Μεγάλος αριθμός έργων πολιτικού μηχανικού αναπτύσσουν μηχανισμούς ολίσθησης. Η ευστάθεια πρανούς που καταπονείται από σεισμικές διεγέρσεις είναι ένα πρόβλημα που απασχόλησε πληθώρα μελετητών κατά την διάρκεια των χρόνων και οδήγησε στην ανάπτυξη διαφόρων μεθόδων για την εκτίμηση των μόνιμων παραμορφώσεων με το πέρας της κίνησης. Σκοπός της παρούσας εργασίας είναι να μελετήσει το φαινόμενο της ασύμμετρης ολίσθησης πρανούς προσομοιώνοντάς το, με ένα μοντέλο που αναπτύχθηκε το 1965 από τον Newmark και να καταδείξει το μέγεθος των μετατοπίσεων που αναπτύσσονται , το πώς η πολικότητα του σεισμού επηρεάζει την συμπεριφορά του πρανούς καθώς και την περεταίρω μελέτη που επιβάλλεται να διεξαχθεί. Αναπτύσσεται αναλυτικά η λογική της κίνησης καθώς και οι τρόποι προσέγγισης του προβλήματος, μία λύση κλειστής μορφής και μία με το μοντέλο Bouc- Wen, διερευνούνται οι παράμετροι που επηρεάζουν το πρόβλημα και τέλος παρατίθενται αφενός τα αποτελέσματα συγκριτικά με αυτά της βιβλιογραφίας και αφετέρου των αναλύσεων πλήθους σεισμικών διεγέρσεων εγγύς πεδίου. / Numerous civil engineer’s applications develop sliding mechanisms. Slope’s stability under seismic excitations is a problem that was investigated by several researchers in recent years and led to the development of various methods for the estimation of permanent displacement by the end of the motion. The current study examines the slope’s asymmetric sliding by Newmark’s analogue, calculates the residual slippage, shows how polarity affects slope’s behavior and suggests further analysis. The concept of behavior is analysed thoroughly, the two approaches of the problem are presented (a closed form solution and a Bouc-Wen Model analysis), the parameters of the problem are investigated and eventually, a literature comparison and analysis results are listed.

Discontinuous deformation analysis (DDA) is a newly developed simulation method for discontinuous systems. It was designed to simulate systems with arbitrary shaped blocks with high efficiency while providing accurate solutions for energy dissipation. But DDA usually exhibits damping effects that are inconsistent with theoretical solutions. The deep reason for these artificial damping effects has been an open question, and it is hypothesized that these damping effects could result from the time integration scheme. In this thesis two time integration methods are investigated: the forward Euler method and the Newmark method. The work begins by combining the Newmark method and the DDA. An integrated Newmark method is also developed, where velocity and acceleration do not need to be updated. In simulations, two of the most widely used models are adopted to test the forward Euler method and the Newmark method. The first one is a sliding model, in which both the forward Euler method and the Newmark method give accurate solutions compared with analytical results. The second model is an impacting model, in which the Newmark method has much better accuracy than the forward Euler method, and there are minimal damping effects. / Master of Science

Denna kandidatuppsats utgår från en egen översättning från franska till svenska av delar ur pjäsen Hôtel Pacifiqueav den franskkanadensiska författaren Fanny Britt.Syftet med examensarbetet är, förutom att skapa en spelbar text som fungerar i sin målspråkskontext, att undersöka det specifika i att översätta dramatik. I syftet ingår också att belysa och skapa förståelse för Québecfranskan och problem relaterade till att översätta språklig varietet. Det talade ordet står genomgående i fokus: replikerna i dramatexten och de karaktäristiska muntliga dragen för Québecfranskan. Newmarks kommunikativa översättningsmetod används som övergripande översättningsprincip för arbetet och visar sig vara kompatibel med texttypen trots vissa undantag. Resultatet blev en modern svensk pjäs med talspråkligt och idiomatiskt språk i replikerna. För att avgöra om texten är spelbar krävs dock att dramat uppförs på scen, vilket är ett framtida mål. / This essay is based on my own translation from French to Swedish of parts of the play Hôtel Pacifiqueby the Québécois author Fanny Britt. The purpose of the essay, apart from creating a text performable in its target language context, is to discuss and analyze the specialized nature of translating drama. The essay also aims to provide new perspectives on Québécois French and problems related to translating language varieties. The spoken word is the focal point: i.e. the lines of the drama and the characteristic oral features of Québécois French. Newmark's communicative translation method is used as the main translation principle. The method proves to be compatible with the text type despite certain exceptions. The result was a modern Swedish play with colloquial and idiomatic language. However, in order to determine if the text is performable, the drama must be presented on stage, which is a future goal.

In this study, the failure mechanism of the shore landslide which occured at Degirmendere coast region during 17 August 1999 Kocaeli (Izmit) - Turkey earthquake is analyzed. Geotechnical studies of the region are at hand, which reveal soil properties and geological formation of the region as well as the topography of the shore basin after deformations. The failure is analyzed as a landslide and permanent displacements are calculated by Newmark Method under 17 August 1999 Izmit record, scaled to a maximum acceleration of 0.4g. There are discussions on the main dominating mechanism of failure / landslide, liquefaction, fault rupture and lateral spreading. According to the studies, the failure mechanism is a seismically induced shore landslide also triggered by liquefaction and fault rupture, accompanied by the mechanism of lateral spreading by turbulence. A seismically induced landslide is discussed and modeled in this study. The finite element programs TELSTA and TELDYN are employed for static and dynamic analyses. Slope stability analyses are performed with the program SLOPE. The permanent displacements are calculated with Newmark Method, with the help of a MATLAB program, without considering the excess pore pressures.

Seismic response of free standing un-anchored objects is required to be studied in Nuclear Power Plants (NPPs) for their own integrity and potential interaction with the surrounding seismically qualified safety systems. Rocking response of a rigid body subject to seismic excitation is not very well covered in the nuclear standards except for an approximate method given in ASCE 43-05 where the design basis earthquake (DBE) response spectrum for the NPPs given in the United States Nuclear Regulatory Commission (USNRC) regulatory guide 1.60 (known as NBK spectrum developed by Newmark, Blume and Kapur (1973)) is considered as seismic input. This study evaluates existing seismic design criteria for unanchored objects that are vulnerable to rocking and overturning inside nuclear power plants. The original work of Newmark et al (1973) is revisited in order to obtain the NBK spectra at unusual damping (8.4% for example), required in order to follow the ASCE 43-05 method. Eight earthquake records are selected from Newmark et al (1973) with varying Peak Ground Accelerations (PGAs) representing strong to moderate ground motions. Rocking response of rigid bodies to various earthquakes is determined by three methods: 1. The ASCE 43-05 method utilizing the NBK spectrum, 2. The ASCE 43-05 method utilizing the response spectrum of the earthquake records, and 3. solving the equations of motion of a rigid body for the earthquake records. Rocking spectra by these three methods created for eight earthquake records are compared with one another. It is concluded that the ASCE 43-05 method provides inaccurate predictions of the response. Considering the significant level of effort required to implement the ASCE 43-05 method, its inherent contradictions, and its inconsistent conservatism in estimating the seismic demands on rocking objects, it is concluded that the results obtained by nonlinear time history analysis are more accurate, reliable and less time consuming than those by the ASCE 43-05 method. The use of nonlinear dynamic analysis is recommended to obtain the pure planar rocking response of unanchored objects in nuclear facilities. / Thesis / Master of Applied Science (MASc)

The meshless local Petrov-Galerkin (MLPG) method is used to numerically find an approximate solution of plane strain/stress linear elastostatic and elastodynamic problems. The MLPG method requires only a set of nodes both for the interpolation of the solution variables and the evaluation of various integrals appearing in the problem formulation. The monomial basis functions in the MLPG formulation have been enriched with those for the linear elastic fracture mechanics solutions near a crack tip. Also, the diffraction and the visibility criteria have been added to make the displacement field discontinuous across a crack. A computer code has been developed in Fortran and validated by comparing computed solutions of three static and one dynamic problem with their analytical solutions. The capabilities of the code have been extended to analyze contact problems in which a displacement component and the complementary traction component are prescribed at the same point of the boundary. The code has been used to analyze stress and deformation fields near a crack tip and to find the stress intensity factors by using contour integrals, the equivalent domain integrals and the J-integral and from the intercepts with the ordinate of the plots, on a logarithmic scale, of the stress components versus the distance ahead of the crack tip. We have also computed time histories of the stress intensity factors at the tips of a central crack in a rectangular plate with plate edges parallel to the crack loaded in tension. These are found to compare favorably with those available in the literature. The code has been used to compute time histories of the stress intensity factors in a double edge-notched plate with the smooth edge between the notches loaded in compression. It is found that the deformation fields near the notch tip are mode-II dominant. The mode mixity parameter can be changed in an orthotropic plate by adjusting the ratio of the Young's moduli in the axial and the transverse direction. The plane strain problem of compressing a linear elastic material confined in a rectangular cavity with rough horizontal walls and a smooth vertical wall has been studied with the developed code. Computed displacements and stresses are found to agree well with the analytical solution of the problem obtained by the Laplace transform technique. The Appendix describes the analysis with the finite element code ABAQUS of the dependence of the energy release rate upon the crack length in a polymeric disk enclosed in a steel ring and having a star shaped hole at its center. A starter crack is assumed to exist in one of the leaflets of the hole. The disk is loaded either by a pressure acting on the surfaces of the hole and the crack or by a temperature rise. Computed values of the energy release rate obtained by modeling the disk material as Hookean are found to be about 30% higher than those obtained when the disk material is modeled as Mooney-Rivlin. The latter set of results accounts for both material and geometric nonlinearities. / Ph. D.

The concept of using aluminum as the primary construction material for high speed ships and the hydroelastic behavior of the structure is widely gaining importance as a significant research topic in naval architecture. Aluminum is lighter than steel and hence can be predominantly used in high speed crafts which experiences significant slamming. This thesis work is focused on wedge shaped models. Free fall wedge impact is studied and a FORTRAN 90 computer program is developed to estimate the structural response of the wedge experiencing slamming by the use of matrix methods, finite element techniques and Newmark-Beta numerical time integration methods. The numerical solution is validated by comparison with the static solution. The theoretical hydrodynamic pressures which are used as input for this work was originally developed by using a flat cylinder theory [26]. The wedge drop at 0.6096 m (24 inch) drop height with an impact veloc- ity of v=3.05 m/s is based as the premise and the experimental pressure distributions measured by the pressure-transducers and the theoretical pressure predictions are used as inputs and the structural response is derived. Additionally, the response is compared for three different plate thicknesses and the results are compared against each other. The maximum deflection is comparable to the deflection evaluated from the experiment and tends to attain convergence as well. As the plate thickness reduces there tends to be a significant rise in the deflection values for the wedge plate, in the manner that when the plate thickness is halved there is a deviation of more than 75% in the deflection values as such.

No description available.

Orientador: Aloisio Ernesto Assan / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Civil, Arquitetura e Urbanismo / Made available in DSpace on 2018-08-07T10:17:54Z (GMT). No. of bitstreams: 1 Gatti_AndersonCarlos_M.pdf: 1799347 bytes, checksum: c5db751be8130693e5a2966d279bc22e (MD5) Previous issue date: 2006 / Resumo: Neste trabalho estuda-se o comportamento de pórticos planos submetidos a ações dinâmicas. Apresenta-se, inicialmente, a Equação de Movimento de Lagrange através das variações das energias cinética, potencial mais o trabalho das forças não conservativas. Em seguida, pelo emprego do Método dos Elementos Finitos são desenvolvidas as matrizes de rigidez, massa e amortecimento para o elemento de pórtico plano. O amortecimento introduzido é o de Rayleigh. Estudam-se dois métodos para a realização da análise dinâmica: o método de Newmark e o Método da Superposição Modal, também sendo realizado um estudo do problema de autovalor e autovetor pelo emprego do Método das Potências e o Método da Deflação de Wielandt. Os autovalores e autovetores fornecerão as freqüências naturais e os modos de vibração da estrutura. Finalmente, são mostrados exemplos numéricos para a análise do comportamento dos pórticos planos / Abstract: In this work, it is studied the behavior of plane frames submitted to dynamic loads. First of all Lagrange¿s Equations of Motion is presented by the kinetic and potential energy variation plus the work of the nonconservative forces. Next, the stiffness, mass and damping matrices for the plane frame element are developed with the use of the Finite Element Method. Damping is introduced from the Rayleigh damping. Both Newmark Method and Modal Superposition Method are studied to carry out the dynamic analysis. It is also carried out a study of the eigenvalue problem by Power Method and Wielandt Deflation Method. Eigenvalues and eigenvectors will provide the natural frequencies and normal modes of the structure, respectively. Finally, numerical examples are related to the analysis of the plane frameworks behavior / Mestrado / Estruturas / Mestre em Engenharia Civil

Millions of lives have been lost over the years as a result of the effects of earthquakes. One of these devastating effects is slope failure, more commonly known as landslide. Over the years, seismologists and engineers have teamed up to better record data during an earthquake. As technology has advanced, the data obtained have become more refined, allowing engineers to use the data in their efforts to estimate earthquakes where they have not yet occurred. Several methods have been proposed over time to utilize the earthquake data and estimate slope displacements. A pioneer in the development of methods to estimate slope displacements, Nathan Newmark, proposed what is now called the Newmark sliding block method. This method explained in very simple ways how a mass, in this case a rigid block, would slide over an incline given that the acceleration of the block surpassed the frictional resistance created between the bottom of the block and the surface of the incline. Because many of the assumptions from this method were criticized by scientists over time, modified Newmark sliding block methods were proposed. As the original and modified Newmark sliding block methods were introduced, the need to account for the uncertainty in the way soil would behave under earthquake loading became a big challenge. Deterministic and probabilistic methods have been used to incorporate parameters that would account for some of the uncertainty in the analysis. In an attempt to use a probabilistic approach in understanding how slopes might fail, the Pacific Earthquake Engineering Research Center proposed a performance-based earthquake engineering framework that would allow decision-makers to use probabilistically generated information to make decisions based on acceptable risk. Previous researchers applied this framework to simplified Newmark sliding block models, but the approach is difficult for engineers to implement in practice because of the numerous probability calculations that are required. The work presented in this thesis provides a solution to the implementation of the performance-based approach by providing a simplified procedure for the performance-based determination of seismic slope displacements using the Rathje & Saygili (2009) and the Bray and Travasarou (2007) simplified Newmark sliding block models. This document also includes hazard parameter maps, which are an important part of the simplified procedure, for five states in the United States. A validation of the method is provided, as well as a comparison of the simplified method against other commonly used approaches such as deterministic and pseudo-probabilistic.