Seismic soil amplification effects
XVIII Lição Manuel Rocha, 2001
DOI:
https://doi.org/10.14195/2184-8394_97_1Abstract
The subject of seismic soil amplification effects is addressed, with an emphasis on the amplification of peak horizontal ground acceleration and the modification of the frequency content of seismic strong motions. After a brief review of some basic seismological and earthquake engineering concepts, the various factors that influence the severity of seismic movements are analysed, related to seismic source, to source-site propagation and to site effects. Some examples are pointed out of macro seismic indications as well as instrumental evidences of the profound influence that site subsoil conditions have upon the amplitude, the frequency content and the duration of seismic movements. With regard to instrumental evidences, several acceleration records both in rock and in soft deep soils obtained during the great Michoacan, Loma Pricta, Kobe and Kocaeli earthquakes are presented and analysed. The main factors and conditions that favour the existence of soil amplification effects are analysed and discussed with the aid of a simplified interpretative model. An appreciation is made of the more recent evolution of code provisions related to the influence of site subsoil conditions on seismic actions. Finally, some considerations are made concerning the relevance of seismic soil amplification effects in Portugal and some topics that need future research and development are pointed out.
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References
Ambraseys, N.N. e Bommer, J.J. The attenuation of ground accelerations in Europe. Earthquake Engineering and Structural Dynamics, Vol. 20, pp. 1179-1202, 1991.
CEC - Commission of the European Communities. Eurocode 8: Structures in seismic regions - Design, Part 1: General and buildings, 1988.
CEN - European Committee for Standardization. Eurocode 8: Design provisions for earthquake resistance of structures, Part 1-1: General rufes - Seismic actions and general requirements for structures. Pré-norma ENV 1998-1-1:1994, 1994.
CEN - European Committee for Standardization. Eurocode 8: Design provisions for earthquake resistance, Part 1: General rufes, seismic actions and rufes for buildings. Versão preliminar nº 3 da norma prEN 1998-1, 2001.
Chang, F.K. e Krinitzsky, E.L. Duration, spectral content and predominant period of strong ground motion earthquake records from western United States. Miscellaneous Paper 5- 73-1, U.S. Army Corps of Engineers Waterways Experiment Station, 1977.
Choffat, P. e Bensaude, A. Estudos sobre o sismo do Ribatejo de 23 de Abril de 1909. Comissão do Serviço Geológico de Portugal, 1912.
Correia, R.M. Efeitos locais de amplificação sísmica pelos solos. Actas do Simpósio sobre Catástrofes Naturais - Estudo, Prevenção e Protecção, Lisboa, pp. 133-145, 1993.
Correia, R.M. Acerca da influência das condições geotécnicas locais no valor máximo da ace leração em movimentos sísmicos. Relatório 222/89-NEGE, Laboratório Nacional de Engenharia Civil, 1989.
CSOPT - Conselho Superior de Obras Públicas e Transportes. Regulamento de segurança e acções para estruturas de edificios e pontes. Decreto-Lei nº 235/83, de 31 de Maio, Imprensa Nacional - Casa da Moeda, Lisboa, 1983.
Dobry, R. et ai. New site coefficients and site classification system used in recent building seismie code provisions. Earthquake Spectra, Vol. 16, nº 1, pp. 41-67, 2000.
Housner et at. Competing against time. Relatório da comissão de inquérito ao sismo de Loma Prieta instituída pelo governador do estado da Califórnia, 1990.
Idriss, I.M. Response of soft soil sites during earthquakes. Proc. Memorial Symposium to Honour Prof. H.B. Seed, Berkeley, Vol. II, pp. 273-289, 1990.
Idriss, I.M. Earthquake ground motions at soft soil sites. Proc. 2nd Intemational Conference on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, St. Louis, Vol. III, pp. 2265-2272, 1991.
ICBO - Intemational Council of Building Officials. Uniform building code, 1997.
IPQ - Instituto Português da Qualidade. Eurocódigo 8: Disposições para projecto de estruturas sismo-resistentes, Parte 1-1: Regras gerais - Acções sísmicas e requisitos gerais para as estruturas. Norma Portuguesa ENV 1998-1-1:2000, 2000.
Jagger, T. A. The Yokohama-Tokyo Earthquake of September /, 1923. Bulletin of the Seismological Society of America, Dezembro, pp. 124-146, 1923.
Kanamori, H. The energy release in great earthquakes. Joumal of Geophysical Research, Vol. 82,pp.2981-2987, 1977.
Kokusho, T. e Matsumoto, M. Nonlinear site response during the Hyogoken-Nanbu earthquake recorded by vertical arrays in view of seismic zonation methodology. Proceedings of Discussion Special Technical Session on Earthquake Geotechnical Engineering, Hamburgo, pp. 61-69, P. Sêco e Pinto (ed.), A.A. Balkema, 1997.
Kramer, S.L. Geotechnical earthquake engineering. Prentice-Hall, New Jersey, 1996.
Lawson, A.C. et al. Prelimina,y report of the state earthquake investigation commission, Berkeley, 1906.
Pereira de Sousa, F.L. O terremoto do 1º de Novembro de 1755 em Portugal e um estudo demográfico. Serviços Geológicos, 1919.
Roesset, J.M. Soil amplification of earthquakes. Em "Numerical methods in geotechnical engineering", Cap. 19, pp. 639-682, C.S. Desai e J.T. Christian (ed.), McGraw-Hill, 1977.
Seed, H.B. et al. Relationships between soil conditions and earthquake ground motions in Mexico City in the earthquake of Set. 19, 1985. Earthquake Engineering Research Center, Report nº UCB/EERC 87-15, Universidade da Califórnia, Berkeley, 1987.
Seed, H.B. et al. Relationships of maximum acceleration, maximum velocity, distance from source and local soil conditions for moderately strong earthquakes. Bulletin of the Seismological Society of America, Vol. 66, nº 1, pp. 221-243, 1976a.
Seed, H.B., Ugas, C. e Lysmer, J. Site-dependent spectra for earthquake-resistant design. Bulletin ofthe Seismological Society of America, Vol. 66, nº 4, pp. 1323-1342, 1976b.
Seed, H.B. e Idriss, I.M. Ground motions and soil liquefaction during earthquakes. Monografia, Earthquake Engineering Research Institute, Berkeley, 1982.
Sousa, M.L., Martins, A. e Oliveira, C.S. Compilação de catálogos sísmicos da região ibérica. Relatório 36/92-NDA, Laboratório Nacional de Engenharia Civil, 1992.
Tiedemann, H. Earthquakes and Volcanic Eruptions - A handbook on risk assessment. Swiss Reinsurance Company, Zurique, 1992.
Vieira, A. e Correia, R.M. Análise estocástica de efeitos locais de amplificação sob acções sísmicas. Actas do 5º Congresso Nacional de Geotecnia, Coimbra, Vol. 2, pp. 171-180, 1995.
Vieira, A. e Correia, R.M. Aplicação de um método de análise sísmica local a dois casos reais. Relatório 125/97-NEGE, Laboratório Nacional de Engenharia Civil, 1997.
Vucetic, M. e Dobry, R. Effects of soil plasticity on cyclic response. Journal of Geotechnical Engineering, ASCE, Vol. 117, nº GTl, pp. 89-107, 1991.
Youd, T.L., Bardet, J.P. e Bray, J.D. (ed.) Kocaeli, Turkey, earthquake of August 17, 1999 reconnaissance report. Earthquake Spectra, Vol. 16, Suplemento A, 2000.
