Επιρροή των συνθηκών στήριξης στην Ανάλυση Τρωτότητας πολυώροφου κτιρίου

Κυνηγός, Νικόλαος; Kynigos, Nikolaos

dc.contributor.author	Κυνηγός, Νικόλαος	el
dc.contributor.author	Kynigos, Nikolaos	en
dc.date.accessioned	2017-05-31T08:33:47Z
dc.date.available	2017-05-31T08:33:47Z
dc.date.issued	2017-05-31
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/44946
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.6757
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	Μονο -κομβικό εδαφικό ελατήριο	el
dc.subject	Συνθήκες στήριξης	el
dc.subject	Ανελαστική επαυξητική δυναμική ανάλυση	el
dc.subject	Καμπύλες τρωτότητας	el
dc.subject	Δείκτης πλαστιμότητας	el
dc.subject	Steel structure design	en
dc.subject	Damping	en
dc.subject	Spectral acceleration	en
dc.subject	Capacity curve	en
dc.title	Επιρροή των συνθηκών στήριξης στην Ανάλυση Τρωτότητας πολυώροφου κτιρίου	el
heal.type	masterThesis
heal.classification	Δομοστατικός Σχεδιασμός	el
heal.classification	ΑΝΑΛΥΣΗ ΤΩΝ ΚΑΤΑΣΚΕΥΩΝ	el
heal.classification	ΜΕΤΑΛΛΙΚΕΣ ΚΑΤΑΣΚΕΥΕΣ	el
heal.classificationURI	http://data.seab.gr/concepts/2a80a2e119d24970988f906c4e19065d9d4f9dce
heal.classificationURI	http://data.seab.gr/concepts/6aa62585dd0180516223521f270569cb0146f613
heal.language	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2017-03-01
heal.abstract	The purpose of this study, is to investigate the effect of the conditions assigned to the base of the structure during the modeling process and thus to evaluate one aspect of the soil – structure interaction phenomenon. For this purpose, a four – storey braced frame steel structure is designed according to the modern provisions of Eurocodes (Ec-3, Ec-8). A modal analysis is implemented which is needed for the spectral modal analysis of the seismic load design. The following analysis steps are afterwards defined. 1. The differentiation of the base constraints is succeeded inducing the following assignments in the ground level of the structure: fixes, pins and single – node springs with damping adopted from the study “Formulas and charts for impedances of surface and embedded foundations” (Gazetas, 1991), which are referred to the corresponding to the soil-structure interaction directives of ATC–40 and ATC–58. A single – node element is considered to be an accurate assumption as it is enough reliable when the foundation elements are stiff footings, according to ATC-40. This is also an assumption which is not unnecessary increasing the complexity of the mathematical model of the analysis, which is desirable for the effectiveness of non – linear analysis procedures. The information about the ground properties in the site of the structure and the foundation geometry is needed for the calculation of the foundation impedances and effective damping. The foundation type is chosen to be surface footings, and their typical geometry is extracted from their design that is implemented according to the provisions of Eurocode 7. A mid-class soil (between soft and stiff) is considered to exist in the building site and the values of its properties are adopted from the literature. The thickness of the ground layer is considered to be such large that an elastic half-space assumption can be made about it. 2. The seismic response of the structure is exported, with non – linear time history analysis of eight scaled accelerograms applied increasingly to the structure for the 3 different test cases, to adapt the capacity curve, following the IDA method, adopting the proposals of Vamvatsikos & Cornell (2003) and following the directives of FEMA – P – 58 -1. The chosen accelerograms must be representative of the seismic conditions that are expected to strike the structure during its life period. An appropriate scale factor (λ) is chosen to scale the ground acceleration that is induced to the structure for the time – history analyses, from small values until the structure’s failure. An intensity measure (IM) is chosen to express the seismic magnitude and a damage measure (DM) is chosen to express the internal intensity of the structure’s seismic response. Peak ground acceleration (PGA) and spectral acceleration (SA) of the fundamental elastic period (T1) are examined as intensity measures in this study and maximum inter – storey drift is selected as damage measure. The failure of the structure is the moment of the IDA analysis that dynamic instability occurs, which is considered that happens when the scale factor is such that excessive deformations arise or the mathematical model can’t converge, during the non linear dynamic analysis. The fulfillment of the IDA analysis procedure can be said that is determined by two distinct steps. The first one is the implementation of such number of single – record analysis as the number of the chosen accelerograms and the second one is the synthesis of their results, which determines the final step of the method. Afterwards the seismic evaluation of the structure is able. Additionally, a method for the calculation of the structure ductility factor is proposed in this study, with the use of IDA analyses. 3. Finally, the fragility analysis is chosen as an assessment method of the results of the test cases, and so, performance levels and their fragility curves need to be defined. Fragility curves are expressed with the median values and the dispersion of the response of the structure. Three limit states are examined and the damage measure threshold for which the structure proceeds to each one, during the analysis needs to be defined. Semi - empeirical values are used, which are derived from the values of average inter- storey drift proposed in Hazus - MH building module’s technical manual for each limit – state and from studies similar to the present. Afterwards the median value and the dispersion of the intensity measure which define these thresholds are calculated based on the assumption that the intensity measure follows the probability density function of log-normal distribution, which is an approach based to the work of Shinozuka et al (1999). All the information needed is then available for the plotting of the fragility curves. With the use of the available information for the seismic hazardness, which is the seismic hazard curve of the building site’s area, an association of the intensity measure’s fragility curve that defines the limit state and the probability of its proportionate value that is expected in the building’s site can be made. In the end of this process the mean annual frequency of exceedance and the return period of each performance level are extracted. The results of the fragility analysis for each base condition are finally compared and conclusions are derived. In summary it can be said, that a considerable variation is recognized for the results of the three different support conditions tested. Therefore, it is concluded that the soil-structure interaction is an important issue of Structural design which must be responsibly taken into account, while it should be neglected after thorough research. The finite element structural program SAP2000 was used for the design of the structure and the non – linear dynamic analyses that were performed. Key words: steel structure design, soil-structure interaction (SSI), support conditions, single – node foundation spring, damping, capacity curve, inelastic incremental dynamic analysis (IDA), maximum inter – storey drift, peak ground acceleration, spectral acceleration, base shear, ductility factor, performance levels, fragility curves, mean annual frequency of exceedance, return period	en
heal.advisorName	Ραυτογιάννης, Ιωάννης	el
heal.committeeMemberName	Αβραάμ, Τάσος	el
heal.committeeMemberName	Θανόπουλος, Παύλος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Πολιτικών Μηχανικών	el
heal.academicPublisherID	ntua
heal.numberOfPages	162 σ.	el
heal.fullTextAvailability	true