A Numerical Study on Comparison of 1D and 2D Seismic Responses of a Basin in Turkey
Local site conditions such as seismic bedrock depth, bedrock slope of the edge, geometry and characteristics of soil layers, topographical irregularities, etc. are the most important factors affecting earthquake ground motion in a specific site. The amplitude and frequency content of bedrock motion can be changed by local site effects, and this variation is denoted as an amplification or de-amplification. Among the several factors, basin edge effect plays an important role in the transformation of earthquake waves and increase of the surface motion duration and amplitude. The limited width of the soil layers or the edge geometry at the deep formations cause earthquake wave transformations, thus the amplitude of the surface ground motion may vary depending on its location. For this reason the frequency content of surface ground motion may differ from the calculated surface ground motion by one dimensional dynamic analysis. In this case two dimensional analysis is required. In this study, in order to compare the soil response under different strong ground motion, one and two dimensional dynamic analyses were performed by using the Dinar Basin model in Turkey. The acceleration time histories and absolute acceleration spectra were obtained for pre-selected points on the ground surface. The 2D/1D spectral acceleration ratios were calculated by dividing the absolute acceleration spectra obtained from two dimensional (2D) and one dimensional (1D) dynamic analysis. The variations of the spectral acceleration ratios (2D/1D) with distance from basin edge were evaluated for different period values. The calculated 2D/1D spectral acceleration ratios reached their maximum values at a certain zone (X/D<3) near basin edge for every interested period value. While approaching to center of basin models, especially at the zones after X/D=3 point it can be noticed that 2D/1D spectral acceleration ratios generally converged to 1 regardless of the edge bedrock slope values. The highest average spectral acceleration ratios were calculated when the relevant period values were between T=0.2~0.5 s. They took values varying between 2 and 3 for this period interval. A relationship between the results of 1D and 2D dynamic analyses was established. In addition, the approximate validity range of 1D and 2D dynamic analysis at the basin edges was investigated for the model.
Murat Emre Hasal,
A Numerical Study on Comparison of 1D and 2D Seismic Responses of a Basin in Turkey, American Journal of Civil Engineering.
Vol. 2, No. 5,
2014, pp. 123-133.
G. A. Athanasopoulos, P. C. Pelekis, and E. A. Leonidou, “Effects of surface topography on seismic ground response in the Egion (Greece) 15 June 1995 Earthquake”, Soil Dynamics and Earthquake Engineering, vol. 18, pp. 135-149, 1999.
E. Safak, “Local site effects and dynamic soil behaviour”, Soil Dynamics and Earthquake Engineering, vol. 21, pp. 453-458, 2001.
S. L. Kramer, Geotechnical Earthquake Engineering, Prentice-Hall, Upper Saddle River, USA, 1996.
K. Pitilakis, Recent Advances in Earthquake Geotechnical Engineering and Microzonation, A. Ansal (ed.), Kluwer Academic Publishers, Netherlands, pp. 139-193, 2004.
R. Iyisan and H. Khanbabazadeh, "A numerical study on the basin edge effects on soil amplifıcation", Bulletin of Earthquake Engineering, vol. 11, Issue 5, pp. 1305-1323, 2013.
M. Rassem, A. Ghobarah, and A. C. Heidebrecht, “Engineering perspective for the seismic site response of alluvial valleys”, Earthquake Engineering and Structural Dynamics, vol. 26, pp. 477-493, 1997.
R. Iyisan and M. E. Hasal, “The effect of ground motion characteristics to the dynamic response of alluvial valley models”, 13th Asian Regional Conference of Soil & Geotechnical Engineering, Theme-7 Dam Engineering, Paper Code 7.1-8, Kolkata, India, 2007.
DYNEQ, A Computer Program for Dynamic Response Analysis of Level Ground By Equivalent Linear Method, Version 3.23, Revised from Original Version (May 1995) by Yoshida and Suetomi., 2003.
QUAKE/W, Finite Element Dynamic Earthquake Analysis Software, Geo-Slope Office.
B. S. Bakir, M. Y. Ozkan, and S. Ciliz, “Effects of basin edge on the distribution of damage in 1995 Dinar, Turkey Earthquake”, Soil Dynamics and Earthquake Engineering, vol. 22, pp. 335-345, 2002.
A. Ozturk, “Tectonics of Dinar Sandıklı-Isıklı region”, Communications of Faculty of Science, University of Ankara, No.25, pp. 1-58, 1982.
M. E. Hasal, R. Iyisan, H. Khanbabazadeh, A. Bayin, G. Cevikbilen, and O. Kepceoglu, “A preliminary seismic microzonation study based on microtremor measurements”, International Conference on Earthquake Engineering, Skopje, Macedonia, 2013.
R. Iyisan, M. E. Hasal, G. Cevikbilen, and A. Bayin, “Estimation of site response by microtremor measurements”, 2013 International Van Earthquake Symposium, Abstract ID:100, Van, Turkey, 2013.
A. J. Choobbasti, S. Rezaei, and F. Farrokhzad, “Evaluation of site response characteristics using microtremors”, Gradevinar, 65, pp. 731-741, 2013.
S. Rezaei, A. J. Choobbasti, and S. S. Kutanaei, “Site effect assessment using microtremor measurement, equivalent linear method, and artificial neural network (case study: Babol, Iran)”, Arabian Journal of Geosciences, DOI 10.1007/s12517-013-1201-1, 2013.
M. K. Kockar and H. Akgun, “Evaluation of the site effects of the Ankara basin, Turkey”, Journal of Applied Geophysics, vol. 83, pp. 120-134, 2012.
P. Teves-Costa and P. Y. Bard, “Seismic behaviour estimation of thin alluvium layers using microtremor recordings”, Soil Dynamics and Earthquake Engineering, vol. 15, pp. 201-209, 1996.
R. Iyisan and A. Ansal, “Estimation of local soil conditions with microtremor”, 7th National Congress on Soil Mechanics and Foundation Engineering (in Turkish), YTU, İstanbul, pp. 542-549, 1998.
R. Iyisan, U. Gulerce, H. Yamanaka, and A. Ansal, “Estimation of shear wave velocity by microtremor observations”, 9th National Congress on Soil Mechanics and Foundation Engineering (in Turkish), Anadolu Üniversitesi, Eskişehir, 2002.
H. Yamanaka, “Geophysical exploration of sedimentary structures and their characterization”, The Effects of Surface Geology on Seismic Motion, Balkema, Rotterdam, pp.15-33, 1998.
M. Horike, “Geophysical exploration using microtremor measurements”, Proc. of 11th World Conf. on Earthquake Engineering, paper no. 2033, 1996.
H. Yamanaka and H. Ishida, “Application of genetic algorithms to an inversion of surface-wave dispersion data”, Bulletin of the Seism. Society of America, vol. 86, No.2, pp.436-444, 1996.
M. E. Hasal, The Effects of Topographical Irregularities on Soil Amplification, Ph. D. Thesis (in Turkish), ITU Institute of Science and Technology, İstanbul, 2008.
I. Ishibashi and X. Zhang, “Unified dynamic shear moduli and damping ratios of sand and clay”, Japanese Society of Soil Mechanics and Foundation Eng., vol. 33, No.1, pp. 182-191, 1993.
P. B. Schnabel, J. Lysmer, and H. B. Seed, Shake: A Computer Program for Earthquake Response Analysis of Horizontally Layered Sites, Report No. UCB/EERC 72-12, Earthq. Eng. Research Center, University of California, Berkeley, p. 102, 1972.
M. A. Ansal, R. Iyisan, and H. Gullu, “Microtremor measurements for the microzonation of Dinar”, Pure and Applied Geophysics, vol. 158, pp. 2525-2541, 2001.
B. Gatmiri, C. Arson, and K.V. Nguyen, “Seismic site effects by an optimized 2D BE/FE method: Theory, numerical optimization and application to topographical irregularities”, Soil Dynamics and Earthquake Engineering, vol. 28, pp. 632-645, 2008.
J. Lysmer and R. L. Kuhlemeyer, “A finite dynamic model for infinite media”, Journal of the Engineering Mechanics Division, ASCE, vol. 95, No. EM4, pp. 859-877, August, 1969.
J. L. Von Thun, L. H. Rochim, G. A. Scott and J. A. Wilson, “Earthquake ground motions for design and analysis of dams”, Earthquake Engineering and Soil Dynamics II, Recent Advance in Ground-Motion Evaluation, Geotec. Special Publication, vol. 20, ASCE, New York, pp. 463-481, 1988.
K. Makra, D. Raptakis, F. J. Chavez-Garcia, and K. Pitilakis, “Site effects and design provisions: The case of Euroseistest”, Journal of Pure and Applied Geophysics, vol. 158, N.12, pp. 2349-2367, 2001.