Rocking-isolated frame structures: Margins of safety against toppling collapse and simplified design approach

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

dc.contributor.author	Gelagoti, F	en
dc.contributor.author	Kourkoulis, R	en
dc.contributor.author	Anastasopoulos, I	en
dc.contributor.author	Gazetas, G	en
dc.date.accessioned	2014-03-01T01:37:36Z
dc.date.available	2014-03-01T01:37:36Z
dc.date.issued	2012	en
dc.identifier.issn	0267-7261	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/21569
dc.subject.classification	Engineering, Geological	en
dc.subject.classification	Geosciences, Multidisciplinary	en
dc.subject.other	A-frames	en
dc.subject.other	Analytical solutions	en
dc.subject.other	Design approaches	en
dc.subject.other	Displacement capacity	en
dc.subject.other	Foundation design	en
dc.subject.other	Frame structure	en
dc.subject.other	Horizontal displacements	en
dc.subject.other	Illustrative examples	en
dc.subject.other	Isolated footings	en
dc.subject.other	Key factors	en
dc.subject.other	Non-linear FE	en
dc.subject.other	Nonlinear dynamic time-history analysis	en
dc.subject.other	Rigid body	en
dc.subject.other	Seismic demands	en
dc.subject.other	Seismic load	en
dc.subject.other	Seismic Performance	en
dc.subject.other	Simplified procedure	en
dc.subject.other	Spectral displacement	en
dc.subject.other	Design	en
dc.subject.other	Estimation	en
dc.subject.other	Numerical analysis	en
dc.subject.other	Seismology	en
dc.subject.other	Structural frames	en
dc.subject.other	Seismic design	en
dc.subject.other	collapse	en
dc.subject.other	finite element method	en
dc.subject.other	footing	en
dc.subject.other	mathematical analysis	en
dc.subject.other	seismic design	en
dc.subject.other	structural analysis	en
dc.subject.other	structural component	en
dc.subject.other	toppling	en
dc.title	Rocking-isolated frame structures: Margins of safety against toppling collapse and simplified design approach	en
heal.type	journalArticle	en
heal.identifier.primary	10.1016/j.soildyn.2011.08.008	en
heal.identifier.secondary	http://dx.doi.org/10.1016/j.soildyn.2011.08.008	en
heal.language	English	en
heal.publicationDate	2012	en
heal.abstract	This paper aims to explore the limitations associated with the design of "rocking-isolated" frame structures. According to this emerging seismic design concept, instead of over-designing the isolated footings of a frame (as entrenched in current capacity-design principles), the latter are under-designed with the intention to limit the seismic loads transmitted to the superstructure. An idealized 2-storey frame is utilized as an illustrative example, to investigate the key factors affecting foundation design. Nonlinear FE analysis is employed to study the seismic performance of the rocking-isolated frame. After investigating the margins of safety against toppling collapse, a simplified procedure is developed to estimate the minimum acceptable footing width B-min, without recourse to sophisticated (and time consuming) numerical analyses. It is shown that adequate margins of safety against toppling collapse may be achieved, if the toppling displacement capacity of the frame delta(topl), (i.e. the maximum horizontal displacement that does not provoke toppling) is sufficiently larger than the seismic demand delta(dem). With respect to the capacity, the use of an appropriate "equivalent" rigid-body is suggested, and shown to yield a conservative estimate of delta(topl). The demand is estimated on the basis of the displacement spectrum, and the peak spectral displacement SDmax a is proposed as a conservative measure of delta(dem). The validity and limitations of such approximation are investigated for a rigid-block on rigid-base, utilizing rigorous analytical solutions from the bibliography; and for the frame structure on nonlinear soil, by conducting comprehensive nonlinear dynamic time history analyses. In all cases examined, the simplified SDmax approach is shown to yield reasonably conservative estimates. (C) 2011 Elsevier Ltd. All rights reserved.	en
heal.publisher	ELSEVIER SCI LTD	en
heal.journalName	Soil Dynamics and Earthquake Engineering	en
dc.identifier.doi	10.1016/j.soildyn.2011.08.008	en
dc.identifier.isi	ISI:000297449200007	en
dc.identifier.volume	32	en
dc.identifier.issue	1	en
dc.identifier.spage	87	en
dc.identifier.epage	102	en