a practical drift design method for high-rise buildings. In the resizing technique, the structural weight is re-distributed to minimize the target displacement without a change in structural weights. However, the structural weight determined from resizing algorithm is bound to the structural weight based on the preliminary design. Therefore, in this paper, a drift design method that can control the weight of the structure without causing drift control performance to deteriorate is proposed by incorporating the weight control factor in the formulation of resizing algorithm. The proposed drift design method is applied to the drift design of two frame-shear wall systems. The proposed drift design method, in this study, makes it possible to control both the drift and weight of a high-rise building.

Development of Performance-Based Seismic Design of RC Column Using FRP Jacket by Displacement Coefficient Method (FRP 보강 철근콘크리트기둥의 변위계수법에 의한 내진성능설계기법 개발)

  • Cho, Chang-Geun;Ha, Gee-Joo;Bae, Su-Ho
    • Journal of the Korea Concrete Institute
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    • v.19 no.4
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    • pp.491-497
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    • 2007
  • In the current research, the scheme of displacement-based seismic design for seismic retrofit of concrete structures using FRP composite materials has been proposed. An algorithm of the nonlinear flexural analysis of FRP composite concrete members has been presented under multiaxial constitutive laws of concrete and composite materials. An algorithm for performance-based seismic retrofit design of reinforced concrete columns with FRP jacket has been newly introduced to modify the displacement coefficient method used in reinforced concrete structures. From applications of retrofit design, the method are easy to apply in the practice of retrofit design and give practical prediction of nonlinear seismic performance evaluation of retrofitted structures.

Effect of Nonlinear Analysis Procedures for Seismic Responses of Reinforced Concrete Wall Structure (철근콘크리트 벽체구조물의 지진응답에 대한 비선형 해석기법의 영향)

  • Song, Jong-Keol;Jang, Dong-Hui;Chung, Yeong-Hwa
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.4A
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    • pp.659-675
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    • 2006
  • Recently, significant progress has been made in performance-based engineering methods that rely mainly on nonlinear static seismic analysis procedures. The Capacity Spectrum Method (CSM) and the Displacement Coefficient Method (DCM) are the representative nonlinear static seismic analysis procedures. In order to evaluate the applicability of the procedures to the seismic evaluation and design process of new and existing structures, the accuracy of both CSM and DCM should be evaluated in advance. The accuracy of seismic responses by the nonlinear static procedures is evaluated in comparison with the shaking table test results for the structural wall specimen subjected to the far field and near field earthquakes. Also conducted are comparative studies where the shaking table test results are compared with those from nonlinear dynamic analysis procedures, i.e., Single-Degree-of-Freedom (SDOF), equivalent SDOF and Multi-Degree-of-Freedom (MDOF) systems.

Non-statistical Stochastic Finite Element Method Employing Higher Order Stochastic Field Function (고차의 추계장 함수와 이를 이용한 비통계학적 추계론적 유한요소해석)

  • Noh, Hyuk-Chun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.2A
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    • pp.383-390
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    • 2006
  • In this paper, a stochastic field that is compatible with Monte Carlo simulation is suggested for an expansion-based stochastic analysis scheme of weighted integral method. Through investigation on the way of affection of stochastic field function on the displacement vector in the series expansion scheme, it is noticed that the stochastic field adopted in the weighted integral method is not compatible with that appears in the Monte Carlo simulation. As generally recognized in the field of stochastic mechanics, the response variability is not a linear function of the coefficient of variation of stochastic field but a nonlinear function with increasing variability as the intensity of uncertainty is increased. Employing the stochastic field suggested in this study, the response variability evaluated by means of the weighted integral scheme is reproduced with high precision even for uncertain fields with moderately large coefficient of variation. Besides, despite the fact that only the first-order expansion is employed, an outstanding agreement between the results of expansion-based weighted integral method and Monte Carlo simulation is achieved.

Modified Nonlinear Static Pushover Procedures of MDOF Bridgesfor Seismic Performance Evaluation (내진성능평가를 위한 다자유도 교량의 수정 비선형 등가정적해석법)

  • Cho, Chang-Geun;Kim, Young-Sang;Bae, Soo-Ho
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.4
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    • pp.175-184
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    • 2006
  • Two methods of the nonlinear static pushover analysis have been presented for the performance-based seismic design and evaluation of MDOF continuous bridges. Guidelines for buildings presented in FEMA-273 applying the Displacement Coefficient Method (DCM) and in ATC applying the Capacity Spectrum Method(CSM) have been modified for MDOF bridges. Two methods are compared with the time- history analysis. The lateral load distribution pattern for seismic loads has been examined in the static pushover analysis. The force-based fiber frame finite element has been implemented in the modeling of reinforced concrete piers.

Earthquake Response Analyses of Underground Structures Using Displacement Responses of Soil (응답변위법을 이용한 지중구조물의 지진해석)

  • Kim, Doo-Kie;Seo, Hyeong-Yeol;Park, Jin-Woo;Choe, In-Jung
    • Journal of the Korea institute for structural maintenance and inspection
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    • v.10 no.6
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    • pp.133-142
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    • 2006
  • This study performed earthquake response analyses of underground structures using displacement responses of soil. In this study, spring coefficients of surrounding soil proposed by specifications and researchers were adopted and then their corresponding analysis results were compared. The free field analyses using ProShake were carried out in order to predict ground responses of the field without underground structures. Several earthquakes such as El Centro, Ofunato, and Hachinohe earthquakes were considered to calculate maximum displacements. Numerical examples were analyzed, and then the results were compared and commented depending on spring coefficients of soil for the analyses using displacement responses of soil. The soil coefficients ranged from 0.05 to 14.39 times of those calculated by Korean Bridge Design Specification (2005). In conclusion, the coefficients of soil proposed by standard specifications seemed to be overestimated compared with those by the finite element method(FEM).

A Study of Aerodynamic Modelling for Fin Unfolding Motion Analysis (공력면 전개 모사를 위한 공력 모델링 연구)

  • Jung, Suk-Young;Yoon, Sung-Joon
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.36 no.5
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    • pp.420-427
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    • 2008
  • For simulation of a fin unfolding motion for the various aerodynamic conditions, equations and moments applying to the unfolding fin were modelled. Aerodynamic roll moment consists of the static roll moment and the damping moment, which were obtained through wind tunnel tests and numerical analyses respectively. Panel method was used to compute the roll damping coefficient with deflected fin, whose angle was equivalent to angle of attack due to the deployment motion. Roll damping coefficient is a function of angle of attack, sideslip angle, and deployment angle but not of angular velocity of deployment. Simulation with aerodynamic damping model gave more similar deployment time compared to fin deployment test results.

Estimation of Elastic Modulus in Rock Mass for Assessing Displacment in Rock Tunnel (암반터널에서의 변위파악을 위한 암반 탄성계수 추정)

  • Son, Moorak;Li, Sudan;Lee, Wonki
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.31 no.2C
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    • pp.83-92
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    • 2011
  • Elastic modulus in rockmass is an important factor to represent the characteristic of rock deformation and is used to estimate the displacement due to tunnel excavation. Nevertheless, the study to estimate the elastic modulus, which condisiders the rock type and joint characteristics (joint shear strength and joint inclination angle), has been done in less frequency. Accordingly, this study is aimed at providing the method to estimate the elastic modulus of rockmass in the various rock and joint conditons and the results grasped from the study. For this purpose, the 2D discrete numerical analysis will be carried out and the displacements due to tunnel excavation will be investigated with the consideration of rock and joint conditions. Then the displacement results will be used to estimate the elastic modulus of rockmass in which rock and joint conditions are considered with the utilization of the elastic theory of circular tunnel. The results of elastic modulus, which considers the conditions of various rock and joint, would be expected to have a great practical use in field.

Verification of Direct Back Analysis Software Using FLAC as a Subroutine (FLAC을 이용한 직접법 역해석 소프트웨어의 개발과 검증)

  • Kim Chee-Hwan
    • Tunnel and Underground Space
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    • v.15 no.5 s.58
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    • pp.344-351
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    • 2005
  • Direct back analysis software is coded based on Simplex method using FLAC as a subroutine. For the verification of the software, 12 different cases are assumed combining various displacements in different measuring locations around a tunnel. The number of displacements for cases varies from 3 to 240. It is verified that the exact elasticity and the primary stress state of rock around a tunnel could be found through iterative calculation regardless of the locations and number of displacements and initial values needed for the direct back analysis.