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1
Cilingir, Ulas. "Seismic response of tunnels." Thesis, University of Cambridge, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608467.
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Ucer, Serkan. "Seismic Response And Vulnerability Assessment Of Tunnels:a Case Study On Bolu Tunnels." Phd thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12615005/index.pdf.
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The aim of the study is to develop new analytical fragility curves for the vulnerability assessment of tunnels based on actual damage data of tunnels obtained from past earthquakes. For this purpose, additional important damage data belonging to Bolu Tunnels, Turkey was utilized as a case study.
Bolu Tunnels constitute a very interesting case from the earthquake hazard point of view, since two major earthquakes, 17 August 1999 Marmara and 12 November 1999 Düzce, occurred during the construction of the tunnels. The August 17, 1999 earthquake was reported to have had minimal impact on the Bolu Tunnels. However, the November 12, 1999 earthquake caused some sections of both tunnels to collapse. The remaining sections of the tunnels survived with various damage states which were subsequently documented in detail. This valuable damage data was thoroughly utilized in this study. To develop analytical fragility curves, the methodology described by Argyroudis et al. (2007) was followed. Seismic response of the Tunnels was assessed using analytical, pseudo-static and full-dynamic approaches. In this way, it was possible to make comparisons regarding the dynamic analysis methods of tunnels to predict the seismically induced damage. Compared to the pseudo-static and full-dynamic methods, the predictive capability of the analytical method is found to be relatively low due to limitations inherent to this method. The pseudo-static and full-dynamic solution results attained appear to be closer to each other and better represented the recorded damage states in general. Still, however, the predictive capability of the pseudo-static approach was observed to be limited for particular cases with reference to the full-dynamic method, especially for the sections with increasingly difficult ground conditions. The final goal of this study is the improvement of damage indexes corresponding to the defined damage states which were proposed by Argyroudis et al. (2005) based on the previous experience of damages in tunnels and engineering judgment. These damage indexes were modified in accordance with the findings from the dynamic analyses and actual damage data documented from Bolu Tunnels following the Dü
zce earthquake. Three damage states were utilized to quantify the damage in this study.
3
Sun, Qiangqiang. "Seismic response of tunnels in soils : From deterministic to probabilistic approaches." Thesis, Université Grenoble Alpes, 2020. http://www.theses.fr/2020GRALI067.
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Les tunnels constituent une des parties essentielles des systèmes d'infrastructure et jouent un rôle de plus en plus important dans le processus d'urbanisation. Néanmoins, de graves dommages, dont des effondrements, se sont produits et ont été recensés dans le monde entier au cours des dernières décennies. Par conséquent, la recherche sur la conception des tunnels notamment en zone sismique afin d’atténuer efficacement les risques et de réduire les pertes socio-économiques importantes dues aux tremblements de terre a reçu une attention croissante. D'autre part, de nouveaux défis tels que les tunnels de grande section excavés à l’aide de tunneliers dans des horizons multicouches, la perturbation du champ de contraintes induit par les tunnels, ainsi que l’incertitude des propriétés des sols, nécessitent une étude détaillée de leurs influences potentielles.Cette thèse vise à étudier la réponse sismique de tunnels à l'aide d'approches déterministes et probabilistes. Les analyses sont basées sur des simulations non linéaires bidimensionnelles utilisant le code de différences finies explicite FLAC. Tout d'abord, une évaluation critique de l'utilisation de l'amortissement de Rayleigh dans les modèles numériques non linéaires est menée afin de mettre en évidence son importance et de fournir des règles pour les analyses ultérieures. L'impact de la construction des tunnels a ensuite été intégré dans les modèles numériques en utilisant la méthode convergence-confinement. La réponse sismique des tunnels pour divers états de contrainte initiaux est ensuite présentée. Des études théoriques et numériques sont effectuées pour contribuer à une meilleure compréhension des mécanismes liées à la présence d’une couche de sol compressible sous-jacente pour la protection sismique des ouvrages souterrains. Enfin, l'incertitude des paramètres du sol est introduite dans les modèles numériques sous forme de variables aléatoires. La méthode probabiliste Sparse Polynomial Chaos Expansion combinée à une analyse de sensibilité globale et des simulations de type Monte Carlo sont utilisées pour identifier les variables les plus importantes et quantifier la variabilité des déformations sismiques en tunnel. Le travail présenté considère un système d’interaction sol/tunnel réaliste qui permet de fournir des informations précieuses sur le comportement des tunnels sous chargement sismiqueTunnels are an essential part of infrastructure systems and play an ever-increasing role in the process of urbanization. Nevertheless, severe damage, including collapse, occurred and was reported worldwide in recent decades. Therefore, the research on the design of tunnel against seismic events to effectively mitigate risks and reduce large socio-economic losses due to earthquake disasters received increasing attention. On the other hand, new challenges such as large shield-driven tunnelling in multi-layered formations, tunnelling-induced stress perturbation, as well as uncertain soil property lead to the need for detailed investigation of their potential influences.This dissertation aims at investigating the tunnel seismic response using deterministic and probabilistic approaches. The analyses are based on two-dimensional nonlinear simulations using the explicit finite difference code FLAC. First, a critical assessment of the Rayleigh damping use in nonlinear numerical models is conducted to highlight its significant importance and to provide a selection guideline for the subsequent analyses. Then, the tunnel construction impact is incorporated in the numerical models with the convergence-confinement method. The tunnel seismic responses for various initial stress states are then presented. Next, theoretical and numerical studies are performed to reveal the mechanical mechanism of an underlying soft soil layer for the tunnel seismic protection. Finally, the uncertainty of the soil parameters is introduced into the model as random variables. The sparse polynomial chaos expansion based Global Sensitivity Analysis and the conventional Monte Carlo simulations are respectively utilized to identify the most important variables and quantify the variability in the tunnel seismic deformations. The presented work considers a more realistic soil-tunnel system, thus it provides valuable insights for the behavior of tunnels under seismic loadings
4
Hoque, Md Zaydul Carleton University Dissertation Engineering Civil. "Seismic response of retaining walls." Ottawa, 1992.
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5
Ertugrul, Niyazi. "Analysis Of Seismic Behavior Of Underground Structures: A Case Study On Bolu Tunnels." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612735/index.pdf.
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In today&rsquos world, buried structures are used for a variety of purposes in many areas such as transportation, underground depot areas, metro stations and water transportation. The serviceability of these structures is crucial in many cases following an earthquake
that is, the earthquake should not impose such damage leading to the loss of serviceability of the structure. The seismic design methodology utilized for these structures differs in many ways from the above ground structures. The most commonly utilized approach in dynamic analysis of underground structures is to neglect the inertial forces of the substructures since these forces are relatively insignificant contrary to the case of surface structures. In seismic design of these underground structures, different approaches are utilized like free-field deformation approach and soil-structure interaction approach. Within the confines of this thesis, seismic response of highway tunnels is considered through a case study on Bolu Tunnels, which are well documented and subjected to Dü
zce earthquake. In the analyses, the seismic response of a section of the Bolu tunnels is examined with 2-D finite element models and results are compared with the recorded data to evaluate the capability of the available analysis methods. In general, the results of analyses did not show any distinct difference from the recorded data regarding the seismic performance of the analyzed section and that the liner capacities were sufficient, which is consistent with the post earthquake condition of the Bolu Tunnels.
6
Nishiyama, Minehiro. "Seismic Response and Seismic Design of Prestressed Concrete Building Structures." Kyoto University, 1993. http://hdl.handle.net/2433/74644.
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MacRae, G. A. "The seismic response of steel frames." Thesis, University of Canterbury. Civil Engineering, 1989. http://hdl.handle.net/10092/7925.
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The seismic behaviour of moment-resisting and eccentrically-braced steel frames is studied. Inelastic time history analyses are presented to show that simple design techniques may be developed to encourage earthquake resisting structures to behave well, even though their seismic response may be complex.
Complementary to the analytical study, eight steel I-section beam-columns were tested under a regime of cyclic bending. The units exhibited very good hysteretic behaviour prior to their failure by means of fracture or various modes of buckling. The cyclic post-elastic behaviour of beams and beam-columns in steel multistorey frames, and some parameters influencing their deformation capacity are discussed.
8
Harrison, Fiona Anne. "Seismic response to sedimentary facies variation." Thesis, University of Aberdeen, 1997. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU089772.
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This project investigates the seismic response to facies variation by modelling facies variation itself, using two different modelling techniques, and then by modelling the seismic response to this variation. This study looks at a new set of attributes, examines their potential both as standard seismic attributes (a qualitative approach), and uses geostatistical analysis to further develop the ability of these attributes to differentiate the seismic response to facies variation. Sedpak, a basin modelling package was used to try to create facies models as a basis for further geophysical modelling. A case study using data from the Beryl area was unsuccessful at trying to create facies models due largely to the limited amount of input data and the scale of the models being attempted. Although an impressive package, Sedpak is most useful when modelling at a basin scale. In order to study the seismic response of sedimentary facies variation simple, deterministic models were set up using the geophysical modelling package, Gxii. An established methodology for analysing seismic data is the study of seismic attributes. The study considers some autocorrelation and power spectrum-derived functions previously described in the literature (Sinvhal and Sinvhal, 1992), and treats them as seismic attributes. Initial analysis of these new attributes in 2D showed them to be successful at detecting the presence of channels within seismic data. On the basis of this, a multivariate study was carried out. Results of this analysis show these attributes to have the potential to detect the presence of channels within seismic data. A suite of computer programs were developed to calculate 3D volumes of the new attributes, and to produce colour sections through the attribute volumes. The volumes were granted using a moving time window and calculating attribute values down through the data volume. Evaluation of the colour sections themselves to illustrate facies changes was disappointing. It is apparent that more work is needed to evaluate the window length over which the attributes are calculated.
9
Morgan, Andrew Scott. "Seismic Response of Stiffening Elastic Systems." BYU ScholarsArchive, 2012. https://scholarsarchive.byu.edu/etd/3491.
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Traditional seismic load resisting systems in buildings are designed to undergo inelastic deformations in order to dissipate energy, resulting in residual displacements. This work explores an approach to eliminate these residual displacements. The systems investigated have low initial stiffness which increases at a predefined displacement, and are therefore called stiffening elastic systems. This thesis begins with an examination of single-degree-of-freedom stiffening elastic systems. A case study is presented which suggests that the benefits from stiffening elastic behavior may be limited to systems which would have long periods if designed traditionally. A thorough parameter study is also presented which indicates the benefit of stiffening elastic behavior for SDOF systems with periods greater than four seconds. A final case study is presented that compares the response of a twelve-story stiffening elastic system to a ductile system and an elastic system. The stiffening elastic system was able to eliminate the residual displacements inherent in a ductile system while lowering the base shear experienced by the elastic system, but is not clearly better than the ductile system because the base shear force was much higher.
10
Morton, Ellen Cathrine. "Seismic Response of Large-scale Structures." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/75065.
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Towashiraporn, Peeranan. "Building Seismic Fragilities Using Response Surface Metamodels." Diss., Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/4793.
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Building fragility describes the likelihood of damage to a building due to random ground motions. Conventional methods for computing building fragilities are either based on statistical extrapolation of detailed analyses on one or two specific buildings or make use of Monte Carlo simulation with these models. However, the Monte Carlo technique usually requires a relatively large number of simulations in order to obtain a sufficiently reliable estimate of the fragilities, and it quickly becomes impractical to simulate the required thousands of dynamic time-history structural analyses for physics-based analytical models.
An alternative approach for carrying out the structural simulation is explored in this work. The use of Response Surface Methodology in connection with the Monte Carlo simulations simplifies the process of fragility computation. More specifically, a response surface is sought to predict the structural response calculated from complex dynamic analyses. Computational cost required in a Monte Carlo simulation will be significantly reduced since the simulation is performed on a polynomial response surface function, rather than a complex dynamic model. The methodology is applied to the fragility computation of an unreinforced masonry (URM) building located in the New Madrid Seismic Zone. Different rehabilitation schemes for this structure are proposed and evaluated through fragility curves. Response surface equations for predicting peak drift are generated and used in the Monte Carlo simulation. Resulting fragility curves show that the URM building is less likely to be damaged from future earthquakes when rehabilitation is properly incorporated.
The thesis concludes with a discussion of an extension of the methodology to the problem of computing fragilities for a collection of buildings of interest. Previous approaches have considered uncertainties in material properties, but this research incorporates building parameters such as geometry, stiffness, and strength variabilities as well as nonstructural parameters (age, design code) over an aggregation of buildings in the response surface models. Simulation on the response surface yields the likelihood of damage to a group of buildings under various earthquake intensity levels. This aspect is of interest to governmental agencies or building owners who are responsible for planning proper mitigation measures for collections of buildings.
12
Schroeder, Brianna Lynn. "Seismic response assessment of skew highway bridges /." abstract and full text PDF (free order & download UNR users only), 2006. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1440918.
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Thesis (M.S.)--University of Nevada, Reno, 2006."December, 2006." Includes bibliographical references (leaves 183-186). Online version available on the World Wide Web. Library also has microfilm. Ann Arbor, Mich. : ProQuest Information and Learning Company, [2006]. 1 microfilm reel ; 35 mm.
13
Dezhdar, Ehsan. "Seismic response of cantilever shear wall buildings." Thesis, University of British Columbia, 2012. http://hdl.handle.net/2429/43678.
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Nonlinear time history analysis was carried out in order to estimate the demands on cantilever shear wall buildings due to the design level earthquakes. A hysteretic bending moment - curvature relationship was developed and implemented into computer program OpenSees. The study included 15 different shear wall buildings that ranged in height from 10 to 50 stories with a range of elastic bending moment demand at the base as a ratio of bending moment capacity from 1.3 to 3.7.
The influence of ground motion selection and scaling on different structural response quantities was studied. The input ground motions were scaled to uniform hazard spectrum (UHS) and conditional mean spectrum (CMS). It was observed that a fewer number of spectrum matched ground motions can be used to establish the mean response, while a reasonable similarity was found between the mean demand parameters from spectrum matched and the envelope of CMS ground motions.
Mean roof displacements from nonlinear time history analysis were used to determine appropriate effective stiffness values to be used in response spectrum analysis to accurately predict the maximum roof displacement. It was observed that stiffness reduction factor reduced from 1.0 to about 0.5 as the ratio of elastic bending moment demand at the base to the wall flexural capacity increased from 1.3 to 3.7. In addition, models were proposed for the complete envelopes of curvature demand and interstory drift demand over the wall height, including an accurate estimate of the maximum curvature demand at the wall base, midheight curvature demand, and maximum interstory drift at the roof. The developed models for base curvature and roof interstory drift demands were expressed in term of roof displacement demand. The midheight curvature demand was found to be less than the recommended values for yield curvature. Lastly, the results of nonlinear time history analysis were used to determine an expression for estimating base shear force demands. The shear amplification factor, defined as the ratio that the design base shear force needs to be increased, was found to be independent of the building height and to have a maximum value of 2.0.
14
Bristowe, Stuart J. (Stuart James). "Seismic response of precast concrete wall panels." Thesis, McGill University, 1994. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=22641.
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Precast concrete structures are not widely used in severe seismic regions due the limited knowledge of the response of these systems to reversed cyclic loading. A series of four precast concrete wall panels were tested to evaluate their response to reversed cyclic loading. These units represent the wall panels of a typical single storey precast concrete structure. In order to achieve improved ductility and energy absorption characteristic, it was found that the horizontal sliding of the wall panel along the grout-wall interface must be controlled. Due to the reversed cyclic loading and the increased wall panel participation from limiting the horizontal sliding of the wall, it was determined that shear reinforcement of each precast specimen was separated into three separate component parts, joint rotation, wall panel deformations and horizontal wall panel sliding, to compare and evaluate the seismic performance of the wall panels.
15
Itagawa, Wendy. "Seismic response of a concrete bridge bent." Thesis, McGill University, 2005. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=82499.
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In this research, the seismic response of an existing bridge bent built in the 1960's in the Montreal area is studied in order to determine its seismic deficiencies. Bridges built in the 1960's were designed with outdated codes which had inadequate seismic design detailing provisions and therefore, are expected to behave poorly during an earthquake. The existing bridge bent examined has three major design deficiencies such as large spacing of ties in the column, total lack of shear reinforcement in the beam, and lack of shear reinforcement in the beam-column joint. A one-half scale model of the existing bridge bent was designed and constructed in the laboratory. This model was tested under reversed cyclic loading to determine the maximum applied load and failure mechanisms. The experimental results of the specimen are then compared to the response predictions. Both the experimental and predicted results revealed that the bridge bent is vulnerable to shear failure in the cap beams and hence, has inadequate performance. Research should be continued on the damaged specimen to determine the repair and retrofit techniques.
16
Javed, Khalid. "Non linear seismic response of asymmetric buildings." Thesis, University of East London, 1999. http://roar.uel.ac.uk/1260/.
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The study presented in this thesis is an attempt towards a better understanding of the coupled lateral-torsional response of buildings subject to seismic ground motion. Some of the problems identified in the past studies are thoroughly investigated and some new areas of study are explored. Some of these problems encountered in the literature include (a) the existence of several definitions of uncoupled torsional to lateral frequency ratio (b) an arbitrary selection of structural parameters in a parametric analysis resulting in a physically inadmissible structure and (c) the effect of nonlinearity. Because of the simplified models with either eccentricity in one direction or the ground motion applied in only one direction, the effects of a bi-directional loading have not been investigated in detail. These effects may include the relative differences in the amplitude or phase components of the individual accelerograms and their orientation with respect to the building. The phase properties of accelerograms are of particular interest and these have not received much attention in the past. Using analytical methods such as Chasle's[16] and Gerschgorin's[39] theorems, the equation of motion of a bi-eccentric system is derived and all of the existing problems regarding the definition of structural parameters and their bounds are studied in depth. To facilitate nonlinear parametric study, a paraboloid non-linear elastic stiffness model is proposed. Fourier spectral methods are used to study the frequency domain characteristics of the accelerogram pair. The difference in phase and amplitude of the component frequencies in each direction are studied for their effects on the response. For phase difference, cross-correlation function is used as a comparative statistical indicator. USA earthquake records obtained from US National Geophysical Data Centre are grouped into four soil types and the analysis is performed for each group in order to explore the soil-dependency of the aforementioned effects on the response. Computer programs are written in FORTRAN for both parametric and numerical model analyses. The latter can handle any number and orientation of columns with the assumed nonlinear stiffness properties. Newmark's and Runge-Kutta methods of numerical integration with adaptive step size control have been used to calculate parametric and the hysteretic responses of the system. The response to harmonic ground acceleration is used as a preliminary investigation into the response to actual accelerogram frequency components. The study has developed relationships for different definitions of the uncoupled torsional to lateral frequency ratio. Detailed derivation of the Equation of Motion has clarified the confusion that produced different definitions in the past studies. Graphical descriptions of the admissibility bounds on system parameters are produced. The variation in the response quantities is studied for a range of amplitude and phase contents of the applied ground acceleration. The difference in phase and amplitude in x and y ground accelerations have been found to affect the response quite significantly. More generally, the relationship of these differences to the torsional mode amplification has been observed. The effects of structural frequency and eccentricity parameters are also studied. Graphs showing the relationship between, the angle of incidence of the accelerogram with respect to the principal axis of the building, and the phase difference in the accelerogram pair, have been produced. The proposed analysis involving the bi-directional ground acceleration on a bi-eccentric system is an improvement on the current methods employed in design practice. Further work is, however, required before simplified design recommendations can be made and some proposals for future research are given at the end of this thesis.
17
CARDOSO, TARCISIO DE FREITAS. "OVERVIEW ON SECONDARY SYSTEM SEISMIC RESPONSE SPECTRA." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2008. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=12977@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROCOORDENAÇÃO DE APERFEIÇOAMENTO DO PESSOAL DE ENSINO SUPERIOR
A indústria de geração elétrica de fonte nuclear baseia-se em princípios de segurança e, nos critérios de projeto, considera-se a hipótese de terremoto. Os sistemas necessários à segurança são projetados para resistir e manter a operabilidade durante e após eventos sísmicos postulados. Propõe-se um roteiro para a produção de espectros de resposta sísmica para projeto de sistemas secundários, SS, incluindo a influência do acoplamento e em base probabilística. O roteiro utiliza a ferramenta SASSI, pode ser utilizado em situações gerais de cálculo e fornece um conjunto de programas para considerar modelos tridimensionais e suas respostas para uma excitação genérica em 3 direções ortogonais; representar os efeitos de acoplamento entre o SS e o sistema principal, SP; incluir a influência dos deslocamentos relativos entre os nós de apoio do sistema secundário no sistema principal; utilizar os fatores de transposição entre espectros elásticos e inelásticos; permitir a análise probabilística e a obtenção de Espectros de Resposta Uniformemente Prováveis, acoplados ou não; incluir interfaces para a utilização de seus resultados com outros programas de utilização geral, como o MS-EXCEL. O elevado grau de automatização permite a produção de espectros de resposta com refinamentos de modelagem, alcançando uma análise mais realista, sem a necessidade de esforços adicionais aos já requeridos pela metodologia convencional. A metodologia proposta enquadra-se no encaminhamento para o contexto atual de análise sísmica de instalações nucleares, com a utilização de espectros de resposta de projeto de ameaça uniforme, específico para o sítio da instalação, e o projeto sísmico de risco consistente.
The electric power reactor industry is based on rigid safety principles. The design criteria include seismic scenario. All safety related systems are designed to resist and to keep the operability during and after a postulated earthquake. It is suggested a procedure for the generation of in-structure seismic response spectra for secondary system design. A probabilistic approach is used and coupling effects between primary and secondary systems are taken into account. The proposed script uses SASSI system and can be used in general situations. A set of computer programs is developed to consider three-dimensional models and their responses for a generic base excitation, acting in 3 orthogonal directions; represent the coupling effect between primary and secondary systems, include the influence, on the response spectra, of the secondary system supports relative displacements; include approximated factors for transposition of elastic into inelastic response spectra; produce Uniformly Probable Response Spectra, including or not coupling effects; consider interfaces with other general programs, as the MS-EXCEL, for pos-processing purpose. The degree of automation, allows the production of response spectra including modeling refinements, reaching a more realistic analysis, without additional efforts beyond those already required by the conventional methodology. The proposed methodology is in the way of a site specific uniform hazard design response spectra, and of a consistent-risk seismic design.
18
Liguori, Nicola. "Seismic response of hospitals at different scales." Doctoral thesis, Pontificia Universidad Católica del Perú, 2018. http://tesis.pucp.edu.pe/repositorio/handle/123456789/13795.
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Nowadays, natural disasters are more frequents and destructives compared to the past, causing many
deaths and injuries. Existing hospitals are defined essential structures that have the goal to protect the
public health of citizen. They are called to resist not only to the impact of a disaster, but also to be
operational in that case. Operational means that all the components of a health facility such as structures,
architectural elements, contents, lifelines, key staff and the whole organizational system have to be
functional. That objective is a challenge for the existing structures, especially for those built with obsolete
seismic codes and in high seismic hazard areas like Lima. Furthermore, in case of an emergency, health
facilities are called to response as a network in order to be more efficient and resilient. It implies that
hospitals have to be managed not only at small-scale referring to the single hospital, but also at large-scale
referring to the whole health system composed by all the health facilities involved in a determined area.
Transfer of patients, staffs, water and medicines, can be moved under the coordination of a headquarters
in this way.
Starting from a developed health sector contingency plan in case of earthquakes for Lima metropolitan
area, an assessment of the seismic performance of health facilities at large and small scale was carried out.
At large-scale, two exploratory models were developed. The first one adapts to evaluate the basic seismic
response capacity of hospitals, while the second one useful to assess the hospital treatment capacity of
health facilities in the aftermath of a seismic event. Both models were carried out considering structural
and nonstructural building damages using fragility curves provided by international standards, given the
lack of Peruvian curves. Both models were proposed for a case study of 41 hospitals in Lima
metropolitan.
Given the lack of data about Peruvian building fragility curves, for a high rise infilled reinforced
concrete hospital building, fragility curves were developed through the capacity spectrum approach
including record-to-record variability. The method also allowed to to assess at small-scale the seismic
structural performance of the investigate hospital building using the capacity analysis method.Tesis
19
Pelecanos, Loizos. "Seismic response and analysis of earth dams." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/23649.
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Many earth dams around the world are located in zones characterised by moderate to high seismicity. Their seismic stability can be particularly critical for the safety of the areas in the downstream side and therefore an in depth understanding of their response during earthquakes is required. This thesis describes a numerical study related to both the seismic response and analysis of earth dams using the finite element method. In the first part of the thesis, the effect of the upstream reservoir hydrodynamic pressures on the elastic seismic response of dams is explored. Firstly, a methodology is proposed in which the reservoir domain is modelled with finite elements focusing in particular on the accurate prediction of the hydrodynamic pressures on the upstream dam face. Secondly, a parametric study of dam-reservoir interaction is carried out to examine the effect of the reservoir on the seismic response of dams. The second part of the thesis is concerned with the nonlinear seismic behaviour of earth dams. Firstly, a well-documented case study, the La Villita dam in Mexico, is analysed in order to validate the numerical model and a good agreement is obtained between the recorded and predicted data. Subsequently, using as a reference the calibrated model, parametric studies are performed in order to obtain a better insight into the dynamic response and analysis of earth dams. The latter studies provide a means to assess the effect of different modelling considerations on the seismic analysis of dams.
20
Malushte, Sanjeev R. "Seismic response of structures with Coulomb damping." Diss., Virginia Polytechnic Institute and State University, 1989. http://hdl.handle.net/10919/54235.
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The usefulness of Coulomb (friction) damping in earthquake-resistant design of structures is examined by studying the seismic response characteristics of structures with various arrangements of sliding interfaces. First, three basic arrangements are studied for their effectiveness in reducing lateral displacements of the supporting frame, accelerations of the floor slab and the resulting secondary floor spectra. These are: (1) slab sliding system which has the sliding interface between the floor slab and the supporting frame, (2) double sliding system which consists of sliding interfaces at both top and bottom interfaces (a combination of slab sliding and base sliding), and (3) spring-assisted slab sliding system which is a slab sliding system aided by lateral springs attached to the columns to resist excessive sliding displacement of the slab. The responses are obtained for structures with different frequencies and are presented in response spectrum form. The isolation characteristics of one slab sliding system are compared with those of the base sliding and hysteretic systems. Non-dimensional design parameters defined in terms of the corresponding elastic design spectra are introduced for design purposes and for a consistent presentation of the results. Methods for predicting the important response quantities using the non-dimensional parameters are discussed and their applicability is evaluated.
Next, the response of a simple slab sliding arrangement to simultaneous horizontal and vertical ground motion input is studied to see the effects of the vertical excitation on the isolation efficiency of that arrangement. Finally the suitability of adopting such sliding arrangements in multi-story structures is also examined. The seismic responses of multi-story structures with floor slabs sliding at different story levels are obtained and compared with the response of non-sliding structure and base sliding to examine the effectiveness of such sliding arrangement.Ph. D.
21
Doyle, Kelly. "Seismic response of telescope pipe pin connections." abstract and full text PDF (free order & download UNR users only), 2008. http://0-gateway.proquest.com.innopac.library.unr.edu/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1453645.
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22
Kadas, Koray. "Influence Of Idealized Pushover Curves On Seismic Response." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/3/12607761/index.pdf.
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Contemporary approach performance based engineering generally relies on the approximate procedures that are based on the use of capacity curve derived from pushover analysis. The most important parameter in the displacement-based approach is the inelastic displacement demand computed under a given seismic effect and the most common procedures employed for this estimationthe Capacity Spectrum Method and the Displacement Coefficient Method are based on bi-linearization of the capacity curve. Although there are some recommendations for this approximation, there is a vital need for rational guidelines towards the selection of the most appropriate method among several alternatives. A comprehensive research has been undertaken to evaluate the influence of several existing alternatives used for approximating the capacity curve on seismic demands. A number of frames were analyzed under a set of 100 ground motions employing OpenSees. In addition, the pushover curves obtained from nonlinear static analyses were approximated using several alternatives and the resulting curves were assigned as the force-deformation relationships of corresponding equivalent single-degree-of-freedom systems. These simplified systems were later analyzed to compute the approximate seismic response parameters. Using the results of the complex and simplified analyses, the performance of each approximation method was evaluated in estimating the &
#8216
exact&
#8217
inelastic deformations of the multi-degree-of-freedom systems at various degrees of inelasticity. Dependency of the errors on ductility, strength reduction factor and period was also investigated. The interpretations made and the conclusions drawn in this study is believed to clarify the rationality and accuracy of selecting the appropriate idealization of the capacity curve.
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Degirmenci, Can. "Dynamic Pull Analysis For Estimating The Seismic Response." Master's thesis, METU, 2006. http://etd.lib.metu.edu.tr/upload/12607833/index.pdf.
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The analysis procedures employed in earthquake engineering can be classified as linear static, linear dynamic, nonlinear static and nonlinear dynamic. Linear procedures are usually referred to as force controlled and require less analysis time and less computational effort. On the other hand, nonlinear procedures are referred to as deformation controlled and they are more reliable in characterizing the seismic performance of buildings. However, there is still a great deal of unknowns for nonlinear procedures, especially in modelling the reinforced concrete structures.
Turkey ranks high among all countries that have suffered losses of life and property due to earthquakes over many centuries. These casualties indicate that, most regions of the country are under seismic risk of strong ground motion. In addition to this phenomenon, recent studies have demonstrated that near fault ground motions are more destructive than far-fault ones on structures and these effects can not be captured effectively by recent nonlinear static procedures.
The main objective of this study is developing a simple nonlinear dynamic analysis procedure which is named as &ldquoDynamic Pull Analysis&rdquo
for estimating the seismic response of multi degree of freedom (MDOF) systems. The method is tested on a six-story reinforced concrete frame and a twelve-story reinforced concrete frame that are designed according to the regulations of TS-500 (2000) and TEC (1997).
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McAllister, Graeme. "Nonlinear seismic ground response of shallow sand sites." Thesis, University of British Columbia, 2015. http://hdl.handle.net/2429/54505.
Full textAbstract:
Predicting the ground response to the propagation of seismic waves is one of the most important aspects of geotechnical engineering. Advanced soil constitutive models provide significant opportunity to improve the understanding of nonlinear ground response during a seismic event, and offer the capability of simulating complex nonlinear soil behaviour which is not captured by means of traditional ground response analyses in geotechnical engineering. Moreover, observations of distinctive nonlinear soil behaviour during recent large earthquake events such as the 2011 Tohoku earthquake point towards the need to more reliably simulate realistic soil behaviour in order to understand the complex dynamic response of soils. The intent of this thesis is to utilize the SANISAND bounding surface plasticity model based on the work of Dafalias and Manzari (2004) to simulate the response of shallow sand deposits to a number of earthquake motions, with the aim of evaluating the ability of the model to simulate relatively complex nonlinear soil behaviour. Furthermore, both total and effective stress analysis techniques are carried out in order to highlight the importance of modeling the interaction between the pore fluid phase and the soil solid. For this purpose, two sites are analyzed, including a case history of a real downhole seismograph array and a generic site. The capability of the SANISAND model to simulate the phenomenon of high frequency dilation pulses is also explored. The SANISAND constitutive model is shown to adequately simulate the seismic ground response of a shallow sand soil column at a real downhole seismic array in Sendai, Japan by comparison to surface seismograph recordings for several earthquake events on the east coast of Japan. Soil permeability in the effective stress analyses is influential in the dynamic response of the soil to earthquake motions. Furthermore, modeling the pore fluid – soil solid interaction in an effective stress analysis is shown to be important for shallow medium dense sand sites subjected to cyclic mobility and strain stiffening. High frequency ground motion during the seismic response of a generic 10 m deep sand site is suggested to be caused by acceleration pulses as a result of soil dilation.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
25
Qu, Feng. "Seismic response of unanchored cylindrical liquid-tank systems." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/mq22125.pdf.
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Zeyl, Philip E. "Seismic response of two-way bridge column hinges." Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23760.
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Half-scale models of two-way column-footing hinge connections were tested under constant axial load and reversed cyclic lateral load. In one of the specimens, the column and hinge were circular in cross section; in the other specimen, the column and hinge were square in cross section. The main objective was to assess the seismic performance of these details, which are common in existing bridge structures in moderate seismic regions.The test results confirmed that the lateral column displacement was due almost entirely to rotations in the hinge. Horizontal slip at the hinge and flexural deformation in the column were insignificant prior to hinge gap closure, which occurred at large column displacements. Hinge gap closure resulted in sudden increases in stiffness and strength, but these increases occurred at column displacements which would be excessive in the prototype structure. The hinge responses are characterized by hysteretic pinching, poor energy absorption and significant stiffness degradation.
The measured moment-curvature responses of the hinge regions are compared predicted monotonic responses. Special attention is given to the effect of confinement on the hinge concrete in increasing the strength and the ductility of the concrete.
27
Harries, Kent A. (Kent Alexander). "Seismic response of steel beams coupling concrete walls." Thesis, McGill University, 1992. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=56617.
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Ductile coupled flexural walls are critical lateral load resisting systems of many structures. The coupling beams of these structures must exhibit excellent ductility and energy absorption ability. To achieve better ductility and energy absorption than previously possible, the use of steel link beams with their ends embedded in the reinforced concrete walls is proposed. Preliminary experimental results are reported for two full-scale reversed cyclic loading tests of portions of ductile flexural walls coupled with steel link beams. The excellent performance, together with the ease of construction, demonstrate the feasibility of this alternative form of construction. In order to ensure ductile response, design and detailing guidelines for both the clear span and embedded portions of the link beams and the reinforced concrete embedment region are presented. An assessment, based on comparisons with other structural systems, of this novel type of construction is presented.
28
Jeong, Seokho. "Topographic amplification of seismic motion including nonlinear response." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50325.
Full textAbstract:
Topography effects, the modification of seismic motion by topographic features, have been long recognized to play a key role in elevating seismic risk. Site response, the modification of ground motion by near surface soft soils, has been also shown to strongly affect the amplitude, frequency and duration of seismic motion. Both topography effects and 1-D site response have been extensively studied through field observations, small-scale and field experiments, analytical models and numerical simulations, but each one has been studied independently of the other: studies on topography effects are based on the assumption of a homogeneous elastic halfspace, while 1-D site response studies are almost exclusively formulated for flat earth surface conditions.
This thesis investigates the interaction between topographic and soil amplification, focusing on strong ground motions that frequently trigger nonlinear soil response. Recently, a series of centrifuge experiments tested the seismic response of single slopes of various inclination angles at the NEES@UCDavis facility, to investigate the effects of nonlinear soil response on topographic amplification. As part of this collaborative effort, we extended the search space of these experiments using finite element simulations. We first used simulations to determine whether the centrifuge experimental results were representative of free-field conditions. We specifically investigated whether wave reflections caused by the laminar box interfered with mode conversion and wave scattering that govern topographic amplification; and whether this interference was significant enough to qualitatively alter the observed amplification compared to free-field conditions. We found that the laminar box boundaries caused spurious reflections that affected the response near the boundaries; however its effect to the crest-to-free field spectral ratio was found to be insignificant. Most importantly though, we found that the baseplate was instrumental in trapping and amplifying waves scattered and diffracted by the slope, and that in absence of those reflections, topographic amplification would have been negligible. We then used box- and baseplate-free numerical models to study the coupling between topography effects and soil amplification in free-field conditions.
Our results showed that the complex wavefield that characterizes the response of topographic features with non-homogeneous soil cannot be predicted by the superposition of topography effects and site response, as is the widespread assumption of engineering and seismological models. We also found that the coupling of soil and topographic amplification occurs both for weak and strong motions, and for pressure-dependent media (Nevada sand), nonlinear soil response further aggravates topographic amplification; we attributed this phenomenon to the reduction of apparent velocity that the low velocity layers suffer during strong ground motion, which intensifies the impedance contrast and accentuates the energy trapping and reverberations in the low strength surficial layers. We finally highlighted the catalytic effects that soil stratigraphy can have in topographic amplification through a case study from the 2010 Haiti Earthquake. Results presented in this thesis imply that topography effects vary significantly with soil stratigraphy, and the two phenomena should be accounted for as a coupled process in seismic code provisions and seismological ground motion predictive models.
29
Chang, Tsu-Sheng. "Seismic Response of Structures with Added Viscoelastic Dampers." Diss., Virginia Tech, 2002. http://hdl.handle.net/10919/29915.
Full textAbstract:
Several passive energy dissipation devices have been implemented in practice as the seismic protective systems to mitigate structural damage caused by earthquakes. The solid viscoelastic dampers are among such passive energy dissipation systems. To examine the response reducing effectiveness of these dampers, it is necessary that engineers are able to conduct response analysis of structures installed with added dampers accurately and efficiently. The main objective of this work, therefore, is to develop formulations that can be effectively used with various models of the viscoelastic dampers to calculate the seismic response of a structure-damper system.
To incorporate the mechanical effect from VE dampers in the structural dynamic design, it is important to use a proper force-deformation model to correctly describe the frequency dependence of the damper. The fractional derivative model and the general linear model are capable of capturing the frequency dependence of viscoelastic materials accurately. In our research, therefore, we have focused on the development of systematic procedures for calculating the seismic response for these models.
For the fractional derivative model, we use the G1 and L1 algorithms to derive various numerical schemes for solving the fractional differential equations for earthquake motions described by acceleration time histories at discrete time points. For linear systems, we also develop a modal superposition method for this model of the damper. This superposition approach can be implemented to obtain the response time history for seismic input defined by the ground acceleration time history. For random ground motion that is described stochastically by the spectral density function, we derive an expression based on random vibration analysis to compute the mean square response of the system.
It is noted that the numerical computations involved with the fractional derivative model can be complicated and cumbersome. To alleviate computation difficulty, we explore the use of a general linear model with Kelvin chain analog as a physical representation of the damper properties. The parameters in the model are determined through a curve fitting optimization process. To simplify the analytical work, a self-adjoint system of state equations are formulated by introducing auxiliary displacements for the internal elements in the Kelvin chain. This self-adjoint system can then be solved by using the modal superposition method, which can be extended to develop a response spectrum approach to calculate the seismic design response for the structural system for seismic inputs defined by design ground response spectra.
Numerical studies are carried out to demonstrate the applicability of these formulations. Results show that all the proposed approaches provide accurate response values, and the response reduction effects of the viscoelastic dampers can be evaluated to assess their performance using these models and methods. However, the use of a general linear model of the damper is the most efficient. It can capture frequency dependence of the storage and loss moduli as well as the fractional derivative model. The calculation of the response by direct numerical integration of the equations of motion or through the use of the modal superposition approach is significantly simplified, and response spectrum formulation for the calculation of seismic response of design interest can be conveniently formulated.Ph. D.
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Verma, Navin Prakash. "Viscous Dampers for Optimal Reduction in Seismic Response." Thesis, Virginia Tech, 2001. http://hdl.handle.net/10919/43716.
Full textAbstract:
To model dissipation of energy in vibrating civil structures, existence of viscous damping is commonly assumed primarily for mathematical convenience. In such a classical damper, the damping force is assumed to depend only on the velocity of deformation. Fluid viscous dampers that provide this type of damping have been manufactured to provide supplementary damping in civil and mechanical systems to enhance their performance. Some fluid dampers, however, exhibit stiffening characteristics at higher frequencies of deformation. The force deformation relationship of such dampers can be better represented by the Maxwell model of visco-elasticity. This model consists of a viscous dashpot in series with a spring, the latter element providing the stiffening characteristics. This study is concerned with the optimal utilization of such Maxwell dampers for seismic performance improvement of civil structures. The force deformation relationship of Maxwell dampers is described by a first order differential equation. Earlier studies dealing with these dampers, used an unsymmetric set of equations for combined structure and damper system. The solution of such equations for response analysis or for optimization calculation by a modal analysis approach would require the pair of the left and right eigenvectors. In this study, an auxiliary variable is introduced in the representation of a Maxwell damper to obtain symmetric equations of motion for combined structure and damper system. This eliminates the need for working with two sets of eigenvectors and their derivatives, required for optimal analysis.
Since the main objective of installing these dampers is to reduce the structural response in an optimal manner, the optimization problem is defined in terms of the minimization of some response-based performance indices. To calculate the optimal parameters of dampers placed at different location in the structure, Rosen's gradient projection method is employed. For numerical illustration, a 24-story shear building is considered. Numerical results are obtained for seismic input defined by a spectral density function; however, the formulation permits direct utilization of response spectrum-based description of design earthquake. Three different performance indices -- inter story drift-based, floor acceleration-based, and base shear-based performance indices-- have been considered to calculate the numerical results. A computational scheme is presented to calculate the amount of total damping required to achieve a desired level of response reduction. The effect of ignoring the stiffening effect at higher frequencies in the Maxwell model on the optimal performance is evaluated by parametric variation of relaxation time coefficient. It is observed that the models with higher relaxation time parameter show a decreased response reducing damping effect. Thus ignoring the stiffening effect when it is, indeed, present would provide an unconservative estimation of the damping effect. The effect of brace flexibilities on different performance indices is also investigated. It is observed that flexibility in a brace reduces the effectiveness of the damper.Master of Science
31
Burdisso, R. A. "Seismic response analysis of multiply connected secondary systems." Diss., Virginia Polytechnic Institute and State University, 1986. http://hdl.handle.net/10919/49996.
Full textAbstract:
An analytical formulation for seismic analysis of multiply supported secondary systems is developed. The formulation is based on the random vibration theory of structural systems subjected to correlated inputs at several points. The response of the secondary systems is expressed as a combination of the dynamic, pseudo-static and cross response components. The dynamic part is associated with the inertial effect induced by the support accelerations. The pseudo-static part is due to the relative displacement between supports, and the cross part takes into account the correlation between these two parts of the response. The seismic input in this approach is defined in terms of the auto and cross pseudo-acceleration and relative velocity floor spectra. The information about floor displacements and velocities as well as their correlations is required for calculating the pseudo-static and cross response components. These inputs can be directly obtained from the ground response spectra. The interaction effect between the primary and secondary systems is studied. This effect is specially significant when the modes of the secondary system are tuned or nearly tuned to the modes of the primary system. The floor spectral inputs are appropriately modified to take into account this interaction effect. The design response of the secondary system when computed with these modified floor inputs will incorporate the interaction effect. The applicability of the proposed methods is demonstrated by several numerical examples.Ph. D.
incomplete_metadata
32
Qu, Feng Carleton University Dissertation Engineering Civil and Environmental. "Seismic response of unanchored cylindrical liquid-tank systems." Ottawa, 1997.
Find full text
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Casacci, Susanna. "The seismic response of one-storey asymmetric structures." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2012. http://amslaurea.unibo.it/4611/.
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Chui, Kwok-Lun. "Integrated wind tunnel based response analysis and structural optimization for serviceability design of tall buildings /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?CIVL%202004%20CHUI.
Full textAbstract:
Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004.Includes bibliographical references (leaves 187-194). Also available in electronic version. Access restricted to campus users.
35
El-Attar, Mohamed Mohsen. "Nonlinear dynamics and seismic response of power transmission lines." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/NQ30082.pdf.
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Shariatmadar, Hashem. "Seismic response of connections in precast concrete double-tees." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp02/NQ30386.pdf.
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Sarvghad-Moghadam, Abdoreza. "Seismic torsional response of asymmetrical multi-storey frame buildings." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1998. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape11/PQDD_0003/NQ42874.pdf.
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38
Bristowe, Stuart. "Seismic response of normal and high-strength concrete members." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=36757.
Full textAbstract:
A series of full-scale, reversed cyclic tension and compression tests was conducted to aid in the development of constitutive relationships for predicting the seismic response of concrete elements. These specimens were constructed using normal and high-strength concrete and contained varying amounts of transverse reinforcement consistent with both beam and column detailing requirements for different ductility levels. The influence of several parameters was investigated, including the effect of confinement, bar buckling and concrete strength.Reversed cyclic loading tests were carried out on conventionally reinforced nominally ductile and ductile coupling beams constructed with normal and high-strength concrete. These tests investigated the effect of the design and detailing of the transverse reinforcement, as well as the strength of the concrete.
Analytical models for the prediction of the reversed cyclic loading response of concrete and steel are presented and used to predict the reversed cyclic tension-compression response of the axially loaded specimens tested. These tension-compression models were used to develop a plane sections analysis program, which was capable of evaluating the reversed cyclic moment-curvature response of concrete members. These models were very effective at predicting the reversed cyclic responses of the axially loaded specimens, the coupling beams and a flexural wall.
39
Niazi, Fawad Sulaman. "Static axial pile foundation response using seismic piezocone data." Diss., Georgia Institute of Technology, 2014. http://hdl.handle.net/1853/52195.
Full textAbstract:
Ever since the use of cone penetration testing (CPT) in geotechnical site investigations, efforts have been made to correlate its readings with the components of static axial pile capacity: unit base resistance (qb) and unit shaft resistance (fp). Broadly, the pile capacity analysis from CPT data can be accomplished via two main approaches: rational (or indirect) methods, and direct methods. The rational methods require a two-step approach, whereby CPT data are first used to provide assessments of geoparameters that are further utilized as input values within a selected analytical framework to enable the evaluation of the pile capacity components. In contrast, direct CPT methods use the measured penetrometer readings by scaling relationships or algorithms in a single-step process to obtain fp and qb for full-size piling foundations. The evolution of the CPT from mechanical to electrical to electronic versions and single-channel readings (i.e., measured tip resistance, qc) to the piezocone penetration test (CPTu), that provides three readings of point stress (qt), sleeve friction (fs), and porewater pressure (u1 or u2), has resulted in the concurrent development of multiple CPT-based geotechnical pile design methods. It is noted, however, that current CPT-based methods focus only on an estimate of "axial pile capacity", corresponding to a limiting load or force at full mobilization.
A more comprehensive approach is sought herein utilizing the CPT readings towards producing a complete nonlinear load-displacement-capacity (Q-w-Qcap) on axial pile response. In particular, the seismic cone penetration test (SCPT) provides the profile of shear wave velocity (Vs) that determines the fundamental small-strain shear modulus: Gmax = gt?Vs2, where gt = total mass density of soil. With the penetrometer readings useful in assessing foundation capacity, the stiffness Gmax finds application within elastic continuum solutions towards evaluating the load-displacement (Q-w) response.
In this study, a concise review of the deep foundation systems is presented, including pile types and characteristics, various arrangements of axial pile load testing in static mode, and interpretations of the load test data. In addition a comprehensive state-of-the-art review of CPT-based rational and direct methods of pile capacity evaluations is compiled. It is recognized that the direct methods offer more convenience in their straightforward approach in estimation of the pile capacity. The piezocone-based UniCone direct method proposed by Eslami and Fellenius (1997) is selected for further refinements, as it utilizes all three CPT readings in its design formulations. Concerning the analysis of pile deformations under axial loading, a brief review covers designs employing empirical formulations, analytical solutions, load-transfer (t-z) methods, numerical simulations, variational approaches, and those using hybrid methods. Specifically, the analytical elastic solution by Randolph and Wroth (1978; 1979) is covered in more detail since it is simple and convenient in application with extended applications to uplift and bidirectional O-cell types of loadings. This elastic approach also serves well in modeling a stacked pile solution for layered soil profiles. The last part of the review covers various shear modulus reduction schemes, since evaluation of the applicable stiffnesses is considered to be the most delicate phase in the nonlinear Q-w response analysis of axially loaded piles. It is identified that the most appropriate scheme applicable to static axial loading of pile foundations is the one that can be derived from the back-analyses of actual load tests within the framework of analytical elastic solution.
In order to conduct a comprehensive research study on the axial Q-w-Qcap response of deep foundations from CPT readings, a large database is compiled. This includes 330 case records of pile load tests at 70 sites from 5 continents and 19 different countries of the world, where pile foundations were load tested under top-down compression or top-applied uplift (tension) loading, or both, or by bi-directional Osterberg cell setups. All test sites had been investigated using CPT soundings; in most cases by the preferred SCPTu that provides all four readings from the same sounding: qt, fs, u2, and Vs. In a few cases, sites were subjected to CPT or CPTu and the profiles of shear wave velocities were obtained by other field geophysical techniques, otherwise by empirical estimations.
Results of the new correlation efforts are offered to derive coefficients Cse for shaft component and Cte for base component of the axial pile capacity from CPTu data. The UniCone type of soil classification chart is refined by delineating 11 soil sub-zones along with their respective Cse, in contrast to the 5 zones originally proposed. The CPT material index, Ic (Robertson, 2009) is then used to establish direct correlations linking Cse vs. Ic and Cte vs. Ic. Statistical relationships offer continuous functions for estimating the coefficients over a wide range of Ic values, thereby eliminating the need for use of the soil classification chart as well as improving the reliability in the evaluations of fp and qb. The effects of the pile loading direction (compression vs. uplift) and loading rate are also incorporated in the proposed design formulations.
New sets of shear stiffness reduction curves are developed from the back-analysis of pile load tests and Gmax profiles obtained from the SCPT data. Alternative functions formats are provided in terms of hyperbolic tangent expressions or exponential curves, developed as normalized shear stiffness (G/Gmax) vs. logarithm of percent pseudo-strain (gp = w/d, where w = pile displacement and d = pile diameter). These charts offer convenience in the axial Q-w analysis of different pile categories within the framework of analytical elastic solution. The results also account for the plasticity characteristics of the soil formations within the database.
A stacked pile model for Q-w analysis is presented in which certain adaptations are proposed in the elastic continuum solution. These adaptations enable plotting of separate modulus reduction curves (G/Gmax vs. gp) as function of depth for each layer, and treating pile as a stack of smaller pile segments embedded in a multi-layered soil media. The solution can be used to address the question of progressive failure with depth in a multi-layer soil media that exhibits nonlinear soil stiffness response.
Finally, the closed-from analytical elastic pile solution for predicting the Q-w response is decoupled and modified to account for different setup cases and multi-stage loading of bi-directional O-cell tests. The decoupling accounts for separate assessments of the response to axial loading for different segments of pile shaft and different stages of loading, while the modifications include: (1) reduced maximum radius of influence for the upward displacements of the upper shaft segment, and (2) modeling the non-linear ground stiffness from the back-analysis of a well-documented dataset of O-cell load tests.
40
Maheetharan, A. "Modelling the seismic response of piles and pile groups." Thesis, University of Cambridge, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.358741.
Full text
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Panagiotidou, Andriani Ioanna. "Seismic response of wharf structures supported in liquefiable soil." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82845.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 108-110).
This research analyzes the vulnerability of wharf structures supported on loose granular waterfront fills that are susceptible to liquefaction during seismic events and considers the effectiveness of pre-fabricated Vertical (PV) drain systems in mitigating potential damage. The analyses are based on non-linear finite element simulations using the OpenSees open-source software framework. The analyses make extensive use of an advance macroelement formulation by Varun (PhD, 2010), which captures efficiently the fundamental mechanisms of saturated granular soil behavior. The thesis explains in detail the mechanical components of the macroelement as well as the necessary calibration steps. Numerical simulations of a typical berth of port facilities on the US West coast have been carried out using as earthquake loading the time histories of free field displacements and of excess pore pressures predicted by Vytiniotis (PhD, 2011) at specific locations along the embedded length of piles (for a suite of 56 ground motions). The results show that the primary cause of the structural damage is indeed the lateral spreading of the soil and therefore retrofitting efforts should be targeted in limiting the development of pore pressures that cause the lateral spreading. This argument is then tested by comparing the performance in numerical simulations for the case where full-depth PV drains are installed at locations behind the crest of the slope (i.e. minimally-intrusive mitigation system) and for the case of a fully densified slope for the same suite of ground motions. These results indicate that soil improvement methods assist in reducing structural damage to pile-deck connection locations. The results also show that the densification of the slope is only marginally superior to the less intrusive improvement with PV-drains.
by Andriani Ioanna Panagiotidou.
S.M.
42
Seymour, Douglas (Douglas Benjamin). "Design of innovative dynamic systems for seismic response mitigation." Thesis, Massachusetts Institute of Technology, 2012. http://hdl.handle.net/1721.1/74497.
Full textAbstract:
Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.Cataloged from PDF version of thesis.
Includes bibliographical references (p. 97-99).
Rocking wall systems consist of shear walls, laterally connected to a building, that are moment-released in their strong plane. Their purpose is to mitigate seismic structural response by constraining a building primarily to a linear fundamental mode. This constraint prevents mid-story failure, and maximizes energy dissipation by activating the maximum number of plastic hinges throughout the structure. This is a useful response mitigation system, but suffers from some difficulties, stemming primarily from the considerable mass of the wall. Those difficulties are notably expensive foundations, and very high inertial forces imparted to the building, with subsequent need for expensive lateral connectors. The purposes of this work are to analyze current implementations of rocking wall systems, present an early reference on their application, present the first systematic methodology for their design, clarify their analysis, and introduce an alternative structural system that avoids their difficulties. A quasi-static analysis model is used for predicting the seismic mitigation performance of rocking walls and rocking columns. The stiffness matrix is generalized for an N-story building equipped with these structural systems. The model presented enables optimization of the design parameters, and consequently improved system effectiveness, analytical tractability, and material usage. The case study is a rocking wall system installed in a building located in Tokyo, Japan. A software package is developed, providing an illustrative implementation of the methods derived.
by Douglas Seymour.
S.M.
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Malushte, Sanjeev R. "Prediction of seismic design response spectra using ground characteristics." Thesis, Virginia Tech, 1987. http://hdl.handle.net/10919/45802.
Full textAbstract:
The available earthquake records are classified into five groups according to their site stiffness and epicentral distance as the grouping parameters. For the groups thus defined, normalized response spectra are obtained for single-degree-ofâ freedom and massless oscillators. The effectiveness of the grouping scheme is examined by studying the variance of response quantities within each group. The implicit parameters of average frequency and significant duration are obtained for each group and their effect on the response spectra is studied. Correlation analyses between various ground motion characteristics such as peak displacement, velocity, acceleration and root mean square acceleration are carried out for each group.
Smoothed design spectra for relative and pseudo velocities and relative acceleration responses of single degree of freedom oscillators and the velocity and acceleration responses of massless oscillators are proposed for each group. Methods to predict relative velocity and relative acceleration spectra directly from the pseudo velocity spectra are presented. It is shown that the relative spectra can be reliably estimated from the pseudo spectra. The site dependent design spectra are defined for a wide range of oscillator periods and damping ratios.
Master of Science
44
Kumar, Mukesh. "Inelastic seismic response assessment of moment resisting steel frames." Thesis, Imperial College London, 2012. http://hdl.handle.net/10044/1/14524.
Full textAbstract:
To improve the predictability of structural and non-structural damage of structures for a given hazard scenario, it is essential to identify factors that influence the response and evaluate their contribution. Several studies have therefore focused on the assessment of parameters that influence the inelastic response of structures under seismic loading. However, these studies have in most cases been limited to single degree of freedom (SDF) systems and generic frames with controlled strength and stiffness distribution characteristics. In addition to this, the influence of the frequency content of ground motion on the inelastic response of structures has not been fully explored and utilized. Therefore, this thesis aims to understand the influence of frequency content and key properties of structure, designed to Eurocode provisions, on the inelastic response. A suitable frequency content measure that can be related to magnitude, distance and site characteristics of an earthquake event, and easily adopted as a design input, is selected from the available literature in order to understand the influence of frequency content. The applicability of the selected parameter is first explored and established by studying the inelastic displacement demand of SDF systems as well as global drift, base shear and maximum storey drift profile of a selected multi-degree freedom (MDF) system, using a suite of 128 far-field ground motion records. Subsequently, incremental dynamic analysis of a large set of moment resisting steel frames designed to Eurocode 8 is conducted using 72 far-field ground motion records. The influence of salient structural properties on the inelastic drift and strength demands and their interaction with frequency content is investigated. Based on extensive parametric studies, regression models are developed as a function of the parameters that influence drift and strength demands of the frames. Finally, implications of the findings on current seismic design and assessment provisions, with emphasis on the guidelines of Eurocode 8, are discussed. Furthermore, recommendations are proposed for future work that can lead to further improvements in codified procedures.
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Malasavage, Nicholas Eugene Wartman Joseph. "Post-seismic displacement response in normally consolidated clay slopes /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3202.
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Kasinos, Stavros. "Seismic response analysis of linear and nonlinear secondary structures." Thesis, Loughborough University, 2018. https://dspace.lboro.ac.uk/2134/33728.
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Understanding the complex dynamics that underpin the response of structures in the occurrence of earthquakes is of paramount importance in ensuring community resilience. The operational continuity of structures is influenced by the performance of nonstructural components, also known as secondary structures. Inherent vulnerability characteristics, nonlinearities and uncertainties in their properties or in the excitation pose challenges that render their response determination as a non-straightforward task. This dissertation settles in the context of mathematical modelling and response quantification of seismically driven secondary systems. The case of bilinear hysteretic, rigid-plastic and free-standing rocking oscillators is first considered, as a representative class of secondary systems of distinct behaviour excited at a single point in the primary structure. The equations governing their full dynamic interaction with linear primary oscillators are derived with the purpose of assessing the appropriateness of simplified analysis methods where the secondary-primary feedback action is not accounted for. Analyses carried out in presence of pulse-type excitation have shown that the cascade approximation can be considered satisfactory for bilinear systems provided the secondary-primary mass ratio is adequately low and the system does not approach resonance. For the case of sliding and rocking systems, much lighter secondary systems need to be considered if the cascade analysis is to be adopted, with the validity of the approximation dictated by the selection of the input parameters. Based on the premise that decoupling is permitted, new analytical solutions are derived for the pulse driven nonlinear oscillators considered, conveniently expressing the seismic response as a function of the input parameters and the relative effects are quantified. An efficient numerical scheme for a general-type of excitation is also presented and is used in conjunction with an existing nonstationary stochastic far-field ground motion model to determine the seismic response spectra for the secondary oscillators at given site and earthquake characteristics. Prompted by the presence of uncertainty in the primary structure, and in line with the classical modal analysis, a novel approach for directly characterising uncertainty in the modal shapes, frequencies and damping ratios of the primary structure is proposed. A procedure is then presented for the identification of the model parameters and demonstrated with an application to linear steel frames with uncertain semi-rigid connections. It is shown that the proposed approach reduces the number of the uncertain input parameters and the size of the dynamic problem, and is thus particularly appealing for the stochastic assessment of existing structural systems, where partial modal information is available e.g. through operational modal analysis testing. Through a numerical example, the relative effect of stochasticity in a bi-directional seismic input is found to have a more prominent role on the nonlinear response of secondary oscillators when compared to the uncertainty in the primary structure. Further extending the analyses to the case of multi-attached linear secondary systems driven by deterministic seismic excitation, a convenient variant of the component-mode synthesis method is presented, whereby the primary-secondary dynamic interaction is accounted for through the modes of vibration of the two components. The problem of selecting the vibrational modes to be retained in analysis is then addressed for the case of secondary structures, which may possess numerous low frequency modes with negligible mass, and a modal correction method is adopted in view of the application for seismic analysis. The influence of various approaches to build the viscous damping matrix of the primary-secondary assembly is also investigated, and a novel technique based on modal damping superposition is proposed. Numerical applications are demonstrated through a piping secondary system multi-connected on a primary frame exhibiting various irregularities in plan and elevation, as well as a multi-connected flexible secondary system. Overall, this PhD thesis delivers new insights into the determination and understanding of the response of seismically driven secondary structures. The research is deemed to be of academic and professional engineering interest spanning several areas including seismic engineering, extreme events, structural health monitoring, risk mitigation and reliability analysis.
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Wan, Siu Pong. "Field monitoring of ground response to EPBM tunnelling close to existing tunnels in London Clay." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/42249.
Full textAbstract:
Field monitoring research was performed by Imperial College London, as part of an Engineering and Physical Sciences Research Council (EPSRC) funded research project, in collaboration with Crossrail urban railway project, to investigate how tunnelling affects adjacent existing tunnels. This field research aims to establish a high-quality case history involving comprehensive instrumentation and monitoring around earth pressure balance tunnel boring machine (EPBM) tunnelling in London Clay. Surface and subsurface instruments were installed in Hyde Park and bordering Bayswater Road, beneath which the new Crossrail twin-bore tunnels were constructed by EPBMs in London Clay below the existing London Underground Central Line tunnels. Responses to tunnel construction of the 'greenfield' ground and the ground near the existing tunnels were measured. Sufficient resolution and accuracy of the monitoring systems were established through pre-construction measurements to ensure that reliable data were obtained. The Hyde Park monitoring data are analysed and interpreted to characterise the surface and subsurface ground displacements and stress changes which are compared with similar results from other case histories of tunnelling in cohesive soils. They are also studied together with the Crossrail contractor's measurements from instruments within the existing tunnels and in Hyde Park. It is demonstrated from the monitoring results during the construction of the first tunnel that the surface and subsurface settlement troughs were wider in the ground near the existing tunnels, compared with the troughs in the 'greenfield' ground, indicating the influence of the presence of the old tunnels. The form of the surface and subsurface settlement troughs induced by the second tunnel construction is found to be dictated by the more recent construction of the first tunnel, with larger settlements and wider trough widths on the side of the first tunnel, indicating the strain-softening effect of the ground by the tunnel construction. The measured ground displacement field in near vicinity of the EPBM tunnelling, determined from the subsurface vertical and horizontal displacement measurements, is found to be directed towards the tunnel construction (i.e. 'inward' displacement field), as opposed to the 'outward' displacement field observed in an instrumented site at Dagenham for a similar EPBM tunnelling for the Channel Tunnel Rail Link project (Standing and Selemetas, 2013). It is believed that the nature of the ground displacement field in close proximity of an EPBM tunnelling (i.e. 'inwards' or 'outwards') depends largely on the relative magnitudes of the machine face pressure and tail grout pressure compared with the in-situ overburden pressure. The mechanisms of ground displacements in the near vicinity of EPBM tunnelling are established by analysing key EPBM operation variables in conjunction with the measured surface and subsurface ground response.
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KASAI, Akira, 昭. 葛西, Qingyun LIU, 青芸 劉, Tsutomu USAMI, and 勉. 宇佐美. "INELASTIC SEISMIC RESPONSE ANALYSIS OF ECCENTRICALLY LOADED STEEL BRIDGE PIERS." 土木学会, 2000. http://hdl.handle.net/2237/8649.
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Tupper, Bryce. "Seismic response of reinforced concrete walls with steel boundary elements." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0023/MQ50667.pdf.
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Koch, Pierre-Alexandre. "Seismic response of high-strength concrete beam-column-slab specimens." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0030/MQ50632.pdf.
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