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۱EFFECTS OF NEAR–FAULT GROUND MOTIONS IN SEISMIC PERFORMANCE EVALUATION OF A SYMMETRY ARCH DAM ON RIGID AND MASS–LESS FOUNDATIONS
اطلاعات انتشار: ششمین کنفرانس بین المللی زلزله شناسی و مهندسی زلزله، سال
تعداد صفحات: ۸
In this paper near–fault ground motions effects in comparison with far–fault ground motions on seismic performance of a symmetry concrete arch dam are investigated. Various sets of nearfault and far–fault ground motions with approximate identical peak ground acceleration were used for analyses of coupled system. For this purpose Karaj arch dam was selected as case study and two different options were considered for dam–foundation interaction. In the first case foundation rock was supposed as rigid and in second one foundation rock was simulated as mass–less medium. The behavior of dam and foundation were expressed in term of displacement and reservoir was modelled based on fluid elements. The seismic performance evaluation of arch dam was performed by using demand–capacity ratios obtained from linear analyses. In addition displacements, principal stresses, total cumulative inelastic duration and the percentage of overstressed areas in upstream and downstream faces of dam body were calculated and compared in near–fault and far–fault ground motions. It was concluded that generally near–fault ground motions are more effective than far–fault ground–motions in non–cumulative damage indices; however it is vice–versa in cumulative damage indices.<\div>

۲Linear seismic response of arch dams to non–uniform excitations considering load combination effects
نویسنده(ها): ،
اطلاعات انتشار: اولین همایش ملی مهندسی سازه ایران، سال
تعداد صفحات: ۱۳
In the present paper, the effect of non–uniform excitation due to spatially varying earthquake ground motions(SVEGM) on linear responses of concrete arch dams is investigated. An iterative scheme is utilized to generate seismicground motion time–histories at several locations along foundation boundaries that are compatible with prescribedtarget response spectra and are correlated according to a given coherence function including the wave propagationeffect. A double curvature arch dam is selected as case study in which the reservoir is modeled as a compressiblemedium and the foundation is assumed to be massless. Various load combinations are considered based on thecorresponding reservoir water levels and thermal loads. It is observed that using SVEGM leads to higher values in bothtensile stresses and percentage of overstressed parts within the dam body in comparison with uniform excitation andtherefore to be more realistic in calculating the dam response, this phenomenon should be incorporated in seismicanalyses especially in high seismicity regions.<\div>

۳Wave Passage and Incoherency Effects on Nonlinear Response of High Arch Dams
نویسنده(ها): ،
اطلاعات انتشار: اولین همایش ملی مهندسی سازه ایران، سال
تعداد صفحات: ۱۴
In the present paper, effects of incoherency and wave–passage on nonlinear responses of concrete arch dams wereinvestigated. A double curvature arch dam was selected as numerical example. Reservoir was modeled as acompressible material and foundation was modeled as a mass–less medium. Ground motion time–histories wereartificially generated using Monte Carlo simulation approach. Four different FE models were considered including;Uniform excitation; Incoherence effect; Wave passage effect and; finally both incoherence and wave passage effects. Itwas revealed that modeling multiple–supports excitation could have significant effects on the structural response of thedam by inducing pseudo–static effect. Also, it was concluded that coherency effect overshadow wave passage effectand results obtained from non–uniform exciting of FEM including wave passage effect is close to the results of the FEmodel exited uniformly.<\div>
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