Dissertations / Theses on the topic 'Incremental dynamic analysis'

This thesis presents the details of a study regarding both the use of linear viscous fluid dampers in controlling the interstory drift in steel moment frames, and the use of incremental dynamic analysis as a method of visualizing the behavior of these moment frames when subjected to seismic load effects. Models of three story and nine story steel moment frames were designed to meet typical strength requirements for office buildings in Seattle, Washington. These models were intentionally designed to violate seismic interstory drift restrictions to test the ability of the linear viscous fluid dampers to reduce these drifts to the point of code compliance. Dampers were included in one bay of every story in each model. These devices were used to produce total structural damping ratios of 5%, 10%, 20%, and 30% of critical. Undamped, traditional stiffness controlled models of both three stories and nine stories were also created for comparison purposes. Incremental dynamic analysis was used to subject these models to ten ground motions, each scaled to twenty incremental levels. Two new computer applications were written to facilitate this process. The results of these analyses were studied to determine if the linear viscous fluid dampers were able to cause compliance with codified drift limits. Also, incremental dynamic analysis plots were created to examine the effects of the dampers on structural behavior as damping increased from inherent to 30% of critical. It was found that including linear viscous fluid dampers in steel moment frame design can satisfactorily control interstory drift, and incremental dynamic analysis is a beneficial tool in visualizing dynamic structural behavior.
Master of Science

This thesis presents the results of a study of the effect of variations of systemic parameters on the structural response of single degree of freedom systems subjected to Incremental Dynamic Analysis. The systemic parameters are mass, stiffness, damping, yield strength and geometric stiffness. Each of these parameters was varied one at a time while the other values were kept constant. For each variation of parameters a set of single-record IDA curves was obtained. Five to six ground motions were used for this study to generate the single-record IDA curves. These ground motions were scaled prior to their application on the structure. The scaling factor was based on the spectral acceleration at the fundamental frequency of the structure at 5% of critical damping. The scale factor is affected if the system parameters are changed. An important issue for this study was whether to persist with scaling corresponding to the median value from the range of the values of the parameter or to update the scaling according to the system. Based on some tests using both methods, the median scaling approach was found to be more suitable. The IDA curves for variation of parameters were then investigated to identify any trends that may help in qualitatively predicting the response of a system relative to another system. The response was measured by the peak displacement and the maximum base shear of the system. A clear trend was identified when the damping or the yield strength was varied. However, no definite trend was observed when the material stiffness or the geometric stiffness of the system was varied.
Master of Science

The first purpose of this research is to investigate the effect of added viscous fluid dampers on a nine story special steel moment frame designed for strength in Seattle. At the initial stages of the work, knowing the fact that moment frames are almost always controlled by drift, it was thought that two different moment frames, controlled by strength or controlled by drift (stiffness), could be designed in Seattle and the effect of additional dampers on the structural behavior of the strength controlled design could be studied.

However, since ASCE 7 permits determining the elastic drifts by using the seismic design forces based on the computed fundamental period of the structure, without the upper limit (CuTa), the strength controlled design satisfied the drift limit requirements of ASCE 7. Although the strength controlled design meets the drift requirements, the stability checks of both ASCE 7 and the AISC Seismic Design Manual were not satisfied. Thus, the strength controlled frame was redesigned to meet the stability requirements, and the process is called stability controlled design.

By adding supplemental dampers to the strength controlled design, it was expected that the seismic drift would be controlled and a better structural behavior would be obtained in terms of dynamic stability. Incrementral Dynamic Analysis (IDA) was implemented to investigate the benefits of the dampers on the structural behavior. Using ten different earthquakes scaled up to a maximum target multiplier two, with ten increments, damage measures such as interstory drift, residual displacement, IDA dispersion, base shear, and roof displacement were studied. Using IDA dispersion, the effect of dampers on dynamic instability was also investigated in this study.

As a result, it was found that as the damping of the structure increases with the help of added dampers, the structural response gets better. Maximum and residual roof displacements, interstory drifts, and IDA dispersion decreases with increasing damping. In addition, by using supplemental damping, most of the collapses that occur for the inherently damped frames are prevented.

The second purpose of this research is to develop an improved â Hybridâ moment frame without added damping but by controlling the inelastic behavior. Hybrid Frames were designed as the combination of three different moment frames: Special, Intermediate and Ordinary Moment Frames (SMF, IMF, OMF). The design procedure of each bay, which corresponds to different moment frame systems, follows the rules of the related moment frame for that bay. By varying the plastic hinge capacities across the same level stories, four different Hybrid Frame designs were obtained. Nonlinear static pushover analysis was applied to these frames, and as expected, the more reduction in the plastic capacity of the Hybrid Frame, the earlier the pushover curve starts yielding and the later the negative post yield stiffness of the pushover curve was reached. It was observed that the effect of early plastic hinge forming in the frame, which caused inelastic hysteretic damping, and the relatively late formation of negative post yield stiffness resulted in a better dynamic behavior.

As a result of the IDA studies, as the frames become more â hybridâ , the residual displacements decrease significantly and then collapses are even prevented. This is considered as the positive effect of reaching the negative post yield stiffness late. The residual displacement was reduced for low intensity gentle earthquakes. The ductility demand IDA study proves that as the frames become more hybrid, the ductility demand increases for the special detailing frame, where plastic capacity was reduced, and decreases for the ordinary detailing frame, where the plastic capacity was increased. The Hybrid Frame system is expected to perform better than the traditional special moment frame, and to be more economical than the special moment frame because of the limited amount of special detailing.
Master of Science

During the months I have been at Virginia Tech, I have experienced the most exciting time of my life. There are many persons who helped me to pursue my Masterâ s degree. I would like to take this opportunity to express my appreciations to them. I would like to thank my advisor and committee chairman, Dr Finley A. Charney. He has supported me for the entire duration of this project with all of his efforts. Without his assistance, it would have been very difficult for me to learn so many concepts in the field of nonlinear dynamic analysis and practical earthquake engineering. I would also like to acknowledge my other committee members, Dr. Raymond Plaut and Dr. W. Samuel Easterling, for taking the time to review the thesis and providing valuable insights and feedback on this thesis. I would like to thank my father, Chan Kwok Fung, who encouraged me to pursue my Master Degree, and my mother, Yu Yuk Ping, who brought me to life. I would like to thank my sister, Doris Chan, and my girlfriend, Ka Man Chan, for supporting and encouraging me during the past two years at Virginia Tech. Finally, I would like to give thanks to the rest of my family, friends, professors, and fellow graduate students for their help and encouragement during my stay at Virginia Tech.
Master of Science

This thesis presents the results of a study that uses Incremental Dynamic Analysis to assess the seismic performance of steel moment-resisting frames with fluid viscous dampers subjected to earthquake ground motions. The study systematically investigated the effects of linear and nonlinear dampers on the response of steel moment-resisting frames to earthquakes that varied in intensity and type. Both near-field and far-field motions were considered. Two different types of nonlinear dampers were investigated; one had a hardening and the other had a softening force-velocity relationship. The nonlinear dampers were calibrated to the linear dampers so that there was a basis of comparison. Maximum damper displacement is one of the parameters of the calibration, and it was varied to investigate its effect on structural response. Several nonlinear inelastic time history analyses were performed to obtain responses, such as peak base shear, peak interstory drift, or residual displacement index, which were plotted versus earthquake intensity to create individual IDA curves. Sets of related IDA curves provide a useful summary of the structural behavior for a wide range of variables. IDA curves for the tests with different damping types are presented. The results show that for both near-field and far-field ground motions the nonlinear dampers with a hardening force-velocity relationship are best suited to reduce undesirable drifts and residual displacements; however, these reductions come at the cost of high base shear forces.
Master of Science

Unreinforced masonry (URM) structures have shown tobe susceptible to significant damage during strong earthquakes. Vulnerability assessment of URM buildings is needed so that appropriate mitigation strategies can be implemented. The existing Canadian practice consists of rapid seismic screening of buildings to assign priorities for further and more refined assessments, followed by refined analysis of individual critical buildings. The current seismic screening procedure, from 1992, is based on qualitative observations of seismic vulnerability, enabling the assignment of seismic priority indices, quantified on the basis of expert opinion and experience. More refined tools are needed for seismic vulnerability assessment of URM buildings in Canada, based on the current Canadian seismic hazard values. The objective of the research project is to fulfill these needs by developing fragility curves that provide a probabilistic assessment of different levels of building performance under different intensities ofeastern and western seismicity. Using an inventory of over 50,000 structures, a seismic assessment of typical low-rise and mid-rise URM structures located in eastern and western Canada was carried out. The required analyses were done using applied element method software which effectively modeled the in-plane and out-of-plane behaviour of masonry walls. Using incremental dynamic analysis, fragility curves were developed to reflect the capacity of URM structures with a wide variety of selected structural and ground motion parameters. The results were verified against available fragility information in the literature. They show the significance of selected parameters, while providing effective tools for seismic vulnerability assessment of URM buildings in eastern and western Canada.

There is a need to develop efficient multi-hazard performance based design (PBD) tools to analyze and optimize buildings at a preliminary stage of design. The first step was to develop a database and it is supported by five major contributions: 1) development of nomenclature of variables in PBD; 2) creation of mathematical model to fit data; 3) collection of data; 4) identification of gaps and methods for filling data in PBD; 5) screening of soil, foundation, structure, and envelope (SFSE) combinations.. A unified nomenclature was developed with the collaboration of a multi-disciplinary team to navigate through the PBD. A mathematical model for incremental dynamic analysis was developed to fit the existing data in the database in a manageable way. Three sets of data were collected to initialize the database: 1) responses of structures subjected to hazard; 2) fragility curves; 3) consequence functions. Fragility curves were critically analyzed to determine the source and the process of development of the curves, but structural analysis results and consequence functions were not critically analyzed due to lack of similarities between the data and background information respectively. Gaps in the data and the methods to fill them were identified to lay out the path for the completion of the database. A list of SFSE systems applicable to typical midrise office buildings was developed. Since the database did not have enough data to conduct PBD calculations, engineering judgement was used to screen SFSE combinations to identify the potential combinations for detailed analysis. Through these five contributions this thesis lays the foundation for the development of a database for multi- hazard PBD and identifies potential future work in this area.
Master of Science

This thesis presents the results of basically two separate studies. The first study involved identifying structural and earthquake parameters that influenced seismic structural collapse. The parameter study involved nonlinear dynamic analyses using single-degree-of-freedom (SDOF) bilinear models. Four parameters were associated with the SDOF models â the lateral stiffness, the post-yield stiffness ratio, the yield strength, and the stability ratio (P-Delta effects). Then, three parameters were associated with the ground motions â the records themselves, the lateral ground motion scales, and the vertical ground motion scales.

From the parameter study, it was found that the post-yield stiffness ratio augmented by P-Delta effects (rp) in conjunction with the ductility demand was the best predictor of collapse. These two quantities include all four structural parameters and the seismic displacement demands. It was also discovered in the parameter study that vertical accelerations did not significantly influence lateral displacements unless a given combination of model and earthquake parameters was altered such that the model was on the verge of collapsing.

The second study involved Incremental Dynamic Analysis (IDA) using bilinear SDOF models representative of low rise buildings in both the Western United States (WUS) and the Central and Eastern United States (CEUS). Models were created that represented three, five, seven, and nine story buildings. Five sites from both the WUS and CEUS were used. Four different damage measures were used to assess the performance of the buildings. The IDA study was primarily interested in the response of the structures between the earthquake intensities that have a 10 percent probability of occurring in 50 years (10/50) and 2 percent probability of occurring in 50 years (2/50).

The results showed that all structures could be in danger of severe damage and possible collapse, depending on which damage measure and which earthquake was used. It is important to note, though, that the aforementioned is based on a damage-based collapse rule. The damage-based rule results were highly variable.

Using an intensity-based collapse rule, proved to be more consistent. Due to the nature of the bilinear models, only those structures with negative rp values ever collapsed using an intensity-based collapse rule. Most of the WUS models had positive rp values and many of the CEUS models had negative rp values. While many of the CEUS structures had negative rp values, which made them prone to collapse, most of the CEUS structures analyzed did not collapse at the 2/50 intensity. The reason was that the periods of the CEUS models were much longer than the approximate periods that were required to determine the strengths. Consequently, the strength capacity of most of the CEUS models was much greater than the seismic strength demands. While many of the CEUS models did have sudden collapses due to the large negative rp values, the collapses happened at intensities that were generally much higher than the 2/50 event.

In the IDA, it was also shown that vertical accelerations can significantly affect the ductility demands of a model with a negative rp post-yield stiffness ratio as the earthquake intensity approaches the collapse intensity. Since IDA is concerned with establishing collapse limit states, it seems that the most accurate collapse assessments would include vertical accelerations.
Master of Science

This study investigates seismic response of the Moment-Resisting-Steel Frames (MRSF) with the architectural setbacks. The main objective of the study is to understand the variation of the elastic and inelastic, static and dynamic behavior with changes in the geometric dimensions of the tower portion. A second objective of the study is to determine the adequacy of the analysis procedures of various rigors, specified in current seismic design provision, in predicting those behaviors for MRSF with various size of setback. The analytical study is conducted using a regular and 16 irregular models to capture all possible combinations of configuration of setback in five-story, five-bay MRSFs. An irregular model is developed by gradually changing the horizontal and vertical dimensions of the tower portion of the regular base 2D frame-model. All models were designed for (a) equal global displacement and uniform distribution of inter-story drift under First-Mode (FM) lateral force distribution pattern at first significant yield, and (b) equal period of vibration at the first mode, using Nonlinear Static Seismic analysis procedure. Among the conclusions derived from the research is that the variation of (a) the elastic and inelastic inter-story drift, the ductility demand for the top three stories, and (b) the elastic and inelastic global displacement exhibited a pattern similar to the variation of the FM participation factor at the roof, PF1Φr,1. The square-root-of-sum-of-square (SRSS) distribution provided accurate estimates of elastic story shear and inter-story drift demand as well as the story yield strength and drift.

The rapid growth of high-rise high-density urban areas in coastal and near coastal, hurricane-prone cities has been observed globally and in the United States in recent decades. Favored by modern urban growth and planning policies, this trend is expected to accelerate in future. Recent climate change studies suggest a significant increase in the destructiveness of hurricanes in past 30 years by both increases in lifetime and intensity of hurricanes. Current prescriptive wind design approach does not provide transparent methods and criteria to reliably quantify the performance of buildings as well as the functional requirements necessary to accommodate large populations during extreme wind. Since this approach primarily intends to keep the structural system essentially elastic, the more efficient design may be achievable by allowing controlled inelasticity in structural components. All these facts put a great emphasis on using a reliable wind design and assessment approach evidently describing the performance of high-rise building to wind loads beyond the current design wind loads. This dissertation presents the development of a wind performance-based engineering approach and its practical implementation for three, 47-, 40- and 30-story steel moment frame high-rise buildings. In this study, the nonlinear dynamic responses of the buildings to different wind hazard levels were evaluated by developing 3D nonlinear finite element models and utilizing a wind incremental dynamic analysis (IDA) approach. The wind loading for the 47-story building was measured by conducting wind pressure testing on a scaled rigid model at the Wall of Wind (WOW) facility at Florida International University. For two other buildings wind loads were acquired using TPU Aerodynamic Database. Using the IDA results and adopting available wind performance criteria, a wind performance assessment approach was developed representing the estimated performance levels as a function of the basic wind speed. Three types of wind performance were evaluated: structural component performance; cladding performance to wind-induced shear deformation; and serviceability motion comfort performance. This evaluation indicated remarkable lateral capacity associated with allowing controlled structural nonlinearity, in contrast to considerations required to assure acceptable serviceability and non-structural (e.g. cladding) performances.

A general framework to design structural systems for a system-reliability goal is proposed. Component-based structural design proceeds on a member to member basis, insuring acceptable failure probabilities for every single structural member without explicitly assessing the overall system safety, whereas structural failure consequences are related to the whole system performance (the cost of a building or a bridge destroyed by an earthquake) rather than a single beam or column failure. Engineering intuition tells us that the system is safer than each individual component due to the likelihood of load redistribution and al- ternate load paths, however such conservatism cannot be guaranteed without an explicit system-level safety check. As a result, component-based structural designs can lead to both over-conservative components and a less-than-anticipated system reliability. System performance depends on component properties as well as the load-sharing network, which can possess a wide range of behaviors varying from a dense redundant system with scope for load redistribution after failure initiates, to a weakest-link type network that fails as soon as the first member exceeds its capacity. The load-sharing network is characterized by its overall system reliability and the system-reliability sensitivity, which quantifies the change in system safety due to component reliability modifications. A general algorithm is proposed to calculate modified component reliabilities using the sensitivity vector for the load-sharing network. The modifications represent an improvement on the structural properties of more critical components (more capacity, better ductility), and provide savings on less important members which do not play a significant role. The general methodology is applied to light steel-framed buildings under seismic loads. The building is modeled with non-linear spring elements representing its subsystems. The stochastic response of this model under seismic ground motions provides load-sharing, system reliability and sensitivity information, which are used to propose target diaphragm and shear wall reliability to meet a building reliability goal. Finally, diaphragm target reliability is used to propose modified component designs using stochastic simulations on geometric and materially non-linear finite-element models including every individual component.
Ph. D.

Despite the fact that masonry is one of the oldest and most used building materials, the number of existing studies and experimental data, as well as the applicability of its results (i.e. extrapolation), are substantially lower than those available for much more recent materials, such as concrete or steel. Furthermore, currently in Europe, a large number of residential buildings belong to masonry typologies. These circumstances justify the study of the characteristics and behaviour of the masonry to guide studies on seismic vulnerability. In particular, the Eixample district of Barcelona, in Spain, presents an urban park of functional housing made up 73% of unreinforced masonry structures, solved by means of load-bearing wall systems, without any consideration of seismic action and that, for the most part, exceed 100 years of useful life. These buildings, characteristics of Barcelona, have elements that differentiate them from other buildings of the same construction typology that can be found in other regions of Europe: 1) the number of floors significantly exceeds the average, being able to find buildings with up to 10 or 11 levels; 2) The buildings share dividing walls (e.g. lateral), thereby generating frameworks of buildings known as aggregates; 3) The properties and qualities of the different construction elements are closely linked to the production processes, not yet mechanized, of the time; 4) The level of construction techniques and the qualification of the workforce were very high. In this work, numerical 3D models of isolated structural configurations (i.e. individual building) and in aggregate, of existing buildings have been made, in order to determine and compare the behaviour between the different structural configurations. The buildings have been modelled incorporating the variability of their mechanical parameters and the seismic demand has also been selected taking into account its uncertainty. The structural analysis has been carried out using and comparing different non-linear static calculation procedures and using the incremental non-linear dynamic analysis as a reference. A discussion was carried out comparing the results and the degree of reliability of the different procedures used in relation to the typology of unreinforced masonry buildings. It can be concluded that the simplified methods (i.e. non-linear static) overestimate the damage corresponding to low values of PGA and underestimate the damage for higher values of PGA. Using different criteria, and including the probabilistic consideration of mechanical properties, as well as seismic demand, the foreseeable damage for these structures has been characterized by fragility functions and matrices and damage indices. A study of the correlation between the mechanical parameters and the observed damage is also provided, from which, a high correlation between the obtained results and the variables of interest, is observed, being the Young’s modulus, E, the variable with the highest correlation coefficients. The common difficulties, in any work that involves large samples in relation to the amount of resources and computing time, have been solved through the design of adequate and sufficiently representative samples and by using current computational methods and tools, such as parallel and distributed computing.
A pesar de que la mampostería es uno de los materiales de construcción más antiguos y usados, el número de estudios y datos experimentales existentes, así como la aplicabilidad de sus resultados (i.e. extrapolación), son substancialmente inferiores a aquellos disponibles para materiales mucho más recientes, tales como el hormigón o el acero. Además, actualmente en Europa, un gran número de edificaciones habitacionales pertenecen a tipologías de mampostería. Estas circunstancias justifican el estudio de las características y comportamiento de la mampostería para orientar estudios sobre vulnerabilidad sísmica. En particular, el distrito del Ensanche de Barcelona, en España, presenta un parque urbano de viviendas funcionales compuesto en un 73% por estructuras de mampostería no reforzada, resueltas mediante sistemas de muros de carga, sin ninguna consideración de la acción sísmica y que, en su mayoría, sobrepasan 100 años de vida útil. Estos edificios, característicos de Barcelona, tienen elementos que los diferencian de otras edificaciones de la misma tipología constructiva que pueden encontrarse en otras regiones de Europa: 1) el número de plantas supera significativamente la media, pudiendo encontrar edificios con hasta 10 u 11 niveles; 2) Los edificios comparten paredes medianeras (e.g. laterales), generando con ello entramados de edificios conocidos como agregados; 3) Las propiedades y calidades de los distintos elementos constructivos están estrechamente ligados con los procesos de producción, aún no mecanizados, de la época; 4) El nivel de las técnicas constructivas y la cualificación de la mano de obra eran muy elevados. En este trabajo se han realizado modelos numéricos 3D de configuraciones estructurales aisladas (i.e. edificio individual) y en agregado, de edificios existentes, con la finalidad de determinar y comparar el comportamiento entre las distintas configuraciones estructurales. Los edificios se han modelado incorporando la variabilidad de sus parámetros mecánicos y la demanda sísmica también se ha seleccionado teniendo en cuenta su incertidumbre. El análisis estructural se ha realizado utilizando y comparando diferentes procedimientos de cálculo estático no-lineal y utilizando el análisis dinámico no lineal incremental como referencia. Se ha realizado una discusión comparando los resultados y el grado de confiabilidad de los diferentes procedimientos utilizados en relación con la tipología de edificios de mampostería no reforzada. Se concluye que los métodos simplificados (i.e. estáticos no-lineales) sobrestiman el daño correspondiente a valores bajos de PGA, mientras que lo subestiman para valores elevados de PGA. Utilizando diferentes criterios, e incluyendo la consideración probabilista de las propiedades mecánicas, así como de la demanda sísmica, se ha caracterizado el daño predecible para estas estructuras mediante funciones de fragilidad y matrices e índices de daño y también se aporta un estudio de la correlación entre los parámetros mecánicos y el daño observado, a partir del cual se observa que existe una alta correlación entre los resultados obtenidos y las variables aleatorias seleccionadas, siendo el módulo de Young, E, aquella que presenta los coeficientes de correlación más altos. Las dificultades comunes en cualquier trabajo que involucra muestras de gran tamaño en relación con la cantidad de recursos y tiempos de computación, han sido resueltas mediante el diseño de muestras adecuadas y suficientemente representativas, así como el empleo de métodos y herramientas de cómputo actuales, como lo son el cómputo paralelo y distribuido.
Enginyeria sísmica i dinàmica estructural

El Perú, debido a su ubicación geográfica en el Cinturón de Fuego del Pacífico, es un país con alta sismicidad; lo que hace que nuestras edificaciones se encuentren experimentando la ocurrencia de sismos con mucha frecuencia. A lo largo de los años, dichos eventos no habrían liberado la energía sísmica acumulada en su totalidad, por lo que el país se encuentra en un silencio sísmico, a la espera de un sismo de gran magnitud. Asimismo, existen muchas edificaciones esenciales, tales como hospitales, que fueron construidos antes de la emisión de la primera norma de Diseño Sismorresistente en 1970; siendo diseñadas posiblemente solo considerando cargas de gravedad. Es por esta razón que se tiene la incertidumbre de cuán preparadas están dichas edificaciones esenciales ante la ocurrencia de próximos eventos sísmicos de gran magnitud Este estudio presenta una serie de metodologías de tratamiento de registros sísmicos, modelamiento no lineal de una estructura de albañilería artesanal y su calibración con resultados experimentales, aplicación del análisis dinámico incremental (IDA) y proceso estadístico de los resultados. Todo ello para generar funciones de fragilidad analíticas que permitan estimar la probabilidad de exceder cada estado de daño para una determinada demanda sísmica. Los resultados muestran que las funciones de fragilidad analíticas son una herramienta útil para estimar la vulnerabilidad sísmica, puesto que se obtuvo altas probabilidades de colapso en ambas direcciones ortogonales.
Peru, due to its geographical location in the Pacific Ring of Fire, is a country with high seismicity; which makes our buildings are experiencing the occurrence of earthquakes very frequently. Over the years, these events would not have released the seismic energy accumulated in its entirety, so that’s why the country is waiting for a big earthquake. Also, there are many essential buildings, such as hospitals, that were built before the issuance of the first Seismic-Resistant Design standard in 1970; being designed possibly considering gravity loads. It’s for this reason that exist an uncertainty of how prepared our essential buildings are in the face of the occurrence of earthquakes of great magnitude. This study presents a series of methodologies for the treatment of seismic records, nonlinear structure modeling, application of incremental dynamic analysis (IDA) and statistical process of the results. All this to generate analytical fragility functions that allow estimating the probability of exceeding each damage state for a given seismic demand. The results show that analytical fragility functions are a useful tool to estimating the seismic vulnerability, because we obtain high probability of collapse in both orthogonal directions. Also, the results show the needed to reinforce this facilities.
Tesis

Nuclear power plays a crucial role in energy supply in the world: around 15% of the electricity generated worldwide is provided from nuclear stations avoiding around 2.5 billion tonnes of CO2 emissions. As of January 2016, 442 reactors that generated 380+ GW were in operation and 66 new reactors were under construction. The seismic design of new nuclear power plants (NPPs) has gained much interest after the high-profile Fukushima Dai-ichi accident. In the UK, a tectonically stable continental region that possesses medium-to-low seismic activity, strong earthquakes capable of jeopardising the structural integrity of NPPs, although infrequent, can still occur. Despite that no NPP has been built in Great Britain after 1995, a New Build Programme intended to build 16 GW of new nuclear capacity by 2030 is currently under way. This PhD project provides a state-of-the-art framework for seismic probabilistic safety assessment and risk control of NPPs in Northwest Europe with particular application to the British Isles. It includes three progressive levels: (i) seismic input, (ii) seismic risk analysis, and (iii) seismic risk control. For seismic input, a suitable model to rationally define inputs in the context of risk assessments is proposed. Such a model is based on the stochastic simulation of accelerograms that are compatible with seismic scenarios defined by magnitude 4 < Mw < 6.5, epicentral distance 10 km < Repi < 100 km, and different types of soil (rock, stiff soil and soft soil). It was found to be a rational approach that streamlines the simulation of accelerograms to conduct nonlinear dynamic analyses for safety assessments. The model is a function of a few variables customarily known in structural engineering projects. In terms of PGA, PGV and spectral accelerations, the simulated accelerograms were validated by GMPEs calibrated for the UK, Europe and the Middle East, and other stable continental regions. For seismic risk analysis, a straightforward and logical approach to probabilistically assess the risk of NPPs based on the stochastic simulation of accelerograms is studied. It effectively simplifies traditional approaches: for seismic inputs, it avoids the use of selecting/scaling procedures and GMPEs; for structural outputs, it does not use Monte Carlo algorithms to simulate the damage state. However, it demands more expensive computational resources as a large number of nonlinear dynamic analyses are needed. For seismic risk control, strategies to control the risk using seismic protection systems are analysed. This is based on recent experience reported elsewhere of seismically protected nuclear reactor buildings in other areas of medium-to-low seismic activity. Finally, a scenario-based incremental dynamic analysis (IDA) is proposed aimed at the generation of surfaces for unacceptable performance of NPPs as function of earthquake magnitude and distance. It was found that viscous-based devices are more efficient than hysteretic-based devices in controlling the seismic risk of NPPs in the UK. Finally, using the proposed scenario-based IDA, it was found that when considering all controlling scenarios for a representative UK nuclear site, the risk is significantly reduced ranging from 3 to 5 orders of magnitude when using viscous-based devices.

Precast prestressed hollow core units are commonly used in the construction of the flooring system in precast buildings. These units without transverse reinforcement bars are designed to resist seismic loading as replacement for fixed-base precast wall panels in the construction of warehouse buildings. Thus, this research seeks to investigate the seismic performance of the units constructed as a subassemblage (single wall) subjected to biaxial loading and as a superassemblage (multi-panel) subjected to quasi-static lateral loading. A design procedure for warehouse building using precast hollow core walls under Damage Avoidance Design (DAD) is proposed. In addition, a risk assessment under Performance-Based Earthquake Engineering (PBEE) is evaluated using the latest computational tool known as Incremental Dynamic Analysis (IDA). A comparative risk assessment between precast hollow core walls and fixed-base monolithic precast wall panels is also performed. Experimental results demonstrate that rocking precast hollow core walls with steelarmouring do not suffer any non-structural damage up to 2.0% drift and minor structural damage at 4.0% drift. Results revealed that the wall with unbonded fuse-bars and 50% initial prestressing of unbonded tendons performed the best compared with other types of energy dissipators. Furthermore, 12mm diameter of fuse-bar is recommended as there is no uplifting of the foundation beam during ground shaking. Hence, this type of energy dissipator is used for the construction of seismic wall panels in warehouse buildings. One of the significant findings is that the capacity reduction factor (Ø ) which relates to global uncertainty of seismic performance is approximately equal to 0.6. This value can be used to estimate the 90th percentile of the structures without performing IDA. Therefore, the structural engineers are only required to compute Rapid-IDA curve along with the proposed design procedure.

Incremental Dynamic Analysis (IDA) procedures are advanced and then applied to a quantitative risk assessment for bridge structures. This is achieved by combining IDA with site-dependent hazard-recurrence relations and damage outcomes. The IDA procedure is also developed as a way to select a critical earthquake motion record for a one-off destructive experiment. Three prototype bridge substructures are designed according to the loading and detailing requirements of New Zealand, Japan and Caltrans codes. From these designs 30 percent reduced scale specimens are constructed as part of an experimental investigation. The Pseudodynamic test is then to control on three specimens using the identified critical earthquake records. The results are presented in a probabilistic riskbased format. The differences in the seismic performance of the three different countries' design codes are examined. Each of these current seismic design codes strive for ductile behaviour of bridge substructures. Seismic response is expected to be resulting damage on structures, which may threaten post-earthquake serviceability. To overcome this major performance shortcoming, the seismic behaviour under bi-directional lateral loading is investigated for a bridge pier designed and constructed in accordance with Damage Avoidance principles. Due to the presence of steel armoured rocking interface at the base, it is demonstrated that damage can be avoided, but due to the lack of hysteresis it is necessary to add some supplemental damping. Experimental results of the armoured rocking pier under bi-directional loading are compared with a companion ductile design specimen.

La vulnerabilità sismica degli edifici scolastici in C.A. è un aspetto molto importante in Italia, come mostrato da recenti terremoti che hanno causato danni rilevanti in diverse scuole. La maggior parte delle scuole italiane è stata costruita tra gli anni ’50 e ’90, quindi in assenza o con basso livello di resistenza sismica. Nel presente studio è stata sviluppata una metodologia per la valutazione speditiva del rischio sismico è stata sviluppata. Essa si basa sul metodo dell’indice di vulnerabilità, assumendo 15 indicatori di vulnerabilità a cui assegnare dei punteggi sulla base di un giudizio esperto. I punteggi sono stati determinati mediante analisi pushover effettuate su diversi modelli strutturali rappresentativi delle principali caratteristiche dei due campioni di scuole Pre 1974 e Post 1974. A tal fine un set di circa 40 istituti scolastici superiori è stato analizzato per rilevare le vulnerabilità tipiche e specifiche, ed una progettazione simulata è stata effettuata in accordo ai Codici in vigore nei due periodi di riferimento. Delle correlazioni tra l’indice di vulnerabilità globale Iv e la capacità in termini di PGA, sia per lo stato di danno leggero che per il collasso, sono state determinate per ottenere curve di danno trilineari così come nel metodo GNDT. La validazione numerica del metodo proposto è stata effettuata confrontando le curve di danno trilineari ottenute per due edifici prototipo, rappresentativi in media delle classi Pre 1974 e Post 1974, con le curve di danno analitiche fornite per gli stessi edifici sia da analisi pushover che dinamiche incrementali. Inoltre, una validazione sperimentale è stata fatta confrontando, per le scuole superiori delle province di Ancona e Macerata, il danno subito a causa della sequenza sismica del centro Italia del 2016, con il danno stimato, per lo stesso livello di intensità, mediante il metodo proposto. Entrambe le procedure di validazione hanno confermato una buona affidabilità del metodo proposto per valutazioni rapide e di tipo comparativo. Infine, due tipologie di scenari di danno rapido sono state sviluppate per il campione di edifici, al fine di stimare le perdite fisiche, umane ed economiche. Il primo tipo considera una pericolosità sismica uniforme sull’intero territorio e livelli di intensità crescenti, invece l’altra tipologia considera tre singoli eventi sulla base del sistema di faglie presente nella zona di interesse (fissando per ognuno un epicentro, magnitudo e profondità), quindi i valori di PGA sono calcolati per ogni edificio mediante una legge di attenuazione.
The seismic vulnerability of RC school buildings is a very important issue in Italy, as shown from recent earthquakes that caused heavy damage of several school buildings. Most of Italian schools were built between the 50s and the 90s, so without or with low seismic resistance criteria. In this study a methodology for rapid seismic risk assessment of RC school buildings is developed. It is based on the vulnerability index method, assuming 15 vulnerability indicators to which assign scores on the base of expert judgment. The scores were determined through pushover analyses performed on several structural models representative of the main characteristics of the Pre 1974 and Post 1974 school building stocks. To this aim a set of about 40 high schools were analysed to detect typical and specific vulnerabilities, and a simulated design procedure was carried according to the Codes in force in the two reference periods. Correlations between the global vulnerability index Iv and the capacity in terms of PGA, for both slight damage and collapse, were determined to obtain trilinear damage curves such as in GNDT method. The numerical validation of the proposed method was made by comparing the trilinear damage curves obtained for two prototype buildings, representative in average of the Pre 1974 and Post 1974 classes, with analytical damage curves provided for the same buildings by both pushover and incremental dynamic analyses. Also, experimental validation was carried out by comparing, for the high schools of the provinces of Ancona and Macerata, the damage occurred because of the Centre Italy 2016 seismic sequence, with the damage estimated, for the same intensity level, through the proposed method. Both validation procedures have confirmed a good reliability of the proposed method for rapid and comparative evaluations. Finally, two typologies of rapid damage scenarios were developed for the building stock, in order to estimate physical, human and economic losses. The first typology considers uniform seismic hazard on the whole territory and increasing intensity levels, instead the second one considers three single events on the base of the fault system of the region (fixing for each an epicentre, magnitude and depth), thus the PGA values are calculated for every school building by means an attenuation law.

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Esse trabalho apresenta o uso de métodos de adaptação automática dos incrementos de tempo utilizados na integração numérica passo-a-passo das análises dinâmicas de sistemas estruturais, no domínio do tempo, em estruturas de um e de múltiplos graus de liberdade. Buscou-se comparar as performances das diferentes estratégias adaptativas estudadas. Inicialmente, foi feita uma revisão dos principais processos adotados na solução numérica das equações de equilíbrio dinâmico de sistemas de um grau de liberdade, se concentrando na família de métodos de Newmark, discutindo seus mais amplos aspectos. Posteriormente foi tratado o problema de estruturas de múltiplos graus de liberdade, descrevendo a formação das matrizes estruturais envolvidas através do conceito do método dos elementos finitos e da análise matricial de estruturas, considerando o amortecimento estrutural do tipo viscoso e proporcional, e generalizando os processos de solução numérica das equações dinâmicas. Em seguida foi descrito o escopo de um programa computacional que aplicasse a teoria desenvolvida em análise de estruturas de pórticos planos, o qual foi construído no ambiente de programação do software Matlab. As estratégias de adaptação do incremento de tempo são analisadas na sequência, escolhendo-se três algoritmos principais a serem abordados na implementação, dentre os vários disponíveis, por se basearem em conceitos distintos uns dos outros. Por fim, são apresentados exemplos numéricos resolvidos, onde se comparam as performances das diferentes estratégias adaptativas e se propõem melhorias e diretrizes de aplicação das mesmas
This work presents methods of automatic adaptive time increment used in numerical step-by-step integration analyses of structural systems, in time domain, for single and multi-degree-of-freedom structures. The main purpose was to compare the different strategies performances. Initially, the major processes formulations adopted in the numerical solution of dynamic equilibrium equations were shown for single-degree-of-freedom systems, focusing on the Newmark family of integration methods, discussing about its various aspects. Later, the problem of multi-degree-of-freedom systems was discussed, by describing the structural matrix formulations, considering viscous and proportional structural damping, and generalizing the numerical solution of dynamic equations. Then, it is described a computational program that apply the developed theory on plane frame structures analysis, which was built in the programing software Matlab. The adaptive strategies of time increment are then analyzed, having three major algorithms been chosen to be addressed in the implementation, among the various others available, because they are based on three different concepts. Finally, several numerical examples are presented, on which the performances of the different adaptive strategies are compared, and improvements and guidelines for application are suggested

This thesis is a study into the response and seismic safety of three-dimensional multi-storey concrete structures under concurrent orthogonal seismic excitations. It employs the nonlinear time-history method as its analysis tools. Time-history analyses rely heavily on their utilised earthquake records. Accordingly, this study examines the different approaches of selecting earthquake suites and develops a methodology of selecting representative earthquake scenarios. This methodology is credibly implemented in selecting a far- and a near field suites representative of the New Zealand seismic hazard. The study investigates the response of 6-, 9- and 12-storey concrete structures of different n-X-bays × m-Y-bays. Bidirectional responses of these considered structures are examined and consequently the current combination rules are scrutinised. Consequently this study strongly recommends the use of the 40-percent combination rule in lieu of the widely used 30-percent rule; and the use of time-history analysis in lieu of quasi/equivalent static and response modal analysis methods to avoid their strong dependence on combination rules. An intensive study is conducted employing the incremental dynamic analysis (IDA) technique to investigate structural demands of interstorey drifts, lateral storey drifts and storey accelerations. The study utilises the developed far-field suite and identifies the 50th and 90th percentile demands. Hence it provides easy-to-use expressions to facilitate rapid calculation of the structural demands and the effects of biaxial interactions. An implementation into the Demand and Capacity Factor Design (DCFD) format is presented that infers confidence in the performance levels of the considered structures. The study also draws attention to the importance of considering storey accelerations as their storey values reach as high as 10 × PGA. A sensitivity study is conducted by repeating the IDA investigation while using the developed near-field suite. Subsequently a comparison between the near- and the far-field results is conducted. The results were markedly similar albeit of less magnitudes until the (seismic hazard) intensity measure IM = Sa(T₁) = 0.4g when the near-field results show sudden flat large increase in demands suggesting a brittle collapse. This is attributed to the higher content of the higher mode frequencies contained in near-field ground motions. Finally, the study examines the (vectorial) radial horizontal shear demands in columns and beam-column joints of the previous far- and near-field studies. The combined radial shear demands in corner, edge and internal columns and joints are evaluated that roughly show a square-root proportional relationship with IM that exhibit somewhat brittle failure at IM ≥ 0.35g. Shears demands in the (4-way) internal columns and the (2-way) corner joints show highest magnitude in their respective class. The results suggest transverse joint shear reinforcement of 1.5, 1.0 and 0.5 of the longitudinal reinforcement of the neighbouring beam respectively for corner, edge and internal joints. An implementation of a proposed practical (and simpler) DCFD format shows satisfactory confidence in columns performance in shear up to IM = 0.35g, conversely to joints unsatisfactory performance in shear at the onset of inelastic behaviour (IM > 0.05g).

Dissertação de Mestrado em Construção Metálica e Mista apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra.
The earthquake resistance design plays an essential role in the design of steel structures. Cyclic behaviour of beam-to-column in crucial in seismic behaviour of moment resisting steel frames. At the moment, the European design code in practice does not provide analytical tools to predict rotational capacity and cyclic performance of selected connection typology, but the code requires design supported by experimental testing or existing data on experimental tests performed on similar connections, what is unfeasible from designer’s point of view. A European project has recently been started with the aim to develop design tool with typical beam-to-column connections used in European practice. In that way, designers will be able to directly use pre-qualified connection without performing experimental tests or literature reviews. One part of this European project is to estimate the seismic demand of the joints in typical D-CBF frames. In order to achieve these objectives seismic performance and dynamic response were estimated on basic of non-linear static analysis and non-linear time history analysis. Numerical models were create in order to perform non-linear static and dynamic analysis using OPENSEES software. Both analysis were performed in accordance with current European design code. The results of non-linear static analysis are presented in form of pushover curve and schematic illustration of formed plastic hinges. Dynamic response was estimated in term of i) maximum floor acceleration, ii) maximum interstorey drift ratio, iii) residual interstorey drift ratio and iv) maximum beam rotation ratio (at the exterior, one-side beam-column joints) at three performance levels: design (D), near collapse (NC) and twice near collapse (2xNC). As main conclusion, the analyses have showed that lateral resistance of D-CBFs is suddenly decrease when brace in compression buckles. This decrease is immediately followed by an increase of lateral stiffness. In seismic demand between selected parameters an important rule have hazard level and height of a structure.

Increasingly, researchers and developers of knowledge based systems (KBS) have been attempting to incorporate the notion of context. For instance, Repertory Grids, Formal Concept Analysis (FCA) and Ripple-Down Rules (RDR) all integrate either implicit or explicit contextual information. However, these methodologies treat context as a static entity, neglecting many connectionists’ work in learning hidden and dynamic contexts. This thesis argues that the omission of these higher forms of context, which allow connectionist systems to generalise effectively, is one of the fundamental problems in the application and interpretation of symbolic knowledge. This thesis tackles the problems of KBSs by addressing these contextual inadequacies over a three stage approach: philosophically, methodologically and through the application of prudence analysis. Firstly, it challenges existing notions of knowledge by introducing a new philosophical view referred to as Intermediate Situation Cognition. This new position builds on the existing SC premise, that knowledge and memory is re-constructed at the moment required, by allowing for the inclusion of hidden and dynamic contexts in symbolic reasoning. This philosophical position has been incorporated into the development of a hybridised methodology, combining Multiple Classification Ripple-Down Rules (MCRDR) with a function-fitting technique. This approach, referred to as Rated MCRDR (RM), retains a symbolic core acting as a contextually static memory, while using a connection based approach to learn a deeper understanding of the knowledge captured. This analysis of the knowledge map is performed dynamically, providing constant online information. Results indicate that the method developed can learn the information that experts have difficulty providing. This supplies the information required to allow for generalisation of the knowledge captured. In order to show that hidden and dynamic contextual information can improve the robustness of a KBS, RM must reduce brittleness. Brittleness, which is widely recognised as the primary impediment in KBS performance, is caused by a system’s inability to realise when its knowledge base is inadequate for a particular situation. RM partly addresses this through providing better generalisation; however, brittleness can be more directly addressed by detecting when such inadequacies occur. This process is commonly referred to as prudence analysis. The final part of this thesis proves the methods philosophical and methodological approach by illustrating how RM’s use of hidden and dynamic contextual information, allows the system to perform this analysis. Results show how experts can confidently leave the verification of cases when not warned, reducing brittleness and the knowledge acquisition effort. This thesis shows that the idea of incorporating higher forms of context in symbolic reasoning domains is both possible and highly effective, vastly improving the robustness of the KBS approach. Not only does this facilitate improved classification through better generalisation, but also reduces the KA effort required by experts. Additionally, the methodology developed has further potential for many possible applications across numerous domains, such as Information Filtering, Data Mining, incremental induction and even reinforcement learning.

The seismic response of steel monopole wind turbine towers is investigated and their risk is assessed in the Canadian seismic environment. This topic is of concern as wind turbines are increasingly being installed in seismic areas and design codes do not clearly address this aspect of design. An implicit finite element model of a 1.65MW tower was developed and validated. Incremental dynamic analysis was carried out to evaluate its behaviour under seismic excitation, to define several damage states, and to develop a framework for determining its probability of damage. This framework was implemented in two Canadian locations, where the risk was found to be low for the seismic hazard level prescribed for buildings. However, the design of wind turbine towers is subject to change, as is the design spectrum. Thus, a methodology is outlined to thoroughly investigate the probability of reaching predetermined damage states under seismic loading for future considerations.

碩士
中原大學
土木工程研究所
106
The fragility curve is an important index to assess the damage degree of structures under earthquake excitations. In this study, the incremental dynamic analyses (IDA) of two multi-span bridges are performed using 20 sets of ground motion acceleration time histories to establish the corresponding fragility curves. The limit-states, corresponding to immediate occupancy (IO), life safety (LS), and collapse prevention (CP), of the fragility curves are calculated according to the allowable system displacement from the seismic assessments. On the other hand, we combined the seismic hazard analysis and the response curve from incremental dynamic analyses (IDA curve) to estimate the limit-state displacements corresponding to different earthquake return periods. The estimated limit-state displacement can be used to check the allowable displacements which are specified in the highway bridge design code for different seismic performance levels. Numerical results demonstrate that the displacement requirements from the refined seismic assessments (based on pushover analyses) for level I and level II earthquakes are consistent with those from IDA curve (based on seismic hazard analyses). However, the displacement requirement from the refined seismic assessment is much less than that from IDA curve for level III earthquake (corresponding to 2500-year return period). Particularly the near fault effects are not well considered in the design code.

The present Ph.D. Thesis was developed within a collaboration between the Department of Civil and Environmental Engineering of the University of Perugia, Italy, and the Department of Civil Engineering of the University of Minho, Portugal. The main objective of this research work concerned the development and validation of an innovative methodology aimed at the detection, localization and quantification of earthquake-induced damages in historic masonry structures. The high cultural, economic and political value set upon historic buildings spread out all over the world has made the earthquake-induced damage identification, as well as preservation and conservation of architectural heritage, a subject of outstanding importance. The proposed methodology, called DORI, is based on the combination of data-driven, as well as innovative model-based methods, addressing the Damage identification based on Operational modal analysis (OMA), Rapid surrogate modeling and Incremental dynamic analysis (IDA) for Cultural Heritage (CH) masonry buildings subjected to earthquakes. More in detail, the DORI methodology proposes the static-and-dynamic data fusion in the OMA-based damage detection method, and extends it through the introduction and implementation of two independent and complementary innovative model-based methods, for localization and quantification of earthquake-induced damage in permanently monitored historic masonry buildings: the former is a surrogate model-based method, a rapid tool which combines long-term vibration monitoring data (i.e. OMA) and numerical modeling, while the latter is based on non-linear seismic IDA. The Thesis focuses on the validation of different aspects of the DORI methodology, through application to four case study structures: an internationally well-known laboratory masonry structure, called the Brick House, and three CH masonry buildings equipped with permanent Structural Health Monitoring systems, namely the Consoli Palace, the Sciri Tower and the San Pietro Bell Tower. The adopted enhanced vibration-based SHM tool, by introducing crack amplitudes as predictors in the dynamic MLR model, was validated in the case of the Consoli Palace, enabling rapid and automated earthquake-induced damage detection, even for small structural damages at an early stage, conceivably caused by a moderate/light seismic event. Afterwards, the surrogate model-based procedure for earthquake-induced damage detection and localization was applied in the case of the Sciri Tower, using long-term vibration monitoring data and numerical modeling. In particular, a quadratic surrogate model is used, whose objective function considers not only experimentally identified and numerically predicted damage-induced decays in natural frequencies but also on changes in mode shapes. The procedure was validated by considering both simulated damage scenarios, as well as a slight change in structural behavior experimentally observed after a seismic event. Finally, the proposed seismic IDA-based method, introduced for the first time in this Thesis and aimed at localization and quantification of earthquake-induced damages in masonry structures, is applied to the Brick House and San Pietro Bell Tower. It relies on a priori IDA carried out from a numerical model and construction of multidimensional IDA curve sets relating meaningful local damage parameters to selected seismic intensity measures. The IDA-based procedure has demonstrated to correctly localize damage in specific parts of the structures and to quantify earthquake-induced damage with a good level of approximation. The results are particularly interesting in the case of the San Pietro Bell Tower due to the integration of the IDA-based damage identification with seismic SHM data recorded during the 2016 Central Italy seismic sequence, allowing the proposal and exploitation of some original response intensity measures. In conclusion, the DORI methodology proposed in this Thesis for earthquake-induced damage detection, localization and quantification is a novel methodological approach, successfully applied and validated in historic masonry structures, constituting a promising tool for rapid post-earthquake damage assessment of CH structures under long-term SHM monitoring.

Tese de Doutoramento Engenharia Civil
O principal objetivo deste trabalho de investigação dizia respeito ao desenvolvimento e validação de uma metodologia inovadora para a deteção, localização e quantificação de danos causados por sismos em estruturas históricas de alvenaria. A metodologia proposta, designado por DORI, baseia-se na combinação de métodos baseados em dados e métodos inovadores baseados em modelos, abordando a identificação de dano com base na análise modal operacional (OMA), modelação rápida de substitutos e análise dinamica incremental (IDA) para edifícios de alvenaria do Património Cultural (CH) sujeitos a sismos. Mais detalhadamente, a metodologia DORI propõe a fusão de dados estáticos e dinamicos no método de deteção de dano baseado em OMA e estende a OMA através da introdução e implementação de dois métodos inovadores independentes e complementares baseados em modelos, para localização e quantificação de danos induzidos por sismos em construções históricas de alvenaria com monitorização permanente: o primeiro método é baseado num modelo substituto, uma ferramenta rápida que combina dados de monitorização de vibração a longo prazo (ou seja, OMA) e a modelação numérica, enquanto o segundo método é baseado em IDA não linear sísmica. A Tese está focada na validação de diferentes aspetos da metodologia DORI, através da aplicação a quatro estruturas que servem de casos de estudo: uma estrutura de alvenaria ensaiada em laboratório e reconhecida internacionalmente, designada por Brick House, e tres edifícios de alvenaria de CH equipados com sistemas permanentes de monitorização de saúde estrutural, nomeadamente o Palácio de Consoli, a Torre Sciri e a Torre sineira de San Pietro. Em conclusão, a metodologia DORI proposta nesta Tese para deteção, localização e quantificação de danos induzidos por sismos é uma nova abordagem metodológica, aplicada e validada com sucesso em estruturas históricas de alvenaria, constituindo uma ferramenta promissora para a rápida avaliação de danos pós-sismo das estruturas de CH sob monitorização SHM a longo prazo.
The main objective of this research work concerned the development and validation of an innovative methodology aimed at the detection, localization and quantification of earthquake-induced damages in historic masonry structures. The high cultural, economic and political value set upon historic buildings spread out all over the world has made the earthquake-induced damage identification, as well as preservation and conservation of architectural heritage, a subject of outstanding importance. The proposed methodology, called DORI, is based on the combination of data-driven, as well as innovative model-based methods, addressing the Damage identification based on Operational modal analysis (OMA), Rapid surrogate modeling and Incremental dynamic analysis (IDA) for Cultural Heritage (CH) masonry buildings subjected to earthquakes. More in detail, the DORI methodology proposes the static-and-dynamic data fusion in the OMA-based damage detection method, and extends it through the introduction and implementation of two independent and complementary innovative model-based methods, for localization and quantification of earthquake-induced damage in permanently monitored historic masonry buildings: the former is a surrogate model-based method, a rapid tool which combines long-term vibration monitoring data (i.e. OMA) and numerical modeling, while the latter is based on non-linear seismic IDA. The Thesis focuses on the validation of different aspects of the DORI methodology, through application to four case study structures: an internationally well-known laboratory masonry structure, called the Brick House, and three CH masonry buildings equipped with permanent Structural Health Monitoring systems, namely the Consoli Palace, the Sciri Tower and the San Pietro Bell Tower. In conclusion, the DORI methodology proposed for earthquake-induced damage detection, localization and quantification is a novel methodological approach, successfully applied and validated in historic masonry structures, constituting a promising tool for rapid post-earthquake damage assessment of CH structures under long-term SHM monitoring.