انجمن ملی ژئوفیزیک ایران مجله ژئوفیزیک ایران 2008-0336 17 3 2023 09 23 Three-dimensional seismic response of earth dams subjected to spatially varying earthquake ground motion Three-dimensional seismic response of earth dams subjected to spatially varying earthquake ground motion 1 12 165923 10.30499/ijg.2023.360389.1455 FA Amir Ghalyanchi Langroudi Ph.D. Candidate, Department of Civil Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran Mohammad Davoodi Associate Professor, Geotechnical Engineering Research Center, International Institute of Earthquake Engineering and Seismology (IIEES), Tehran, Iran 0000-0001-5111-3994 Mohammad Kazem Jafari Professor, International Institute of Earthquake Engineering and Seismology, Tehran, Iran Masoud Nekooei Assistant Professor, Department of Structural Engineering, Science and Research Branch, Islamic Azad University, Tehran, Iran Journal Article 2022 09 13 For extended structure, the seismic load has a spatiotemporal variation that simultaneously changes with time and space. The incorporation of the seismic wave spatial random variability effect is <br />especially important when large structures such as long bridges, dams, and large buildings are <br />analyzed. The effect of spatially varying earthquake ground motion (SVEGM) on the seismic <br />response of earth dams is analyzed in this paper. To this end, a parametric study is conducted to investigate the effects of length to height ratio ( ) on the 3D seismic response of the studied dams. Ground motions, consistent with the three-directional lagged coherency model, are generated at <br />different discretized cells at the base of the dam. The dams are assumed to sit on trapezoidal and <br />V-shaped canyons and vibrate in all three directions, upstream-downstream, vertical, and <br />longitudinal. The average coherency of different frequencies is calculated and used for the generation of SVEGM. The time histories are simulated using a spectral representation-based method. The <br />separation distance between the cells is determined in such a way that 90% of correlation between seismic input motions can be captured. For each case of  ratio, a numerical model of the dam and its foundation is constructed using the finite difference numerical method. The 3D seismic <br />behavior of the earth dams is evaluated under the artificially generated three-directional components of SVEGM. Generally, it is concluded that with increasing  ratio, at the midpoint of the dam crest, the difference between maximum of acceleration values obtained by applying uniform and SVEGM excitations decreases. In all cases of analyses, SVEGM has decreasing effect on the vertical displacement of dam crest. For extended structure, the seismic load has a spatiotemporal variation that simultaneously changes with time and space. The incorporation of the seismic wave spatial random variability effect is <br />especially important when large structures such as long bridges, dams, and large buildings are <br />analyzed. The effect of spatially varying earthquake ground motion (SVEGM) on the seismic <br />response of earth dams is analyzed in this paper. To this end, a parametric study is conducted to investigate the effects of length to height ratio ( ) on the 3D seismic response of the studied dams. Ground motions, consistent with the three-directional lagged coherency model, are generated at <br />different discretized cells at the base of the dam. The dams are assumed to sit on trapezoidal and <br />V-shaped canyons and vibrate in all three directions, upstream-downstream, vertical, and <br />longitudinal. The average coherency of different frequencies is calculated and used for the generation of SVEGM. The time histories are simulated using a spectral representation-based method. The <br />separation distance between the cells is determined in such a way that 90% of correlation between seismic input motions can be captured. For each case of  ratio, a numerical model of the dam and its foundation is constructed using the finite difference numerical method. The 3D seismic <br />behavior of the earth dams is evaluated under the artificially generated three-directional components of SVEGM. Generally, it is concluded that with increasing  ratio, at the midpoint of the dam crest, the difference between maximum of acceleration values obtained by applying uniform and SVEGM excitations decreases. In all cases of analyses, SVEGM has decreasing effect on the vertical displacement of dam crest. https://www.ijgeophysics.ir/article_165923_ebbdb0a66097b7fb2f06914b41331e90.pdf