Seismic wave propagation in a very soft alluvial valley: Sensitivity to ground-motion details and soil nonlinearity, and generation of a parasitic vertical component

Gelagoti, F; Kourkoulis, R; Anastasopoulos, I; Tazoh, T; Gazetas, G

dc.contributor.author	Gelagoti, F	en
dc.contributor.author	Kourkoulis, R	en
dc.contributor.author	Anastasopoulos, I	en
dc.contributor.author	Tazoh, T	en
dc.contributor.author	Gazetas, G	en
dc.date.accessioned	2014-03-01T01:34:33Z
dc.date.available	2014-03-01T01:34:33Z
dc.date.issued	2010	en
dc.identifier.issn	0037-1106	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/20752
dc.subject.classification	Geochemistry & Geophysics	en
dc.subject.other	2-D wave	en
dc.subject.other	Alluvial valleys	en
dc.subject.other	Base motion	en
dc.subject.other	Focusing effect	en
dc.subject.other	Frequency contents	en
dc.subject.other	Ground-motion	en
dc.subject.other	High frequency	en
dc.subject.other	High frequency HF	en
dc.subject.other	Low frequency	en
dc.subject.other	Multi-cycle	en
dc.subject.other	Non-Linearity	en
dc.subject.other	Numerical studies	en
dc.subject.other	P waves	en
dc.subject.other	Problem parameters	en
dc.subject.other	Seismic excitations	en
dc.subject.other	Seismic motions	en
dc.subject.other	Single-pulse	en
dc.subject.other	Soil amplification	en
dc.subject.other	Soil nonlinearity	en
dc.subject.other	Test case	en
dc.subject.other	Vertical component	en
dc.subject.other	Wave focusing	en
dc.subject.other	Focusing	en
dc.subject.other	Seismic waves	en
dc.subject.other	Seismology	en
dc.subject.other	Soils	en
dc.subject.other	Surface waves	en
dc.subject.other	Wave propagation	en
dc.subject.other	Landforms	en
dc.subject.other	alluvial plain	en
dc.subject.other	ground motion	en
dc.subject.other	numerical method	en
dc.subject.other	P-wave	en
dc.subject.other	seismic wave	en
dc.subject.other	surface wave	en
dc.subject.other	wave propagation	en
dc.subject.other	wave reflection	en
dc.title	Seismic wave propagation in a very soft alluvial valley: Sensitivity to ground-motion details and soil nonlinearity, and generation of a parasitic vertical component	en
heal.type	journalArticle	en
heal.identifier.primary	10.1785/0120100002	en
heal.identifier.secondary	http://dx.doi.org/10.1785/0120100002	en
heal.language	English	en
heal.publicationDate	2010	en
heal.abstract	This paper explores the sensitivity of 2D wave effects to crucial problem parameters, such as the frequency content of the base motion, its details, and soil nonlinearity. A numerical study is conducted, utilizing a shallow soft valley as a test case. It is shown that wave focusing effects near valley edges and surface waves generated at valley corners are responsible for substantial aggravation (AG) of the seismic motion. With high-frequency seismic excitation, 1D soil amplification is prevailing at the central part of the valley, while 2D phenomena are localized near the edges. For low-frequency seismic excitation, wave focusing effects are overshadowed by laterally propagating surface waves, leading to a shift in the location of maximum AG toward the valley center. If the response is elastic, the details of the seismic excitation do not seem to play any role on the focusing effects at valley edges, but make a substantial difference at the valley center, where surface waves are dominant. The increase of damping mainly affects the propagation of surface waves, reducing AG at the valley center, but does not appear to have any appreciable effect at the valley edges. Soil nonlinearity may modify the 2D valley response significantly. For idealized single-pulse seismic excitations, AG at the valley center is reduced with increasing nonlinearity. Quite remarkably, for real multicycle seismic excitations AG at the valley edges may increase with soil nonlinearity. In contrast to the vertical component of an incident seismic motion, which is largely the result of P waves and is usually of too high frequency to pose a serious threat to structures, the valley-generated parasitic vertical component could be detrimental to structures: being a direct result of 2D wave reflections/refractions, it is well correlated and with essentially the same dominant periods as the horizontal component.	en
heal.publisher	SEISMOLOGICAL SOC AMER	en
heal.journalName	Bulletin of the Seismological Society of America	en
dc.identifier.doi	10.1785/0120100002	en
dc.identifier.isi	ISI:000284997900010	en
dc.identifier.volume	100	en
dc.identifier.issue	6	en
dc.identifier.spage	3035	en
dc.identifier.epage	3054	en