Αποτίμηση σεισμικής διακινδύνευσης τετραώροφου κτιρίου ΩΣ κατασκευασμένου το 1974 στη Αθήνα και οικονομική μελέτη χρηματικών απωλειών

Βαρβαρίγου, Ρούσα; Varvarigou, Rousa

dc.contributor.author	Βαρβαρίγου, Ρούσα	el
dc.contributor.author	Varvarigou, Rousa	en
dc.date.accessioned	2022-10-20T10:16:16Z
dc.date.available	2022-10-20T10:16:16Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/55967
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.23665
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	Αποτίμηση	el
dc.subject	Ανελαστική Στατική Μέθοδος	el
dc.subject	Δευτεροβαθμιος έλεγχος	el
dc.subject	Τεχνοοικονομική Αποτίμηση	el
dc.subject	Τριτοβάθμιος έλεγχος	el
dc.subject	Pushover	el
dc.subject	Reinforced concrete	en
dc.subject	Financial losses	en
dc.subject	Second level Assessment	en
dc.subject	Assessment	en
dc.title	Αποτίμηση σεισμικής διακινδύνευσης τετραώροφου κτιρίου ΩΣ κατασκευασμένου το 1974 στη Αθήνα και οικονομική μελέτη χρηματικών απωλειών	el
dc.title	Seismic risk assessment of a four-story reinforced concrete building constructed in 1974 in Athens & study of financial losses	en
heal.type	masterThesis
heal.classification	Structural engineering	el
heal.classification	Civil Engineering	el
heal.language	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2022-06-28
heal.abstract	Η αποτίμηση της φέρουσας ικανότητας υφιστάμενων κτιρίων από ωπλισμένο σκυρόδεμα είναι ένα από τα θέματα που κάθε δομοστατικός μηχανικός καλείται να αντιμετωπίσει. Στην Ελλάδα η διαδικασία αποτίμησης βασίζεται στον Κανονισμό Επεμβάσεων (ΚΑΝ.ΕΠΕ.) και είναι μια διαδικασία επίπονη και χρονοβόρα. Για το λόγο αυτό έχουν αναπτυχθεί δευτεροβάθμιοι προσεισμικοί έλεγχοι με στόχο η διαδικασία αυτή να απλοποιηθεί και ταυτόχρονα τα αποτελέσματα που θα δίνουν να είναι κοντά στην αναλυτική λύση. Στις σελίδες που ακολουθούν επιλέχθηκε να μελετηθεί ένα τετραώροφο κτίριο ωπλισμένου σκυροδέματος κατασκευασμένο στη Νέα Χαλκηδόνα Αττικής το 1974. Το κτίριο αυτό μελετήθηκε χωρίς αντισεισμικούς κανονισμούς, κάτι που όπως θα δούμε από τον Πρωτοβάθμιο Προσεισμικό Έλεγχο που περιγράφεται αναλυτικά κατατάσσει το κτίριο σε υψηλή κατηγορία προτεραιότητας περαιτέρω ελέγχου. Μια πρώτη αποτίμηση της φέρουσας ικανότητας του φορέα γίνεται μέσω των ταχέων μεθόδων δευτεροβάθμιου προσεισμικού ελέγχου του Σ. Δρίτσου και του Ε. Βουγιούκα. Για κάθε μια από τις μεθόδους προσδιορίζεται προσεγγιστικά η τέμνουσα βάσης για κάθε διεύθυνση του κτιρίου. Για τις δύο αυτές μεθόδους τα αποτελέσματα είναι διαφορετικά με χαρακτηριστικό ότι η μέθοδος του Σ. Δρίτσου δίνει πιο συντηρητικά αποτελέσματα σε σχέση με αυτά του Ε. Βουγιούκα. Για να επαληθευθεί η ακρίβεια των αποτελεσμάτων από τις δευτεροβάθμιες μεθόδους παρουσιάζεται και η αναλυτική λύση βάσει ΚΑΝ.ΕΠΕ. , δηλαδή η μέθοδος της ανελαστικής στατικής ανάλυσης. Για την αναλυτική λύση χρησιμοποιήθηκε το λογισμικό της SeismoSoft, SeismoBuild. Για μια πληρέστερη εικόνα της σεισμικής συμπεριφοράς της κατασκευής έγινε χρήση του λογισμικού SPO2FRAG, όπου η ανελαστική στατική ανάλυση μεταφράζεται σε μια δυναμική ανάλυση με τη μέθοδο του μονοβάθμιου ταλαντωτή. Τα αποτελέσματα που πήραμε ήταν οι καμπύλες τρωτότητας του κτιρίου. Οι καμπύλες αυτές χρησιμοποιήθηκαν στο λογισμικό PACT όπου εισάγοντας τα δομικά στοιχεία που αποτελούν τον φορέα και τα κόστη επισκευών για δεδομένα Ελλάδας, προσδιορίστηκαν οι μέσες ετήσιες επισκευαστικές απώλειες της κατασκευής λόγω σεισμού. Ολοκληρώνεται έτσι η εικόνα της σεισμικής αποτίμησης της κατασκευής μεταφρασμένη σε χρηματικό κόστος.	el
heal.abstract	Assessing the load-bearing capacity of existing reinforced concrete buildings is one of the issues that every structural engineer is called upon to address. In Greece, the valuation process is based on the Greek Code for Structural Interventions (KAN.EPE.). The third-level analytical assessment, described in KAN.EPE. is a difficult and time-consuming process. For this reason, second-level assessments have been developed in order to simplify this process. This Diploma Thesis is an attempt to check the results of those second-level assessments and compare them with the third-level assessment to evaluate the results. Using those results from the analytical solution, the seismic risk was translated into cost, by determining the average annual repair losses due to earthquake. In the following pages a four-story reinforced concrete building was chosen as a study case. It was built in Nea Chalkidona, Attica Greece. The average height of the building is 11.6m. It was constructed in 1974, according to the existing codes at that period. The slabs have relatively small dimensions with a maximum length up to 6m and an average height of 12cm. The majority of beams feature typical dimensions 20/60 cm with an average length of 6m, while the dimensions of the columns vary between 20x20cm and 30x60cm. There is a wall, which dimensions are 135x20cm, but without sufficient longitudinal and transverse reinforcement. In every floor, there are infill elements with regular distribution, and they don’t create additional vulnerability in seismic loads, such as eccentricities or short columns. Generally, the structure is in relatively good condition, and no significant reinforcement corrosion or local concrete spalling is observed. The area of Nea Chalkidona is categorized in the Lowest Seismic Hazard Zone in Greece (0.16g), and the design is based on type 1 elastic spectrum according to Eurocode 8. The building under consideration was constructed without seismic resistance regulations, which classifies it in the highest category due to seismic risk, as the first-level seismic assessment confirms. The first-level assessment is a rapid visual check which takes into consideration the date, the regulations, and the hazard spectrum of the area the building was built. Furthermore, for this assessment, the plans and a section of the building are needed. The second-level assessments which were chosen for the comparison were those of S. Dritsos and E. Vougioukas. The method of S. Dritsos is based on thirteen different criteria which evaluate the capacity of the building to carry the seismic loads. To apply those criteria there is no need to use statical analysis software, as all the calculations can be done in excel. Some of those criteria are the serious structural injuries of the building, the total axial load size, the distribution of mass and stiffness of the building, the mass distribution by height, vertical discontinuities, neighboring buildings, and defects and injuries of the building. The goal of this method is to find the deficiency index λ. This indicator shows how many times the Vreq is bigger than the VRD of the building and therefore how crucial a further third-level analysis and structural intervention is. The method of S. Dritsos is mainly based on Eurocodes. . The method of E. Vougioukas is a quick seismic assessment of existing buildings based strictly on KAN.EPE. It is a method that mostly applies in old buildings, constructed before 1985, where usually the columns have less shear capacity than the beams and they reach their maximum resistance first. In this method, the shear capacity for each column of the ground floor is calculated separately and the shear capacity of the building is calculated as the sum of all shear capacities of each column. This process is being followed in both directions individually. Using those methods, a first assessment of the bearing capacity of the building is made for both directions. The results we get from these two methods are different with the characteristic that the method of S. Dritsos gives more conservative results compared to those of E. Vougioukas. For the third-order assessment, two models were studied. The one without the contribution of the masonry walls and one with the contribution of the masonry walls. As a first step is being carried out a modal analysis, which will be needed to assess the results and will be used from the pushover analysis. From the modal analysis, the eigenmodes and eigenperiods of the building in each direction were determined. The contribution of the masonry walls in this analysis was the reduction of the value of the eigenperiod mostly in the Y direction, where there were more walls. This means that the building became stiffer because of the presence of the masonry walls and therefore the value of the eigenperiod was reduced. In order to verify the accuracy of the results from the second-level methods, the analytical solution is based on KAN.EPE. was carried out using the SeismoBuild software. The nonlinear static analysis is the reference method in assessment practice of existing buildings. It is based on pushover analyses carried out under constant gravity loads and increasing lateral forces, applied at the location of the masses to simulate the inertia forces induced by the seismic action. As the model may account for both geometrical and mechanical nonlinearity, this method can describe the evolution of the expected plastic mechanisms and structural damage. The introduced vertical loads applied to the model, in addition to incremental loads, are equal to 1.00G+0.30Q. The analysis runs for 64 different load combinations, each of which takes into consideration another seismic direction, a different eccentricity of the applied loads, and different vertical distribution (one as a uniform pattern and one for a modal pattern). Each pushover analysis leads to a capacity curve, which is a relationship between the total base shear and the horizontal displacement of a representative point of the structure, termed “control node”. The demand at the considered Performance Level - Life Safety or Collapse Prevention- is determined by the appropriate comparison between the capacities determined by the pushover curve. Comparing the results of the pushover analysis from the two models, with and without the masonry walls, it is confirmed that the presence of the walls made the building a lot stiffer but at the same time the strengths of the building remain the same. Therefore, the masonry walls did not help the overall performance of the building. As for the checks through KAN.EPE. we can see that the building does not pass the criteria and it fails earlier than expected due to shear failure. After carrying out nonlinear static analysis at different peak ground accelerations (PGA), it was found that the PGA of the first shear failure in the model without the masonry walls and for the X direction was ag=0.07g. For the Y direction, it was ag=0.105g. For the model without the masonry walls, the first shear failure in the X direction happens in PGA ag=0.03g and for the Y direction in PGA ag=0.036g. Finally, from the comparison between the second-level assessment and the third-level assessment, it is obvious that the method of S. Dritsos has more conservative results from the analytical solution and gives about 263.55kN and 429.53kN less shear capacity of the building on directions X and Y respectively. The method of E. Vougioukas is very close to the analytical solution and gives in the X direction 119.86kN more shear capacity and in the Y direction about 85.54kN less shear capacity in direction X. For the complete picture of the seismic behavior of the building, it was used the SPO2FRAG software, where the static pushover analysis was translated into a dynamic analysis by the method of the single degree of freedom approximation of the structure. SPO2FRAG software is using the results of the static pushover analysis and estimates the structure-specific seismic fragility curve of the building. It avoids the need for computationally demanding dynamic analysis by simulating the results of incremental dynamic analysis via the SPO2IDA algorithm and an equivalent single-degree-of-freedom approximation of the structure. Fragility functions for the limit states of Life Safety and Collapse Prevention were calculated using the intensity-measure-based analytical approach. The results we obtained were the fragility curves of the building for each limit state. These curves were used in the Performance Assessment Calculation Tool software (PACT) provided by FEMA P-5. By entering the structural elements of the building and the repair costs for the Greek market, the average annual repair losses of the building due to seismic actions were determined. In Pact software it was entered data for the structural analysis results such as the median demand for drift ratio, peak floor acceleration, and residual drift for each floor. It was selected four (4) different seismic intensity scenarios in terms of spectral acceleration (SA). Those scenarios for SA correspond to 50%, 10.34%, 10%, and 2% probabilities of over 50 years. The 10.34% over the 50 years probability corresponds to the possibility of the first shear failure over 50 years. Those probabilities were provided through the EFEHR database, and it was converted into mean annual frequency of exceedance (MAFE). For each scenario is calculated the cost of repair and it is shown which elements of the building are expected to get damaged and therefore need repair. For all of the scenarios, the main elements that need repair are the internal and external masonry walls that are used for infills. Moreover, column C11 which fails first in every scenario is one of the elements that contribute to the repair cost. The repair cost varies from 41.000€ for the first scenario to 536.666,6€ for the fourth scenario. Finally, the annual cost of repairs is estimated to be equal to 3.524,71 € and corresponds to 0.55% of the total replacement cost.	en
heal.advisorName	Βαμβάτσικος, Δημήτριος	el
heal.advisorName	Vamvatsikos, Dimitrios	en
heal.committeeMemberName	Βουγιούκας, Εμμανουήλ	el
heal.committeeMemberName	Αβραάμ, Τάσος	el
heal.committeeMemberName	Vougioukas, Emmanouil	en
heal.committeeMemberName	Avraam, Tasos	en
heal.committeeMemberName	Βαμβατσικος, Δημήτριος	el
heal.committeeMemberName	Vamvatsikos, Dimitrios	en
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Πολιτικών Μηχανικών. Τομέας Δομοστατικής. Εργαστήριο Μεταλλικών Κατασκευών	el
heal.academicPublisherID	ntua
heal.numberOfPages	71 σ.	el
heal.fullTextAvailability	false