Newmark 기반 변형해석에 의한 필댐의 내진저항성 연구 |
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학술지명 한국지진공학회
저자 박동순
발표일 2014-07-15
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Newmark type deformation analysis have rarely been done in Korea due to popularity of simple pseudo-static limit equilibrium analysis and detail time-history FE/FD dynamic analysis. However, according to the Korean seismic dam design code updated in 2011, Newmark type deformation analysis was specified as a major dynamic analysis method for seismic evaluation of fill dams. In addition, a design PGA for dynamic analysis was significantly increased in the code. This paper aimed 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 the in-situ geo-physical surveys were applied as input parameters. For the FEM/Newmark analyses, sensitivity analyses were performed to study the effects of input PGA and Gmax of shell zone on the Newmark deformation. As a result, in terms of deformation, four fill dams were reasonably safe under PGA of 0.22g with the yield coefficient of 0.136 to 0.187, which are pretty resistant for extreme events. Sensitivity analyses as a function of PGA show that PGA30cm (a limiting PGA to cause the 30cm of Newmark permanent displacement on the critical slip surface) is a good indicator for seismic safety check. CFRD showed a higher seismic resistance than ECRD. Another sensitivity analyses show that Gmax per depth does not significantly affect site response characteristics, however lower Gmax 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 to govern the permanent displacements. |