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.

Viscous dampers are widely used to ensure seismic resistance of pipelines and equipment in nuclear power plants. Damping characteristics of these dampers are nonlinearly frequency dependent and thus causing complications in computational modelling of seismic response. Engineers commonly use two ways to deal with this nonlinearity: The first option is to consider damper by means of “snubber”. This is essentially linear spring element that is active for dynamic load and does not resist static loads. Snubber behaviour during seismic event is described by a equivalent stiffness (sometimes called pseudostiffness). The equivalent stiffness could be defined by the iterative calculations of piping natural frequencies and mode shapes taking into account seismic excitation. However, in complicated structures such as the main circulation loop of nuclear power plant the iterative calculation is difficult and could bring significant inaccuracies. On the other hand, the benefit of such modelling is a possibility to apply the commonly used linear response spectrum method for a solution. The second option is to describe damping characteristics using suitable rheological model. The seismic response is than determined by direct integration of the equations of motion. The behaviour of dampers is described exactly enough but the calculation and post-processing, especially nodal stresses time-histories, are time consuming. The goal of this work was to find a methodology for determining the seismic response of complex pipe systems with viscous dampers. Methodology allows a sufficiently accurate determination of the seismic response of piping systems and also allows obtaining of the results in effective time. The procedure is as follows. Firstly, specialized piping program (AutoPIPE) is used for the development of computational model. Next step is to determine a static response of structure and its verification with experimental measurements, if possible. Using script in Python language a computational model is converted from AutoPIPE into general finite element model in ANSYS system. Four-parameter Maxwell rheological model is used to describe behaviour of viscous dampers. Seismic load is represented by synthetic accelerograms. Newmark algorithm of direct integration of the equation of motion is used to obtain seismic response (only reactions and displacements in nodes of interest are necessary). Than is the equivalent stiffness is than gained from displacements and reactions as median value of their ratios. Received stiffness are subsequently transferred to AutoPIPE program where the seismic solution is performed using response spectra method. Finally, the dynamic response is combined with the static response and stress assessment according standards is done. The created methodology was applied in the seismic resistance calculation of the main circulation piping and piping of pressurizer in nuclear power plants type VVER 440 and type VVER 1000.

<p>Most of the attention to the seismic performance of tunnels has been devoted to shear waves propagating in a direction perpendicular to the tunnel axis, with motion perpendicular to the tunnel axis, causing the so-called “ovaling or racking response”. Body waves, however, can travel through the ground and intersect the tunnel at different angles, thus inducing a complex seismic response that requires a comprehensive understanding of all modes of deformation. This study provides analytical solutions to capture the behavior of the liner and the surrounding ground, for a deep circular tunnel subjected to body waves, for all five possible modes of deformation: (i) axial compression-extension; (ii) transverse compression-extension; (iii) ovaling; (iv) axial shear; and (v) axial bending or snaking. The main assumptions used to derive the analytical solutions include: (i) the tunnel is deep and very long and has a circular cross section; (ii) the ground and the support are homogeneous and isotropic, and their response remains elastic; (iii) the interface between the ground and the liner is either no-slip or full-slip; (iv) the pseudo-static approach, i.e. inertia forces can be neglected, is acceptable to estimate seismic deformations; (v) for the transverse compression-extension and ovaling deformation modes, plane strain conditions in the direction of the tunnel axis apply at any cross section; and (vi) for the axial compression-extension and axial bending deformation modes, the wavelength of the seismic motions is much larger than the tunnel radius. Two and three-dimensional numerical simulations with the finite element codes ABAQUS, for static drained/undrained loading and dynamic drained loading conditions, and MIDAS GTS NX, for dynamic undrained loading conditions, are carried out to validate the analytical solutions and further investigate the seismic response of the tunnel. All the comparison results show good agreement between the analytical and numerical solutions.</p> <p>Dynamic amplification effects on the tunnel cross section are studied for the axial compression-extension, transverse compression-extension, and axial bending deformation modes, through a set of dynamic time-history models where the input frequency of the far-field seismic motion is changed. The results reveal the limits of the analytical solutions, in the form of minimum wavelength-to-tunnel diameter (/D) ratios such that the errors are less than twenty percent, including: (i) 25 (drained) and 20 (undrained) for axial compression-extension; (ii) 25 (drained) and 12.5 (undrained) for transverse compression- extension; and (iii) 7.5 (unsupported tunnel), 7.5 (supported tunnel with no-slip interface), and 12.5 (supported tunnel with full-slip interface) for axial bending or snaking. These ratios are also the limits of applicability of quasi-static (instead of dynamic) numerical simulations to estimate the seismic behavior of the liner and the surrounding ground.</p>

<p>Proučeno je oscilatorno kretanje i disipacija energije stuba napravljenog<br />od nekoliko krutih blokova, koji pri horizontalnom seizmičkom dejstvu<br />mogu da klize jedan po drugom. Pored međusobnog kontakta sa trenjem, koje je<br />modelirano neglatkom viševrednosnom funkcijom, veze između blokova<br />sadrže i viskoelastične elemente, čije konstitutivne relacije uključuju<br />frakcione izvode, kao i ograničenja na koeficijente koja slede iz<br />Klauzius-Dijemove nejednakosti. Postavljeni Košijev problem predstavlja<br />uopštenje klasičnog problema ponašanja konstrukcija pod dejstvom<br />seizmičkog opterećenja, jer objedinjuje izvode proizvoljnog realnog reda<br />sa teorijom neglatkih viševrednosnih funkcija. Predložena je numerička<br />procedura za rešavanje postavljenog problema.</p> / <p> Seismic response and energy dissipation of a column made of several rigid<br /> blocks, which can slide along each other, was considered. Besides friction<br /> contact, which was modeled by a set valued function, viscoelastic elements<br /> whose constitutive equations include fractional derivatives as well as restrictions<br /> on the coefficients that follow from Clausius-Duhem inequality are present in<br /> connections between blocks. The posed Caushy problem represents the<br /> generalization of a classical problem of seismic response because it merges<br /> fractional derivatives with the theory of set valued functions. The numerical<br /> procedure for solving the problem was suggested.</p>

[pt] O Peru se localiza na região denominada cinturão de fogo do Pacífico, onde se registra aproximadamente 85 porcento da atividade sísmica mundial. Como grande produtor de minérios, importantes estruturas são construídas no país para desenvolvimento de projetos de mineração, incluindo barragens de rejeitos. Nesta dissertação é investigado o potencial de liquefação dinâmica de uma barragem de rejeitos localizada na região central do Peru, que atualmente passa por uma etapa de alteamento pelo método construtivo da linha de centro. A liquefação dos solos é um fenômeno caracterizado pela perda de rigidez e resistência durante curto intervalo de tempo, mas suficiente para causar instabilidades e, em casos extremos, o colapso da estrutura. Análises numéricas foram realizadas para verificar o potencial de liquefação dinâmica da barragem, representando o comportamento cíclico dos materiais suscetíveis à liquefação pelo modelo constitutivo UBCSand e de Byrne, considerando terremotos de magnitude 8,2, 7,8 e 8,1. Resultados numéricos obtidos foram comparados com formulações simplificadas, utilizadas na prática de engenharia para determinação do fator de segurança contra liquefação dinâmica. As análises indicaram que rejeitos finos, abaixo do nível de lençol freático, apresentam potencial de liquefação, conforme valores do parâmetro de razão de poropressão (ru) computados, porém sem provocar risco à estabilidade geral da estrutura. São também apresentados resultados de deslocamentos permanentes em alguns pontos da barragem e dos rejeitos. / [en] Peru is located in the region called the Pacific fire belt, where approximately 85 percent of the world seismic activity is recorded. As a major ore producer, important structures are built in the country to develop mining projects, including tailings dam. The dissertation investigates the potential for dynamic liquefaction of a tailings dam located in the central region of Peru, whose height is currently being raised by the center line construction method. Liquefaction of soils is a phenomenon characterized by loss of stiffness and resistance over a short period of time, but sufficient to cause instability and, in extreme cases, the collapse of the structure. Numerical analyses were carried out to verify the dynamic liquefaction potential of the dam, representing the cyclical behavior of the materials susceptible to liquefaction by the constitutive model UBCSand and Byrne, considering an earthquakes of magnitude 8,2, 7,8 and 8,1. Numerical results obtained were compared with simplified formulations used in the practice of engineering in order to determine the safety factor against dynamic liquefaction. The analyses indicated that fine tailings, below the water table level, have potential for liquefaction, according to the values of the poropression parameter (ru) computed, but without risk to the general stability of the structure. Results are also presented in terms of permanent displacements at some points of the dam and tailings.

A new methodology is proposed to perform nonlinear time domain analysis on three-dimensional reinforced concrete bridge structures subjected to spatially varying seismic ground motions. A stochastic algorithm is implemented to generate unique and correlated time history records under each bridge support to model the spatial variability effects of seismic wave components traveling in the longitudinal and transverse direction of the bridge. Three-dimensional finite element models of highway bridges with variable geometry are considered where the nonlinear response is concentrated at bidirectional plastic hinges located at the pier end zones. The ductility demand at each pier is determined from the bidirectional rotations occurring at the plastic hinges during the seismic response evaluation of the bridge models. Variability of the soil characteristics along the length of the bridge is addressed by enforcing soil response spectrum compatibility of the generated time history records and of the dynamic stiffness properties of the spring sets modeling soil rigidity at the soil-foundation interface at each support location. The results on pier ductility demand values show that their magnitude depends on the type of soil under the pier supports, the pier location and the overall length and geometry of the bridge structure. Maximum ductility demand values were found to occur in piers supported on soft soils and located around the mid span of long multi-span bridges. The results also show that pier ductility demand values in the transverse direction of the bridge can be significantly different than the values in the longitudinal direction and in some instances, the maximum value occurs in the transverse direction. Moreover, results also show that ignoring the effects of spatial variability of the seismic excitation, the pier ductility demand can be severely underestimated. Finally, results show that increasing the vertical acceleration component in the seismic wave will generate an increase in the pier axial loads, which will reduce the ductility range of the pier plastic zones. As result, even though the increase in pier ductility demand associated with the increase in the vertical acceleration component was found to be relatively small, the number piers exhibiting significant structural damage increased.

Dans cette thèse nous nous sommes intéressés à établir une formulation probabiliste pour l’analyse du comportement d’un sol multicouche avec des caractéristiques aléatoires. Deux grands axes sont traités : ?la consolidation primaire et ?la réponse sismique des sols multicouches ayant des caractéristiques aléatoires. Nous utilisons les simulations de Monte Carlo associées à des méthodes semi-analytiques adaptées aux sols multicouches avec une stratification horizontale. Nous avons aussi comparés les résultats obtenus à partir de cette formulation à ceux fournis par les règlements parasismiques suivants : RPA 99 (version 2003), UBC 97 et l’EC8. Cette étude a montré que les valeurs maximales des forces de cisaillement à la base des bâtiments variaient substantiellement en fonction de la variation de la hauteur du profil de sol ainsi que de son hétérogénéité pouvant atteindre un rapport relatif de l’ordre de 3 dans les cas les plus défavorables. Ce rapport peut également être inférieur à 1 conduisant à des structures moins économiques / In this thesis we are interested to establish a probabilistic formulation for the behavior analysis of a multilayered soil with random characteristics. Two main axes are treated: ?primary consolidation and ?seismic response of multilayered soils with uncertain characteristics. We use Monte Carlo simulations associated with semi-analytical methods adapted for the multilayered soils with horizontal stratification. We have also compared the results obtained from this formulation with those provided by the following seismic codes: RPA 99 (version 2003), UBC 97 and EC8. This study showed that the maximum values of the shear forces at the base of the buildings vary substantially according to the variation of the soil profile height as well as its heterogeneity which can reach a relative ratio of about 3 in the extreme cases. This ratio can also be lower than 1 leading to less economic structures

Les couches de sol présentent fréquemment des hétérogénéités spatiales qui proviennent des processus d’érosion, de sédimentation et de l’effet de l’activité humaine. A ces hétérogénéités géologiques de premier ordre viennent s’ajouter des hétérogénéités de petite échelle au sein d’une même couche géologique. Sous sollicitation sismique faible ou forte, ces hétérogénéités spatiales des propriétés du sous-sol sont susceptibles de conduire à une variabilité spatiale importante des propriétés du mouvement sismique en surface (amplitude, durée, contenu fréquentiel, …). Dans cette thèse, une analyse probabiliste est réalisée pour évaluer l’effet de la variabilité spatiale de la vitesse des ondes de cisaillement (V_s) sur la variabilité du mouvement sismique en surface. Pour simplifier, une simple structure de sol 2D (une couche sédimentaire sur un demi-espace) est considérée. La structure 2D de V_s est modélisé comme un champ aléatoire en utilisant la méthode EOLE (Expansion Optimal Linear Estimation) et 9 modèles probabilistes sont considérés en faisant varier les trois paramètres de fluctuation du sol: le coefficient de variation (COV) sur V_s, les distances d'autocorrélation horizontale (θ_x) et verticale (θ_z). Les mouvements sismiques du sol en surface sont simulés à l’aide du logiciel de différences finies FLAC2D pour une excitation d'onde plane avec une polarisation SV.Une première partie porte sur l’étude de la variabilité en surface de différents indicateurs du mouvement sismique (fréquence de résonance, amplification, Intensité d’Arias, durée, corrélation spatiale). Nos simulations purement linéaires soulignent l’importance des ondes de surface diffractées localement au niveau des hétérogénéités du sol sur ces différents indicateurs et le contrôle de COV sur leur variabilité. Elles mettent également en évidence que, bien que les approches probabilistes 1D reproduisent correctement en moyenne les fréquences de résonance fondamentales et les amplifications associées, elles sous-estiment l’amplification à haute fréquence, l’Intensité d’Arias et la durée du mouvement sismique ainsi que leur variabilité. La deuxième partie porte sur la cohérence spatiale, calculée sur la phase forte et sur la coda des vitesses simulées en surface. Les résultats montrent que la perte de cohérence avec la fréquence ou la distance est principalement contrôlée par COV. A cette perte de cohérence globale s’ajoute la présence de fortes cohérences dans certaines bandes de fréquences étroites causées par les caractéristiques de propagation d’ondes de volume et de surface (résonance des ondes SV, phases d’Airy des ondes de Rayleigh). Ces observations sont cohérentes avec les observations sur les données réelles du site d’Argostoli en Grèce. La troisième partie s’intéresse à la prise en compte du comportement non-linéaire des sols. Le comportement non-linéaire du sol est basé sur des tests triaxiaux effectués sur la plaine alluviale de Nahr Beyrouth. L’effet du comportement non-linéaire et de sa variabilité est étudié pour les différents indicateurs du mouvement sismique (Intensité d’Arias, durée, corrélation spatiale, cohérence décalée). / Soil layers frequently exhibit spatial heterogeneities that arise from the erosion, sedimentation processes and from the effects of human activity. To these first order geological heterogeneities are added small-scale heterogeneities within the same geological layer. Under weak or strong seismic loading, these spatial heterogeneities of the subsurface properties are likely to lead to a significant variability in the ground motion properties within short distance on surface (amplitude, duration, frequency content, ...). In this thesis, a probabilistic analysis is carried out to evaluate the effect of the spatial variability of shear wave velocity (V_s) on the variability of surface seismic response. For sake of simplicity, a simple 2D soil structure (a sedimentary layer over a half-space) is considered. The 2D structure of V_s is modeled as a random field using the EOLE (Expansion Optimal Linear Estimation) method and nine probabilistic models are considered by varying the three soil fluctuation parameters: the coefficient of variation (COV) on V_s, the horizontal and vertical autocorrelation distances (θ_x and θ_z, respectively). The surface ground seismic motion is simulated using the FLAC2D finite difference code using a SV plane-wave plane excitation.The first part deals with the study of the surface variability of different ground motion indicators (resonance frequency, amplification, Arias intensity, duration, spatial correlation). Our purely linear simulations emphasize the importance of the locally diffracted surface waves due to soil heterogeneities on these different indicators and the control of COV on their variability. They also show that, although 1D probabilistic approaches correctly estimate the average of the fundamental resonant frequencies and the associated amplifications, they underestimate the high frequency amplification, the Arias intensity and the duration of the ground motion on surface, as well as their variability. The second part deals with another estimator the ground motion spatial variability: the coherency and it is calculated on the strong phase and on the coda of simulated seismograms on surface. The results show that the variation of the coherency as a function of frequency or distance is mainly controlled by COV. To this overall behavior of the average coherency on surface is superimposed the presence of strong loss or increase of coherency in certain narrow frequency bands caused by the propagation characteristics of body and surface waves (resonance of SV waves, Airy phases of Rayleigh waves). These observations are consistent with the observations on real data from the Argostoli site in Greece. The third part focuses on taking into account the non-linear behavior of soils. The definition of non-linear properties of the soil is based on triaxial tests carried out on the alluvial plain of Nahr Beirut. The effect of non-linear behavior and its variability is studied for the different ground motion indicators, mainly in the time domain (Arias intensity, duration, spatial correlation, Lagged coherency).

3D seismic data are widely used for many different purposes. Despite different objectives, a common goal in almost all 3D seismic programs is to attain better understanding of the subsurface features. In gas injection projects, which are mainly for Enhanced Oil Recovery (EOR) and recently for environmental purposes, seismic data have an important role in the gas monitoring phase. This thesis deals with a 3D seismic investigation at the CO2 injection site at Ketzin, Germany. I focus on two critical aspects of the project: the internal architecture of the heterogeneous Stuttgart reservoir and the detectability of the CO2 response from surface seismic data. Conventional seismic methods are not able to conclusively map the internal reservoir architecture due to their limited seismic resolution. In order to overcome this limitation, I use the Continuous Wavelet Transform (CWT) decomposition technique, which provides frequency spectra with high temporal resolution without the disadvantages of the windowing process associated with the other techniques. Results from applying this technique reveal more of the details of sand bodies within the Stuttgart Formation. The CWT technique also helps to detect and map remnant gas on the top of the structure. In addition to this method, I also show that the pre-stack spectral blueing method, which is presented for the first time in this research, has an ability to enhance seismic resolution with fewer artifacts in comparison with the post-stack spectral blueing method. The second objective of this research is to evaluate the CO2 response on surface seismic data as a feasibility study for CO2 monitoring. I build a rock physics model to estimate changes in elastic properties and seismic velocities caused by injected CO2. Based on this model, I study the seismic responses for different CO2 injection geometries and saturations using one dimensional (1D) elastic modeling and two dimensional (2D) acoustic finite-difference modeling. Results show that, in spite of random and coherent noises and reservoir heterogeneity, the CO2 seismic response should be strong enough to be detectable on surface seismic data. I use a similarity-based image registration method to isolate amplitude changes due to the reservoir from amplitude changes caused by time shifts below the reservoir. In support of seismic monitoring using surface seismic data, I also show that acoustic impedance versus Poisson’s ratio cross-plot is a suitable attribute for distinguishing gas-bearing sands from brine-bearing sands. / CO2SINK Project

Στην παρούσα εργασία μελετήθηκε η δυναμική συμπεριφορά μιας τυπικής σφαιρικής δεξαμενής για την εφαρμογή διάφορων συστημάτων σεισμικής προστασίας. Πέντε διαφορετικά συστήματα σεισμικής προστασίας εξετάζονται:Οι αποσβεστήρες ιξώδους απόσβεσης, οι αποσβεστήρες τριβής και οι μη-λυγίζοντες μεταλλικοί σύνδεσμοι που η λειτουργία τους βασίζεται στην κατανάλωση σεισμικής ενέργειας, και τα ελαστομερή εφέδρανα υψηλής απόσβεσης και αυτά με πυρήνα μολύβδου που η λειτουργία τους βασίζεται στην απομόνωση της βάσης της δεξαμενής. Η αριθμητική ανάλυση έγινε με την χρήση ενός λεπτομερούς μοντέλου πεπερασμένων στοιχείων που προσομοιώνει την ακριβή γεωμετρία της σφαιρικής δεξαμενής, την επίδραση του φαινομένου αλληλεπίδρασης υγρού-δεξαμενής για ενδεικτικά ποσοστά πλήρωσης, την αλληλεπίδραση εδάφους-δεξαμενής και την μη-γραμμική συμπεριφορά των συστημάτων σεισμικής προστασίας. Παρουσιάζονται αποτελέσματα της τέμνουσας δύναμης βάσης, της κατακόρυφης μετατόπισης της ελεύθερης επιφάνειας του περιεχόμενου υγρού και οριζόντιες μετατοπίσεις χαρακτηριστικών σημείων της δεξαμενής, για καθε περίπτωση συστήματος σεισμικής προστασίας υπό σεισμική διέγερση, και συγκρίνονται με τα αντίστοιχα που προκύπτουν για την σφαιρική δεξαμενή με τους συμβατούς χιαστούς συνδέσμους. / Various seismic protection systems are used to study numerically the dynamic behavior of a typical spherical liquid storage tank. Five different anti-seismic devices are investigated; nonlinear viscous dampers, buckling restrained braces and friction devices based on the passive energy dissipation technique and lead core and high damping rubber bearings based on base isolation technique. The numerical analysis is performed by means of a detailed finite element model, taking into account the exact geometry of the steel tank, the fluid-structure interaction effects for an arbitrary level of filling, the soil-structure interaction as well as the non-linearities introduced by either the dissipative bracing systems. Representative results for base shear forces, vertical displacements of the fluid content and displacements at characteristic locations of the spherical tank are presented and compared to those corresponding to a tank with a conventional bracing system.