Dissertations / Theses: 'Seismic Isolation System'

1

Kelly, John P. (John Peter) 1977. "The installation of a seismic isolation system for building retrofit." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84262.

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2

LUCIA, TROZZO. "Low Frequency Optimization and Performance of Advanced Virgo Seismic Isolation System." Doctoral thesis, Università di Siena, 2018. http://hdl.handle.net/11365/1052744.

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The Gravitational Waves are perturbations of the metric of the space-time. Their effect on free falling masses is to alter their distance. The typical order of magnitude of the gravitational wave signal (for kilometer-scale distances), it is around 10−18m and for this reason it has been chosen to exploit the precision allowed by laser optics and symmetric interferometric detection for these devices. Since present interferometers are ground-based, the mirror suspension attenuation system, as well as its control strategy, is fundamental. Virgo detector was designed not to be limited by seismic noise starting from 10 Hz. To this purpose the INFN-Pisa Group developed and built a sophisticated system, the so-called Superattenuator, allowing to consider the mirror test masses as free-falling from few Hz. In order to be compatible with the amplitude of the gravitational signal to be detected, a hierarchical control scheme for the suspensions must be implemented. The main control implemented, applied to the Superattenuator top-stage is the active mode damping, the so-called Inertial Damping. The sophisticated mechanical design of the overall suspension and the performance of the Inertial Damping are among the key features of Virgo. The target of this thesis is the reduction of the impact of this control on the actual AdV sensitivity and the study of possible alternative developments, as Kalman filtering and Optimal control approach. In this document, modeling and simulation studies based upon actual data are presented in the context of AdV commissioning works.

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3

Kalantari, Afshin. "Artificially generated nonlinear structural system by smart seismic isolation using variable dampers." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/144542.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第11870号
工博第2563号
新制||工||1358(附属図書館)
23650
UT51-2005-N704
京都大学大学院工学研究科土木システム工学専攻
(主査)教授家村浩和, 教授松久寛, 助教授五十嵐晃
学位規則第4条第1項該当

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4

ZEESHAN, BADAR-UL-ALI. "Constructing an Innovative Base-Isolation System under Masonry Structures." Doctoral thesis, Politecnico di Torino, 2014. http://hdl.handle.net/11583/2540704.

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Seismic up-gradation of existing buildings is a very challenging task, as it requires us to consider historical and economical aspects of building. While proposing a seismic-retrofit scheme for a historical building, one should keep in mind that it should be compatible with existing materials, be least intrusive, monitorable and removable. A novel base-isolation technique has been proposed for the up-gradation of existing buildings against seismic actions which does not involve any alteration in existing buildings, and it is monitorable and removable. The method asks for the uncoupling of soil under, and around the building, with the help of closely spaced microtunnels, trenches and retaining walls. Closely spaced microtunnels will lay under the foundation of building, running parallel to one of the dimension of the building, and base-isolation devices will be fitted in lining of these microtunnels. These closely spaced micro-tunnels, along with the trenches and retaining walls around the building, will isolate the structure from seismic actions. This assembly of microtunnels, fitted with isolation devices, and trenches, around the building, will be able to filter seismic forces in both directions of building. The construction of these micro-tunnels, for realisation of innovative base-isolation technique, is the most critical phase, because it can have a detrimental effect on building. This work explores the potential applicability of the novel base-isolation method on masonry buildings by assessing susceptibility of masonry wall, having different physical and material characteristics, to damage (relating to aesthetic of building) inflicted by the construction of microtunnels in various soil conditions. The effect of transverse ground movements is considered in this study. A parametric study is conducted using 2-D (coupled) nonlinear finite element analyses, considering factors such as strength and stiffness of masonry, stiffness of soil, soil-structure interface, excavation sequence of tunnels, different physical characteristics of wall and depth of tunnels. The study shows the applicability of innovative base-isolation technique, highlights the vulnerability levels of walls of different physical characteristics, emphasizes the importance of excavation sequence of microtunnels in reducing risk of damage, and mentions symptoms that correlate with damage.

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5

Eroz, Murat. "Advanced models for sliding seismic isolation and applications for typical multi-span highway bridges." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19709.

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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.
Committee Chair: DesRoches, Reginald; Committee Member: Goodno, Barry; Committee Member: Jacobs, Laurence; Committee Member: Streator, Jeffrey; Committee Member: White, Donald.

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6

Zhang, Zhi, and Zhi Zhang. "Analytical Investigation of Inertial Force-Limiting Floor Anchorage System for Seismic Resistant Building Structures." Diss., The University of Arizona, 2017. http://hdl.handle.net/10150/625385.

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This dissertation describes the analytical research as part of a comprehensive research program to develop a new floor anchorage system for seismic resistant design, termed the Inertial Force-limiting Floor Anchorage System (IFAS). The IFAS intends to reduce damage in seismic resistant building structures by limiting the inertial force that develops in the building during earthquakes. The development of the IFAS is being conducted through a large research project involving both experimental and analytical research. This dissertation work focuses on analytical component of this research, which involves stand-alone computational simulation as well as analytical simulation in support of the experimental research (structural and shake table testing). The analytical research covered in this dissertation includes four major parts: (1) Examination of the fundamental dynamic behavior of structures possessing the IFAS (termed herein IFAS structures) by evaluation of simple two-degree of freedom systems (2DOF). The 2DOF system is based on a prototype structure, and simplified to represent only its fundamental mode response. Equations of motions are derived for the 2DOF system and used to find the optimum design space of the 2DOF system. The optimum design space is validated by transient analysis using earthquakes. (2) Evaluation of the effectiveness of IFAS designs for different design parameters through earthquake simulations of two-dimensional (2D) nonlinear numerical models of an evaluation structure. The models are based on a IFAS prototype developed by a fellow researcher on the project at Lehigh University. (3) Development and calibration of three-dimensional nonlinear numerical models of the shake table test specimen used in the experimental research. This model was used for predicting and designing the shake table testing program. (4) Analytical parameter studies of the calibrated shake table test model. These studies include: relating the shake table test performance to the previous evaluation structure analytical response, performing extended parametric analyses, and investigating and explaining certain unexpected shake table test responses. This dissertation describes the concept and scope of the analytical research, the analytical results, the conclusions, and suggests future work. The conclusions include analytical results that verify the IFAS effectiveness, show the potential of the IFAS in reducing building seismic demands, and provide an optimum design space of the IFAS.

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7

TROVATO, DANIELE. "Degradation of Dissipative Characteristics of Friction Pendulum Isolators due to Thermal Effect." Doctoral thesis, Politecnico di Torino, 2013. http://hdl.handle.net/11583/2518996.

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The purpose of the research is to predict the reliability of friction pendulum devices during their service life. These bearings are characterized by the capability to undergo large displacements despite their compact size. This peculiar property makes this device competitive among other commonly used isolation devices such as lead-rubber bearings. In these supports the dissipation of seismic motion occurs exclusively by the friction produced during sliding of the surfaces while the seismic isolation is obtained by the shifting of the natural period of the superstructure. Over the time, the interest of the scientific community for such devices has focused on the study of the friction coefficient involved during the motion and also on its dependence on certain mechanical variables such as velocity and apparent pressure. Several studies have shown that the friction coefficient in a contact problem between polymer (PTFE) and stainless steel deviates from the Coulomb’s friction law. Furthermore, most recent studies have shown that the coefficient of friction is closely related to the increase of temperature due to the thermal effect. This phenomenon consists in a cyclic degradation of the dissipative capacities of friction pendulum that in the design phase is not considered. The observed reduction of energy dissipated during repetitive cycles is often coupled with peak displacements larger than predicted with potential consequences on the whole structure’s safety. This PhD study is composed by 8 chapter and it start with an introduction of the basic concept in seismic base isolation (Chapter 2) while the main characteristics of friction pendulum devices are introduced are defined in Chapter 3. The basic theory of frictional heating useful to describe the increase of temperature which occurs in polymer-stainless steel surface is introduced in chapter 4. Through an experimental campaign carried out with single pendulum bearings, the dependence of the friction coefficient with the temperature rise has been investigated in chapter 5, in order to propose a phenomenological model able to assess the real performance of the friction pendulum. Specifically, in chapter 5 is described the experimental analysis carried out in Caltrans SRMD Testing Facility of San Diego University of California. A series of friction pendulum have been tested at Caltrans SRMD which is equipped with a shaking table test specifically designed for full-scale tests. During the tests, the table was also equipped with a thermographic camera specially calibrated for the type of material tested (polished stainless steel). Thanks to the use of the camera it has been possible to evaluate the temperature rise during the whole testing time and in the portion of the concave surface affected by the thermal heating. In chapter 6, an analytical comparison has been carried out between the friction coefficient recorded during the test and the temperature rise obtained with the analytical model of degradation of the friction coefficient introduced in chapter 4. Finally in chapter 7 a prediction model that takes into account mechanical variables such as velocity and apparent pressure, and also the degradation of dissipative characteristics of a friction pendulum due to thermal effects, is given. The proposed friction model is suitable for immediate implementation in generalized structural analysis codes and provides an important design tool for a more realistic assessment of the seismic response of structures equipped with Friction Pendulum devices.

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8

Wenzel, Moritz. "Development of a Metamaterial-Based Foundation System for the Seismic Protection of Fuel Storage Tanks." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/256685.

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Metamaterials are typically described as materials with ’unusual’ wave propagation properties. Originally developed for electromagnetic waves, these materials have also spread into the field of acoustic wave guiding and cloaking, with the most relevant of these ’unusual’ properties, being the so called band-gap phenomenon. A band-gap signifies a frequency region where elastic waves cannot propagate through the material, which in principle, could be used to protect buildings from earthquakes. Based on this, two relevant concepts have been proposed in the field of seismic engineering, namely: metabarriers, and metamaterial-based foundations. This thesis deals with the development of the Metafoundation, a metamaterial-based foundation system for the seismic protection of fuel storage tanks against excessive base shear and pipeline rupture. Note that storage tanks have proven to be highly sensitive to earthquakes, can trigger sever economic and environmental consequences in case of failure and were therefore chosen as a superstructure for this study. Furthermore, when tanks are protected with traditional base isolation systems, the resulting horizontal displacements, during seismic action, may become excessively large and subsequently damage connected pipelines. A novel system to protect both, tank and pipeline, could significantly augment the overall safety of industrial plants. With the tank as the primary structure of interest in mind, the Metafoundation was conceived as a locally resonant metamaterial with a band gap encompassing the tanks critical eigenfrequency. The initial design comprised a continuous concrete matrix with embedded resonators and rubber inclusions, which was later reinvented to be a column based structure with steel springs for resonator suspension. After investigating the band-gap phenomenon, a parametric study of the system specifications showed that the horizontal stiffness of the overall foundation is crucial to its functionality, while the superstructure turned out to be non-negligible when tuning the resonators. Furthermore, storage tanks are commonly connected to pipeline system, which can be damaged by the interaction between tank and pipeline during seismic events. Due to the complex and nonlinear response of pipeline systems, the coupled tank-pipeline behaviour becomes increasingly difficult to represent through numerical models, which lead to the experimental study of a foundation-tank-pipeline setup. Under the aid of a hybrid simulation, only the pipeline needed to be represented via a physical substructure, while both tank and Metafoundation were modelled as numerical substrucutres and coupled to the pipeline. The results showed that the foundation can effectively reduce the stresses in the tank and, at the same time, limit the displacements imposed on the pipeline. Leading up on this, an optimization algorithm was developed in the frequency domain, under the consideration of superstructure and ground motion spectrum. The advantages of optimizing in the frequency domain were on the one hand the reduction of computational effort, and on the other hand the consideration of the stochastic nature of the earthquake. Based on this, two different performance indices, investigating interstory drifts and energy dissipation, revealed that neither superstructure nor ground motion can be disregarded when designing a metamaterial-based foundation. Moreover, a 4 m tall optimized foundation, designed to remain elastic when verified with a response spectrum analysis at a return period of 2475 years (according to NTC 2018), reduced the tanks base shear on average by 30%. These results indicated that the foundation was feasible and functional in terms of construction practices and dynamic response, yet unpractical from an economic point of view. In order to tackle the issue of reducing the uneconomic system size, a negative stiffness mechanism was invented and implemented into the foundation as a periodic structure. This mechanism, based on a local instability, amplified the metamaterial like properties and thereby enhanced the overall system performance. Note that due to the considered instability, the device exerted a nonlinear force-displacement relationship, which had the interesting effect of reducing the band-gap instead of increasing it. Furthermore, time history analyses demonstrated that with 50% of the maximum admissible negative stiffness, the foundation could be reduced to 1/3 of its original size, while maintaining its performance. Last but not least, a study on wire ropes as resonator suspension was conducted. Their nonlinear behaviour was approximated with the Bouc Wen model, subsequently linearized by means of stochastic techniques and finally optimized with the algorithm developed earlier. The conclusion was that wire ropes could be used as a more realistic suspension mechanism, while maintaining the high damping values required by the optimized foundation layouts. In sum, a metamaterial-based foundation system is developed and studied herein, with the main findings being: (i) a structure of this type is feasible under common construction practices; (ii) the shear stiffness of the system has a fundamental impact on its functionality; (iii) the superstructure cannot be neglected when studying metamaterial-based foundations; (iv) the complete coupled system can be tuned with an optimization algorithm based on calculations in the frequency domain; (v) an experimental study suggests that the system could be advantageous to connected pipelines; (vi) wire ropes may serve as resonator suspension; and (vii) a novel negative stiffness mechanism can effectively improve the system performance.

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9

Wenzel, Moritz. "Development of a Metamaterial-Based Foundation System for the Seismic Protection of Fuel Storage Tanks." Doctoral thesis, Università degli studi di Trento, 2020. http://hdl.handle.net/11572/256685.

Full text

Abstract:

Metamaterials are typically described as materials with ’unusual’ wave propagation properties. Originally developed for electromagnetic waves, these materials have also spread into the field of acoustic wave guiding and cloaking, with the most relevant of these ’unusual’ properties, being the so called band-gap phenomenon. A band-gap signifies a frequency region where elastic waves cannot propagate through the material, which in principle, could be used to protect buildings from earthquakes. Based on this, two relevant concepts have been proposed in the field of seismic engineering, namely: metabarriers, and metamaterial-based foundations. This thesis deals with the development of the Metafoundation, a metamaterial-based foundation system for the seismic protection of fuel storage tanks against excessive base shear and pipeline rupture. Note that storage tanks have proven to be highly sensitive to earthquakes, can trigger sever economic and environmental consequences in case of failure and were therefore chosen as a superstructure for this study. Furthermore, when tanks are protected with traditional base isolation systems, the resulting horizontal displacements, during seismic action, may become excessively large and subsequently damage connected pipelines. A novel system to protect both, tank and pipeline, could significantly augment the overall safety of industrial plants. With the tank as the primary structure of interest in mind, the Metafoundation was conceived as a locally resonant metamaterial with a band gap encompassing the tanks critical eigenfrequency. The initial design comprised a continuous concrete matrix with embedded resonators and rubber inclusions, which was later reinvented to be a column based structure with steel springs for resonator suspension. After investigating the band-gap phenomenon, a parametric study of the system specifications showed that the horizontal stiffness of the overall foundation is crucial to its functionality, while the superstructure turned out to be non-negligible when tuning the resonators. Furthermore, storage tanks are commonly connected to pipeline system, which can be damaged by the interaction between tank and pipeline during seismic events. Due to the complex and nonlinear response of pipeline systems, the coupled tank-pipeline behaviour becomes increasingly difficult to represent through numerical models, which lead to the experimental study of a foundation-tank-pipeline setup. Under the aid of a hybrid simulation, only the pipeline needed to be represented via a physical substructure, while both tank and Metafoundation were modelled as numerical substrucutres and coupled to the pipeline. The results showed that the foundation can effectively reduce the stresses in the tank and, at the same time, limit the displacements imposed on the pipeline. Leading up on this, an optimization algorithm was developed in the frequency domain, under the consideration of superstructure and ground motion spectrum. The advantages of optimizing in the frequency domain were on the one hand the reduction of computational effort, and on the other hand the consideration of the stochastic nature of the earthquake. Based on this, two different performance indices, investigating interstory drifts and energy dissipation, revealed that neither superstructure nor ground motion can be disregarded when designing a metamaterial-based foundation. Moreover, a 4 m tall optimized foundation, designed to remain elastic when verified with a response spectrum analysis at a return period of 2475 years (according to NTC 2018), reduced the tanks base shear on average by 30%. These results indicated that the foundation was feasible and functional in terms of construction practices and dynamic response, yet unpractical from an economic point of view. In order to tackle the issue of reducing the uneconomic system size, a negative stiffness mechanism was invented and implemented into the foundation as a periodic structure. This mechanism, based on a local instability, amplified the metamaterial like properties and thereby enhanced the overall system performance. Note that due to the considered instability, the device exerted a nonlinear force-displacement relationship, which had the interesting effect of reducing the band-gap instead of increasing it. Furthermore, time history analyses demonstrated that with 50% of the maximum admissible negative stiffness, the foundation could be reduced to 1/3 of its original size, while maintaining its performance. Last but not least, a study on wire ropes as resonator suspension was conducted. Their nonlinear behaviour was approximated with the Bouc Wen model, subsequently linearized by means of stochastic techniques and finally optimized with the algorithm developed earlier. The conclusion was that wire ropes could be used as a more realistic suspension mechanism, while maintaining the high damping values required by the optimized foundation layouts. In sum, a metamaterial-based foundation system is developed and studied herein, with the main findings being: (i) a structure of this type is feasible under common construction practices; (ii) the shear stiffness of the system has a fundamental impact on its functionality; (iii) the superstructure cannot be neglected when studying metamaterial-based foundations; (iv) the complete coupled system can be tuned with an optimization algorithm based on calculations in the frequency domain; (v) an experimental study suggests that the system could be advantageous to connected pipelines; (vi) wire ropes may serve as resonator suspension; and (vii) a novel negative stiffness mechanism can effectively improve the system performance.

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10

Dehghanpoor, Sichani Ahmad. "Soil-pile-superstructure systems under combined horizontal and vertical strong ground motions." Thesis, Queensland University of Technology, 2021. https://eprints.qut.edu.au/207885/1/Ahmad_Dehghanpoor%20Sichani_Thesis.pdf.

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Highway bridges considered as important but possibly vulnerable superstructures must be studied under natural hazards, such as earthquakes, tsunamis, hurricanes. This thesis was a novel investigation on reinforced concrete bridges under coupled horizontal and vertical ground motions. A variety of ground motions has been examined for different classification of bridges and novel conclusions have been presented in the probabilistic and deterministic frameworks.

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11

Hill, K. E. "The utility of ring springs in seismic isolation systems." Thesis, University of Canterbury. Mechanical Engineering, 1995. http://hdl.handle.net/10092/7923.

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Ring springs are frictional devices consisting of inner and outer ring elements assembled to form a spring stack. External load applied to the spring produces sliding action across mating ring interfaces. Large amounts of energy, as much as 60-70% of the total cycle energy, may be absorbed in overcoming frictional forces. This thesis details the characteristics and dynamic behaviour of ring spring systems and describes the design and testing of a seismic isolation system that uses ring springs. Initially the characteristics and fundamental dynamic behaviour of single-degree-of-freedom mass/ring spring systems are studied. This study uses a model based upon the non-linear force/deflection characteristics of the ring spring. A prototype ring spring cartridge that enables dynamic inputs to be applied to a ring spring was then designed and subjected to short duration shock excitation. Experimental results are compared with those given by computer simulation and are seen to be in good agreement. Ring springs have been identified as suitable devices for use in earthquake-resistant structures. A particularly attractive candidate for use of ring springs is in protecting columnar structures during earthquakes. To enable further study, a pivotal rocking seismic isolation system was developed. So that computational analyses of these systems could be undertaken, the ring spring model has been incorporated within the computer program RUAUMOKO. Dynamic analyses using RUAUMOKO show that pivotal rocking isolation systems can significantly reduce structural loads during short period type earthquakes. Subsequently, a pivotal rocking seismic isolation system was designed and manufactured. Shaker table tests were then carried out on the rocking system for a range of earthquake inputs. The experimental results show that for columnar structures with fundamental periods in the range of dominant spectral accelerations, structural loads can be significantly reduced during short period type earthquakes. Experimental results compare well with those given by computer simulation, thus confirming the effectiveness of the isolation system. The work outlined in this thesis has established a basis from which further research can be undertaken. The pivotal rocking seismic isolation system developed has potential application to protecting a wide range of columnar structures during short period type earthquakes.

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12

Mori, Atsushi. "Investigation of the behaviour of seismic isolation systems for bridges." Thesis, University of Canterbury. Department of Civil Engineering, 1993. http://hdl.handle.net/10092/2455.

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The thesis is concerned with the experimental and analytical investigations into the behaviour of laminated elastomeric and lead-rubber bearings as seismic isolation bearings for bridges. Seismic isolation as a seismic design option has become popular over the past decade. During last several years, Japan, Italy and the U.S.A. have been making great progress following the great contribution of New Zealand in this area. Despite new developments in seismic isolation systems, the New Zealand lead-rubber bearings (LRB) still lead with their reputation for reliable performance. The design methods for lead-rubber bearings applied for both bridges and buildings are provided in each of these countries but with differences to allow for variations in codes and design applications. However the basic concepts of these design methods are similar and are partially based on empirical backgrounds. Acknowledging the above status, the experimental and analytical investigations into the lead-rubber and laminated elastomeric bridge bearings were carried out under compression, shear and rotation loading states. A maximum bearing compressive strain of about 6% was reached in the compression tests. In the shear tests, a maximum bearing shear strain of 200% was reached in the load-deflection response and the lead-rubber bearings showed almost the same shear stiffness as the elastomeric bearings after yield of the lead. The rotation tests were performed over the limitations stipulated in the current design codes showing a constant linear stiffness independent of the axial load levels on the bearings. The analytical investigation using the finite element method indicated that the steel shims in the bearings might exceed the yield point somewhere between 100% and 150% bearing shear stains, The shear strains in the rubber due to different types of loading calculated by the existing code relationships, and which are usually the governing factor for the bearing design, were not in reasonable agreement with the analytically obtained values except under compression. The relationships for predicting load-deflection response of the bearings used in the bearing design methods always gave excessive values when compared with the experimentally and analytically obtained values. Based on the findings in the experimental and analytical work, several recommendations for the design of seismic isolation bridge bearings are presented. Moreover, the dynamic response analysis for bridges incorporating seismic isolation systems is carried out under different seismic excitations to confirm the benefits of the seismic isolation systems. As a consequence, for continuous multi-span long bridges the benefits due to seismic isolation in terms of reducing member forces in the bridge and keeping the dynamic behaviour of bridge piers uniform regardless of travelling velocities of the seismic wave are greater when compared with those for standard bridge structures.

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13

Susila, Gede Adi. "Experimental and numerical studies of masonry wall panels and timber frames of low-rise structures under seismic loadings in Indonesia." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/experimental-and-numerical-studies-of-masonry-wall-panels-and-timber-frames-of-lowrise-structures-under-seismic-loadings-in-indonesia(3ceb094b-4e6e-432a-b3de-3d4c306b0551).html.

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Indonesia is a developing country that suffers from earthquakes and windstorms and where at least 60% of houses are non-engineered structures, built by unskilled workers using masonry and timber. The non-engineered housing units developed in urban region are also vulnerable to seismic hazard due to the use of low quality of material and constructions method. Those structures are not resistant to extreme lateral loads or ground movement and their failure during an earthquake or storm can lead to significant loss of life. This thesis is concerned with the structural performance of Indonesian low-rise buildings made of masonry and timber under lateral seismic load. The research presented includes a survey of forms of building structure and experimental, analytical and numerical work to predict the behaviour of masonry wall and traditional timber frame buildings. Experimental testing of both masonry and timber have been carried out in Indonesia to establish the quality of materials and to provide material properties for numerical simulations. The experimental study found that the strength of Indonesia-Bali clay brick masonry are below the minimum standard required for masonry structures built in seismic regions, being at least 50% lower than the requirement specified in British Standard and Eurocode-6 (BS EN 1996-1-1:2005). In contrast, Indonesian timber materials meet the strength classes specified in British Standard/Eurocode- 5 (BS EN 338:2009) in the range of strength grade D35-40 and C35).Structural tests under monotonic and cyclic loading have been conducted on building components in Indonesia, to determine the load-displacement capacity of local hand-made masonry wall panels and timber frames in order to: (1) evaluate the performance of masonry and timber frame structure, (2) investigate the dynamic behaviour of both structures, (3) observe the effect of in-plane stiffness and ductility level, and (4) examine the anchoring joint at the base of timber frame that resists the overturning moment. From these tests, the structural ductility was found to be less than two which is below the requirement of the relevant guidelines from the Federal Emergency Management Agency, USA (FEMA-306). It was also observed that the lateral stiffness of masonry wall is much higher than the equivalent timber frame of the same height and length. The experimental value of stiffness of the masonry wall panel was found to be one-twelfth of the recommended values given in FEMA-356 and the Canadian Building code. The masonry wall provides relatively low displacement compared to the large displacement of the timber frame at the full capacity level of lateral load, with structural framing members of the latter remaining intact. The weak point of the timber frame is the mechanical joint and the capacity of slip joint governs the lateral load capacity of the whole frame. Detailed numerical models of the experimental specimens were setup in Abaqus using three-dimensional solid elements. Cohesive elements were used to simulate the mortar behaviour, exhibiting cracking and the associated physical separation of the elements. Appropriate contact definitions were used where relevant, especially for the timber frame joints. A range of available material plasticity models were reviewed: Drucker-Prager, Crystalline Plasticity, and Cohesive Damage model. It was found that the combination of Crystalline Plasticity model for the brick unit and timber, and the Cohesive Damage model for the mortar is capable of simulating the experimental load-displacement behaviour fairly accurately. The validated numerical models have been used to (1) predict the lateral load capacity, (2) determine the cracking load and patterns, (3) carry out a detailed parametric study by changing the geometric and material properties different to the experimental specimens. The numerical models were used to assess different strengthening measures such as using bamboo as reinforcement in the masonry walls for a complete single storey, and a two-storey houses including openings for doors and windows. The traditional footing of the timber structures was analysed using Abaqus and was found to be an excellent base isolation system which partly explains the survival of those structures in the past earthquakes. The experimental and numerical results have finally been used to develop a design guideline for new construction as well as recommendations for retrofitting of existing structures for improved performance under seismic lateral load.

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14

Acar, Emre. "Comparison Of Design Codes For Seismically Isolated Structures." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607015/index.pdf.

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This study presents information on the design procedure of seismic base isolation systems. Analysis of the seismic responses of isolated structures, which is oriented to give a clear understanding of the effect of base isolation on the nature of the structure
and discussion of various isolator types are involved in this work. Seismic isolation consists essentially of the installation of mechanisms, which decouple the structure, and its contents, from potentially damaging earthquake induced ground motions. This decoupling is achieved by increasing the horizontal flexibility of the system, together with providing appropriate damping. The isolator increases the natural period of the overall structure and hence decreases its acceleration response to earthquake-generated vibrations. This increase in period,together with damping, can reduce the effect of the earthquakes, so that smaller loads and deformations are imposed on the structure and its components. The key references that are used in this study are the related chapters of FEMA and IBC2000 codes for seismic isolated structures. In this work, these codes are used for the design examples of elastomeric bearings. Furthermore, the internal forces develop in the superstructure during a ground motion is determined
and the different approaches defined by the codes towards the &lsquo
scaling factor&rsquo
concept is compared in this perspective.

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15

Han, Mengyu. "Application of Base Isolation Systems to Reinforced Concrete Frame Buildings." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35722.

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Seismic isolation systems are widely used to protect reinforced concrete (RC) structures against the effects of strong ground motions. After a magnitude 6.6 earthquake, the outpatient building of Lushan People’s hospital in China remained in good condition due to the seismic isolation technology, while the non-isolated older outpatient building nearby experienced major damage. The building provides a good opportunity to study and assess the contribution of isolation systems to seismic performance of RC structures. In the current research project, the isolated outpatient building was modelled and analyzed using computer software SAP2000. The post-yield behaviour of the structure was modelled by assigning multi-linear plastic links to frame objects. The rubber isolators were represented by rubber isolator link elements, assigned as a single joint element between the ground and the superstructure. The isolated structure was subjected to four earthquake records with increasing intensity. The performances of the isolated structure were compared with those of the fixed-base structures in terms of lateral inter-storey drifts, peak absolute floor accelerations, and residual drifts. The laminated rubber bearings, the high damping isolation devices, composed of rubber bearings and viscous dampers, and the hybrid isolation system of rubber bearings and friction pendulum bearings were analysed. The effectiveness of the three base isolation systems considered in enhancing structural performance was investigated. The results show the level of improvement attained in seismic response by each system. They also illustrate that the rubber bearings coupled with friction pendulum bearings produce the best drift control without causing excessive horizontal displacements at the base level and without adversely affecting floor accelerations.

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16

Taghikhany, Touraj. "Effect of variation of normal force on seismic performance of resilient sliding isolation systems." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/145348.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(工学)
甲第11134号
工博第2413号
新制||工||1321(附属図書館)
22703
UT51-2004-R10
京都大学大学院工学研究科土木システム工学専攻
(主査)教授家村浩和, 教授スコーソンチャールズ, 教授鈴木祥之
学位規則第4条第1項該当

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17

Brisebois, Philippe. "Combination of thermal and seismic displacements for the design of base isolation systems of bridges in Canada." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=107718.

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Base isolation systems are commonly used in the design of new bridges, and in the retrofit of existing ones. However, in Canada, base isolators are relatively new. They act as bridge bearings and isolate or decouple the superstructure from the underlying substructure to reduce the force generated in the structure by ground-motions. Horizontal displacements of isolators due to thermal and seismic loads are addressed in the Canadian Highway Bridge Design Code (CHBDC) CSA-S6-06 and adequate clearance must be provided. However, the Canadian code does not offer any guidance on how to combine these displacements. The objective of this thesis is to present the calculation methods of these displacements and to suggest different ways to combine them. Two bridges are analyzed in this thesis under Montreal's and Vancouver's thermal and seismic provisions to define a proposed thermal and seismic displacement combination formula for the design of base isolators in bridges in Canada.
Les isolateurs sismiques sont utilisés de plus en plus couramment pour la conception des nouveaux ponts ou pour la réfection des ponts existants. Or, ces isolateurs sont relativement nouveaux au Canada. En général, ils protègent la structure du pont en découplant le mouvement du sol du mouvement de la structure et en augmentant la période de vibration afin de réduire les accélérations transmises à la structure. Ces appuis sont conçus pour des déplacements admissibles spécifiés. La norme canadienne des ponts (CSA-S6) adresse les déplacements sismiques et thermiques, mais n'offre aucune directive sur la combinaison de ces déplacements. L'objectif de ma thèse est de présenter les méthodes de calcul pour ces déplacements et de suggérer diverses approches pour faire la combinaison des déplacements. Les ponts de Madrid et de l'autoroute 30 au-dessus du fleuve St-Laurent sont analysés sous les charges sismiques et thermiques de Montréal et Vancouver pour établir une combinaison optimale des déplacements sismiques et thermiques des isolateurs sismiques des ponts au Canada.

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18

Soyoz, Serdar. "Effects Of Soil Structure Interaction And Base Isolated Systems On Seismic Performance Of Foundation Soils." Master's thesis, METU, 2004. http://etd.lib.metu.edu.tr/upload/12605119/index.pdf.

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In this thesis primarily structural induced liquefaction potential was aimed to be analyzed. Also the effect of base isolation systems both on structural performance and liquefaction potential was studied. FLAC software was chosen for the analyses so that structure and soil could be modeled together. By these means the soil structure interaction effects were also examined. Four different structures and three different sites were analyzed under two different input motions. All the structures were also analyzed as base isolated. It was mainly found that depending on the structural type and for a certain depth the liquefaction potential could be higher under the structure than the one in the free field. Also it was concluded that base isolation systems were very effective for decreasing the story drifts, shear forces in the structure and liquefaction potential in the soil. It was also found that the interaction took place between structure, soil and input motions.

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19

Ivanoska-Dacikj, Aleksandra, Gordana Bogoeva-Gaceva, René Jurk, Sven Wießner, and Gert Heinrich. "Assessment of the dynamic behavior of a new generation of complex natural rubber-based systems intended for seismic base isolation." Sage, 2017. https://tud.qucosa.de/id/qucosa%3A35604.

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This work, conceived as a second step in the development of high-performance damping materials suitable for seismic application, describes the preparation and characterization of complex natural rubber-based composites containing hybrid nano- and conventional fillers. The cluster–cluster aggregation model was used to assess the apparent filler networking energy. The values obtained suggested that the presence of the hybrid nanofiller strengthens the filler networking. The same model was used to understand the mechanisms of energy dissipation. The damping coefficient was found to be in the sought range between 10% and 20% (at 0.5 Hz and high shear strain).

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20

Fitoz, Hatice Eda. "Response Of Asymmetric Isolated Buildings Under Bi-directionalexcitations Of Near-fault Ground Motions." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614121/index.pdf.

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Isolator displacements, floor accelerations, roof displacements, base shear and torsional moments are basic parameters that are considered in the design of seismically isolated structures. The aim of this study is to evaluate the effects of bidirectional earthquake excitations of near fault records on the response of base isolated structures in terms of basic parameters mentioned above. These parameters computed from nonlinear response history analysis (RHA) and they are compared with the parameters computed from equivalent lateral force procedure (ELF). Effect of asymmetry in superstructure is also examined considering mass eccentricity at each floor level. Torsional amplifications in isolator displacements, floor accelerations, roof displacements and base shear are compared for different level of eccentricities. Two buildings with different story heights are used in the analyses.The building systems are modeled in structural analysis program SAP2000. The scaling of ground motion data are taken from the study of &ldquo
Response of Isolated Structures Under Bi-directional Excitations of Near-fault ground Motions&rdquo
(Ozdemir, 2010). Each ground motion set (fault normal and fault parallel) are applied simultaneously for different range of effective damping of lead rubber bearing (LRB) and for different isolation periods.

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21

Wang, Jun. "Seismic isolation analysis of a roller isolation system." 2005. http://proquest.umi.com/pqdweb?did=982824301&sid=28&Fmt=2&clientId=39334&RQT=309&VName=PQD.

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Thesis (Ph.D.)--State University of New York at Buffalo, 2005.
Title from PDF title page (viewed on Mar. 15, 2006) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Lee, George C. Includes bibliographical references.

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22

Huang, Shung-Sheng, and 黃清森. "Seismic Analysis on Sliding Isolation System for Bridges." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/50439861486485839346.

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碩士
國立交通大學
土木工程研究所
83
In this thesis,the seismic behaviors of bridges isolated with sliding systems,including the Teflon bearing and the friction pendulum bearing,are investigated. Since in reality the impact -ing directions of the earthquakes are not necessary along the longitudinal direction of the bridge ,plan motions of the isol -ated are considered in the dynamic analysis.

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23

Kun-AnShiao and 蕭堃安. "An interactive-type dual-isolation system for vertical and horizontal seismic isolation." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/68u66q.

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碩士
國立成功大學
土木工程學系
106
Many studies have confirmed that seismic isolation technology can effectively protect buildings or equipment in strong earthquakes. However, application of seismic isolation systems (SISs) is mostly limited to horizontal isolation, and SISs with both horizontal and vertical isolation capability are rare. Because a vertical SIS must be flexible enough vertically to mitigate vertical ground excitation, this may also reduce the rocking stiffness of the system, simultaneously. As a result, it will easily cause large rocking response and lead to isolation failure in a strong earthquake. On the other hand, an earthquake usually involves both horizontal and vertical ground motions, so the development of horizontal and vertical bi-directional SISs is very important. In this paper, a novel interactive-type dual-isolation system (IDIS) for vertical and horizontal seismic isolation is proposed. The IDIS use the dynamic interaction force between the upper and the bottom substructures exerted by an earthquake to reduce the rocking response (displacement and absolute acceleration) of the isolated structural system. To determine the better parameters for the IDIS, a systematic procedure for parametric study is proposed in this paper. Fourteen sets of earthquake records are considered in the numerical study to verify the capacity of the IDIS. The simulation results show that the IDIS has good anti-rocking capability. As compared with its single-layer isolation counterpart system, the average rocking displacement of the bottom and the upper structure of IDIS can be reduced by 29% and 57%, respectively. The average acceleration of the bottom and the upper substructures of the IDIS can be reduced by 57% and 21%, respectively. Moreover, the corner rocking amplification effect of the IDIS system is less than that of the single-layer system.

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24

Kuo, Tzu-Ching, and 郭子敬. "Seismic protection of structures using stiffness controllable isolation system." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/84084875966927683956.

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碩士
國立高雄第一科技大學
營建工程所
92
Although conventional sliding isolators are very effective for vibration mitigation of structures subjected to regular far-field earthquakes, recent research has shown that they may not be effective for near-field earthquakes, which usually possess a long-period pulse-like waveform. Adding active device in the isolation systems may improve the near-fault responses of conventional sliding isolation, but the required control force is usually very large. In order to overcome this problem, a semi-active sliding isolation system, called Stiffness Controllable Isolation System (SCIS), was proposed in this study. This isolation system produces a semi-active control force by adjusting the isolator’s stiffness. The semi-active force is determined based on a target control force, which is computed according to an active control law. In this study, two types of active control laws were employed to determine the target force, namely, optimal feedback control and modal control. The numerical results showed that for far-field and near-fault earthquakes, the proposed SCIS system is more effective on mitigating both the base displacement and the super-structural acceleration than the pass isolation (conventional sliding isolator), while it requires less control force than its active control counterparts. Finally, a lever mechanism to realize the SCIS system was also proposed in this study. This mechanism alters the restoring stiffness of the isolator by controlling the lever arm. The numerical results demonstrated that the mechanism can achieve the goal of SCIS.

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25

Yeh, Chun-Chih, and 葉俊志. "System Identification of Building with Mid.-Floor Seismic Isolation." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/56048880479693707653.

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26

Kuo, Tai-Chuan, and 郭泰銓. "System Identification of a Building With Mid-story Seismic Isolation." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/95918937497899053939.

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碩士
國立臺灣大學
土木工程學研究所
101
The objective of the research is to establish a system identification procedure of building with mid-story isolation, expecting to identify meaningful and physical parameters of building with a simplified model. We use lump mass method, simplifying a building with mid-story isolation into a four lump mass system. Respectively, these are superstructure, floor above isolation system, substructure and equivalent foundation. And we consider there are three degrees of freedom (longitudinal, transverse and torsional) in every lump mass, total of twelve degrees of freedom. For the superstructure, we use effective modal mass method to simplify multiple degrees of freedom system, and consider torsional coupling effect with it. Bilinear mechanical behavior assumed in isolation story with LRB, following the Skeleton curve in Masing Rule. Besides, in equivalent foundation, we describe the soil-structure interaction system with the Soil Spring Method. Soil and structure are simplified impedance between the effective spring and damping, and assume that the reaction is a non-linear response, following the Bouc-Wen Modal. We use the concept of least square method in the identification. This is a non-linear least square problem because there two eccentricities in superstructure. Therefore, we used Levenberg-Marquardt algorithm to solve non-linear least square problem. In numerical example, we estimated the structure parameter with twelve degrees of freedom of mid-story isolation building modal. Next, we input El Centro earthquake and calculated dynamics response of all degrees of freedom by Newmarkβ linear acceleration method. Subsequently, regarding the behavior of each degree of freedom as measurement data, the identification procedure is executed to verify the suitability of identification theory and modified identification model. The data gathered by strong motion instrumentation program in the New Research Building of Civil Engineering department of National Taiwan University is adopted as measurement data to implement practical analysis, both the single and multi-section identification are accomplished and discussed in the research. Finally, the reliability of the identification procedure is verified by calculating the error index between the result of identification procedure and measurement data.

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27

Fenz, Daniel Mark. "Further development, testing and modeling of the Axon seismic isolation system." 2005. http://wwwlib.umi.com/dissertations/fullcit/1426749.

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Thesis (M.S.)--State University of New York at Buffalo, 2005.
Title from PDF title page (viewed on Feb. 2, 2006) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Michael C. Constantinou.

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28

Chang, Cheng-Lin, and 張正霖. "Effects of Near-Fault Ground Motions on Hysteretic Seismic Isolation System." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/73428312149375981512.

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碩士
國立臺灣科技大學
營建工程系
104
The concept of seismic isolation design method has been accepted as an effective method for the seismic mitigation. However, to design a seismic isolation system against near-fault ground motions has been an important and challenging issue in seismic isolation design. In this study, it is an attempt to identify the effect of various characteristics of near-fault ground motion in affecting the seismic response of isolation system. These important characteristics may include but not limited to the velocity pulse, incremental velocity, peak ground velocity, pulse period, input energy, and momentary input energy. For so doing, 10 far-field ground motions and 30 near-fault ground motions provided by Jack. W. Baker identified based on the wavelet analysis are used for this analytical study. A simple bi-linear base isolation system is assumed and nonlinear response history analysis is conducted to identify the importance of the aforementioned characteristics of near-fault ground motions. The results indicate that peak ground velocity (PGV), incremental velocity, and momentary input energy may be the significant characteristics of near-fault ground motions in affecting the seismic response of isolation system. In addition, the duration of velocity pulse extracted from the original ground motion may also play an important role. However, further study is required to ascertain the importance of the residual ground velocity history after the velocity pulse extraction.

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29

SEBASTIANI, PAOLO EMIDIO. "Performance-based seismic assessment for life-cycle cost analysis of existing bridges retrofitted with seismic isolation." Doctoral thesis, 2016. http://hdl.handle.net/11573/874444.

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This work adopts a probabilistic evaluation approach to investigate the effectiveness of isolation devices for bridges in terms of seismic performance, vulnerability and expected life-cycle cost-benefit. A novel procedure to evaluate a reliable structure-based IM for isolated bridges and an improved life-cycle cost analysis formulation with respect to the existing ones are the two main original contributions. This dissertation has an assessment approach, so for each step some assumptions on the design of intervention, types of modelling and analysis have been introduced. No design optimization is carried out since it was not the purpose of this work, however the assumptions are based on the state of the art and practice and they will be clearly explained together with the limitations that eventually result from them. In order to achieve the purposes, an existing bridge has been selected as case study to take into account the complexity of a real structure. Even though a single case study bridge can restrict the generality of the numerical results, the main contributions mentioned previously consist in procedures that are not conditioned on the case study and that can be readily applied to other bridges. Damage to bridges during an earthquake event can lead to significant service breaks in the transportation system, causing primarily difficulties to the emergency operations. The main consequences due to bridge failure are a potential huge human's life loss and in addiction a wide economic impact on the transportation network, represented mainly by direct repair costs of intervention and indirect costs due to the loss of functionality of the bridge during repair. With specific reference to the Italian transportation network, the majority of the bridges was built between 1960 and 1980, consequently these structures are to date suffering structural deterioration and a large number of them was built following antiquated design standards with deficient or missing design criteria against seismic actions, therefore the issue of retrofitting of bridges assumes a key role, and it needs to be addressed with also reference to the Life-Cycle Cost (LCC) analyses. Between all the several design and retrofit strategies for improving the resistance of bridges to earthquakes, the seismic isolation is nowadays an effective choice for the protection of bridges that has been adopted in bridge design or retrofit for over 35 years in the United States and more recently it has been increasingly adopted also in Italy, especially towards the application of elastomeric bearings and friction-pendulum devices. The modern design philosophies, based on probabilistic performance-based earthquake engineering (PBEE) approaches, provides useful tools to identify the best retrofits for non-seismically designed bridges not only in terms of vulnerability assessment but also in order to achieve goals such as risk mitigation or minimization of economic loss. A primary objective of this work is the effectiveness evaluation of seismic protection devices for bridges following the probabilistic Intensity Measure (IM) based approach developed by the Pacific Earthquake Engineering Research (PEER). In fact, if IM-based approaches are well established and widely studied for bridges and buildings, there has been a very limited research to date regarding the performance assessment of bridges for evaluating the effectiveness of seismic isolation devices. This matter is then considered an actual topic implying a number of additional issues with respect to the case of non-isolated bridges. The elastomeric bearings (ERB) and the friction pendulum system (FPS) are here considered as isolation solutions, and they are applied to an existing railway bridge as case study. The bridge has a continuous five-span steel truss deck with a total length of about 500 m carried by four concrete piers with height ranging from 50 to 130 m. Geometry, loads, structural materials and existing bearings are investigated in order to design and estimate the retrofit interventions in an executable manner which can actually be put into practice. The structural modelling is conducted by developing three-dimensional finite element (FE) models of three bridge configurations (as-built, with ERB and with FPS) and subjecting them to a suite of 80 recorded ground motions with a wide range of spectral properties that are appropriate for isolated bridges. The FE models are developed in OpenSees employing fibre beam column elements for bridge piers and bilinear hysteretic elements for isolation devices. The influence of isolation on the demand for various critical bridge elements is evaluated through the development Probabilistic Seismic Demand Models (PSDMs) with 'cloud' approach to derive analytical fragility functions by nonlinear time history analysis (NLTHA) of the models. Peak ground acceleration (PGA) and Spectral Acceleration (Sa) calculated at different periods are adopted and compared as intensity measures (IMs) in terms of efficiency and sufficiency. To deal with the issue of adopting a reliable structure-based IM for isolated bridges, a novel procedure is introduced for the evaluation of the most appropriate period Ts which makes Sa(Ts) a reliable IM by maximizing its correlation to different components of a complex structure. The proposal of a new property for the IM, additional to efficiency and sufficiency, is addressed. Moreover, after the definition of appropriate limit states, the analysis of vulnerability at component level is addressed, followed by the evaluation of the effectiveness of isolation in terms of total probabilities of failure after the convolution with a seismic hazard coherently evaluated with respect to the selected ground motion set. To prevent high level of damage, both isolation systems give better protection in small piers than high ones, while they give more benefits in high pier for slight level of damage. The ERB results to be the most efficient to reduce the expected damage in the piers' base, however in terms of probability of damage at 1/3 height of the pier the effect of the two isolation systems are comparable. The FPS isolation is more efficient for the small piers than higher ones, for all the limit states. Moreover, the ERB provides a more uniform effect on the piers and better results on high piers than FPS. As mentioned above, life-cycle cost (LCC) analysis for bridges has gained widespread interest in recent years. Nevertheless, the effect of adopting seismic isolation devices for existing or new bridges, needs to be correctly addressed in terms of costs. The lack of knowledge regarding the correct estimation of LCC in presence of these kinds of devices needs to be covered by research, since in literature there are only few examples on how the isolation systems are producing cost-effective solutions for bridge owners. In order to give a contribution in this direction, this work provides an insight regarding the damage restoration of bridge components. The nominal retrofitting costs (initial cost in case of intervention), restoration costs (due to the possible damages in bearings and piers) and indirect costs (due to the loss of functionality of the bridge during repair) are estimated in an executable manner. Finally statistical moments of seismic losses, such as the expected value and variance, are calculated for the three examined bridge configurations by different life-cycle cost formulations (Wen and Kang, 2001, Beck et al., 2002, Wen et al., 2003, Ghosh and Padgett, 2011). The proposal of an improved LCC formulation with particular attention to the issue of a correct evaluation of discount functions to commutate future costs into present values is presented. The benefits of isolation in terms of expected costs are calculated comparing the different solutions.

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30

Huang, Cheng-Kang, and 黃承康. "System Identification of Building with Mid.-Floor Seismic Isolation by Using Output-error method." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/29268377010880830894.

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碩士
國立臺灣大學
土木工程學研究所
98
Abstract The objective of the research is to establish a system identification procedure of mid-story isolation building to identify the meaningful parameters of building with simplified building model. The research simplifies the mid-story isolation building as four degree of freedom system by using lump mass method. The four degree of freedom systems are superstructure, floor above isolation system, substructure and equivalent foundation, respectively. By using effective modal mass and effective modal height method, the multiple degrees of freedom system for superstructure are divided into single degree of freedom system. Assuming the mechanical behaviors of superstructure and substructure are linear, and the behavior of isolation story is non-linear; further, the behavior of isolation story is simplified from non-linear to bilinear behavior by using massing criteria. The damping of isolation story is assumed as non-linear damping in the research, the other freedoms are linear damping. As for the equivalent foundation, a set of equivalent damping and spring is adopted to simulate the soil-structure interaction of the mid-story isolation building, and the mechanic behavior of foundation is assumed as linear; finally, the Output-error method is applied to each degree of freedom to identify the linear parameter of superstructure, substructure and equivalent foundation, and the non-linear parameter of LRB. In numerical examples section, according to the 「Structural computation statement in the New Research Building of Civil Engineering department of Nation Taiwan University」, mass, stiffness, damping parameter of each degree of freedom can be estimated voluntarily. Following the research regards the ground acceleration of TAP089EW921 earthquake as input data, and then the Newmark’s linear acceleration method is used to obtain the behavior of each degree of freedom. Subsequently, regarding the behavior of each degree of freedom as measurement data, the identification procedure is executed to verify the suitability of identification theory and modified identification model. The data gathered by Strong Motion Instrumentation Program in the New Research Building of Civil Engineering department of Nation Taiwan University is adopted as measurement data to implement practical analysis, both the single and multi-section identification are accomplished and discussed in the research. Finally, the reliability of the identification procedure is verified by calculating the error indicators between the result of identification procedure and measurement data.

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31

Shih, Chi-Yang, and 施啟揚. "System Identification of a Building with Mid-story Seismic Isolation using Artificial Neural Networks." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/54560133221255595438.

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碩士
國立臺灣大學
土木工程學研究所
102
In the recent years, the techniques against the earthquake are used to mitigate the effects of nature hazards on civil infrastructure, especially in isolation technology, which widely used in a lot of administrative, commercial and residential buildings. It will help a lot if we can clearly get the characteristics by simplifying isolation technology. So an identification model of isolation building can be established. The objective of the research is to establish a system identification model of building with mid-story isolation, expecting to identify meaningful and physical parameters of building with a simplified model. We use lump mass method, simplifying a building with mid-story isolation into a three lump mass system. Respectively, these are superstructure, isolated-structure and substructure. And we consider there are three degrees of freedom (longitudinal, transverse and torsional) in every lump mass, total of nine degrees of freedom. For the superstructure, we use effective modal mass method to simplify multiple degrees of freedom system, and consider torsional coupling effect with it. Bilinear mechanical behavior assumed in isolation story with LRB, following the Skeleton curve in Masing Rule. In the research, integrating following theory and Artificial Neural Network (ANN), we analyze the relationship between the structure vibration and ground-motion and use Back Propagation Network (BPN) to build the model. We can divide it into two stages, linear and nonlinear model, in the process of development. Linear model is major to build the framework with ANN. By the framework, we can set up bilinear mechanical behavior into nonlinear model. After developing, the model will be verified by numerical analysis after developing at each stage of model development. We design the structure parameter with nine degrees of freedom of mid-story isolation building model. Next, we input El Centro earthquake and calculated dynamics response of all degrees of freedom by Newmark β linear acceleration method. Subsequently, regarding the behavior of each degree of freedom as measurement data, the identification model is executed to verify the suitability of identification theory and modified network framework. In identification of real case, the data gathered by strong motion instrumentation program in the New Research Building of Civil Engineering department of National Taiwan University is adopted as measurement data to implement practical analysis, both the single and multi-section identification are accomplished and discussed in the research. At final, the reliability of the frame of network is verified by calculating the error index between the result of identification model and measurement data.

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32

Wu, Bo-Tsang, and 吳柏蒼. "System Identification of a Building with Mid-Floor Seismic Isolation Using Bouc-Wen Model." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/07614116902163865629.

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Abstract:

碩士
國立臺灣大學
土木工程學研究所
99
This thesis constructs a system identification procedure of building with mid-story isolation , expecting to identify physical parameters of a building with a simplified modal. We used lump mass method, simplifying a building with mid-story isolation into a four degree of freedom system. These degrees of freedom are superstructure, floor above isolation system, substructure and equivalent foundation. For the superstructure, concepts of effective modal mass and effective modal height are adopted to simplify multiple degree of freedom to single degree of freedom. Linear mechanical behavior is assumed in superstructure and substructure; nonlinear mechanical behavior is assumed in isolation story, following the Bouc-Wen modal. Besides, in equivalent foundation part, to describe the soil structure interaction system with the Soil Spring Method. Soil and structure is a simplified impedance between the spring and damping, and assume that the reaction is a non-linear response. We used Output-error method to identify superstructure’ s, substructure’s , Bouc-Wen modal in floor above isolation’s and equivalent foundation’s parameters. In numerical example, we considered structural calculation to evaluate four degree of freedoms’ stiffness and damping, and we input TAP089EW921 to state spacement to calculate the response of all degree of freedom. We used the response to identify the parameters. By numerical example, we hope to improve the accurate of the modal and the reasonable of the procedure. Finally, the reliability of present procedure was verified by calculating the error index between the measured data and identified results from new Civil Engineering Building at NTU

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33

Faiella, Diana. "The Intermediate Isolation System for new and existing buildings: seismic behavior and design criteria." Tesi di dottorato, 2017. http://www.fedoa.unina.it/12202/1/Faiella_Diana_30.pdf.

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Seismic isolation is nowadays a mature technology in the field of civil engineering, appreciated for its conceptual simplicity and its effectiveness in mitigating the seismic actions on structures. After decades of applications, in which isolated buildings have exhibited excellent seismic behavior even during major earthquakes, the base isolation system (BIS) technology is today widespread and popular all over the world, representing a valid option for structural designers to ensure superior seismic performance to new buildings or in order to retrofit existing ones. Throughout the years, architectural needs pushed the limits of the isolation technology in search for new structural configurations. Amongst the structural technologies deriving from the base isolation concept, intermediate isolation represents one of the most interesting. The Intermediate Isolation System (IIS, also appointed as mid-story or inter-story isolation) is a very actual topic and it is currently spreading and gaining significant popularity, mainly in Japan. Advantages of the IIS system include a remarkable architectural flexibility (different functions and, as a consequence, different structural systems are allowed for upper and lower structures) and the applicability for high-rise buildings. In some cases, an elevation with inter-story isolation has been proved to serve as a valid retrofit strategy for existing buildings, avoiding massive retrofit interventions in the lower structure and disruption of the hosted activities. However, while the design concept of base isolation is today highly mature and several thousands of applications have been realized, for the IIS not a single, fully shared design approach is defined, but multiple approaches. The overview of the main scientific contributions on this topic provided in the inherent literature reflects the variety of approaches, both in the formulation of the problem and in the definition of the design objectives and parameters. Basically, three major conceptual approaches can be clearly identified, each mainly focusing on one single aspect of the three ones related to IIS, namely: energy dissipation, isolation, mass damping. In this context, the aim of the present thesis is to explore the actual and potential applications of IIS, by identifying the predominant role among the three behavioral aspects, and by defining design criteria for benefit from all these aspects. In a first step of research the analysis of two real building case-studies representative of the wide IIS applicability, has been carried out, in order to interpret the latest design practice in the light of approaches and indications coming from the world of research. Hence, starting from the precious outcomes of the analyses, two parametric analyses have been carried out, considering both new and existing buildings. In the first parametric analysis, developed on 1D-MDOF inter-story isolated models, the influence of different locations of the isolation system along the building height, and of different mass and stiffness distributions, has been investigated. In the second parametric analysis, carried out on 1D-3DOF inter-story isolated models, the response of an IIS vertical addition for retrofitting an existing masonry building, has been investigated, with the aim of identifying the optimal isolated superstructure configuration; then, a 3D FEM model is adopted for the detailed analysis of the IIS structure.

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34

Huang, Chung-Shing, and 黃中興. "A study on strengthening the seismic capacity of mobile equipments by a magnetic isolation system." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/49957191317790751121.

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碩士
國立成功大學
建築學系碩博士班
91
Many building equipment were damaged in past earthquakes due to lack of easy-to-use seismic resistant measures to prevent from overturning or sliding . This study suggests a new seismic resistant measure on mobile equipment : 「 To strengthen the seismic capacity of mobile equipment by magnetic force」. The first step is to install an energy saving electromagnetic chuck beneath or beside the equipment and to place a steel plate to the floor or to the dry wall with 3M’s double-face stickers. When charged by current, the electromagnetic chucks produce sufficient magnetic force which helps to attach the equipment to the steel plate, thus the equipment is anchored. This study has investigated the performance of this new measure by shaking table tests in two kinds of equipments : 1.Show cases in museum, vertically fixed to steel plate on floor by magnetic force. 2.Hospital beds, horizontally fixed to steel plate on dry wall by magnetic force. After the tests, several properties of mobile equipment fixed by magnetic force were founded: 1.The advantage is easy to operate, easy to move, no damage on the floor , and much cheaper than isolators . 2.Magnetic force won’t produce inertia force to the equipment nor extra bearing weight on the floor. 3.To prevent equipment from overturning or sliding, the stronger the magnetic force is used, the more seismic capacity the equipment has. 4.Strengthened by magnetic force, the show case on one hand was prevented from rocking, and on the other hand was allowed to slide moderately on the surface of the steel plate. This behavior provides the energy dissipation and reduces the acceleration of exhibition items inside the show case. 5.Analysis revealed that the vibration patterns of equipment and energy dissipation under seismic excitation are controlled by two factors: 1). The magnetic force 2). The friction between electromagnets and steel plate In conclusion, strengthening the seismic capacity of mobile equipment by magnetic force, which is named “Sliding Magnet Isolators(SMI)”, is easy to operate and can provide sufficient seismic capacity to the mobile equipment.

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羅榮宗. "The Application of Seismic Isolation System-A Case Study of Mid-Story Isolated Building in Taipei." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/21222805432179942327.

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碩士
明新科技大學
土木工程與環境資源管理研究所
100
Abstract The typical seismic-resisting technics used for building structures can not reduce the large amount of lateral displacement and acceleration at the same time. However, seismic-isolated type building can reduce both displacement and acceleration. It is obvious that the latter provides more comfortable and safer structure and, meanwhile, allows the building to maintain its function. In addition, the new appearance of the building may be designed through the innovative development because of the use of above-mentioned building isolation system. In this study, a newly constructed 15-story building in Taipei which is applied by using the isolation system was investigated through detailed literature review, analysis and result comparison. The final conclusions are summarized as follows : 1. Due to the lack of technical experience on the seismic isolation system used in the local building industry, the study has made from literature review of related applications. Detailed discussions are given for different stages when using the isolation system, ie., planning, design, construction, and maintaining management. 2. By using the case study, it is expected that the building utilized by the isolation system can reach its design functions and reduce the structural damages caused by the earthquakes. The isolated system used in the building design may be one of the best selection for structural design. 3. In order to compare the difference between the seismic-resisting and seismic-isolation building, this study presents the design and construction details for the seismic-isolation building. The design specification, construction method, cost, facilities, fire-resistance and maintenance management are also discussed for their differences. Keywords : isolation buildings, seismic-resisting buildings, isolation components

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Peng, Kuan-Wen, and 彭冠文. "Experimental and theoretical study on a vertical and horizontal bi-directional seismic isolation system for equipment in buildings." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/87649575647925369534.

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碩士
國立高雄第一科技大學
營建工程研究所
103
Recent studies have revealed that both horizontal and vertical seismic forces can cause damage to vibration-sensitive equipment within a building. Seismic isolation technology may be used for the protection of the equipment. However, most isolation systems are only applicable to horizontal isolation. Vertical seismic isolation systems are rare, because there is a conflict in the demands of isolation stiffness. In the other words, a seismic isolation system usually calls for a lower stiffness to mitigate the transmitted seismic force, while it also requires a higher vertical stiffness to carry its weight statically. In order to deal with this difficulty, an inertia-type bi-directional isolation system (IBIS) is proposed in this study. The IBIS uses a leverage mechanism and a counterweight to generate a lifting force in its static state and an inertial force in dynamic state. As a result, in the vertical direction, the IBIS has a higher equivalent static stiffness, while a lower equivalent dynamic stiffness. In order to investigate the IBIS behavior thoroughly, this thesis is divided into three topics: (1) Firstly, the equation of motion of the IBIS subjected to both horizontal and vertical ground motions is derived. After verified by a shaking table test, the analysis method was then employed to evaluate the isolation effectiveness of the IBIS. It is shown that because IBIS possesses an anti-resonance property, it performs well in both near-fault and far-field earthquakes. (2) For the second topic, an analysis method for an IBIS mounted on a building floor by considering three-directional floor excitations (namely, horizontal, vertical and rocking) was derived. After verified experimentally, the analysis method was used to assess the isolation effectiveness of an IBIS placed on a building floor. The results demonstrate that the isolation performance of the IBIS subjected to floor excitations is superior to that of IBIS subjected to ground excitations. (3) In the third topics, whether a vertical-horizontal bi-directional isolation system can provide better seismic protection for block-type equipment was investigated. Several possible failure patterns for block-type equipment were defined, first. Then, the performance of various isolation systems was evaluated based on the failure percentages of equipment. The studied parameters include: aspect ratio of equipment, friction coefficient of equipment base, horizontal-to-vertical excitation ratio and earthquake types, etc. The study shows that in a ground excitation, the difference of failure percentages between the bi-directional and the horizontal isolation systems is insignificant. However, in a floor excitation, the bi-directional isolation system is able to greatly improve the safety of equipment, as compared with the horizontal isolation along.

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37

Pasala, Dharma Theja. "Seismic response control of structures using novel adaptive passive and semi-active variable stiffness and negative stiffness devices." Thesis, 2013. http://hdl.handle.net/1911/72017.

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Current seismic design practice promotes inelastic response in order to reduce the design forces. By allowing the structure to yield while increasing the ductility of the structure, the global forces can be kept within the limited bounds dictated by the yield strength. However, during severe earthquakes, the structures undergo significant inelastic deformations leading to stiffness and strength degradation, increased interstory drifts, and damage with residual drift. The research presented in this thesis has three components that seek to address these challenges. To prevent the inelastic effects observed in yielding systems, a new concept “apparent weakening” is proposed and verified through shake table studies in this thesis. “Apparent weakening” is introduced in the structural system using a complementary “adaptive negative stiffness device” (NSD) that mimics "yielding” of the global system thus attracting it away from the main structural system. Unlike the concept of weakening and damping, where the main structural system strength is reduced, the new system does not alter the original structural system, but produces effects compatible with an early yielding. Response reduction using NSD is achieved in a two step sequence. First the NSD, which is capable of exhibiting nonlinear elastic stiffness, is developed based on the properties of the structure. This NSD is added to the structure resulting in reduction of the stiffness of the structure and NSD assembly or “apparent weakening”-thereby resulting in the reduction of the base shear of the assembly. Then a passive damper, designed for the assembly to reduce the displacements that are caused due to the “apparent weakening”, is added to the structure-thereby reducing the base shear, acceleration and displacement in a two step process. The primary focus of this thesis is to analyze and experimentally verify the response reduction attributes of NSD in (a) elastic structural systems (b) yielding systems and (3) multistory structures. Experimental studies on 1:3 scale three-story frame structure have confirmed that consistent reductions in displacements, accelerations and base shear can be achieved in an elastic structure and bilinear inelastic structure by adding the NSD and viscous fluid damper. It has also been demonstrated that the stiffening in NSD will prevent the structure from collapsing. Analogous to the inelastic design, the acceleration and base shear and deformation of the structure and NSD assembly can be reduced by more than 20% for moderate ground motions and the collapse of structure can be prevented for severe ground motions. Simulation studies have been carried on an inelastic multistoried shear building to demonstrate the effectiveness of placing NSDs and dampers at multiple locations along the height of the building; referred to as “distributed isolation”. The results reported in this study have demonstrated that by placing a NSD in a particular story the superstructure above that story can be isolated from the effects of ground motion. Since the NSDs in the bottom floors will undergo large deformations, a generalized scheme to incorporate NSDs with different force deformation behavior in each storey is proposed. The properties of NSD are varied to minimize the localized inter-story deformation and distribute it evenly along the height of the building. Additionally, two semi-active approaches have also been proposed to improve the performance of NSD in yielding structures and also adapt to varying structure properties in real time. The second component of this thesis deals with development of a novel device to control the response of structural system using adaptive length pendulum smart tuned mass damper (ALP-STMD). A mechanism to achieve the variable pendulum length is developed using shape memory alloy wire actuator. ALP-STMD acts as a vibration absorber and since the length is tuned to match the instantaneous frequency, using a STFT algorithm, all the vibrations pertaining to the dominant frequency are absorbed. ALP-STMD is capable of absorbing all the energy pertaining to the tuned-frequency of the system; the performance is experimentally verified for forced vibration (stationary and non-stationary) and free vibration. The third component of this thesis covers the development of an adaptive control algorithm to compensate hysteresis in hysteretic systems. Hysteretic system with variable stiffness hysteresis is represented as a quasi-linear parameter varying (LPV) system and a gain scheduled controller is designed for the quasi-LPV system using linear matrix inequalities approach. Designed controller is scheduled based on two parameters: linear time-varying stiffness (slow varying parameter) and the stiffness of friction hysteresis (fast varying parameter). The effectiveness of the proposed controller is demonstrated through numerical studies by comparing the proposed controller with fixed robust H∞ controller. Superior tracking performance of the LPV-GS over the robust H∞ controller in different displacement ranges and various stiffness switching cases is clearly evident from the results presented in this thesis. The LPV-GS controller is capable of adapting to the parameter changes and is effective over the entire range of parameter variations.

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CILLA, ROSARIO EMANUELE. "New frontiers for seismic isolation systems." Doctoral thesis, 2019. http://hdl.handle.net/11570/3146800.

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Seismic isolation is one of the most relevant topic in research area and it counts different branches and approaches. During the time, different devices have been designed and plenty of experiments have been conducted as well as several attempts have already been put in place in real constructions. Among new experimental proposals, isolation systems based on the concept of Seismic Metamaterial reveal to be very promising, getting increasingly attention from the scientific community. In this thesis, two different approaches of seismic isolation systems based on the concept of Metamaterials are discussed: systems embedded with the ground and systems tuned with structures. For both systems, the working principles are presented and remarks are expressed in the light of the results coming from field investigations and experimental tests carried out about the two methods.

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Lin, Ging-Long, and 林錦隆. "Semi-active isolation systems for seismic structures." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/91622685759917301180.

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博士
國立高雄第一科技大學
工程科技研究所
96
Base isolation technology may be used for seismic protection of critical structures or equipments. However, recent studies have revealed that a conventional passive isolation system may induce an excessive base displacement when subjected to a near-fault earthquake with strong long-period components. In order to enhance the efficiency and safety of seismic isolation for structures in near-fault areas, a semi-active isolation system (SAIS) that consists of isolators and a variable damper is proposed in this study. Three kinds of variable dampers are discussed in this study. The first is the variable stiffness damper, the second is the variable friction damper, and the third is the variable viscous damper. The resistant force of a variable damper can be adjusted by its controllable parameter according to an on-line control law and the measured system response. The seismic response of the SAIS system equipped with each of the three types of variable dampers mentioned previously and subjected to near-fault earthquakes was simulated numerically in this study. In addition, its isolation performance was also evaluated and compared with the performance of a passive and an active isolation system. The results of these comparisons are discussed in this study. The simulation result demonstrates that the SAIS system is able to prevent the excessive displacement and acceleration response of structure induced by long-period pulse components of near-fault earthquakes.

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Liao, Wei-Hsin, and 廖偉信. "Seismic Isolation Systems for Earthquake Protection of Structures." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/51482751342403192725.

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博士
國立交通大學
土木工程系
91
In this thesis, the feasibility and potential of using friction pendulum bearings as well as rocking mechanism for earthquake protection of structures have been explored. Both the friction pendulum bearings and rocking mechanism are considered seismic isolation systems that protect the structures by cutting off the path of earthquake transmission. The friction and rocking mechanisms are similar in that they are both highly nonlinear in nature due to discontinuity at the phase or direction changes of motion. A novel numerical algorithm has been developed for the nonlinear dynamic analysis of structures with sliding isolation. According to the proposed method, a unified motion equation is adopted for both the stick and slip modes of the system. Derived under the framework of state-space representations, the proposed algorithm proves to be more efficient and accurate than existing methods. Moreover, it is general enough for analysis of structures with multiple sliding isolators undergoing unsynchronized support motions. Feasibility of using friction pendulum bearings for seismic isolation of bridges has been investigated under real earthquakes. Under the revised configuration by replacing one of the roller supports on the abutments with hinge support, the isolated bridge performs consistently well during various earthquakes, regardless of the site conditions. The usefulness of seismic isolation of bridges is confirmed. Moreover, effectiveness of friction pendulum bearings on earthquake protection of stepped structures as well as continuous bridges under unsynchronized support motion has been verified. In the second part of this thesis, the feasibility of utilizing rocking mechanism for earthquake protection of viaduct-type structures has been explored both experimentally and analytically. The slender high-pier structure is represented by an A-shaped frame, which exhibits the basic features of RPS. Analytical modeling of this nonlinear dynamic system is derived and a numerical procedure developed based on the fourth-order Runge-Kutta-Nyström method. The amplitude-dependent cycling time and energy-dissipative nature of rocking mechanism has been derived analytically and observed experimentally in the free rocking tests. The coefficient of restitution derived theoretically matches closely with the test results. Good correlation between the experimental and analytical results has been achieved. The proposed analytical modeling and solution algorithm for dynamic analysis of rocking systems has been sufficient. Moreover, stability and effectiveness of the rocking pier system under severe earthquakes have been confirmed via shaking table tests. It has been observed from this series of tests that, the stronger the earthquake intensity the better the control efficiency.

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Peternell, Altamira Luis E. 1981. "Stability-dependent Mass Isolation for Steel Buildings." Thesis, 2012. http://hdl.handle.net/1969.1/148042.

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A new seismic isolation system for steel building structures based on the principle of mass isolation is introduced. In this system, isolating interfaces are placed between the lateral-load-resisting sub-system and the gravity-load-resisting sub-system. Because of the virtual decoupling existing between the two structural sub-systems, the gravity-load resisting one is susceptible to instability. Due to the fact that the provided level of isolation from the ground is constrained by the stability requirements of the gravity-load resisting structure, the system is named stability-dependent mass isolation (SDMI). Lyapunov stability and its association with energy principles are used to assess the stable limits of the SDMI system, its equilibrium positions, the stability of the equi-librium positions, and to propose a series of design guidelines and equations that allow the optimal seismic performance of the system while guaranteeing the restoration of its undistorted position. It is mathematically shown that the use of soft elastic interfaces, between the lateral- and gravity-load-resisting sub-systems, can serve the dual role of stability braces and isolators well. The second part of the document is concerned with the analytical evaluation of the seismic performance of the SDMI method. First, a genetic algorithm is used to find optimized SDMI building prototypes and, later, these prototypes are subjected to a series of earthquake records having different hazard levels. This analytical testing program shows that, with the use of SDMI, not only can structural failure be avoided, but a dam-age-free structural performance can also be achieved, accompanied by average reductions in the floor accelerations of ca. 70% when compared to those developed by typical braced-frame structures. Since the SDMI system is to be used in conjunction with viscous energy dissi-paters, the analytical testing program is also used to determine the best places to place the dampers so that they are most effective in minimizing the floor accelerations and controlling the floors’ drift-ratios. Finally, recommendations on continuing research are made.

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Chiung-LinLiu and 劉瓊琳. "Application of Air Springs for Inertial-type Seismic Isolation Systems." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/m27mcq.

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Aliaari, Mohammad. "Development of seismic infill wall isolator subframe (SIWIS) system." 2005. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-748/index.html.

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44

Harvey, Jr Philip Scott. "Rolling Isolation Systems: Modeling, Analysis, and Assessment." Diss., 2013. http://hdl.handle.net/10161/8012.

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The rolling isolation system (RIS) studied in this dissertation functions on the principle of a rolling pendulum; an isolated object rests on a steel frame that is supported at its corners by ball-bearings that roll between shallow steel bowls, dynamically decoupling the floor motion from the response of the object. The primary focus of this dissertation is to develop predictive models that can capture experimentally-observed phenomena and to advance the state-of-the-art by proposing new isolation technologies to surmount current performance limitations. To wit, a double RIS increases the system's displacement capacity, and semi-active and passive damped RISs suppress the system's displacement response.

This dissertation illustrates the performance of various high-performance isolation strategies using experimentally-validated predictive models. Effective modeling of RISs is complicated by the nonholonomic and chaotic nature of these systems which to date has not received much attention. Motivated by this observation, the first part of this dissertation addresses the high-fidelity modeling of a single, undamped RIS, and later this theory is augmented to account for the double (or stacked) configuration and the supplemental damping via rubber-coated bowl surfaces. The system's potential energy function (i.e. conical bowl shape) and energy dissipation model are calibrated to free-response experiments. Forced-response experiments successfully validate the models by comparing measured and predicted peak displacement and acceleration responses over a range of operating conditions.

Following the experimental analyses, numerical simulations demonstrate the potential benefits of the proposed technologies. This dissertation presents a method to optimize damping force trajectories subject to constraints imposed by the physical implementation of a particular controllable damper. Potential improvements in terms of acceleration response are shown to be achievable with the semi-active RIS. Finally, extensive time-history analyses establish how the undamped and damped RISs perform when located inside biaxial, hysteretic, multi-story structures under recorded earthquake ground motions. General design recommendations, supported by critical-disturbance spectra and peak-response distributions, are prescribed so as to ensure the uninterrupted operation of vital equipment.

Dissertation

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王彥茗. "Analytical Solutions of Interactive Behavior between Seismic Isolation and Soil Systems." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/n26mw4.

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博士
逢甲大學
土木水利工程與建設規劃博士學位學程
107
This paper focuses on investigating the effects of soil-structure interaction (SSI), higher modes, and damping on the response of a mid-story-isolated structure founded on multiple soil layers overlying bedrock. Closed-form solutions were ob-tained for the entire system, which consists of a shear beam type superstructure, seismic isolator, and multiple soil layers overlying bedrock, while subjected to ground motion. The proposed formulations simplify the problem in terms of well-known frequency and mechanical impedance ratios that can take into account the effects of SSI, higher modes, and damping in the entire system, and be capable of explicitly interpreting the major dynamic behavior of a mid-story-isolated structure interacting with the multiple soil layers overlying bed rock. The SSI effects on the dynamic response of a mid-story-isolated structure as a result of multiple soil layers overlying bedrock were extensively investigated through a series of parametric studies and physically explained by virtue of derived formulations. In addition, the results of numerical exercises show that higher damping provided by the isolator may provoke higher mode response of the superstructure; that the lower structure below the isolator may have significantly larger deformations compared to those of the up-per structure above the isolator; and that isolator displacements may be amplified by the SSI effects while compared to those of mid-story-isolated structures with fixed-base.

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Tseng, Yi-Hao, and 曾繹豪. "Effects of Near-Fault Ground Motion Characteristics on Seismic Isolation Systems." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/zke9sz.

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碩士
國立臺灣科技大學
營建工程系
107
The damage potential of near-fault ground motions to structures, in particular the flexible structures such as seismically isolated structures and high-rise buildings, may be much more than that of far-field ground motions. In 1971, Mahin and Bertero discovered that the “maximum incremental velocity” could be one of the indices to well represent the damage potential of near-fault ground motions. In 1995, John Hall et al. showed that the displacement pulse contained in the near fault ground motions could also be another index demonstrating damage potential of near fault ground motions. Considering the two important findings, this study is conducted with an intension to investigate the significance of a parameter which is composed of the maximum incremental velocity (MIV) and the duration of maximum incremental velocity (TIV). The MIV is multiplied by TIV as an index for the seismic response demand on isolation systems by near fault ground motions. For design purpose of isolation system against near-fault ground motions, the current isolation design specifications generated from equivalent linear analysis are examined for their accuracy and appropriateness in predicting the seismic responses of isolation system subject to near fault ground motions. Maximum seismic responses obtained from various equivalent linear models using linear dynamic analysis are compared with those determined by nonlinear dynamic analysis. In addition, maximum responses predicted using iterative static analysis as employed by current seismic isolation design codes are used to compare with the results from nonlinear dynamic analysis so that the damping reduction factor can then be examined for its appropriateness.

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Kuo, Shin-Ming, and 郭世明. "Analytical Study on the Role of Viscous Dampers in Seismic Isolation Systems." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/z53u74.

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碩士
國立臺灣科技大學
營建工程系
94
Abstract The excessive displacement demand on the isolation system by long period and/or near field earthquake ground motions is always a concern when designing a seismically isolated structure. If the isolated structure is designed with respective to the demand of maximum considered earthquakes and/or near field earthquakes, the isolation system may not perform effectively well when the isolated structure is subjected to small and moderate earthquakes. Therefore, it is very difficult to design an isolation system that will perform effectively across small, moderate and major earthquakes (or call it all purpose isolation system, APIS). It has been recognized that to include viscous dampers in an isolation system is an effective method to control the displacement response without dramatically increasing the transmitted force of the isolation system. This is due to the existence of a phase lag between the damper force and damper displacement while most of isolation bearings such as lead-rubber bearings has an in-phase behavior between their force and displacement. In this study, analytical study is conducted to study the significance of damping exponent and in an isolation system composed of viscous dampers and lead-rubber bearings. Conceptually, the purpose for adopting the so far never-used (in civil engineering structures) viscous dampers with is to fulfill the requirement of an APIS. This is because the viscous damper is an redundant when the isolated structure is subjected to small and moderate earthquakes, and is efficiently effective while major earthquakes strike.

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鄭育婷. "Application of Seismic Isolation Systems to High-raised Houses in Lowland Regions." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/85975114074144452783.

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Ozbulut, Osman Eser. "Seismic Protection of Bridge Structures Using Shape Memory Alloy-Based Isolation Systems against Near-Field Earthquakes." Thesis, 2010. http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8687.

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The damaging effects of strong ground motions on highway bridges have revealed the limitations of conventional design methods and emphasized the need for innovative design concepts. Although seismic isolation systems have been proven to be an effective method of improving the response of bridges during earthquakes, the performance of base-isolated structures during near-field earthquakes has been questioned in recent years. Near-field earthquakes are characterized by long period and large- velocity pulses. They amplify seismic response of the isolation system since the period of these pulses usually coincides with the period of the isolated structures. This study explores the feasibility and effectiveness of shape memory alloy (SMA)-based isolation systems in order to mitigate the response of bridge structures against near-field ground motions. SMAs have several unique properties that can be exploited in seismic control applications. In this work, uniaxial tensile tests are conducted first to evaluate the degree to which the behavior of SMAs is affected by variations in loading rate and temperature. Then, a neuro-fuzzy model is developed to simulate the superelastic behavior of SMAs. The model is capable of capturing rate- and temperature-dependent material response while it remains simple enough to carry out numerical simulations. Next, parametric studies are conducted to investigate the effectiveness of two SMA-based isolation systems, namely superelastic-friction base isolator (S-FBI) system and SMA/rubber-based (SRB) isolation system. The S-FBI system combines superelastic SMAs with a flat steel-Teflon bearing, whereas the SRB isolation system combines SMAs with a laminated rubber bearing rather than a sliding bearing. Upon evaluating the optimum design parameters for both SMA-based isolation systems, nonlinear time history analyzes with energy balance assessment are conducted to compare their performances. The results show that the S-FBI system has more favorable properties than the SRB isolation system. Next, the performance of the S-FBI systems is compared with that of traditional isolation systems used in practice. In addition, the effect of outside temperature on the seismic response of the S-FBI system is assessed. It is revealed that the S-FBI system can successfully reduce the response of bridges against near-field earthquakes and has excellent re-centering ability.

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Chen, Ting-Hui, and 陳廷暉. "Effects of Near-Fault Ground Motions on Seismic Isolation Systems and Corresponding Design Strategies." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/8htk62.

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碩士
國立臺灣科技大學
營建工程系
107
The concept of seismic isolation design has been accepted as an effective method for the seismic mitigation of structures. However, in Taiwan, an earthquake prone island, many sites are located in near-fault zones. The recorded seismic waves have near-fault characteristics such as velocity pulses and displacement pulses. These seismic waves may cause excessive displacement demand on the isolation system and transmit significant acceleration to the superstructure. Consequently, the isolation design to the structures located at near fault area is challenging. The objective of the study is to develop a suitable design strategy of an isolation system to resist the near-field ground motions. The code-specified procedure and an existing procedure are examined for their appropriateness in designing the seismic isolation system against near-fault ground motions. A design procedure is proposed for the isolation system composed of lead-rubber bearings and viscous dampers. The results show that the proposed procedure can lead to a controllable maximum displacement of the isolation system and an acceptable transmitted acceleration transmitted to the superstructure.

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