Σφαιρικά εφέδρανα ολίσθησης τύπου εκκρεμούς - Τεχνολογίες και εφαρμογή σε πλαίσιο

Πολάκις, Ελευθέριος; Polakis, Eleftherios

dc.contributor.author	Πολάκις, Ελευθέριος	el
dc.contributor.author	Polakis, Eleftherios	en
dc.date.accessioned	2015-04-28T09:57:00Z
dc.date.available	2015-04-28T09:57:00Z
dc.date.issued	2015-04-28
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/40663
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.5083
dc.description	Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Δομοστατικός Σχεδιασμός και Ανάλυση των Κατασκευών”	el
dc.rights	Default License
dc.subject	Σφαιρικά εφέδρανα	el
dc.subject	Σεισμική μόνωση	el
dc.subject	Spherical bearings	en
dc.subject	Seismic isolation	en
dc.title	Σφαιρικά εφέδρανα ολίσθησης τύπου εκκρεμούς - Τεχνολογίες και εφαρμογή σε πλαίσιο	el
dc.title	Spherical sliding pendulum bearings - Technologies and application at a 2d frame	en
heal.type	masterThesis
heal.classification	Structural engineering	el
heal.classificationURI	http://skos.um.es/unesco6/330532
heal.language	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2014-11-04
heal.abstract	Two different technologies of spherical sliding pendulum bearings are presented and analysed at the current master thesis, ones with a single sliding concave surface and those with multiple concave surfaces. At the same time, their response, under near field ground motions is being examined. Spherical sliding bearings are a mean of seismically isolating the superstructure from the ground motion during an earthquake. Their behavior is totally different from the elastometallic ones. Along the introduction of this thesis, a flashback at the evolution of worlwide aseismic codes, takes place, concerning the philosophy of each code. The all starting philosophy of elastic design is described, along with the transition to the ductility design. Ductility design takes advantage of the ductile behavior of the materials used in the buildings. However, a few reasons, among which was the failure of many aseismically designed buildings, during earthquakes of high magnitude, led to a new way of thinking and a new design philosophy, that of seismic isolation In the first chapter, the benefits of seismic isolation and the way those are achieved, are described, while a general citation of seismically isolated structures’ behavior is done. The technologies of seismic isolation, concerning the different types of bearings, are mentioned. The difference of elastomeric and sliding bearings is also highlighted. Sliding bearings are divided into flat and spherical ones. Spherical bearings have an advantage over the flat ones, because of the existence of a restoring force, during motion and their recentering capabilities. Friction pendulum system isolators and triple friction pendulum bearings are two huge categories of spherical bearings, while the latter are considered to be an advancement of the former. The geometrical characteristics of these two types of bearings are thoroughly described. Finally, several examples of structures, worldwide, being isolated with these types of bearings are mentioned. Second chapter emphasizes on the properties of these bearings. The models used to describe the bearings’ hysteretic behavior and all the parameters which take place to this procedure are mentioned. The codes concerning the different bearings’ geometries and the range of their properties values are defined, with respect to the environmental conditions. Third chapter consists of a brief reference of the installation requirements of seismic isolation devices. Specific configurations usually take place, while base isolation requires modifications to architectural features and services to accommodate the movements. Forth chapter begins with the description of near field ground motions and the reasons they differ from other ground excitations. This introduction is followed by the description of the 2d frame used, for the application of the bearings. The frame’s geometry is thoroughly described along with its modeling details according to the greek codes. The different types of loading and the way of mass calculation is also described. In the fifth chapter, the modal analysis of the three different frames takes place. The three different frames consist of the fixed base frame, the seismically isolated using FPS isolators and finally the isolated using TFPB. The method used for the calculation of the bearings’ properties and their application to the computer software for the analysis (CSi SAP2000) is the method of the equivalent linear, single degree of freedom system and can be used at a predesign level for the approximation of the isolation system’s nonlinear behavior. Once the FPS properties are defined, the TFPB’ dimensions are also calculated at a common basis. In the sixth chapter, response spectrum analysis takes place according to Eurocode 8’s provisions. The goal is to compare the results of this method to the ones derived from the previous one. The seventh chapter contains the nonlinear time history analysis. Time history analysis is a very accurate method of analyzing seismically isolated structures, during which the nonlinear behavior of the bearings is examined in detail, through the whole duration of the ground motion. Hysteretic loops of the two types of bearings are built and their displacements are being monitored. Fourteen time histories in total, are being used in the analysis, separated into two groups. First group contains time histories where the directivity pulse has a period of 3 – 4 sec approximately, whereas in the second group, pulse has a period of 1 – 2 sec. The base shear and the base’s drift, are also presented via comparative diagrams for the tree types of frame. In the eighth chapter the results of the time history analysis are presented along with the conclusions made, in reference to the efficiency of the seismic isolation of buildings, subjected to near field ground motions. The influence of the pulse’s period on the base shear, the base’s drift and bearings’ displacement is examined. In addition, the bearings’ displacements are being compared, for elastic and plastic design of the superstructure.	el
heal.advisorName	Ψυχάρης, Ιωάννης	el
heal.committeeMemberName	Μουζάκης, Χαράλαμπος	el
heal.committeeMemberName	Φραγκιαδάκης, Μιχάλης	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Πολιτικών Μηχανικών. Τομέας Δομοστατικής. Εργαστήριο Αντισεισμικής Τεχνολογίας	el
heal.academicPublisherID	ntua
heal.numberOfPages	84 σ.	el
heal.fullTextAvailability	true