Submitted by Aline Batista (alinehb.ufpel@gmail.com) on 2016-04-08T19:47:07Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-04-08T19:47:19Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) / Approved for entry into archive by Aline Batista (alinehb.ufpel@gmail.com) on 2016-04-08T19:47:29Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) / Made available in DSpace on 2016-04-08T19:47:39Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Monitoramento hidrossedimentológico numa bacia hidrográfica do escudo sul-rio-grandense.pdf: 3298608 bytes, checksum: 197f42a8c4f63d0217bc52c6db4902f1 (MD5) Previous issue date: 2015-04-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / A construção e uso de redes de monitoramento hidrossedimentológicas, são extremamente importantes para compreensão da dinâmica dos fenômenos envolvidos, chuva, vazão e produção de sedimentos. O monitoramento hidrossedimentológico realizado para descrever e compreender o transporte e a produção de sedimentos em uma bacia hidrográfica. Assim o objetivo deste trabalho foi analisar relações entre os processos hidrossedimentológicos numa bacia hidrográfica rural, utilizando técnicas de monitoramento. O trabalho foi realizado na bacia hidrográfica do Arroio do Ouro, localizada entre os municípios de Pelotas e Morro Redondo/RS, com área de 17,17km2, elevação média de 194 metros, predominância de relevo ondulado. Os usos predominantes do solo são das atividades desenvolvidas em pequenas propriedades familiares, observando-se o cultivo de espécies como pêssego, milho e tabaco, além de atividades de pecuária leiteira e avicultura. O monitoramento hidrossedimentológico contínuo teve início em 2014, com sensores de precipitação (pluviógrafos), sensor de pressão (nível) e sensor de turbidez (turbidímetro). Durante o período de monitoramento de 6 meses (abril a outubro de 2014) foram monitorados 13 eventos de precipitação, com diferentes características e em diferentes condições de uso e manejo do solo. Os resultados demonstram que a produção de sedimento tem relação direta com a magnitude dos eventos de precipitação, na qual um evento extremo foi responsável pelo transporte de 1.335,58 toneladas de sedimento, correspondendo a 59,4% da produção total de sedimentos de todos os eventos monitorados. O sedimento transportado em arraste representou de 9 a 43,8% do total de sedimento transportado, destacando sua importância do transporte em arraste no Arroio do Ouro. O laço de histerese não apresentou predominância em um único sentido, observando-se eventos com sentido horário e anti-horário. No entanto os eventos que apresentaram histerese anti-horária foram caracterizados por serem de pequena magnitude, nestes eventos é possível que ocorra a deposição de sedimento na calha fluvial, limitados ao transporte de sedimento proveniente de áreas mais distantes como é o característico deste tipo de histerese. / The construction and the use of hydrosedimentological monitoring networks, are extremely important for the comprehension of the dynamics of phenomena involved, e.g. rain, discharge and sediment production. The hydrosedimentological monitoring is realized to describe and understand the transport and production of sediment in one catchment. Therefore the objective of this work was to analyze the relationship between the hydrosedimentological processes in one rural catchment, using monitoring techniques. This work was developed in the Arroio do Ouro catchment, situated between Pelotas and Morro Redondo/RS, with a drainage area of 17,27km², with average elevation of 194 meters, and undulating relief predominant. The soil uses are destined to activities in small farms, observing the cultivate of peach, corn and tobacco, apart from activities of livestock milk and aviculture. The continuous hydrosedimentological monitoring began in the beginning of 2014, with precipitation sensors (rain gauges), pressure sensors (pressure-sensing limnograph), and turbidity sensors (turbidity meter).During the 6-month monitoring period (April to October, 2014) 13 precipitation events were monitored, with different features and different condition of use and management. The results demonstrate that the sediment production has a direct relation with the magnitude of the precipitation events, in which one of these events was responsible for the transport of 1335,58 tons of sediment, corresponding to 59,4% of the total production of sediments of the all monitoring events. The bedload transported represented from 9 to 43,8% of the total of sediment rate, highlighting the importance of the total bedload in Arroio do Ouro. The hysteretic loops did not produce predominance of one type of way, presenting clockwise and counter-clockwise events. However, the events which presented counter-clockwise hysteretic loops were characterized by the lower magnitude. In these events it is possible the occurence of sediment deposition in the river channel, limited to transport of sediment from more distant areas, as it is typical in this type of hysteretic loops.

Este trabalho discute o efeito do tamanho de grão e sobre o campo coercivo e perdas magnéticas em aços elétricos. Também foi avaliado o efeito da indução máxima sobre o campo coercivo. Partindo-se de chapas de aço elétrico 0,7%Si, extraídas de uma mesma bobina foram obtidos conjuntos de amostras com diferentes tamanhos de grão, na faixa entre 10 a 150m. Os diferentes tamanhos de grão foram medidos por dois métodos distintos: aumento do tamanho de grão por recristalização e aumento do tamanho de grão por crescimento. Sete conjuntos foram laminados, cada conjunto com um determinado grau de laminação, e posteriormente os conjuntos foram recozidos para sofrerem aumento do tamanho de grão por recristalização. Outros três conjuntos foram somente recozidos em tempos e temperaturas distintos e o aumento do tamanho de grão se deu por crescimento. Um conjunto passou por tratamento térmico para alívio das tensões introduzidas no corte. Os tamanhos de grão foram medidos por um método de análise semiautomático envolvendo a medição das áreas dos grãos individualmente e também pelo método dos interceptos. A caracterização magnética foi executada em regime quase estático para as induções máximas de 0,6; 0,8; 1,0; 1,2; 1,4 e 1,5T e a 60Hz para 1,0 e 1,5T. Os resultados mostram uma relação de linearidade entre o campo coercivo e o inverso do tamanho de grão. As perdas histeréticas apresentam crescimento determinado por uma lei de potência com relação à indução máxima. / This work discusses about grain size effect on the coercive field and magnetic losses in electrical steel. Also, it was evaluated the maximum induction effect on the coercive field and hysteresis loss. Starting from 0,7%Si electrical steel sheet sets of samples with different grain sizes in the range between 10 to 150m were obtained. The different grain sizes were obtained by two different methods: grain size increase by recrystallization and grain size increase by grain growth. Seven sets were cold rolled, each set with a cold work degree. Three other sets were only annealed at different times and temperatures and the increase in grain size was characterized by growth. A set underwent heat treatment to relieve the stress brought into cut. The grain sizes were measured by a method of analysis involving semiautomatic measurement of areas of individual grains and also by the method of intercepts. The magnetic characterization was performed under quasi-static regime for the maximum inductions of 0.6, 0.8, 1.0, 1.2, 1.4 and 1.5 T and 60 Hz for 1.0 and 1.5 T. The results show a linear relation between the coercive field and the inverse grain size. Hysteresis losses presented a growth determined by a power law with respect to the maximal induction.

No description available.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21364号 / 工博第4523号 / 新制||工||1704(附属図書館) / 京都大学大学院工学研究科建築学専攻 / (主査)教授 西山 峰広, 教授 竹脇 出, 准教授 倉田 真宏 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

The objective of this research is to create a computationally efficient seismic analysis framework for cold-formed steel (CFS) framed-buildings supported by hysteretic nonlinear models for CFS members and screw-fastened connections. Design of CFS structures subjected to lateral seismic forces traditionally relies on the strength of subassemblies subjected to lateral loading of systems, such as strapped/sheathed shear walls and diaphragms, to provide adequate protection against collapse. Enabling performance-based seismic design of CFS buildings requires computationally efficient and accurate modeling tools that predict the nonlinear cyclic behavior of CFS buildings, the individual CFS components and connections. Such models should capture the energy dissipation and damage due to buckling and cross-sectional deformations in thin-walled CFS components subjected to cyclic loads such as those induced by earthquakes. Likewise, models for screw-fastened CFS connections should capture the energy dissipation and damage due to tilting, bearing, or screw shear when subjected to cyclic loading. In this dissertation, an analysis framework for CFS structures that captures the nonlinear cyclic behavior of critical components including axial members, flexural members, and screw fastened connections is presented. A modeling approach to simulate thin-walled behavior in CFS members is introduced where parameters were developed using results from an experimental program that investigated the cyclic behavior and energy dissipation in CFS axial members and flexural members. Energy dissipation and cyclic behavior of CFS members were characterized for members experiencing global, distortional and local buckling. Cyclic behavior and energy dissipation in thin steel plates and members was further investigated through finite element analysis in ABAQUS to provide a strategy for modeling steel columns cyclic behavior including local buckling. Model parameters were developed as generalized functions of the hysteretic energy dissipated and slenderness. The capabilities of the analysis framework are demonstrated through simulations of CFS wood sheathed shear wall cyclic responses validated with experimental results from full scale shear wall tests. / Ph. D.

Utilisés dans de nombreux domaines, les matériaux piézoélectriques sont régulièrement soumis à des sollicitations externes ou internes qui modifient leurs propriétés. Dans le but de prévoir et d’anticiper ces altérations, ce travail étudie les propriétés de matériaux piézoélectriques soumis à une contrainte statique de type mécanique ou électrique. Dans un premier temps, nous développons les équations du mouvement d’un matériau piézoélectrique (non hystérétique) au second ordre, en tenant compte des déformations dynamiques, mais aussi statiques. L’étude numérique des vitesses et du coefficient de couplage est faite sur le niobate de lithium, dans différents plans de coupe et différents systèmes de coordonnées afin d’évaluer dans quelles configurations l’application d’une contrainte externe électrique ou mécanique améliore ou dégrade les propriétés du matériau. Nous caractérisons ensuite les comportements hystérétiques de piézocéramiques sous contraintes en modélisant l’évolution des polarisations et déformations rémanentes microscopiques via les mouvements de murs de domaines. La comparaison des résultats numériques avec des évolutions de 4 piézocéramiques nous permet de définir le domaine de validation de nos hypothèses et d’expliciter les comportements hystérétiques de piézocéramiques. Dans une dernière partie, nous mettons en place un dispositif expérimental de mesure de déformations et du déplacement électrique de structures piézoélectriques sous contrainte mécanique. Ces résultats nous permettent de dimensionner notre étude sur le niobate de lithium et apportent une meilleure compréhension de l’évolution des déformations transversales dans les piézocéramiques. / Used in many domains, piezoelectric materials are frequently submitted to external or internaI stresses which modify their properties. In order to prevent and anticipate these modifications, this work studies the properties of piezoelectric materials under static electrical or mechanical stress. First, the motion equations of a piezoelectric (non hysteretic) rnaterial are developed at the second order taking to account the static strain and the dynamic ones. The numerical study of plane wave velocities and coupling coefficients is performed on lithium niobate, in different cuts and different coordinate systems. Then, we evaluate in which configurations the application of an electrical or mechanical stress improves or degrades the material properties. In a second part, the hysteretic behaviours of piezocerarnic materials under electrical and mechanical stresses are characterized by modelling the evolutions of microscopic remanent polarization and strains through the movements of domain walls. Numerical results are compared to evolutions of 4 piezoceramics and allow us to define the validation domain of our hypothesis and to explain hysteretic behaviours of soft and hard piezoceramics. In the last part, an experimental device to measure strains and electrical displacements under mechanical stress is developped. Results allow study on lithium niobate to be planned and bring a better understanding of transversal strain evolutions in piezoceramics.

High-pass filtering that is one of the most efficient methods in removing long-period noise of accelerograms is investigated for its effect on nonlinear oscillator deformation response. Within this context, uncertainty in filter cut-off periods that would significantly modify the low-frequency content of accelerograms come into prominence for obtaining reliable long-period displacement response. Analog and digital ground-motion records from recently compiled Turkish strong-motion database are used and these records are high-pass filtered with a consistent methodology by randomly generated filter cut-offs that represent different filter cut-off decisions of the analysts. The uncertainty in inelastic spectral and residual displacements (SDIE and SDR, respectively) due to variations in filter cut-offs is examined to derive the usable period ranges where the effect of high-pass filtering is tolerable. Non-degrading, stiffness degrading and stiffness and strength degrading oscillator behavior are considered in these analyses. The level of nonlinear behavior in single degree of freedom (SDOF) response is described by varying the yield strength (R, normalized yield strength) and displacement ductility (&micro / ) levels. The usable period ranges that depend on magnitude, recording quality, level of inelasticity and level of degradation are determined for SDIE through robust probabilistic methodologies.

The purpose of this research is to investigate the seismic behavior of plane moment resisting frames (MRFs) consisting of concrete filled steel tube (CFT) columns and steel I beams through targeted studies utilizing advanced computational methodologies calibrated on the basis of existing experimental results and to propose a preliminary performance-based seismic design method for this kind of frames. A computational study is conducted first to investigate the nonlinear cyclic response of square concrete-filled steel tubes (CFT) in bending and compression. An accurate nonlinear finite element model is created and its validity is established by comparing its results with those of existing experiments. Using this finite element model, extensive parametric studies are performed to provide information on the hysteretic and deteriorating behavior of CFT columns. Thus, on the basis of this computational study, three simple yet sufficiently accurate concentrated plasticity hysteretic models for simulating the cyclic behavior of square concrete-filled steel tube (CFT) columns, are developed. The seismic behavior of plane MRFs consisting of I steel beams and CFT columns is investigated next. More specifically, the effect of modelling details of each individual component of CFT-MRFs, such as the CFT columns, the beam-column connections, the panel zones and the steel I beams, on their seismic behavior is studied through comparisons against available experimental results. Then, fragility curves are constructed for composite frames for various levels of modelling sophistication through nonlinear time history analyses involving three typical CFT-MRFs which have been designed according to the European seismic design codes. On the basis of these fragility curves, one can select the appropriate modelling level of sophistication that can lead to the desired seismic behavior for a given seismic intensity. The third part of this work deals with the establishment of all the necessary ingredients for this kind of composite frames to be seismically designed by the performance-based hybrid force-displacement (HFD) seismic design method, which combines the advantages of the well-known force-based and displacement-based seismic design methods. Thus, extensive parametric studies are conducted involving nonlinear dynamic analysis of 96 frames under 100 seismic motions in order to create a databank with the response quantities of interest. Based on regression analysis, simple formulae for estimating the maximum roof displacement, the maximum inter-storey drift ratio, the maximum rotation ductility along the height of the frame and the behavior factor are developed. Comparison of the proposed design method with those adopted by current seismic design codes demonstrates that the proposed procedure seems to be more rational and controls deformation better than current seismic design codes. Nonlinear time history analyses proved the consistency of the proposed method to accurately estimate inelastic deformation demands and the tendency of the current seismic design codes to overestimate the maximum roof displacement and underestimate the maximum inter-storey drift ratio along the height of the frames. Finally, comparisons between CFT-MRFs and all steel ones reveal that the CFT-MRFs seem to have better seismic behavior than the all steel ones and seem to be more economical structures. / Ο σκοπός της παρούσας έρευνας είναι να διερευνήσει τη σεισμική συμπεριφορά επίπεδων καμπτικών πλαισίων με υποστυλώματα από τετραγωνικές χαλύβδινες κοιλοδοκούς γεμισμένες με σκυρόδεμα και με μεταλλικές δοκούς τύπου Ι και να προτείνει μία μέθοδο αντισεισμικού σχεδιασμού με βάση την επιτελεστικότητα για αυτόν τον τύπο κατασκευών. Αρχικά, διεξάγεται μία υπολογιστική μελέτη ώστε να διερευνηθεί η μη-γραμμική ανελαστική απόκριση υπό ανακυκλιζόμενη φόρτιση και σταθερή θλίψη των τετραγωνικών σύμμικτων υποστυλωμάτων. Ένα ακριβές και προηγμένο μοντέλο πεπερασμένων στοιχείων δημιουργείται όπου η ακρίβεια των αποτελεσμάτων του ελέγχεται μέσω συγκρίσεων των αναλυτικών λύσεων με υπαρκτά πειραματικά δεδομένα. Κατόπιν, χρησιμοποιώντας αυτό το μοντέλο πεπερασμένων στοιχείων, πραγματοποιoύνται εκτενείς παραμετρικές μελέτες με σκοπό να παραχθούν πληροφορίες σχετικά με την υστερητική συμπεριφορά των σύμμικτων υποστυλωμάτων. Έτσι, στη βάση αυτής της υπολογιστικής μελέτης, τρία απλά και αρκετά ακριβή υστερητικά μοντέλα συγκεντρωμένης πλαστιμότητας αναπτύσσονται για την προσομοίωση της συμπεριφοράς σύμμικτων υποστυλωμάτων υπό ανακυκλιζόμενη φόρτιση και σταθερή θλίψη. Έπειτα, διερευνάται η σεισμική συμπεριφορά επίπεδων καμπτικών πλαισίων με σύμμικτα υποστυλώματα και με μεταλλικές δοκούς τύπου Ι. Πιο συγκεκριμένα εξετάζεται η επίδραση της λεπτομερής μοντελοποίησης των επιμέρους δομικών στοιχείων μια κατασκευής, όπως των σύμμικτων υποστυλωμάτων, των μεταλλικών δοκών, των κόμβων διατμητικής παραμόρφωσης και των συνδέσεων, στη σεισμική συμπεριφορά των πλαισίων μέσω συγκρίσεων με υπαρκτά πειραματικά δεδομένα. Επιπλέον, διαμορφώνονται καμπύλες τρωτότητας για τρία σύμμικτα πλαίσια σχεδιασμένα με τους Ευρωπαϊκούς κανονισμούς για διάφορα επίπεδα μοντελοποίησης χρησιμοποιώντας μη-γραμμικές αναλύσεις χρονοιστορίας. Στη βάση αυτών των καμπυλών τρωτότητας, κάποιος μπορεί να επιλέξει το κατάλληλο επίπεδο πολυπλοκότητας της μοντελοποίησης των σύμμικτων πλαισίων ώστε να οδηγηθεί στην επιθυμητή συμπεριφορά για μια δεδομένη σεισμική ένταση. Το τρίτο μέρος της παρούσας έρευνας πραγματεύεται την ανάπτυξη της διαδικασίας που απαιτείται από την Υβριδική Δυνάμεων-Μετατοπίσεων (ΥΔΜ) μέθοδο αντισεισμικού σχεδιασμού με βάση την επιτελεστικότητα, η οποία συνδυάζει τα πλεονεκτήματα της μεθόδου των δυνάμεων και της μεθόδου των μετακινήσεων, ώστε να εφαρμόζεται για τον αντισεισμικό σχεδιασμό σύμμικτων καμπτικών πλαισίων. Έτσι, πραγματοποιούνται εκτενείς παραμετρικές μελέτες περιλαμβάνοντας μη-γραμμικές δυναμικές αναλύσεις σε 96 πλαίσια υπό 100 σεισμικές καταγραφές με σκοπό τη δημιουργία τράπεζας δεδομένων με αποκρίσεις ενδιαφέροντος. Κατόπιν αναλύσεων γραμμικής παλινδρόμησης, απλές σχέσεις προτείνονται που απαιτούνται από την ΥΔΜ μέθοδο οι οποίες συνδέουν τη μέγιστη μετακίνησης κορυφής των πλαισίων με τη στοχευόμενη μέγιστη γωνιακή παραμόρφωσης των ορόφων ή την τοπική στροφική πλαστιμότητα των μελών και την απαιτούμενη συνολική πλαστιμότητας του πλαισίου με τον συντελεστή συμπεριφοράς q. Η σύγκριση της προτεινόμενης ΥΔΜ μεθόδου αντισεισμικού σχεδιασμού με εκείνης που προτείνεται από τον Ευρωπαϊκό κανονισμό αποδεικνύει ότι η προτεινόμενη διαδικασία φαίνεται να είναι πιο ακριβής και ελέγχει καλύτερα τις παραμορφώσεις. Μη-γραμμικές αναλύσεις χρονοιστορίας δείχνουν την συνέπεια της ΥΔΜ να εκτιμά με ακρίβεια τις απαιτήσεις των ανελαστικών παραμορφώσεων στα διάφορα επίπεδα επιτελεστικότητας σε αντίθεση με την τάση του κανονισμού να υποεκτιμά τη μέγιστη γωνιακή μετακίνησης ορόφων και να υπερεκτιμά την μέγιστη μετακίνηση κορυφής. Τέλος, συγκρίσεις σύμμικτων πλαισίων με σχεδιασμένα πλαίσια εξ’ ολοκλήρου από χάλυβα σύμφωνα με την ΥΔΜ, δείχνουν ότι τα σύμμικτα πλαίσια έχουν καλύτερη σεισμική συμπεριφορά από τα μεταλλικά και φαίνεται να είναι πιο οικονομικές κατασκευές.

The ability to adjust structural response to external loading and ensure structural safety and serviceability is a characteristic of Smart Systems. The key to achieving this is through the development and implementation of smart materials. An example of a smart material is a Shape Memory Alloy (SMA). Reinforced concrete structures are designed to sustain severe damage and permanent displacement during strong earthquakes, while maintaining their integrity, and safeguarding against loss of life. The design philosophy of dissipating the energy of major earthquakes leads to significant strains in the steel reinforcement and, consequently, damage in the plastic hinge zones. Most of the steel strain is permanent, thus leading to large residual deformations that can render the structure unserviceable after the earthquake. Alternative reinforcing materials such as superelastic SMAs offer strain recovery upon unloading, which may result in improved post-earthquake recovery. Shape Memory Alloys have the ability to dissipate energy through repeated cycling without significant degradation or permanent deformation. Superelastic SMAs possess stable hysteretic behavior over a certain range of temperature, where its shape is recoverable upon removal of load. Alternatively, Martensite SMAs also possess the ability to recover its shape through heating. Both types of SMA demonstrate promise in civil infrastructure applications, specifically in seismic-resistant design and retrofit of structures. The primary objective of this research is to investigate experimentally the performance of concrete beams and shear walls reinforced with superelastic SMAs in plastic hinge regions. Furthermore, this research program involves complementary numerical studies and the development of a proposed hysteretic constitutive model for superelastic SMAs applicable for nonlinear finite element analysis. The model considers the unique characteristics of the cyclic response of superelastic materials.

Understanding the complex dynamics that underpin the response of structures in the occurrence of earthquakes is of paramount importance in ensuring community resilience. The operational continuity of structures is influenced by the performance of nonstructural components, also known as secondary structures. Inherent vulnerability characteristics, nonlinearities and uncertainties in their properties or in the excitation pose challenges that render their response determination as a non-straightforward task. This dissertation settles in the context of mathematical modelling and response quantification of seismically driven secondary systems. The case of bilinear hysteretic, rigid-plastic and free-standing rocking oscillators is first considered, as a representative class of secondary systems of distinct behaviour excited at a single point in the primary structure. The equations governing their full dynamic interaction with linear primary oscillators are derived with the purpose of assessing the appropriateness of simplified analysis methods where the secondary-primary feedback action is not accounted for. Analyses carried out in presence of pulse-type excitation have shown that the cascade approximation can be considered satisfactory for bilinear systems provided the secondary-primary mass ratio is adequately low and the system does not approach resonance. For the case of sliding and rocking systems, much lighter secondary systems need to be considered if the cascade analysis is to be adopted, with the validity of the approximation dictated by the selection of the input parameters. Based on the premise that decoupling is permitted, new analytical solutions are derived for the pulse driven nonlinear oscillators considered, conveniently expressing the seismic response as a function of the input parameters and the relative effects are quantified. An efficient numerical scheme for a general-type of excitation is also presented and is used in conjunction with an existing nonstationary stochastic far-field ground motion model to determine the seismic response spectra for the secondary oscillators at given site and earthquake characteristics. Prompted by the presence of uncertainty in the primary structure, and in line with the classical modal analysis, a novel approach for directly characterising uncertainty in the modal shapes, frequencies and damping ratios of the primary structure is proposed. A procedure is then presented for the identification of the model parameters and demonstrated with an application to linear steel frames with uncertain semi-rigid connections. It is shown that the proposed approach reduces the number of the uncertain input parameters and the size of the dynamic problem, and is thus particularly appealing for the stochastic assessment of existing structural systems, where partial modal information is available e.g. through operational modal analysis testing. Through a numerical example, the relative effect of stochasticity in a bi-directional seismic input is found to have a more prominent role on the nonlinear response of secondary oscillators when compared to the uncertainty in the primary structure. Further extending the analyses to the case of multi-attached linear secondary systems driven by deterministic seismic excitation, a convenient variant of the component-mode synthesis method is presented, whereby the primary-secondary dynamic interaction is accounted for through the modes of vibration of the two components. The problem of selecting the vibrational modes to be retained in analysis is then addressed for the case of secondary structures, which may possess numerous low frequency modes with negligible mass, and a modal correction method is adopted in view of the application for seismic analysis. The influence of various approaches to build the viscous damping matrix of the primary-secondary assembly is also investigated, and a novel technique based on modal damping superposition is proposed. Numerical applications are demonstrated through a piping secondary system multi-connected on a primary frame exhibiting various irregularities in plan and elevation, as well as a multi-connected flexible secondary system. Overall, this PhD thesis delivers new insights into the determination and understanding of the response of seismically driven secondary structures. The research is deemed to be of academic and professional engineering interest spanning several areas including seismic engineering, extreme events, structural health monitoring, risk mitigation and reliability analysis.