Дисертації з теми "Seismic fragility curve"
Щоб переглянути інші типи публікацій з цієї теми, перейдіть за посиланням: Seismic fragility curve.
Оформте джерело за APA, MLA, Chicago, Harvard та іншими стилями
Ознайомтеся з топ-39 дисертацій для дослідження на тему "Seismic fragility curve".
Біля кожної праці в переліку літератури доступна кнопка «Додати до бібліографії». Скористайтеся нею – і ми автоматично оформимо бібліографічне посилання на обрану працю в потрібному вам стилі цитування: APA, MLA, «Гарвард», «Чикаго», «Ванкувер» тощо.
Також ви можете завантажити повний текст наукової публікації у форматі «.pdf» та прочитати онлайн анотацію до роботи, якщо відповідні параметри наявні в метаданих.
Переглядайте дисертації для різних дисциплін та оформлюйте правильно вашу бібліографію.
1
Ay, Bekir Ozer. "Fragility Based Assessment Of Low." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607629/index.pdf.
Анотація:
In this study, structural vulnerability of reinforced concrete frame structures by considering the country&ndashspecific characteristics is investigated to manage the earthquake risk and to develop strategies for disaster mitigation. Low&ndash
rise and mid&ndash
rise reinforced concrete structures, which constitute approximately 75% of the total building stock in Turkey, are focused in this fragility&ndash
based assessment. The seismic design of 3, 5, 7 and 9&ndash
story reinforced concrete frame structures are carried out according to the current earthquake codes and two dimensional analytical models are formed accordingly. The uncertainty in material variability is taken into account in the formation of structural simulations. Frame structures are categorized as poor, typical or superior according to the specific characteristics of construction practice and the observed seismic performance after major earthquakes in Turkey. The demand statistics in terms of maximum interstory drift ratio are obtained for different sets of ground motion records. The capacity is determined in terms of limit states and the corresponding fragility curves are obtained from the probability of exceeding each limit state for different levels of ground shaking. The results are promising in the sense that the inherent structural deficiencies are reflected in the final fragility functions. Consequently, this study provides a reliable fragility&ndash
based database for earthquake damage and loss estimation of reinforced concrete building stock in urban areas of Turkey.
2
Saler, Elisa. "Seismic vulnerability and fragility of school buildings in Italy. A multiscale approach to assessment, prioritisation, and risk evaluation." Doctoral thesis, Università degli studi di Trento, 2022. http://hdl.handle.net/11572/348119.
Анотація:
The importance of school buildings, among the built heritage of a community, is largely acknowledged. Due to past seismic events, damage or even collapse of schools have had a huge social impact. The safety of children and youth has a fundamental priority and, in addition, the unsafety of schools can aggravate social dispersion phenomena which follow an earthquake. In the aftermath of the Molise earthquake (2002), which caused the collapse of a primary school in San Giuliano di Puglia (Campobasso, Italy) and the consequent death of 27 children and a teacher, the Italian government issued a national plan for the seismic vulnerability assessment of relevant and strategic structures all over the country. The huge number of structures to be evaluated makes this operation extremely complex and, after almost twenty years, it still requires efficient and cost-effective (also in terms of execution time) tools to be effectively planned.
More recently, the United Nations adopted, in March 2015, the Sendai Framework for Disaster Risk Reduction 2015-2030, which is articulated in “priorities”, providing actions to be implemented. Specifically, Priority 1 is focused on “understanding disaster risk”, while Priority 2 sets the goal of “strengthening disaster risk governance to manage disaster risk”. Both objectives require to deepen knowledge of risks and of its components (i.e., hazard, exposure and vulnerability) at various territorial scale (e.g., national or urban).
This thesis presents the seismic vulnerability and fragility assessment of school buildings in Italy, to address this problem at multiple scales, at municipality level and at national level, also including investigations on case studies for refined modelling.
First, a prioritisation procedure to sort school buildings part of an urban stock by their seismic vulnerability is proposed. This procedure has the aim of supporting local administrations and enterprises in charge with built stocks in decision-making for the allocation of limited funds for retrofit. The knowledge process of the building stock is comprised of on-site visual surveys and retrieval of original projects documentations. Then, the priority list is defined based on the combination of a qualitative evaluation and of a quantitative capacity/demand ratio resulting from a simplified mechanics-based model. The former results from the application of a form, counting structural and non-structural deficiencies, which is proposed in this work for masonry, reinforced concrete (r.c.), and mixed masonry-r.c. buildings, by updating an existing form. The priority-ranking procedure was applied to r.c. school buildings managed by the Municipality of Padova, in north-east Italy.
Then, in the second part of the thesis, the research focuses on the fragility assessment of macro-classes of buildings, representative of the Italian school taxonomy, aimed at risk evaluation at national scale.
Based on the Italian school building census, macro-classes of buildings were identified according to a limited number of parameters (i.e., the construction material, age of construction, number of stories, and plan area). Fragility curves were derived for five damage states (from slight damage to complete collapse), with reference to the European Macroseismic Scale (EMS98).
For masonry schools, fragility curves were derived for 265 building types by means of a simplified mechanics-based approach, named Vulnus, which accounts for both in-plane and out-of-plane responses.
Fragility assessment was also carried out for a macro-class of r.c. school buildings by selecting two representative schools from the above-mentioned urban stock managed by the Municipality of Padova. A non-linear fibre model was developed for each prototype building, taking into account its specific features, such as the presence of infills and of non-seismic joints. Non-Linear Time History Analyses (NLTHA) were carried out by applying a great number of natural and scaled ground motion records, covering a large range of seismic intensities. Fragility curves were derived by statistically processing the outcomes of NLTHA.
Thus, the application of two alternative approaches for fragility estimate are provided in this work.
Finally, damage maps at national scale are provided by implementing the obtained fragilities, showing the distribution of expected damage for a selected return period and for observation time windows.
3
Avsar, Ozgur. "Fragility Based Seismic Vulnerability Assessment Of Ordinary Highway Bridges In Turkey." Phd thesis, METU, 2009. http://etd.lib.metu.edu.tr/upload/3/12610693/index.pdf.
Анотація:
Recent devastating earthquakes revealed that bridges are one of the most vulnerable components of the transportation systems. These seismic events have emphasized the need to mitigate the risk resulting from the failure of the bridges. Depending on the seismicity of the bridge local site, seismic vulnerability assessment of the bridges can be done based on the fragility curves. These curves are conditional probability functions which give the probability of a bridge attaining or exceeding a particular damage level for an earthquake of a given intensity level. In this dissertation, analytical fragility curves are developed for the ordinary highway bridges in Turkey constructed after the 1990s to be used in the assessment of their seismic vulnerability. Bridges are first grouped into certain major bridge classes based on their structural attributes and sample bridges are generated to account for the structural variability. Nonlinear response history analyses are conducted for each bridge sample with their detailed 3-D analytical models under different earthquake ground motions having varying seismic intensities. Several engineering demand parameters are employed in the determination of seismic response of the bridge components as well as defining damage limit states in terms of member capacities. Fragility curves are obtained from the probability of exceeding each specified damage limit state for each major bridge class. Skew and single-column bent bridges are found to be the most vulnerable ones in comparison with the other bridge classes. Developed fragility curves can be implemented in the seismic risk assessment packages for mitigation purposes.
4
伊藤, 義人, Yoshito ITOH, 光永 和田 та Mitsunaga WADA. "イベントを考慮した交通基盤施設のライフサイクル評価手法に関する研究". 土木学会, 2003. http://hdl.handle.net/2237/8633.
5
Bélec, Gilbert. "Seismic Assessment of Unreinforced Masonry Buildings In Canada." Thesis, Université d'Ottawa / University of Ottawa, 2016. http://hdl.handle.net/10393/34301.
Анотація:
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.
6
Ceran, H. Burak. "Seismic Vulnerability Of Masonry Structures In Turkey." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612745/index.pdf.
Анотація:
This study focuses on the evaluation of seismic safety of masonry buildings in Turkey by using fragility curves. Fragility curves for masonry buildings are generated by two behavior modes for load bearing walls: in-plane and out-of-plane. By considering the previous research and site investigations, four major parameters have been used in order to classify masonry buildings with in-plane behavior mode. These are number of stories, strength of load-bearing wall material, regularity in plan and the arrangement of walls (required length, openings in walls, etc.). In addition to these four parameters, floor type is also taken into account for the generation of fragility curves by considering out-of-plane behavior mode. During generation of fragility curves, a force-based approach has been used. In this study there exist two limit states, or in other words three damage states, in terms of base shear strength for in-plane behavior mode and flexural strength for out-of-plane behavior mode. To assess the seismic vulnerability of unreinforced masonry buildings in Turkey, generated fragility curves in terms of in-plane behavior, which is verified by damage statistics obtained during the 1995 Dinar earthquake, and out-of-plane behavior, which is verified by damage statistics obtained during the 2010 Elazig earthquake, is combined. Throughout the analysis, ground motion uncertainty, material variability and modeling uncertainty have also been considered. In the final part of the study, a single-valued parameter, called as &lsquovulnerability score&rdquo
, has been proposed in order to compare the seismic safety of unreinforced masonry buildings in Fatih sub province of Istanbul and to assess the influence of out-of-plane behavior together with the in-plane behavior of these existing masonry buildings.
7
Ucer, Serkan. "Seismic Response And Vulnerability Assessment Of Tunnels:a Case Study On Bolu Tunnels." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615005/index.pdf.
Анотація:
The aim of the study is to develop new analytical fragility curves for the vulnerability assessment of tunnels based on actual damage data of tunnels obtained from past earthquakes. For this purpose, additional important damage data belonging to Bolu Tunnels, Turkey was utilized as a case study.
Bolu Tunnels constitute a very interesting case from the earthquake hazard point of view, since two major earthquakes, 17 August 1999 Marmara and 12 November 1999 Düzce, occurred during the construction of the tunnels. The August 17, 1999 earthquake was reported to have had minimal impact on the Bolu Tunnels. However, the November 12, 1999 earthquake caused some sections of both tunnels to collapse. The remaining sections of the tunnels survived with various damage states which were subsequently documented in detail. This valuable damage data was thoroughly utilized in this study. To develop analytical fragility curves, the methodology described by Argyroudis et al. (2007) was followed. Seismic response of the Tunnels was assessed using analytical, pseudo-static and full-dynamic approaches. In this way, it was possible to make comparisons regarding the dynamic analysis methods of tunnels to predict the seismically induced damage. Compared to the pseudo-static and full-dynamic methods, the predictive capability of the analytical method is found to be relatively low due to limitations inherent to this method. The pseudo-static and full-dynamic solution results attained appear to be closer to each other and better represented the recorded damage states in general. Still, however, the predictive capability of the pseudo-static approach was observed to be limited for particular cases with reference to the full-dynamic method, especially for the sections with increasingly difficult ground conditions. The final goal of this study is the improvement of damage indexes corresponding to the defined damage states which were proposed by Argyroudis et al. (2005) based on the previous experience of damages in tunnels and engineering judgment. These damage indexes were modified in accordance with the findings from the dynamic analyses and actual damage data documented from Bolu Tunnels following the Dü
zce earthquake. Three damage states were utilized to quantify the damage in this study.
8
Huh, Jungwon, Quang Tran, Achintya Haldar, Innjoon Park, and Jin-Hee Ahn. "Seismic Vulnerability Assessment of a Shallow Two-Story Underground RC Box Structure." MDPI AG, 2017. http://hdl.handle.net/10150/625742.
Анотація:
Tunnels, culverts, and subway stations are the main parts of an integrated infrastructure system. Most of them are constructed by the cut-and-cover method at shallow depths (mainly lower than 30 m) of soil deposits, where large-scale seismic ground deformation can occur with lower stiffness and strength of the soil. Therefore, the transverse racking deformation (one of the major seismic ground deformation) due to soil shear deformations should be included in the seismic design of underground structures using cost- and time-efficient methods that can achieve robustness of design and are easily understood by engineers. This paper aims to develop a simplified but comprehensive approach relating to vulnerability assessment in the form of fragility curves on a shallow two-story reinforced concrete underground box structure constructed in a highly-weathered soil. In addition, a comparison of the results of earthquakes per peak ground acceleration (PGA) is conducted to determine the effective and appropriate number for cost- and time-benefit analysis. The ground response acceleration method for buried structures (GRAMBS) is used to analyze the behavior of the structure subjected to transverse seismic loading under quasi-static conditions. Furthermore, the damage states that indicate the exceedance level of the structural strength capacity are described by the results of nonlinear static analyses (or so-called pushover analyses). The Latin hypercube sampling technique is employed to consider the uncertainties associated with the material properties and concrete cover owing to the variation in construction conditions. Finally, a large number of artificial ground shakings satisfying the design spectrum are generated in order to develop the seismic fragility curves based on the defined damage states. It is worth noting that the number of ground motions per PGA, which is equal to or larger than 20, is a reasonable value to perform a structural analysis that produces satisfactory fragility curves.
9
Al, Mamun Abdullah. "Seismic Damage Assessment of Reinforced Concrete Frame Buildings in Canada." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36188.
Анотація:
The emphasis on seismic design and assessment of reinforced concrete (RC) frame structure has shifted from force-based to performance-based design and assessment to accommodate strength and ductility for required performance of building. RC frame structure may suffer different levels of damage under seismic-induced ground motions, with potentials for formation of hinges in structural elements, depending on the level of stringency in design. Thus it is required to monitor the seismic behaviour and performance of buildings, which depend on the structural system, year of construction and the level of irregularities in the structural system. It is the objective of the current research project to assess seismic performance of RC frame buildings in Canada, while developing fragility curves as analytical tools for such assessment. This was done through dynamic inelastic analysis by modelling selected building structures and using PERFORM-3D as analysis software, while employing incremental dynamic analysis to generate performance data under incrementally increasing seismic intensity of selected earthquake records. The results lead to probabilistic tools to assess the performance of buildings designed following the National Building Code of Canada in different years of construction with and without irregularities. The research consists of three phases; i) regular buildings designed after 1975, ii) regular buildings designed prior to 1975, and iii) irregular buildings designed prior to 1975. The latter two phases address older buildings prior to the development of modern seismic building codes. All three phases were carried out by selecting and designing buildings in Ottawa, representing the seismic region in eastern Canada, as well as buildings in Vancouver, representing the seismic region in western Canada. Buildings had three heights (2; 5; and 10-stories) to cover a wide range of building periods encountered in practice. The resulting fragility curves indicated that the older buildings showed higher probabilities of exceeding life safety and/or collapse prevention performance levels. Newer buildings showed higher probabilities of exceeding target performance levels in western Canada than those located in the east.
10
SANCIN, LJUBA. "SEISMIC VULNERABILITY EVALUATION OF R.C. AND MASONRY BUILDINGS IN THE CENTRE OF GORIZIA." Doctoral thesis, Università degli Studi di Trieste, 2021. http://hdl.handle.net/11368/2998137.
Анотація:
The aim of this research study is to investigate the vulnerability of the building heritage in Gorizia, a town in north-eastern Italy, on the border with Slovenia. This town has not been considered seismic until the year 2003 and then in 2010 it has been classified in a higher seismicity class. For this reason, most of the buildings are not designed to resist seismic action at all and an even lower percentage fulfils the requirements of the current technical standard.
Four real existing buildings are analysed as case study buildings, representative of the main structural types that can be found in the town. Two of them are high - rise (11 and 12 storeys) reinforced concrete (RC) framed buildings with a brittle concrete stairwell, designed for gravitational load only and built in the 60’s-70’s. In the last years, a growing attention has been payed to the seismic vulnerability of existing RC framed structures, but this type of buildings, with a core of concrete walls, has been investigated much less, although it is a structural type that is very spread. The other two case studies are masonry buildings built in 1740 and in 1903, respectively. One of the masonry buildings is the city hall of Gorizia, on which many in-situ tests have been performed within a project of the Department of Engineering and Architecture with the Municipality of Gorizia. For both RC buildings, some considerations are made about the influence of the masonry infills on the seismic behaviour of the building and of the numerical model. The vibration periods found with numerical modelling are also compared to the periods evaluated with vibrational measurements. The two numerical models without infills are then analysed with non-linear static and dynamic analyses. The results are processed with a cloud analysis in order to calculate fragility curves of the buildings, that show a very brittle behaviour. The two masonry buildings are analysed also with pushover analysis.
For the evaluation of the seismic vulnerability of the analysed buildings, two types of seismic hazard assessments have been considered for the extraction of the seismic inputs: Probabilistic Seismic Hazard Assessment (PSHA) method, by the Italian code response spectra and Neo Deterministic Seismic Hazard Assessment (NDSHA) method, with response spectra of two specific possible scenarios for the town of Gorizia. The physics-based scenarios are calculated for the two faults that are the closest to Gorizia: Idrija and Medea. A comparison is made between the demand given by the seismic inputs defined with the two methods. The importance of using both methods for the design of low-damage retrofitting solutions is highlighted.
At last, a theoretical study has been carried out within the present research study in order to find an innovative and effective solution for the retrofit of the RC high-rise brittle buildings. It consists in the application of an exo - or endo - skeleton, with the additional introduction of a sliding system at the base of the RC building, in order to decouple its motion from the ground motion. In this way, the exo- or endo-skeleton can be designed independently from the features of the existing building, that remains undamaged. The characteristics of the exo/endo-skeleton can be calibrated on the seismic input of the site of interest, with the possibility to adapt it to new seismic classifications of the territory.The aim of this research study is to investigate the vulnerability of the building heritage in Gorizia, a town in north-eastern Italy, on the border with Slovenia. This town has not been considered seismic until the year 2003 and then in 2010 it has been classified in a higher seismicity class. For this reason, most of the buildings are not designed to resist seismic action at all and an even lower percentage fulfils the requirements of the current technical standard. Four real existing buildings are analysed as case study buildings, representative of the main structural types that can be found in the town. Two of them are high - rise (11 and 12 storeys) reinforced concrete (RC) framed buildings with a brittle concrete stairwell, designed for gravitational load only and built in the 60’s-70’s. In the last years, a growing attention has been payed to the seismic vulnerability of existing RC framed structures, but this type of buildings, with a core of concrete walls, has been investigated much less, although it is a structural type that is very spread. The other two case studies are masonry buildings built in 1740 and in 1903, respectively. One of the masonry buildings is the city hall of Gorizia, on which many in-situ tests have been performed within a project of the Department of Engineering and Architecture with the Municipality of Gorizia. For both RC buildings, some considerations are made about the influence of the masonry infills on the seismic behaviour of the building and of the numerical model. The vibration periods found with numerical modelling are also compared to the periods evaluated with vibrational measurements. The two numerical models without infills are then analysed with non-linear static and dynamic analyses. The results are processed with a cloud analysis in order to calculate fragility curves of the buildings, that show a very brittle behaviour. The two masonry buildings are analysed also with pushover analysis. For the evaluation of the seismic vulnerability of the analysed buildings, two types of seismic hazard assessments have been considered for the extraction of the seismic inputs: Probabilistic Seismic Hazard Assessment (PSHA) method, by the Italian code response spectra and Neo Deterministic Seismic Hazard Assessment (NDSHA) method, with response spectra of two specific possible scenarios for the town of Gorizia. The physics-based scenarios are calculated for the two faults that are the closest to Gorizia: Idrija and Medea. A comparison is made between the demand given by the seismic inputs defined with the two methods. The importance of using both methods for the design of low-damage retrofitting solutions is highlighted. At last, a theoretical study has been carried out within the present research study in order to find an innovative and effective solution for the retrofit of the RC high-rise brittle buildings. It consists in the application of an exo - or endo - skeleton, with the additional introduction of a sliding system at the base of the RC building, in order to decouple its motion from the ground motion. In this way, the exo- or endo-skeleton can be designed independently from the features of the existing building, that remains undamaged. The characteristics of the exo/endo-skeleton can be calibrated on the seismic input of the site of interest, with the possibility to adapt it to new seismic classifications of the territory.
11
Tran, Anh-Dung. "Application de l'apprentissage automatique pour la construction des courbes de fragilité sismique." Electronic Thesis or Diss., université Paris-Saclay, 2024. https://www.biblio.univ-evry.fr/theses/2024/interne/2024UPAST017.pdf.
Анотація:
L'évaluation des risques sismiques pour les structures est nécessaire pour prévenir les pertes humaines et matérielles en cas de catastrophes naturelles. La construction des courbes de fragilité sismique, l'outil qui définit la probabilité de défaillance d'une structure en fonction de l'intensité des séismes, joue un rôle important dans cette évaluation. En général, la méthode de construction de cette courbe demande des procédures coûteuses, très souvent par appel des analyses par éléments finis, nécessitant des ressources considérables en termes de temps et d'informatique. Cette difficulté empêche l'utilisation de cet outil en temps réel ou l'application de cet outil pour les structures plus populaires.L'apprentissage automatique a connu un développement spectaculaire avec son l'application dans plusieurs domaines. Il est reconnu comme un outil puissant pour modéliser une relation complexe entre les entrées et les sorties à partir des données. Une approche novatrice émerge : l'utilisation des modèles d'apprentissage automatique pour prédire la réponse des structures sous séismes. Par conséquent, la motivation principale de la thèse est d'étudier l'application de l'apprentissage automatique à la génération de réponses sismiques pour l'évaluation des risques sismiques, plus spécifiquement pour construction de la courbe de fragilité.L'étude débute par une revue de la littérature, qui présente les courbes de fragilité sismique et le défi lié à la charge de calculs pour leur construction. Après une brève présentation de l'apprentissage automatique, le premier chapitre se concentre sur son application pour modéliser les réponses sismiques des structures. Devant un très large choix parfois contradictoire des caractéristiques, il est nécessaire de proposer des procédures pratiques avec les caractéristiques les plus pertinentes et faciles à la mise en œuvre.La thèse examine ce problème et donne une proposition innovante consiste à utiliser et sélectionner efficacement le spectre de réponse en accélération échantillonnées aux différentes périodes pour construire les modèles d'apprentissage automatique. Deux procédures, nommées PRO-LIN et PRO-NONLIN, sont proposées pour des structures linéaires et non-linéaires respectivement. Pour valider ces propositions, des tests sont effectués sur des structures linéaires et non-linéaires en combinant avec des enregistrements synthétiques, démontrant une réduction significative du temps de simulation tout en maintenant la précision dans la construction des courbes de fragilité.Bien que les premières validations des procédures soient réalisées avec des enregistrements synthétiques, une validation avec des enregistrements réels est indispensable pour valider ces propositions. Les enregistrements sont sélectionnés suivant le spectre conditionnel depuis des bases de données. Finalement, une autre validation vise à tester les procédures proposées avec des bases de données existantes dans en littérature. La première base de données concerne une structure linéaire en béton armé. La deuxième base de données concerne des portiques non-linéaires résistantes aux moments en acier.En conclusion, basant sur les résultats obtenus dans les études, ce travail met en lumière l'efficacité des procédures proposées de la thèse. Ces procédures améliorent de façon efficace la construction des courbes de fragilité sismique et l'évaluation des risques sismiquesThe evaluation of seismic risks for structures is necessary to prevent human and material losses in the event of natural disasters. The construction of seismic fragility curves, the tool that defines the probability of failure of a structure based on earthquake intensity, plays a significant role in this assessment. Generally, the method of constructing these curves requires costly procedures, often involving finite element analyses, which require considerable time and computing resources. This difficulty hinders the real-time use of this tool or its application for more common structures.Machine learning has experienced a remarkable development with its application in various fields. It is recognized as a powerful tool for modeling complex relationships between inputs and outputs from data. An innovative approach is emerging: the use of machine learning models to predict structural responses to earthquakes. Therefore, the main motivation of the thesis is to study the application of machine learning to generate seismic responses for seismic risk assessment, specifically for constructing fragility curves.The study begins with a literature review, which presents seismic fragility curves and the challenge related to the computational burden for their construction. After a brief introduction to machine learning, the first chapter focuses on its application to model seismic responses of structures. Given the sometimes contradictory wide range of characteristics, it is necessary to propose practical procedures with the most relevant and easy-to-implement features.The thesis addresses this issue and proposes an innovative approach to efficiently use and select the acceleration response spectrum sampled at different periods to build machine learning models. Two procedures, named PRO-LIN and PRO-NONLIN, are proposed for linear and nonlinear structures respectively. To validate these proposals, tests are performed on linear and nonlinear structures combined with synthetic records, demonstrating a significant reduction in simulation time while maintaining accuracy in constructing fragility curves.Although the initial validations of the procedures are conducted with synthetic records, validation with real records is essential to validate these proposals. The records are selected according to the conditional spectrum from databases. Finally, another validation aims to test the proposed procedures with existing databases in the literature. The first database concerns a linear reinforced concrete structure. The second database concerns nonlinear moment-resistant steel frames.In conclusion, based on the results obtained in the studies, this work highlights the effectiveness of the proposed procedures in the thesis. These procedures effectively improve the construction of seismic fragility curves and seismic risk assessment
12
Nielson, Bryant G. "Analytical Fragility Curves for Highway Bridges in Moderate Seismic Zones." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7542.
Анотація:
Historical seismic events such as the San Fernando earthquake of 1971 and the Loma Prieta earthquake of 1989 did much to highlight the vulnerabilities in many existing highway bridges. However, it was not until 1990 that this awareness extended to the moderate seismic regions such as the Central and Southeastern United States (CSUS). This relatively long neglect of seismic issues pertaining to bridges in these moderate seismic zones has resulted in a portfolio of existing bridges with seismic deficiencies which must be assessed and addressed.
An emerging decision tool, whose use is becoming ever increasingly popular in the assessment of this seismic risk, is that of seismic fragility curves. Fragility curves are conditional probability statements which give the probability of a bridge reaching or exceeding a particular damage level for an earthquake of a given intensity level. As much research has been devoted to the implementation of fragility curves in risk assessment packages, a great need has arisen for bridge fragility curves which are reliable, particularly for those in moderate seismic zones. The purpose of this study is to use analytical methods to generate fragility curves for nine bridge classes which are most common to the CSUS. This is accomplished by first considering the existing bridge inventory and assessing typical characteristics and details from which detailed 3-D analytical models are created. The bridges are subjected to a suite of synthetic ground motions which were developed explicitly for the region. Probabilistic seismic demand models (PSDM) are then generated using these analyses. From these PSD models, fragility curves are generated by considering specific levels of damage which may be of interest. The fragility curves show that the most vulnerable of all the bridge nine bridge classes considered are those utilizing steel girders. Concrete girder bridges appear to be the next most vulnerable followed by single span bridges of all types. Various sources of uncertainty are considered and tracked throughout this study, which allows for their direct implementation into existing seismic risk assessment packages.
13
Ramanathan, Karthik Narayan. "Next generation seismic fragility curves for california bridges incorporating the evolution in seismic design philosophy." Diss., Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/44883.
Анотація:
Quantitative and qualitative assessment of the seismic risk to highway bridges is crucial in pre-earthquake planning, and post-earthquake response of transportation systems. Such assessments provide valuable knowledge about a number of principal effects of earthquakes such as traffic disruption of the overall highway system, impact on the regions' economy and post-earthquake response and recovery, and more recently serve as measures to quantify resilience. Unlike previous work, this study captures unique bridge design attributes specific to California bridge classes along with their evolution over three significant design eras, separated by the historic 1971 San Fernando and 1989 Loma Prieta earthquakes (these events affected changes in bridge seismic design philosophy). This research developed next-generation fragility curves for four multispan concrete bridge classes by synthesizing new knowledge and emerging modeling capabilities, and by closely coordinating new and ongoing national research initiatives with expertise from bridge designers.
A multi-phase framework was developed for generating fragility curves, which provides decision makers with essential tools for emergency response, design, planning, policy support, and maximizing investments in bridge retrofit. This framework encompasses generational changes in bridge design and construction details. Parameterized high-fidelity three-dimensional nonlinear analytical models are developed for the portfolios of bridge classes within different design eras. These models incorporate a wide range of geometric and material uncertainties, and their responses are characterized under seismic loadings. Fragility curves were then developed considering the vulnerability of multiple components and thereby help to quantify the performance of highway bridge networks and to study the impact of seismic design principles on the performance within a bridge class. This not only leads to the development of fragility relations that are unique and better suited for bridges in California, but also leads to the creation of better bridge classes and sub-bins that have more consistent performance characteristics than those currently provided by the National Bridge Inventory. Another important feature of this research is associated with the development of damage state definitions and grouping of bridge components in a way that they have similar consequences in terms of repair and traffic implications following a seismic event. These definitions are in alignment with the California Department of Transportation's design and operational experience, thereby enabling better performance assessment, emergency response, and management in the aftermath of a seismic event. The fragility curves developed as a part of this research will be employed in ShakeCast, a web-based post-earthquake situational awareness application that automatically retrieves earthquake shaking data and generates potential damage assessment notifications for emergency managers and responders.Errata added at request of advisor and approved by Graduate Office, March 15 2016.
14
Wang, Mengg. "Deep Learning-based Time-dependent Seismic Fragility Analysis of Aging Highway Bridges." Thesis, University of Sydney, 2020. https://hdl.handle.net/2123/24334.
Анотація:
Highway bridges, as exposed to the threats induced by both long-term aging effects and unexpected earthquakes, are most crucial but vulnerable components in a transportation network. The traditional time-dependent seismic fragility curves generation methods for aging bridges require highly repetitive and extremely time-consuming analysis when changing the aging years of the bridges. Additionally, a transportation network generally comprises hundreds of bridges, making it impractical to generate fragility curves for individual bridge in a network using the traditional fragility curves generation methodology. These limitations have motivated the study of developing efficient and accurate seismic fragility curves generation methodology. In this study, a deep learning-based fragility curves generation methodology has been proposed. A new improved activation function named DLog is proposed to address the limitations and problems of the current deep neural networks and being used to construct the deep neural network for fragility curves generation. The Proposed framework, numerical tests and applications are concluded in this work.
15
Rafie, Nazari Yasamin. "Seismic Fragility Analysis of Reinforced Concrete Shear Wall Buildings in Canada." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36090.
Анотація:
Damage observed after previous earthquakes indicates that a large number of existing buildings are vulnerable to seismic hazard. This research intends to assess seismic vulnerability of regular and irregular shear wall buildings in Canada, having different heights and different levels of seismic design and detailing. As seismic hazard is a probabilistic event, a probabilistic methodology has been adopted to assess the seismic vulnerability of the shear wall buildings. The proposed research encompasses a comprehensive fragility analysis for seismic vulnerability of shear wall buildings in Canada. The first phase of the investigation involves shear wall buildings with different heights (hence different structural periods), designed based on the 2010 National Building Code of Canada. The second phase involves shear wall buildings designed prior to 1975, representing pre-modern seismic code era. The third phase involves the evaluation of pre-1975 shear wall buildings with irregularities.
3-Dimensional simulations of the buildings were constructed by defining nonlinear modelling for shear wall and frame elements. These models were subjected to dynamic time history analyses conducted using Perform 3D software. Two sets of twenty earthquake records, compatible with western and eastern Canadian seismicity, were selected for this purpose. Spectral acceleration and peak ground acceleration were chosen as seismic intensity parameters and the first storey drift was selected as the engineering demand parameter which was further refined for irregular cases. The earthquake records were scaled to capture the structural behaviour under different levels of seismic excitations known as Incremental Dynamic Analysis. The resulting IDA curves were used as the input for seismic fragility analysis. Fragility curves were derived as probabilistic tools to assess seismic vulnerability of the buildings. These curves depict probability of exceeding immediate occupancy, life safety and collapse prevention limit states under different levels of seismic intensity.
16
BRUNELLI, ANDREA. "SEISMIC FRAGILITY CURVES ACCOUNTING FOR SITE AND SOIL STRUCTURE INTERACTION EFFECTS ON URM BUILDINGS." Doctoral thesis, Università degli studi di Genova, 2022. http://hdl.handle.net/11567/1093913.
Анотація:
Significant site-amplification effects have been observed in various historic centers following the recent seismic events in Italy (e.g., L'Aquila 2009, Emilia 2012, Central Italy 2016-17), but also examples of Soil Foundation Structure (SFS) interaction in ordinary unreinforced masonry (URM) buildings. In the past, SFS interaction effects were usually considered for masonry buildings only in slender or massive URM monumental structures. Following the latest observed evidence, this research aims to further investigate the role of site amplification and SFS interaction in the seismic response of URM residential structures. The final goal is to provide an effective procedure to consider these effects in large-scale risk assessment as well.
The first part of the research validated the numerical approach to analyze the SFS interaction by reproducing the seismic response of the Visso school affected by the earthquake sequence in central Italy. This school constituted a very emblematic case study, since it was permanently monitored by the Italian Department of Civil Protection and suffered very severe damage, allowing validation even in a highly nonlinear phase.
The procedure is based on the decoupled approach. Therefore, the input motion of the foundation is calculated from the site response analyses and the structural performance is analyzed through a structural model with springs at the base and characterized by equivalent damping. This school's validated procedure and numerical model were exploited to derive fragility curves that include site effects and SFS interaction under different subsurface conditions. The predicted damage probability was also compared with the results obtained from different amplifications of the simplified Code-compliant approach.
Finally, the research was further generalized by considering multiple building types and different soil profiles. The structural types were inspired by the most frequent building types in the municipality of Visso, consisting of aggregate masonry structures.
The set of derived fragility curves was finally applied to an urban scale to develop damage scenarios. In particular, the resulting damage under ground motion of the Central Italy earthquake was compared with that observed and predicted by existing faster and less accurate approaches, to assess the potential of the developed tools also to support possible future large-scale mitigation policies.
17
Wright, Alexander David. "Comparison of Performance-Based Liquefaction Initiation Analyses Between Multiple Probabilistic Liquefaction Models Using the Standard Penetration Test." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3710.
Анотація:
For the most recent and correct article, please click here: http://ascelibrary.org/doi/abs/10.1061/9780784412787.086
This study examines the use of performance-based approaches in liquefaction hazard analysis. Two new methods of performance-based liquefaction initiation analysis are proposed which use the works of Juang et al. (2012) and Boulanger and Idriss (2012). Further advances are made by incorporating the performance-based magnitude scaling factors as proposed by Cetin et al. (2012). Using these new equations a comparative study is made between the three methods. Further comparisons are made between the performance-based approaches and the more widely used deterministic approaches. The comparisons reveal that on average for the 11 sites used in this study, the performance-based approaches tend to be slightly less conservative than deterministic approaches overall, with large differences possible for some locations in the country. They also reveal that the newer performance-based approaches are generally less conservative than the approach proposed by Kramer and Mayfield (2007). Some cases where this relationship does not hold true and the new relationships are more conservative are outlined.
18
Mammone, Angelo. "Innovative probabilistic methodologies to assess seismic vulnerability of simple supported girder bridges." Doctoral thesis, Universita degli studi di Salerno, 2019. http://elea.unisa.it:8080/xmlui/handle/10556/4279.
Анотація:
2017 - 2018Since the end of the eighties, numerous studies have been conducted analysing the relationship between the infrastructures and the economic development of the territory, highlighting its close correlation. In the last decades, the costs for the management and maintenance of these networks have increased considerably considering the age of the same and the increase in demand that has been witnessed. The phenomenon is particularly evident in some elements of transport networks such as bridges, viaducts and tunnels, which, as evidenced by the telluric events that have hit Italy in recent decades, have shown a high level of vulnerability also towards media events. Intensity. The problems encountered are essential because the Italian infrastructural network is constituted for the vast majority of bridges built in the 60s and 80s, structures conceived in seismic territories generally only afterwards and, therefore, without seismic engineering criteria. Furthermore, the lack of routine maintenance policies and practices has accentuated the decay of structural services in some cases. This thesis study focuses on the analysis of the efficiency of adaptation and improvement techniques for multi-span bridges simply supported, built in Italy in the 60s-80s, a simple bridge/viaduct suite was used. Defined according to the geometric and mechanical characteristics detected by the bridges built on the Italian motorway and road network. To evaluate the structural performance of bridges and viaducts, the probabilistic method from the basis of Performance Based Earthquake Engineering (PBEE) was used, in particular through the use of fragility curves. The purpose of bridging curves for bridges, however, shows some limitations, since they are complex structures composed of several structural elements that interact with each other, so it is difficult to determine the collapse mechanisms of the whole system. To simplify the comprehension of the global collapse mechanism, thus facilitating the general evaluation of the improvement proposals related to the single structural components, we propose an innovative method of analysis and graphic representation of the fragility curves. [edited by Author]
XXXI ciclo
19
Bowers, Matthew E. "Seismic fragility curves for a typical highway bridge in Charleston, SC considering soil-structure interaction and liquefaction effects." Connect to this title online, 2007. http://etd.lib.clemson.edu/documents/1202500829/.
20
TELESCA, ALESSIO. "ADVANCED MODELLING OF OVER-STROKE DISPLACEMENT CAPACITY FOR CURVED SURFACE SLIDER DEVICES." Doctoral thesis, Università degli studi della Basilicata, 2022. http://hdl.handle.net/11563/153765.
Анотація:
This doctoral dissertation aims to report on the research work carried out and to provide a contribution to the field of seismic base isolation. Since its introduction, the base isolation strategy proved to be an effective solution for the protection of structures and their components from the earthquake-induced damage, enhancing their resilience and implying a significative decrease in time and cost of repair compared to a conventional fixed-base structure.
Sliding isolation devices feature some important characteristics, over other devices, that make them particularly suitable for the application in the existing buildings retrofit such as the high displacements capacity combined with limited plan dimensions. Even though these devices diffusion has gotten more popular worldwide in last years, a full understanding of their performances and limits as well as their behaviour under real seismic excitations has not been yet completely achieved. When Curved Surface Sliders reach their displacement capacity, they enter the so-called over-stroke sliding regime which is characterized by an increase in stiffness and friction coefficient. While in the over-stroke displacements regime, anyways, sliding isolators are still capable, until certain threshold values, of preserving their ability to support gravity loads.
In this doctoral dissertation, the analysis of Curved Surface Sliding devices influence on different structures and under different configurations is presented and a tool for to help professionals in the design phase is provided. The research main focuses are: i) the numerical investigation of the over-stroke displacement influence on base isolated structures; ii) the numerical investigation of displacement retaining elements influence on base isolated structures; iii) the development of a mechanical model and an algebraic solution describing the over-stroke sliding regime and the associated limit displacements.
21
FREDDI, FABIO. "Local engineering demand parameters for seismic risk evaluation of low ductility reinforced concrete buildings." Doctoral thesis, Università Politecnica delle Marche, 2012. http://hdl.handle.net/11566/242022.
Анотація:
The damage occurred during recent earthquakes in many existing reinforced concrete (RC)
buildings designed before the introduction of modern anti-seismic codes has shown that
these structures are very vulnerable to the seismic action due to their reduced ductility
capacity. This underlines the need to develop retrofit techniques for reducing the
vulnerability of existing structures and of reliable tools for assessing the effectiveness of
the retrofit and the resulting structural safety. Earthquake risk mitigation and seismic risk
evaluation are among the engineering's most complex challenges. Seismic risk evaluation
must include a proper assessment of the system vulnerability and seismic hazard. Seismic
vulnerability analysis of structural systems can be a rather hard task especially, amongst
others, due to the high degree of uncertainty affecting the system properties, the capacity
and the input definition and hence should be performed within a probabilistic framework.
The Performance Based Earthquake Engineering (PBEE) framework introduced by the
Pacific Earthquake Engineering Research Centre (PEER) is currently the more advanced
probabilistic methodology adopted in seismic engineering. The effort of many researchers
has been employed along the last decades to reach the present state of development,
however, there are still drawbacks in the design and seismic performance assessment of
certain type of structures.
The objective of this Thesis is to investigate the probabilistic response and vulnerability of
a class of low ductility reinforced concrete (RC) frame buildings and investigates about the
use of buckling retrained braces as retrofit technique. Traditionally, structural response is
measured by Engineering Demand Parameters (EDPs), such as the overall maximum
interstory drift over the height of the building. The use of this EDP is adequate to describe
the seismic response of ductile frame designed by strength hierarchy rules, but may lead to
a high approximation in the vulnerability evaluation since in this case there is not direct
relation between local failure mechanism and global interstory drifts. To obtain a more
thorough characterization of the vulnerability of the structure, a multi-component fragility
study is necessary, hence, the use of local EDP is investigated in order to enable a more
realistic and thorough description of the failure mechanisms for structural vulnerability.
The study proposes an optimized methodology for the probabilistic evaluation of seismic
demand of low ductility RC frames by exploring a range of intermediate, local and global
EDPs, identifying appropriate regression models and comparing performances of different
ground motion intensity measures used in the probabilistic analysis. In particular, different
EDPs are considered in order to highlight the most significant failure modalities in RC lowductility
frame buildings, optimal PSDMs of single components are developed for various
EDPs, and the viability of alternative IMs is explored. While the form of PSDMs and
efficiency of various IMs has been readily explored for global response parameters of RC
buildings, this study provides insight into the form of regression model appropriate for such
local and intermediate level EDPs as steel and concrete strains, moments and shears on
beams and columns, and global responses such as base shear or story accelerations. Furthermore, ground motion IMs are analyzed to identify the IMs that are most appropriate
for Probabilistic Seismic Demand Analysis (PSDA) of low ductility RC frames on the basis
of such characteristics as IM efficiency and sufficiency. Additionally, the uncertainty about
these demand models is assessed including hypothesis tests of the typical lognormal
distribution of demands and homoscedasticity assumptions. All the considerations are
based on the results of a PSDA performed on a case study.
Moreover, a probabilistic methodology for assessing the vulnerability of existing RC
buildings with limited ductility capacity and retrofitted by means of dissipative braces is
proposed. The methodology use local EDP in order to develop component and system
fragility curves of the bare and the retrofitted frame and allows to evaluate the safety level
reached by the frame before and after the retrofit by taking into account the probabilistic
properties of the seismic response and at the same time, employing an efficient structure
dependent IM. The proposed approach allows to highlight the possible changes in the most
significant collapse modalities before and after the retrofit and to evaluate the effectiveness
of the retrofit.
A benchmark 2-dimensional reinforced concrete frame with low ductility capacity is
considered as case study. The frame is designed for gravity-loads only and does not comply
with modern anti-seismic code requirements. It is retrofitted by introducing elasto-plastic
dissipative braces designed for different levels of their target base-shear capacity, following
a design method involving the pushover analysis of the bare frame. The obtained results
show the effectiveness of the use of component level vulnerability evaluation of low
ductility frames, and the effectiveness of the methodology in describing the changes in the
performance due to retrofit. The lack of accuracy as consequence of the use of these global
EDPs for evaluating vulnerability of retrofitted frames is posed in evidence. Finally, an
increase of the dispersion of the retrofitted frames with respect to the bare frame is shows
and this result implies the importance of considering the dispersion in the evaluation of
seismic safety level achieved after the retrofit. The proposed methodology also allows
testing the effectiveness of this simplified criterion employed for the design of braces.
22
Nardin, Chiara. "Seismic experimental analyses and surrogate models of multi-component systems in special-risk industrial facilities." Doctoral thesis, Università degli studi di Trento, 2022. https://hdl.handle.net/11572/362462.
Анотація:
Nowadays, earthquakes are one of the most catastrophic natural events that have a significant human, socio-economic and environmental impact. Besides, based on both observations of damage following recent major/moderate seismic events and numerical/experimental studies, it clearly emerges that critical non-structural components (NSCs) that are ubiquitous to most industrial facilities are particularly and even disproportionately vulnerable to those events.
Nonetheless and despite their great importance, seismic provisions for industrial facilities and their process equipment are still based on the classical load-and-resistance factor design (LRFD) approach; a performance-based earthquake engineering (PBEE) approach should, instead, be preferred. Along this vein, in recent years, much research has been devoted to setting computational fragility frameworks for special-risk industrial components and structures.
However, within a PBEE perspective, studies have clearly remarked: i) a lack of definition of performance objectives for NSCs; ii) the need for fully comprehensive testing campaigns data on coupling effects between main structures and NSCs. In this respect, this doctorate thesis introduces a computational framework for an efficient and accurate seismic state-dependent fragility analysis; it is based on a combination of data acquired from an extensive experimental shake table test campaign on a full-scale prototype industrial steel frame structure and the most recent surrogate-based UQ forward analysis advancements. Specifically, the framework is applied to a real-world application consisting of seismic shake table tests of a representative industrial multi-storey frame structure equipped with complex process components, carried out at the EUCENTRE facility in Italy, within the European SPIF project: Seismic Performance of Multi-Component Systems in Special Risk Industrial Facilities. The results of this experimental research campaign also aspire to improve the understanding of these complex systems and improve the knowledge of FE modelling techniques. The main goals aim to reduce the huge computational burden and to assess, as well, when the importance of coupling effects between NSCs and the main structure comes into play. Insights provided by innovative monitoring systems were then deployed to develop and validate numerical and analytical models. At the same time, the adoption of Der Kiureghian's stochastic site-based ground motion model (GMM) was deemed necessary to severely excite the process equipment and supplement the scarcity of real records with a specific frequency content capable of enhancing coupling effects. Finally, to assess the seismic risk of NSCs of those special facilities, this thesis introduces state-dependent fragility curves that consider the accumulation of damage effects due to sequential seismic events. To this end, the computational burden was alleviated by adopting polynomial chaos expansion (PCE) surrogate models. More precisely, the dimensionality of a seismic input random vector has been reduced by performing the principal component analysis (PCA) on the experimental realizations. Successively, by bootstrapping on the experimental design, separate PCE coefficients have been determined, yielding a full response sample at each point. Eventually, empirical state-dependent fragility curves were derived.
23
Maio, Rui André Simões Dias. "Seismic vulnerability assessment of old building aggregates." Master's thesis, Universidade de Aveiro, 2013. http://hdl.handle.net/10773/12839.
Анотація:
Mestrado em Engenharia CivilThe present dissertation approaches the assessment of the seismic vulnerability of old stone masonry building aggregates. With this topic it is presented a review on the most recent methods and tools used for the seismic vulnerability assessment of masonry buildings, focusing the research developed both in Italy and Portugal. Moreover, a case study of an old stone masonry building aggregate was assessed, which is located in San Pio delle Camere (Abruzzo, Italy), slightly a ected by the 6th April 2009 L'Aquila earthquake. This building aggregate was modelled using the STA DATA software 3muri®. On one hand, static non-linear numerical analysis was performed to obtain capacity curves and a prediction of the damage distribution in the structure, caused by the input seismic action (hybrid method), on the other hand indirect methods were used, based on di erent vulnerability index formulations.
A presente dissertação insere-se no estudo da avaliação da vulnerabilidade sísmica de agregados de edifícios antigos de alvenaria de pedra. É feita uma revisão geral da literatura sobre os mais recentes estudos e ferramentas para a avaliação da vulnerabilidade sísmica de agregados de edifícios de alvenaria de pedra, enfatizando o trabalho de investigação desenvolvido em Itália e em Portugal nesta temática. É avaliada a vulnerabilidade sísmica de um caso de estudo de um agregado de edifícios, localizado em San Pio delle Camere (na região de Abruzzo, em Itália), afectado pelo sismo de L'Aquila e modelado com o recurso ao programa da STA DATA 3muri®. Numa primeira fase, a avaliação da vulnerabilidade sísmica do agregado foi conseguida através de uma metodologia híbrida, que estima as curvas de fragilidade com base nos deslocamentos espectrais resultantes de análises estáticas não-lineares. Posteriormente foram aplicados métodos indirectos, baseados na estimativa de um índice de vulnerabilidade, para diferentes formulações correntes.
La presente tesi di laurea magistrale si propone di contribuire allo sviluppo dello studio sulla valutazione della vulnerabilità sismica degli aggregati di edi ci in muratura di pietra. È stata fatta una ricerca e una revisione sui più recenti metodi e strumenti utilizzati per la valutazione della vulnerabilità sismica di edi ci in muratura, con particolare attenzione per la ricerca sviluppata in Italia e in Portogallo. È stato presentato il modello equivalente di un caso di studio che ha coinvolto un edi cio aggregato situato a San Pio delle Camere (Abruzzo, Italia) paese colpito dal terremoto de l'Aquila nell'aprile del 2009. Per la redazione del modello è stato utilizzato il software di STA DATA 3muri®, dove sono stati discussi l'in uenza di alcuni parametri sulla costruzione del comportamento globale e delle corrispondenti pushover curve. Sono stati anche discussi i risultati ottenuti per le curve di fragilità e le distribuzioni di danni dovuti all' azione sismica considerata. In una seconda fase sono stati applicati e discusse metodologie sempli cate basate nella valutazione dell'indice di vulnerabilità. In ne è stato fatto il confronto tra metodologie per ulteriori sviluppi della ricerca.
24
Perrault, Matthieu. "Evaluation de la vulnérabilité sismique de bâtiments à partir de mesures in situ." Phd thesis, Université de Grenoble, 2013. http://tel.archives-ouvertes.fr/tel-00934454.
Анотація:
L'objectif de cette thèse est d'analyser et de caractériser le lien entre les mouvements du sol et la réponse des bâtiments. En particulier, on s'intéresse à réduire les incertitudes qui entrent en jeu dans les méthodes de vulnérabilité, afin d'estimer plus précisément la vulnérabilité des structures au risque sismique. Pour ce faire, cette thèse est basée sur l'utilisation de données enregistrées au sein de bâtiments. Les enregistrements de vibrations ambiantes et de séismes de faibles amplitudes au sein de bâtiments permettent de caractériser le comportement élastique de ces structures. Des modèles peuvent ensuite être définis afin d'étudier les différentes composantes de la variabilité présente au sein des courbes de fragilité. On s'intéresse dans un premier temps au premier niveau de dommage, au-delà duquel les caractéristiques élastiques des bâtiments sont modifiées et les modèles définis ne sont plus valables. Des enregistrements de séismes ayant eu lieu depuis le début des années 1970 dans des bâtiments californiens sont ensuite utilisés. A partir de ces données, on a pu mettre en évidence des relations entre le déplacement au sein des structures et des paramètres décrivant la nocivité des signaux sismiques. Suivant l'indicateur utilisé pour représenter la nocivité des séismes, la réponse des bâtiments peut être estimée plus ou moins précisément. Notamment, les indicateurs faisant intervenir les paramètres dynamiques des bâtiments sont davantage liés avec la réponse des structures, représentée par son déplacement inter-étage moyen. La variabilité de la réponse des bâtiments peut être améliorée en regroupant les bâtiments par typologies (définies suivant leur matériau principal de construction et leur hauteur). En apportant davantage d'informations sur les structures, on peut ainsi diminuer la composante épistémique de la variabilité. De plus, en combinant des indicateurs de nocivité, on peut améliorer la précision pour la prédiction de la réponse de la structure. Une forme fonctionnelle est ainsi proposée afin d'estimer le déplacement inter-étage moyen au sein des structures, pour plusieurs typologies de bâtiments, à partir de quatre indicateurs de nocivité. Cette forme fonctionnelle est utilisée pour établir des courbes de fragilité et peut également être utilisée afin de donner une première estimation des dommages à la suite d'un séisme, en comparant les valeurs de déformations inter-étages avec des valeurs de référence (FEMA, 2003). Enfin, une méthode hybride est proposée pour la construction de courbes de fragilité, faisant intervenir un modèle de comportement non linéaire. Les paramètres de ce modèle sont définis de telle sorte que la réponse du modèle s'ajuste aux enregistrements de séismes effectués dans les bâtiments. Ce modèle est ensuite utilisé pour évaluer les composantes d'incertitudes et pour construire des courbes de fragilité pour tous les niveaux de dommages.
25
Limoge, Claire. "Méthode de diagnostic à grande échelle de la vulnérabilité sismique des Monuments Historiques : Chapelles et églises baroques des hautes vallées de Savoie." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLN014/document.
Анотація:
L’objectif de ce travail est de proposer une méthode d’analyse de vulnérabilité sismique adaptée à l’étude d’un patrimoine historique complet très étendu, indépendamment de la renommée de chaque bâtiment. En effet la grande vulnérabilité sismique du patrimoine ancien, très souvent en maçonnerie, impose, afin d’éviter tout dommage irréparable, de se donner les moyens d’intervenir en amont. Notre démarche doit donc répondre à trois impératifs principaux: développer des outils de choix à grande échelle afin de hiérarchiser les besoins, offrir une analyse pertinente du comportement sous séisme d'une structure historique maçonnée même en première approche, et trouver des méthodes pour gérer le nombre important d’incertitudes qui caractérise le diagnostic des édifices anciens. Pour ce faire, nous étudions les églises et chapelles baroques des hautes vallées de la Savoie française, témoignages d'une période particulièrement prospère dans l'histoire de la Savoie et d'un mouvement artistique unique dans un environnement hostile. Dans ce contexte nous avons donc développé ou adapté différents outils afin de pouvoir traiter les particularités des édifices anciens et utiliser pour des édifices anciens en maçonnerie rustique les potentialités des techniques proposées pour les édifices modernes : modélisations numériques non-linéaires dynamiques temporelles, mesures vibratoires in-situ, analyse multi modale non-linéaireThe aim of this thesis is to propose a seismic vulnerability assessment method well suited to the study of a complete historical heritage, regardless of the prestige of each building. Indeed the great seismic vulnerability of the historical heritage, often in masonry, requires to act preventively in order to avoid irreparable damage. Our approach must tackle three main requirements: to develop large-scale tools of choice to prioritize the needs, to provide relevant analysis of seismic behavior on the structural scale even in the first study, and to manage the large number of uncertainties characterizing the old buildings structural assessment. To this aim, we study the baroque churches and chapels in the high valleys of the French Savoie. They witness to a particularly prosperous period in the history of Savoy and a unique artistic movement adapted to a harsh environment. In this context we have therefore developed or adapted different tools in order to handle the peculiarities of the old buildings. This way we can use the today proposed techniques for modern buildings to study these ancient buildings in rustic masonry: non-linear temporal dynamics numerical modeling, vibratory in situ measurements, non-linear multi modal analysis
26
Mosleh, Araliya. "Seismic vulnerability assessment of existing concrete highway Iranian bridges." Doctoral thesis, Universidade de Aveiro, 2016. http://hdl.handle.net/10773/17173.
Анотація:
Doutoramento em Engenharia CivilSismos recentes mostram que as pontes são uma das infraestruturas mais vulneráveis dos sistemas de transporte rodoviário, e comprovam a necessidade de avaliação da vulnerabilidade deste tipo de estruturas, especialmente as projetadas segundo a filosofia patente nos códigos antigos. A avaliação da vulnerabilidade sísmica das pontes rodoviárias localizadas em áreas de elevada perigosidade sísmica e a estimativa do seu desempenho sísmico representam tarefas importantes para a segurança dos sistemas de transporte. Neste contexto, esta investigação tem como objetivo estudar a vulnerabilidade sísmica das pontes de betão armado existentes no Irão. O trabalho foca-se principalmente nas seguintes tarefas: desenvolvimento de análises estatísticas, classificação das pontes mais comuns no Irão, seleção da ação sísmica representativa, definição de estados de dano, estudo dos efeitos das práticas de construção e, finalmente, análise de curvas de fragilidade para avaliar a vulnerabilidade sísmica de pontes tipo representativas das obras existentes no Irão. O primeiro capítulo resume trabalhos no domínio da caracterização da sismicidade na área geográfica em estudo, em função das diferentes placas tectónicas e da distribuição das zonas de rotura prováveis, com base em informação recolhida em sismos passados e uma revisão geral dos estudos anteriores e a pesquisa bibliográfica, nomeadamente em termos de curvas de fragilidade para as pontes com base em diferentes abordagens. O Capítulo 2 descreve os tipos de ponte mais comuns existentes no Irão e classifica-as de acordo com as suas características estruturais primárias. Capítulo 3 explicar os modelos analíticos não lineares 3-D das estruturas de pontes amostra usando modelos analíticos detalhados para os seus componentes. O Capítulo 4 é dedicado à seleção de um conjunto de registos sísmicos reais que sejam representativos das diferentes fontes sísmicas. O Capítulo 5 é dedicado à definição de estados limite de dano. Neste capítulo, foi realizada uma revisão das propostas para a avaliação dos estados limite de dano disponíveis na literatura. Para isso, diferentes tipos de incertezas associadas a parâmetros que influenciam o comportamento das pontes foram consideradas, nomeadamente em termos de seção e altura dos pilares, presença da emenda da armadura longitudinal e vão. Além disso, a influência das propriedades dos materiais com base na resistência à compressão do betão e da resistência do aço são analisadas e os resultados são tratados em termos de curvas de fragilidade para cada classe de pontes considerada. O Capítulo 6 apresenta os principais resultados da análise sísmica tridimensional realizada sobre vários casos de estudo. Capítulos 7 indicam o estudo da resposta estocástica de pontes de betão considerando a incerteza na rigidez de rolamento e de encosto. Finalmente, no capítulo 8, as principais conclusões são tiradas a partir do trabalho desenvolvido no âmbito do presente estudo.
Past earthquakes occurred in seismically active areas around the world show that bridges are one of the most vulnerable components of the highway transportation systems, and evidence the need to study the vulnerability of bridges, especially the ones designed with the old codes. Thus, the seismic vulnerability assessment of the highway bridges located in high seismic hazard areas and the assessment of the bridges’ performance under seismic demands play an important role for the safety of transportation systems. In this context, this research aimed to study the seismic vulnerability of existing old concrete bridges in Iran. The research work was mainly focused on the following tasks: identification of the most common bridges in Iran, ground motion selection, damage state definition, real construction practices and finally the analysis of fragility curves to assess the seismic vulnerability of common bridges in Iran. The first chapter presents the study of seismicity in a geographical area of interest for this study, covered by different tectonic plates and distribution of probable rupture zones of past earthquakes and the general overview of previous studies and a literature survey developed to generate the bridge fragility curves based on different approaches. Chapter 2 describes the most common existing ordinary highway bridges and classifies them according to their primary structural characteristics. Chapter 3 explains the 3-D nonlinear analytical models of the sample bridge structures using detailed analytical models for its components. Chapter 4 is devoted to the procedure followed in the selection of earthquake ground motion records that are representative of the different seismic sources, based on ground motion intensity. Chapter 5 addresses aspects related with the definition of damage limit states. In this chapter, a review of the damage states definitions and strategies available in the literature is also made. For this, different types of bridges uncertainties, in terms of column height, superstructure type, lap splice and span length are investigated for the selected case studies. Also, the influence of material properties, namely the compressive strength of concrete and the yield strength of steel is described. In Chapter 6 the results are generated in terms of fragility curves for each bridges class. Chapter 7 indicates the study of the stochastic response of concrete bridges considering the uncertainty in the bearing and abutment stiffness. Finally in chapter 8, the main conclusions are drawn from the work developed within the present study.
27
Suescun, Juliana Ruiz. "Courbes de fragilité pour les ponts au Québec tenant compte du sol de fondation." Mémoire, Université de Sherbrooke, 2010. http://savoirs.usherbrooke.ca/handle/11143/1576.
Анотація:
Abstract : Fragility curves are a very useful tool for seismic risk assessment of bridges. A fragility curve describes the probability of a structure being damaged beyond a specific damage state for different levels of ground shaking. Since more than half of all bridges in the province of Quebec (Canada) are in service for more than 30 years and that these bridges were designed at that time without seismic provisions, generating fragility curves for these structures is more than necessary. These curves can be used to estimate damage and economic loss due to an earthquake and prioritize repairs or seismic rehabilitations of bridges. Previous studies have shown that seismic damage experienced by bridges is not only a function of the epicentral distance and the severity of an earthquake but also of the structural characteristics of the bridge and the soil type on which it is built. Current methods for generating fragility curves for bridges do not account for soil conditions. In this work, analytical fragility curves are generated for multi-span continuous concrete girder bridges, which account for 21% of all bridges in Quebec, for the different soil profile types specified in the Canadian highway bridge design code (CAN/CSA-S6-06). These curves take into account the different types of abutment and foundation specific to these bridges. The fragility curves are obtained from time-history nonlinear analyses using 120 synthetic accelerograms generated for eastern Canadian regions, and from a Monte Carlo simulation to combine the fragility curves of the different structural components of a bridge||Résumé : Les courbes de fragilité sont un outil très utile pour l’évaluation du risque sismique des ponts. Une courbe de fragilité représente la probabilité qu'une structure soit endommagée au-delà d'un état d'endommagement donné pour différents niveaux de tremblement de terre. Étant donné que plus de la moitié des ponts dans la province de Québec (Canada) ont plus de 30 années de service et que ces ponts n'ont pas été conçus à l'époque à l'aide de normes sismiques, la génération de courbes de fragilité pour ces structures est plus que nécessaire. Ces courbes peuvent servir à estimer les dommages et les pertes économiques causés par un tremblement de terre et à prioriser les réparations ou les réhabilitations sismiques des ponts. Des études antérieures ont montré que l'endommagement subi par les ponts suite à un tremblement de terre n'est pas seulement fonction de la distance de l'épicentre et de la sévérité du tremblement de terre, mais aussi des caractéristiques structurales du pont et du type de sol sur lequel il est construit. Les méthodes actuelles pour générer les courbes de fragilité des ponts ne tiennent pas compte des conditions du sol. Dans ce travail de recherche, des courbes de fragilité analytiques sont générées pour les ponts à portées multiples à poutres continues en béton armé, soit pour 21% des ponts au Québec, pour les différents types de sol spécifiés dans le Code canadien sur le calcul des ponts routiers (CAN/CSA-S6-06). Ces courbes prennent en compte les différents types de culée et de fondation spécifiques à ces ponts. Les courbes de fragilité sont obtenues à partir d'analyses temporelles non linéaires réalisées à l'aide de 120 accélérogrammes synthétiques généres pour l’est du Canada, et d'une simulation de Monte Carlo pour combiner les courbes de fragilité des différentes composantes du pont.
28
Tavano, Matteo. "Seismic response of tank-fluid systems: state of the art review and dynamic buckling analysis of a steel tank with the added mass method." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/3006/.
29
Zaghlool, Baher SalahElDeen Othman Ahmed. "Behaviour of three-dimensional concrete structures under concurrent orthogonal seismic excitations." Thesis, University of Canterbury. Civil Engineering, 2007. http://hdl.handle.net/10092/1177.
Анотація:
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).
30
伊藤, 義人, Yoshito Itoh, M. Wada, and Chunlu Liu. "Lifecycle Environmental Impact and Cost Analyses of Steel Bridge Piers with Seismic Risk." 2005. http://hdl.handle.net/2237/5328.
31
Ciano, Matteo. "On the accuracy of seismic fragilities for actual linear/nonlinear structural systems: the modified intensity measure method." Doctoral thesis, 2021. http://hdl.handle.net/2158/1269611.
Анотація:
Tesi presentata e approvata dalla Facoltà di Architettura, Ingegneria Civile e Scienze Ambientali Technische Universität Braunschweig e dal Dipartimento di Ingegneria Civile e Ambientale dell'Università degli Studi di Firenze per candidarsi al titolo di Doktor-Ingenieur (Dr.-Ing.) / Dottore di Ricerca in Ingegneria Civile e Ambientale*)
*) Può essere utilizzata la forma tedesca o italiana del titolo.
Dissertation submitted to and approved by the Faculty of Architecture, Civil Engineering and Environmental Sciences Technische Universität Braunschweig and the Department of Civil and Environmental Engineering University of Florence in candidacy for the degree of a Doktor-Ingenieur (Dr.-Ing.) / Dottore di Ricerca in Civil and Environmental Engineering*)
*) Either the German or the Italian form of the title may be used.
32
Lin, Jhong-You, and 林忠佑. "Fragility Curves of Corrosion Steel Cylindrical Tanksunder Seismic Loadings." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/22013267861076253059.
Анотація:
碩士國立金門大學
土木與工程管理學系碩士班
105
The objective of this research is to develop the corrosion cylindrical steel tanks subjected to seismic loading. The fluid-structure-soil interactions are incorporated in the dynamic analysis. The tanks are modeled as thin shells. The hydraulic loading includes impulsive mass and convective mass. The soil mediums are simulated three dimensional solid elements. The viscous transmitting boundary is attached to boundary to avoid seismic wave reflection. The nearfault seismic ground accelerations only consider the horizontal components. Chapter 1 is devoted to introduction, including motivation of this research, methodology, literature review of the previous studies, and the organization of this thesis. Chapter 2 addresses the description of cylindrical steel tanks with various ratios of heights and radii. In the chapter 3, the forty-six near-fault earthquake components with pulse-like velocities are served as horizontal input ground accelerations. Chapter 4 is concerned with modal analysis and dynamic analyses of steel tanks with different degree of corrosion. Based on results of chapter 4, the fragility curves of corrosion steel tanks subjected to near fault earthquakes are developed in chapter 5. The damage indexes based on the drift ratios use to classify the various damage states. The fragility curves of corrosion steel tanks are developed with this damage indexes, accordingly.Chapter 6 presents the conclusions and final remarks, the contribution and feature of this research as well as the future study. The results of this research can be implemented in the primary design of aged corrosion steel tanks.
33
CHOUDHURY, LALIT. "SEISMIC ANALYSIS AND DEVELOPMENT OF FRAGILTY CURVE FOR AN RCC FRAME." Thesis, 2017. http://dspace.dtu.ac.in:8080/jspui/handle/repository/15961.
Анотація:
In recentzpast, severe earthquakes havezcaused substantial physical losses andzcasualties. Partszof India are inzhigh risk of facingzdevastating earthquakes. Since a majorityzof the populationzis living in earthquakezprone areas, it is probablezthat such terriblezevents may take placezagain in the nearzfuture. Moreover, it isznot easy to cope with thezsubstantial directzand indirect economiczlosses after each devastatingzearthquake for azdeveloping country likezIndia. Because in thiszcountry many reinforcedzconcrete buildings areznot designedzaccording to the currentzbuilding code, seismic behaviour is notztaken into considerationzduring selection of the structural systemzand in most caseszsupervision in the constructionzphase is not adequate whichzin turn induces deficiencieszlike poor concrete quality, inadequatezdetailing of reinforcement etc. It is, therefore,zvital to quantifyzthe earthquake riskzand to develop strategies forzdisaster mitigation. In order tozachieve this goal, anzextensive and inter-disciplinaryzstudy is required.
This study describeszthe methods by which it iszpossible to determine thezvulnerability of existingzengineering structures andzbuilding stock. Theztool that is employedzto assess the seismiczperformance of reinforcedzconcrete framezstructures is the fragilityzcurve, By definition, fragilityzcurves provide estimates for thezprobabilities of reaching orzexceeding various limit stateszat given levels ofzground shaking intensity for anzindividual structurezor population ofzstructures. A limitzstate, which is in thezsame terms as thezresponse, usually representsza damage condition or azlimitation of usage. The seismiczvulnerability of these structureszfor different earthquakezcan be interpreted from thezdeveloped fragility curves.
34
LUSIANTO, LIAUW LUKMAN, and LIAUW LUKMAN LUSIANTO. "SEISMIC EVALUATION AND FRAGILITY CURVES OF EXISTING REINFORCED CONCRETE BRIDGES CONSIDERING CORROSION OF STEEL REINFORCEMENT." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/3r75p7.
Анотація:
碩士國立臺灣科技大學
營建工程系
100
A life-cycle seismic evaluation method of some existing reinforced concrete bridges considering the effects of corrosion of steel reinforcement is proposed in this thesis. The evaluation method is based on the well-known ATC-40 nonlinear static pushover analysis procedure and is implemented in common commercial software familiar to engineers. Chloride and carbonation attacks make a reinforced concrete structure prone to corrosion of steel reinforcement. The effects of steel corrosion are considered by modeling degradation of mechanical properties of steel reinforcement, softening of cover concrete in compression, and reduction of bond between concrete and steel reinforcement. Twenty four existing reinforced concrete bridges in Taiwan are analyzed using the proposed method. Fragility curves express the probabilities of exceeding damage limit stages, under various levels of seismic excitation. In order to know the probability of exceeding damage limit stages and relationship between corrosion level and capacity, the analytical fragility curves are developed by results of the nonlinear static pushover analysis procedure with respect to the Peak Ground Acceleration for seismic damage assessment of bridges. Evaluation of twenty four bridges in Taiwan shows that material degradation due to corrosion in bridges structure affect either the pushover analysis result of the bridges and PGA capacity of the bridges. From the service year and PGA reduction relationship shows that 1st Bridge has the quickest time (47 year) to get Ac X < design PGA. It is because 1st bridge has closer distance to the ocean (0.9 km). That’s why 1st bridge satisfies the performance in the initial condition but After 47 years of service, collapse PGA becomes not satisfying because of corrosion. The relationship also shows that 10th bridge has the highest reduction for PGA, 0.01g /10year. It’s because this bridge located in medium distance to the ocean (6.5 km), have thin cover depth and small diameter size of longitudinal bar. The closer distance to the ocean, thinner depth of cover concrete and smaller size of longitudinal bar will higher reduce the PGA value. Therefore reduction of PGA value depends on distance to the ocean, thin or thickness of cover concrete depth and diameter size of longitudinal reinforcement. Based on the seismic fragility curves, Normalized PGA vs Corrosion level shows that corrosion level 20% in longitudinal reinforcement is enough to get half capacity in x or y direction exceeding 50% damage. Thus it is very important to consider corrosion in reinforced concrete bridges.
35
Sivaramakrishnan, Balaji. "Non-linear modeling parameters for reinforced concrete columns subjected to seismic loads." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2635.
Анотація:
The American Society of Civil Engineers (ASCE) Standard 41-06 Supplement No.1 (2007) assists engineers in modeling and evaluating the non-linear behavior of structures till collapse. Different levels of conservatism were used throughout the standard to produce modeling parameters for different structural elements, which leads to inconsistencies at the system level. Task to update current ASCE 41-06 provisions pertaining to RC structures is now handled by ACI (American Concrete Institute) committee 369 entitled “Seismic Repair and Rehabilitation”. This study is a part of ACI 369 committee’s effort.
Existing provisions for non-linear analysis are re-assessed in this study for both rectangular and circular reinforced concrete columns. A database of 490 column tests was compiled for this project. Median rather than conservative estimates of non-linear modeling parameters were produced to achieve “best” estimates of structural behavior. Proposed modeling parameters show improved fit with experimental data over existing parameters. Data necessary for selection of acceptance criteria are provided.text
36
O'Brien, William Charles Memari Ali M. "Development of a closed-form equation and fragility curves for performance-based seismic design of glass curtain wall and storefront systems." 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-3872/index.html.
37
Monchetti, Silvia. "On the role of uncertainties in the seismic risk assessment of historic masonry towers." Doctoral thesis, 2018. http://hdl.handle.net/2158/1130895.
Анотація:
The research activity developed in the present work achieved both technical and scientific results on the seismic risk assessment of masonry towers. It provided semi empirical formulations for the main frequency estimation based on a wide database of historic masonry towers and a novel framework for the seismic risk assessment starting from the Bayesian model updating using dynamic experimental data.
The recent Italian earthquakes have dramatically highlighted the vulnerability of historic masonry constructions and the need to improve the knowledge on their seismic response. Due to this fact, the challenging issue of obtaining a reliable structural model has become increasingly relevant to the scientific community, promoting the employment of sophisticated tools of analysis and the need of numerical models to be set up. However, the significant lack of knowledge on historical structures (e.g., material properties, geometry, construction techniques, boundary conditions), still makes their numerical modelling difficult. The knowledge of the seismic response of this structural typology, taking into account uncertain parameters, represents a critical issue and the main scientific question to which this work aimed to answer.
The framework proposed in this research started with the Finite Element (FE) model updating of masonry towers through Bayesian approach; the prior distribution of relevant uncertain model parameters was converted into the posterior one by using experimental dynamic data. Nonlinear static analyses were employed to estimate the uncertainties in the seismic response of masonry towers. Taking into account both the modelling and the measurement uncertainties, fragility curves were defined related to different towers damage levels. Eventually, the seismic hazard was considered thus leading to the seismic risk assessment of masonry towers.
The idea of this work started from the necessity of obtaining a better awareness of the uncertainties involved in the seismic capacity prediction of historic constructions, and their effect on the overall reliability.
Although the proposed results are based on the application to a real case study, the procedure may be used for other similar structures and may represent an effective and alternative tool for the seismic risk quantification of historic masonry constructions.
38
Σκαλωμένος, Κωνσταντίνος. "Seismic performance of plane moment resisting frames with concrete filled steel tube columns and steel I beams." Thesis, 2014. http://hdl.handle.net/10889/8442.
Анотація:
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.
39
Ασκούνη, Παρασκευή. "Καμπύλες σεισμικής τρωτότητας γεφυρών οπλισμένου σκυροδέματος". Thesis, 2012. http://hdl.handle.net/10889/5664.
Анотація:
Στην παρούσα εργασία αναπτύχθηκαν καμπύλες τρωτότητας οδικών και σιδηροδρομικών γεφυρών οπλισμένου σκυροδέματος που συναντώνται στην Ευρώπη. Οι κατηγορίες που εξετάστηκαν ήταν αυτές των κανονικών γεφυρών, με συνεχές κατάστρωμα συνδεδεμένο με τα βάθρα είτε μονολιθικά είτε μέσω ελαστομεταλλικών εφεδράνων. Άλλες παράμετροι που θεωρήθηκαν όσον αφορά στην τυπολογία των γεφυρών είναι το μήκος της γέφυρας, το ύψος των βάθρων και η διατομή τους, ο αριθμός των υποστυλωμάτων ανά βάθρο και το επίπεδο αντισεισμικού σχεδιασμού. Ο σχεδιασμός, η διαστασιολόγηση και οι λεπτομέρειες όπλισης έγιναν βάσει του Ευρωκώδικα 2 για γέφυρες που δεν υποβάλλονται σε σεισμική φόρτιση και του Ευρωκώδικας 8 για γέφυρες που σχεδιάζονται αντισεισμικά. Για την εκτίμηση στη συνέχεια των αντισεισμικών απαιτήσεων πραγματοποιήθηκε γραμμική ελαστική ανάλυση σύμφωνα με το μέρος 3 του Ευρωκώδικα 8 χρησιμοποιώντας την επιβατική δυσκαμψία των βάθρων και το ελαστικό φάσμα απόκρισης. Εν τέλει ότι οι συναρτήσεις τρωτότητας κατασκευάστηκαν έχοντας λάβει υπόψη την αβεβαιότητα του μοντέλου όσον αφορά στην σεισμική απόκριση και αντοχή, την διασπορά στην αντοχή των υλικών και τα γεωμετρικά χαρακτηριστικά και την αβεβαιότητα των φασματικών τιμών.This study presents first a literature review of existing fragility functions for bridges and then new fragility curves that were produced for European road and railway RC bridges. Regular bridges with continuous deck, connected to the piers either monolithically or through elastomeric bearings, were studied. Other variable parameters were: bridge length, pier height and cross-section, number of columns per pier and level of seismic design. Each bridge was designed, dimensioned and detailed according to Eurocode 2 and, for bridges with seismic design, according to Eurocode 8. Linear elastic analysis was subsequently performed according to Part 3 of Eurocode 8 to estimate the seismic demand. Fragility functions were then constructed accounting for the model uncertainty for demand and capacity, the dispersion of material and geometric properties and the uncertainty of spectral values.