The smooth and reliable operation of key infrastructure components like water distribution systems, electric power systems, and telecommunications is essential for a nation?s economic growth and overall security. Tragic events such as the Northridge earthquake and Hurricane Katrina have shown us how the occurrence of a disaster can cripple one or more such critical infrastructure components and cause widespread damage and destruction. Technological advancements made over the last few decades have resulted in these infrastructure components becoming highly complicated and inter-dependent on each other. The development of tools which can aid in understanding this complex interaction amongst the infrastructure components is thus of paramount importance for being able to manage critical resources and carry out post-emergency recovery missions. The research work conducted as a part of this thesis aims at studying the effects of fire (a calamitous event) on the electrical distribution network of a city. The study has been carried out on a test bed comprising of a virtual city named Micropolis which was modeled using a Geographic Information System (GIS) based software package. This report describes the designing of a separate electrical test bed using Simulink, based on the GIS layout of the power distribution network of Micropolis. It also proposes a method of quantifying the damage caused by fire to the electrical network by means of a parameter called the Load Loss Damage Index (LLDI). Finally, it presents an innovative graph theoretic approach for determining how to route power across faulted sections of the electrical network using a given set of Normally Open switches. The power is routed along a path of minimum impedance. The proposed methodologies are then tested by running numerous simulations on the Micropolis test bed, corresponding to different fire spread scenarios. The LLDI values generated from these simulation runs are then analyzed in order to determine the most damaging scenarios and to identify infrastructure components of the city which are most crucial in containing the damage caused by fire to the electrical network. The conclusions thereby drawn can give useful insights to emergency response personnel when they deal with real-life disasters.

Structural Health Monitoring (SHM) is an effective alternative to conventional inspections which are time-consuming and subjective. SHM can detect damage early and reduce maintenance cost and thereby help reduce the likelihood of catastrophic structural events to infrastructure such as bridges. After reviewing the Damage Index Method, an Iterative Damage Index Method (IDIM) is proposed to improve the accuracy of damage detection. These two damage detection techniques are compared numerically and experimentally using measurements from two structures, a simply supported beam and a pedestrian bridge. The dynamic properties for the numerical comparison are extracted by modal analysis in ABAQUS, while the dynamic characteristics for the experimental comparison are obtained with the Wireless Sensor Network and the Time Domain Decomposition. In both the numerical and experimental phases, the accuracy of damage predictions from each method is quantified. Compared to the traditional damage detection algorithm, the proposed IDIM is shown to be less arbitrary and more accurate when applied to both structures. The proposed IDIM has the potential to improve SHM.

A detailed seismic performance assessment procedure has been developed for reinforced concrete frame buildings with masonry in-fill walls and reinforced concrete frames including shear walls. The procedure uses member damage functions, in terms of inter-story drift ratios, developed for the primary components: columns, beams, in-fill walls and shear walls. Analytical investigations carried out to determine the influence of a number of parameters on the damageability of components were combined with existing experimental data to develop component damage functions. A new approach has been developed to combine component damage states to determine the story and building level performance states. The procedure has been calibrated and compared with other procedures by predicting the observed performance of seven buildings exposed to recent earthquakes in Turkey. It was observed that the damage experienced by most of the components of these buildings was predicted satisfactorily, and that the observed building damage states were captured. The procedure can be used for a reliable performance assessment as well as performance-based design of the RC frame structures.

The research effort in this thesis is devoted to develop techniques to accurately and rapidly identify the location, orientation, and magnitude of the defects by using structural health monitoring concepts that use Laser Doppler Vibrometer as a non-contact sensor with multi-point sensing capability. The first research area addresses the formulation and validation of an innovative Damage Measure that is based on the ratios of the strain energy distributions of the damaged and undamaged structure. The innovations include use of a single set of actuator/sensor pair to excite and detect the responses of a structure for low frequency vibrations as well as guided wave propagation studies. A second new capability is the estimation of the Damage Measure without requiring any knowledge of the undamaged baseline structure. This method is made possible because of the development of these new technologies: Spatial Decimation and Wavenumber/Frequency filtering. The third contribution is to develop analytical models for the structural dynamics of damaged structure and seek solutions that use perturbation methods to detect damage in a plate structure. The fourth contribution is the development of a comprehensive damage detection technique over a wide frequency dynamic range. The fifth topic of research involves automation in Structural Health Monitoring based on the comprehensive Damage Measure formulation. Under the control of software the Scanning Laser Doppler Vibrometer is used to acquire the low frequency vibration mode data for a coarse identification of all the suspect regions of damage using a threshold criterion on the Damage Measure. Each suspect region of damage is further investigated using the high frequency elastic wave propagation to clearly identify the location, orientation, and extent of the damage. The computer control of the Laser Doppler Vibrometer and a quantitative assessment of the damage provide the enabling technologies for the automation proof of concept. Finally the developed techniques of damage detection are successfully demonstrated on practical structures such as a turbine blade in the laboratory and an F-15 vertical tail in field maintenance conditions

No description available.

Η διατριβή μπορεί να χωριστεί σε δύο μέρη. Το πρώτο μέρος αφορά την παρουσίαση του θεωρητικού υποβάθρου του μαθηματικού προσομοιώματος που χρησιμοποιήθηκε για να περιγράψει τη βλάβη που μπορεί να εμφανιστεί σε μια κατασκευή έπειτα από την επιβολή δυναμικής ή στατικής φόρτισης. Το προσομοίωμα αυτό χρησιμοποιήθηκε στην παρούσα διατριβή για την ανάλυση της γέφυρας της Κόνιτσας και γι’ αυτό το λόγο κρίθηκε απαραίτητη η αναφορά στο θεωρητικό υπόβαθρο, πάνω στο οποίο στηρίζεται. Το δεύτερο μέρος της διατριβής αφορά τη σεισμική ανάλυση της γέφυρας της Κόνιτσας, την αξιολόγηση των αποτελεσμάτων και τη διαδικασία ενίσχυσής της, καθώς και τη μετέπειτα σύγκριση των αποτελεσμάτων. Έτσι λοιπόν, στο πρώτο κεφάλαιο γίνεται αρχικά μια ιστορική ανασκόπηση της τοιχοποιίας ενώ στην συνέχεια γίνεται αναφορά τόσο στις κατηγορίες της όσο και στην τοιχοποιία ως υλικό δόμησης. Επιπλέον, γίνεται μία σύντομη περιγραφή των μηχανικών ιδιοτήτων της τοιχοποιίας. Τέλος, παρουσιάζονται σύντομα οι θεμελιώδεις παραδοχές και οι στόχοι του προσομοιώματος που χρησιμοποιήθηκε και εφαρμόστηκε στην παρούσα εργασία. Το δεύτερο κεφάλαιο, αποτελεί το εισαγωγικό μέρος στο οποίο παρουσιάζεται λεπτομερέστερα τα στοιχεία μηχανικής της τοιχοποιίας. Αρχικά, γίνεται αναφορά στην ταξινόμηση της τοιχοποιίας, ως προς τους τρόπους δόμησης, ενώ στην συνέχεια αναλύονται οι μηχανικές της ιδιότητες. Στις υποπαραγράφους του δευτέρου κεφαλαίου, αναλύεται δηλαδή η αντοχή της τοιχοποιίας σε μονοαξονική θλίψη, σε πολυαξονική θλίψη, η εφελκυστική αντοχή σε κάμψη, η διατμητική αντοχή καθώς και η αντοχή υπό τυχούσα επίπεδη καταπόνηση. Τέλος παρουσιάζονται τα ελαστικά χαρακτηριστικά της τοιχοποιίας ενώ περιγράφεται και η διαδικασία της ομογενοποίησης των συστατικών της τοιχοποιίας προκειμένου να αντιμετωπίζεται ως ένα ισοδύναμο ομογενές υλικό. Στο τρίτο κεφάλαιο γίνεται σύντομη περιγραφή της θεωρίας βλάβης του συνεχούς μέσου και ο τρόπος που εισάγεται αυτή στο μαθηματικό προσομοίωμα που εφαρμόστηκε στο δεύτερο μέρος της διατριβής. Αρχικά, λοιπόν, γίνεται μια μηχανική αναπαράσταση της βλάβης και στη συνέχεια παρουσιάζεται το θεωρητικό υπόβαθρο της θεωρίας βλάβης στα ψαθυρά υλικά. Ακολουθεί μία σύντομη περιγραφή του δείκτη βλάβης και η διατύπωση των συναρτήσεών του, όπως αυτές διαμορφώθηκαν κατά την ανάπτυξη του μαθηματικού προσομοιώματος που εφαρμόστηκε στην εργασία, για μονοαξονική θλιπτική καταπόνηση, για μονοαξονική εφελκυστική καταπόνηση, για διατμητική καταπόνηση μετά ορθής τάσης, για επίπεδη εντατική κατάσταση και τέλος τη γενίκευση του για τριαξονική εντατική κατάσταση. Στο τέταρτο κεφάλαιο περιγράφεται η επιφάνεια οριακής αντοχής. Αρχικά, δηλαδή, παρουσιάζονται συνοπτικά, και σύμφωνα με την βιβλιογραφία, οι μηχανισμοί αστοχίας της τοιχοποιίας καθώς και ο τρόπος υπολογισμού των τάσεων οριακής αντοχής. Στη συνέχεια διατυπώνονται οι μηχανισμοί αστοχίας της τοιχοποιίας υπό επίπεδη εντατική κατάσταση καθώς και ο γεωμετρικός προσδιορισμός της επιφάνειας οριακής αντοχής της τοιχοποιίας ενώ τέλος παρουσιάζονται οι σχέσεις που υπολογίζουν την οριακή αντοχή της τοιχοποιίας υπό συνθήκες τριαξονικής εντατικής κατάστασης. Στο πέμπτο κεφάλαιο, παρουσιάζονται συνοπτικά οι μέθοδοι αποκατάστασης και ενίσχυσης κατασκευών από τοιχοποιία. Μετά από μία σύντομη βιβλιογραφική αναφορά για την τρωτότητα των κατασκευών από φέρουσα τοιχοποιία, των βλαβών υπό τη δράση στατικών και σεισμικών φορτίσεων, των βλαβών υπό τη δράση περιβαλλοντικών παραγόντων, των κριτηρίων και των αρχών επεμβάσεων επισκευής και ενίσχυσης και των τεχνικών επεμβάσεων επισκευής και ενίσχυσης, γίνεται μια περιγραφική αναφορά των ενισχύσεων τοιχοποιίας με μανδύα οπλισμένου σκυροδέματος και με προεντεταμένους ελκυστήρες, καθώς αυτοί οι μέθοδοι ενίσχυσης χρησιμοποιήθηκαν και για τη γέφυρα της Κόνιτσας στον Αώο ποταμό. Στο έκτο κεφάλαιο, περιγράφεται συνοπτικά το λογισμικό που κάνει χρήση πεπερασμένων στοιχείων και επιλέχθηκε για την εφαρμογή του προσομοιώματος. Γίνεται αναφορά στις επιλογές ανάλυσης και τις δυνατότητες του προγράμματος αυτού καθώς και της δυνατότητας γραφικής απεικόνισης των αποτελεσμάτων που παράγει.. Στο έβδομο κεφάλαιο, παρουσιάζεται η κατασκευή που επιλέχθηκε προκειμένου να γίνει αριθμητική εφαρμογή του προσομοιώματος βλάβης. Αρχικά, περιγράφεται η γέφυρα της Κόνιτσας και γίνεται αναφορά των γεωμετρικών στοιχείων της. Έπειτα, παρουσιάζονται ορισμένα ιστορικά στοιχεία της γέφυρας. Στη συνέχεια, περιγράφεται ο τρόπος προσομοίωσης της γέφυρας με τη χρήση πεπερασμένων στοιχείων και αναφέρονται οι μηχανικές ιδιότητες των υλικών της. Επιπλέον, γίνεται αναφορά στις δυναμικές αναλύσεις χρονοϊστορίας που έγιναν τόσο για την αρχική κατάσταση της γέφυρας όσο και στις φάσεις ενίσχυσης με τη χρήση μανδύα οπλισμένου σκυροδέματος ή με τη χρήση προεντεταμένων ελκυστήρων. Τέλος, αναλύονται οι διαδικασίες ενίσχυσης της γέφυρας είτε με μανδύα οπλισμένου σκυροδέματος είτε με προεντεταμένους ελκυστήρες. Στο όγδοο κεφάλαιο, παρουσιάζονται τα αποτελέσματα των αναλύσεων της γέφυρας τόσο για την αρχική κατάστασή της, δηλαδή της μη ενισχυμένης περίπτωσης, όσο και για τις δύο περιπτώσεις στις οποίες η γέφυρα έχει ενισχυθεί με μανδύα σκυροδέματος ή με προεντεταμένους ελκυστήρες. Στο ένατο κεφάλαιο, παρουσιάζονται τα συμπεράσματα που προέκυψαν από τις αναλύσεις της γέφυρας τόσο για την αρχική της κατάσταση όσο και για τις ενισχυμένες περιπτώσεις. / The thesis can be divided into two parts. The first part deals with the presentation of the theoretical background of the mathematical model used to describe the damage that can occur in a construction upon a dynamic or static charge. The model was used in this thesis to analyze the bridge of Konitsa and for this reason the reference to the theoretical background was necessary, on which rests. The second part of the thesis concerns the seismic analysis of the bridge of Konitsa, evaluation of results and building processes and the subsequent comparison of results. Thus, the first chapter is initially a historical overview of the masonry and then refer to both categories and masonry as building material. Moreover, there is a brief description of the mechanical properties of masonry. Finally, presented briefly the fundamental assumptions and objectives of the model used and applied in the present work. The second chapter is the introductory part in which the masonry engineering data presented in more detail. Initially, reference is made to the classification of the masonry, for the construction of ways and then analyzed the mechanical properties. In sub-second chapter, that analyzes the strength of masonry in uniaxial compression, a multiaxial compressive, tensile bending strength, shear strength and durability under arbitrary stress levels. Finally presents the elastic characteristics of masonry and described the process of homogenization of the components of the masonry to be treated as an equivalent homogeneous material. The third chapter is a brief description of the error theory of continuous medium and the way it is introduced in the mathematical model applied in the second part of the thesis. Initially, then, is a mechanical representation of the lesion and then presents the theoretical background of damage theory in brittle materials. Following is a brief description of the index lesion and the expression of functions, like those formed during the development of the mathematical model applied to work, uniaxial compressive stress for uniaxial tensile stress for shear stress after proper voltage for plane stress conditions and end generalization for triaxial stress state. The fourth chapter describes the ultimate strength surface. Initially, ie, summarized, and according to the literature, the masonry failure mechanisms and the calculation of ultimate resistance trends. Then the masonry failure mechanisms are mentioned under plane stress conditions and the geometric definition of the ultimate strength of the masonry surface and finally presents the relations that calculate the ultimate strength of the masonry under conditions of triaxial stress condition. In the fifth chapter summarizes the methods of recovery and strengthening masonry structures. After a brief reference for the vulnerability of masonry structures, damage under the action of static and seismic loads, damage under the action of environmental factors, the criteria and repair operations authorities and aid and technical assistance and repair operations, is a descriptive report of wall reinforcement with concrete jacket and prestressing tractors, as these payment methods used and the bridge of Konitsa Aoos River. In the sixth chapter, summarized the software that makes use of finite element chosen for the implementation of the model. Refer to the analytical options and features of the program and the graphic display feature of the results produced .. In the seventh chapter, the structure was chosen in order to make numerical implementation of the model fault. Initially, described the bridge of Konitsa and reference geometric details. Then are some historical elements of the bridge. Then describe how simulation of the bridge using finite element and are the mechanical properties of the materials. Furthermore, reference is made to the dynamic history analyzes conducted for both the initial state of the bridge and in the amplification stages using concrete jacket or using prestressed tractors. Finally, we analyze the bridge-building processes or concrete jacket or prestressing tractors. In the eighth chapter presents the results of analyzes of the bridge both the initial condition, ie unamplified case, and for two cases in which the bridge has been reinforced with mantle concrete or prestressing tractors. In the ninth chapter presents the conclusions drawn from the analysis of both the bridge in its original condition and for reinforced cases.

As pontes de concreto armado são obras de arte de extrema importância para a infraestrutura de transportes do Brasil. Portanto sua inspeção e manutenção são atividades estratégicas. A inspeção visual, ensaios destrutivos e não destrutivos fornecem informações sobre a sua integridade estrutural e auxiliam na tomada de decisões relativas à necessidade de reparos e reforços. Entre os ensaios não destrutivos, avalia-se neste trabalho a aplicação da identificação modal estocástica na detecção de danos em pontes. A técnica baseia-se na medição das vibrações ambientais da estrutura, aquelas que ocorrem durante seu uso, identificação de suas propriedades modais, comparação com as propriedades modais da estrutura íntegra e consequente detecção de danos. Diferentemente da análise dinâmica experimental clássica, na identificação modal estocástica as ações dinâmicas não são medidas e nem controladas durante o ensaio. Por este motivo foram adotadas técnicas de identificação modal baseadas apenas nas vibrações medidas em alguns pontos da estrutura, funções de densidade espectral de potência e transmissibilidades de vibrações entre os pontos. Desta forma as frequências naturais e modos de vibração experimentais puderam ser precisamente identificados em modelos íntegros e danificados de pontes em escala reduzida. Em cada modelo, uma danificação foi imposta em uma de suas longarinas no meio do vão ou no segundo quarto de vão. Após a realização dos ensaios dinâmicos nas condições íntegra e danificada, duas técnicas de identificação de danos foram utilizadas: Diferença de Curvatura Modal (DCM) e Índice de Dano (ID). Ambas as técnicas tiveram sucesso na detecção de danos nos modelos de pontes avaliados. / Reinforced concrete bridges are extremely important elements of Brazilian transportation infrastructure. Consequently their inspection and maintenance are strategic activities. Visual inspection, destructive or nondestructive tests offer relevant information on their structural integrity and support the decision on the need of retrofitting or strengthening. Among existing types of nondestructive tests, this work focuses on the application of stochastic modal identification in damage detection of bridges. This technique is based on the measurement of environmental vibrations that occur during normal operation of the structure, modal identification, comparison of modal properties between damaged and undamaged bridge and finally damage detection. Opposed to classical dynamic experimental analysis, in stochastic modal identification the loads are not measured or known during the test. For this reason modal identification was only based in vibrations measured in selected points of the structure, power spectral density functions and vibration transmissibilities between these points. With this method natural frequencies and experimental modal shapes could be precisely identified in damaged and undamaged small scale models of bridges. The damage was induced in the middle of the span or in the second quarter of the span in one of the girders. After dynamic testing in undamaged and damaged conditions two damage identification techniques were used: Modal Curvature Difference (MCD) and Damage Index (ID). Both techniques detected successfully the damages imposed to the bridge models.

Dunaliella tertiolecta, uma alga verde fitoplanctônica de ampla distribuição no ambiente marinho, foi escolhida como organismo teste para estudar a possibilidade de ser utilizada no ensaio cometa, um teste de detecção de danos no DNA em células individualizadas muito utilizado na ecotoxicologia. Essas algas foram facilmente lisadas pela solução de lise alcalina iônica, seus cometas foram corados eficientemente pelo brometo de etídio e pela prata, e a análise por índice de danos apresentou boa correlação com momento de cauda, comprimento de cauda e porcentagem de DNA na cauda. As algas foram expostas a concentrações crescentes de 4-nitroquinolina-N-óxido (4NQO) e benzo[a]pireno (BAP) por 1, 2 e 4 h no escuro. Após somente 1 h de exposição, observou-se um aumento significativo de danos no DNA das algas expostas a 0,25 µM de 4NQO, demonstrando a sensibilidade das mesmas em relação a células de animais. Os dados obtidos da exposição ao BAP não foram consistentes e necessitam de verificação. A metabolização de BAP em compostos tóxicos pelas algas e o efeito das condições de luminosidade antes e durante as exposições são discutidos. Os resultados indicam que D. tertiolecta pode ser utilizada em laboratório para avaliação de genotoxicidade na água através do ensaio cometa. / D. tertiolecta, a phytoplanktonic green algae with ubiquitous distribution in the marine environment, was chosen as a test organism to study the possibility of being used in the comet assay, a frequently used test in ecotoxicology to detect DNA damage in single cells. These algae were easily lised by the alkaline ionic lysis solution, their comets were efficiently stained by ethidium bromide and silver and the damage index was well correlated to tail moment, tail length and percentage of DNA in the tail. The algae were exposed to increasing concentrations of 4-nitroquinoline-N-oxide (4NQO) and benzo[a]pyrene (BAP) for 1, 2 and 4 h in the dark. After 1 h exposure, a significant increase in the DNA damage of algae exposed to 0,25 µM of 4NQO was observed, demonstrating their sensitivity in relation to cells from animals. The data of BAP exposure were not consistent and need further verification. The metabolization of BAP to toxic compounds by algae and the light conditions before and during exposure are discussed. The results indicate that D. tertiolecta can be used in laboratory to evaluate water genotoxicity with comet assay.

Dunaliella tertiolecta, uma alga verde fitoplanctônica de ampla distribuição no ambiente marinho, foi escolhida como organismo teste para estudar a possibilidade de ser utilizada no ensaio cometa, um teste de detecção de danos no DNA em células individualizadas muito utilizado na ecotoxicologia. Essas algas foram facilmente lisadas pela solução de lise alcalina iônica, seus cometas foram corados eficientemente pelo brometo de etídio e pela prata, e a análise por índice de danos apresentou boa correlação com momento de cauda, comprimento de cauda e porcentagem de DNA na cauda. As algas foram expostas a concentrações crescentes de 4-nitroquinolina-N-óxido (4NQO) e benzo[a]pireno (BAP) por 1, 2 e 4 h no escuro. Após somente 1 h de exposição, observou-se um aumento significativo de danos no DNA das algas expostas a 0,25 µM de 4NQO, demonstrando a sensibilidade das mesmas em relação a células de animais. Os dados obtidos da exposição ao BAP não foram consistentes e necessitam de verificação. A metabolização de BAP em compostos tóxicos pelas algas e o efeito das condições de luminosidade antes e durante as exposições são discutidos. Os resultados indicam que D. tertiolecta pode ser utilizada em laboratório para avaliação de genotoxicidade na água através do ensaio cometa. / D. tertiolecta, a phytoplanktonic green algae with ubiquitous distribution in the marine environment, was chosen as a test organism to study the possibility of being used in the comet assay, a frequently used test in ecotoxicology to detect DNA damage in single cells. These algae were easily lised by the alkaline ionic lysis solution, their comets were efficiently stained by ethidium bromide and silver and the damage index was well correlated to tail moment, tail length and percentage of DNA in the tail. The algae were exposed to increasing concentrations of 4-nitroquinoline-N-oxide (4NQO) and benzo[a]pyrene (BAP) for 1, 2 and 4 h in the dark. After 1 h exposure, a significant increase in the DNA damage of algae exposed to 0,25 µM of 4NQO was observed, demonstrating their sensitivity in relation to cells from animals. The data of BAP exposure were not consistent and need further verification. The metabolization of BAP to toxic compounds by algae and the light conditions before and during exposure are discussed. The results indicate that D. tertiolecta can be used in laboratory to evaluate water genotoxicity with comet assay.

This study mainly addresses the problem of estimating the prior earthquake damage on the response of reinforced concrete structures to future earthquakes. The motivation has arisen from the heavy damages or collapses that occurred in many reinforced concrete structures following two major earthquakes that recently occurred in the Marmara Region, Turkey. The analysis tool employed for this purpose is the package named IDARC2D. Deterioration parameters of IDARC&#039 / s hysteretic model have been calibrated using a search method. In the calibration process experimental data of a total of twenty-two beam and column specimens, tested under constant and variable amplitude displacement histories, has been used. Fine-tuning of deterioration parameters is essential for more realistic predictions about inelastic behavior and structural damage. In order to provide more realistic damage prediction, three ranges of parameters are proposed. Some damage controlling structural parameters have been assessed via a large number of two-dimensional section analyses, inelastic time history and damage analyses of SDOF systems and seismic vulnerability analyses of reinforced concrete buildings. Inelastic time history and damage analyses of numerous SDOF systems have been carried out to determine whether the loading history has an effect on damage and dissipated hysteretic energy. Then this emphasis is directed to the analyses of MDOF systems. In the analyses of the SDOF systems, various forms of constant and variable amplitude inelastic displacement reversals and synthetic ground motions composed of one of the four earthquake records preceded or followed by its modified records acted as a prior or successive earthquake, have been used. The analyses of two five-story R/C buildings have been caried out using synthetic accelerograms comprised of base input provided by the two recorded ground motions. It is shown that both damage progression and cumulative hysteretic energy dissipated along a path seem to depend on the number and amplitude of cycles constituting the path. However, final damage and accumulated hysteretic energy dissipated along a loading path are independent of the ordering of the same number and amplitude cycles along the path. There is a nonlinear relationship between the earthquake excitation intensity and final damage attained in the end. Increase in the acceleration amplitude leads to exponential increase in damage. As the prior earthquake intensity increases the damage from the succeding main earthquake decreases. A definite ground motion acting as prior and successive earthquake causes substantially different amount of damage. Prior earthquake damage does not substantially affect the maximum drift response in future larger earthquakes. A MDOF frame type structure with aprior damage suffers less overall damage in an earthquake in comparison with the one without a prior damage.