• Title, Summary, Keyword: 지진응답 수정계수

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Evaluation of Accuracy of Modified Equivalent Linear Method (수정된 등가선형해석기법의 정확성 평가)

  • Jeong, Chang-Gyun;Kwak, Dong-Yeop;Park, Duhee;Kim, Kwangkyun
    • Journal of the Korean Geoenvironmental Society
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    • v.11 no.6
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    • pp.5-20
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    • 2010
  • One-dimensional equivalent linear site response analysis is widely used in practice due to its simplicity, requiring only few input parameters, and low computational cost. The main limitation of the procedure is that it is essentially a linear method, in which the time dependent change in the soil properties cannot be modeled and constant values of shear modulus and damping is used throughout the duration of the analysis. Various forms of modified equivalent linear analyses have been developed to enhance the accuracy of the equivalent linear method by incorporating the dependence of the shear strain with the loading frequency. The methods are identical in that it uses the shear strain Fourier spectrum as the backbone of the analysis, but differ in the method in which the strain Fourier spectrum is smoothed. This study used two domestically measured soil profiles to perform a series of nonlinear, equivalent linear, and modified equivalent linear site response analyses to verify the accuracy of two modified procedures. The results of the analyses indicate that the modified equivalent linear analysis can highly overestimate the amplification of the high frequency components of the ground motion. The degree of overestimation is dependent on the characteristics of the input ground motion. Use of a motion rich in high frequency contents can result in unrealistic response.

Seismic Characteristics of Hollow Rectangular Sectional Piers with Reduced Lateral Reinforcements (횡방향철근이 감소된 중공사각단면 교각의 내진거동 특성)

  • Sun, Chang-Ho;Kim, Ick-Hyun
    • Journal of the Earthquake Engineering Society of Korea
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    • v.13 no.3
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    • pp.51-65
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    • 2009
  • The seismic design concept of RC bridges is to attain the proper ductility of piers, yielding a ductile failure mechanism. Therefore, seismic design force for moment is determined by introducing a response modification factor (R), and lateral reinforcements to confine core concrete are specified in the current design code. However, these design provisions have irrationality, which results in excessive amounts of lateral reinforcements for columns in Korea, which are generally designed with large sections. To improve on these provisions, a new design method based on seismic performance has been proposed. To apply this to hollow sectional columns, however, further investigations and improvements must be performed, due to the different seismic behaviors and confinement effects. In this study, hollow sectional columns with different lap-splice of longitudinal bars and lateral reinforcements have been tested. Seismic characteristics and performance were investigated quantitatively. These research results can be used to derive a performance-based design for hollow sectional columns.