Strength prediction of single- and double-lap joints by standard and extended finite element modelling

The structural integrity of multi-component structures is usually determined by the strength and durability of their unions. Adhesive bonding is often chosen over welding, riveting and bolting, due to the reduction of stress concentrations, reduced weight penalty and easy manufacturing, amongst other issues. In the past decades, the Finite Element Method (FEM) has been used for the simulation and strength prediction of bonded structures, by strength of materials or fracture mechanics-based criteria. Cohesive-zone models (CZMs) have already proved to be an effective tool in modelling damage growth, surpassing a few limitations of the aforementioned techniques. Despite this fact, they still suffer from the restriction of damage growth only at predefined growth paths. The eXtended Finite Element Method (XFEM) is a recent improvement of the FEM, developed to allow the growth of discontinuities within bulk solids along an arbitrary path, by enriching degrees of freedom with special displacement functions, thus overcoming the main restriction of CZMs. These two techniques were tested to simulate adhesively bonded single- and double-lap joints. The comparative evaluation of the two methods showed their capabilities and/or limitations for this specific purpose.

Estudo da influência da carga específica na fragmentação de rocha granítica no desmonte em bancada

Mestrado em Engenharia Geotécnica e Geoambiente

Long-term memory in financial prices: evidence from the Dutch stock market returns

Prepared for presentation at the Portuguese Finance Network International Conference 2014, Vilamoura, Portugal, June 18-20

The Transversarium-Bifurcatus Zone boundary at Rocha (Peral area, East-Central Algarve, Portugal)

This paper represents the first detailed study of the Transversarium-Bifurcatus Zone boundary in the Algarve. The boundary studied in the Peral area is associated with a stratigraphic discontinuity, whose hiatus partially affects the Transversarium-Bifurcatus Zones. A discontinuity was also recognized in the Bifurcatus-Birnammatum Zone boundary, which can be correlated with the traces of a Type II unconformity, which separates cycles 4.3-4.4 in HAQ et al. (1987), present on the South Iberian palaeomargin. An analysis was made of the ecostratigraphic evolution in the interval between the uppermost Transversarium Zone and the lower part of the Bimammatum Zone on the basis of the faunal spectra obtained. We conclude that ammonites are the most tolerant cephalopods to the ecological stress caused by the increase of inflows and the decrease of the shelf's ecospace. Benthic fauna decreased considerably in these conditions. A relatively abundant and diversified fauna ofDichotomoceras is noteworthy among the ammonites collected, as this genus was previously little known in the Algarve.

Analysis of sandwich beam structures using kriging based higher order models

Functionally graded composite materials can provide continuously varying properties, which distribution can vary according to a specific location within the composite. More frequently, functionally graded materials consider a through thickness variation law, which can be more or less smoother, possessing however an important characteristic which is the continuous properties variation profiles, which eliminate the abrupt stresses discontinuities found on laminated composites. This study aims to analyze the transient dynamic behavior of sandwich structures, having a metallic core and functionally graded outer layers. To this purpose, the properties of the particulate composite metal-ceramic outer layers, are estimated using Mod-Tanaka scheme and the dynamic analyses considers first order and higher order shear deformation theories implemented though kriging finite element method. The transient dynamic response of these structures is carried out through Bossak-Newmark method. The illustrative cases presented in this work, consider the influence of the shape functions interpolation domain, the properties through-thickness distribution, the influence of considering different materials, aspect ratios and boundary conditions. (C) 2014 Elsevier Ltd. All rights reserved.

Evolução cenozóica da área de Longroiva-Vilariça (NE Portugal)

In the Longroiva-Vilariça area, the identification of Cenozoic lithostratigraphic units, the sedimentology and the characterization of its geometric relations with tectonic structures allowed the interpretation of the palaeogeographic main stages: 1) the greenwhitish Vilariça Arkoses (Middle Eocene to Oligocene ?) represent proximal sediments of a very low gradient drainage towards the eastern Spanish Tertiary Duero Basin; 2)Quintãs Formation (late Miocene ?) are brown-reddish coloured piedmont alluvial deposits, correlative of important vertical displacement (western tectonic block relative uplift) along the NNE-SSW indent-linked strike-slip Bragança-Vilariça-Longroiva fault zone, interpreted as a reactivated deep hercynian fracture, with left-lateral movement; 3) the red Sampaio Formation (Gelasian-early Pleistocene ?)was interpreted as downhill conglomeratic deposits related with important overtrusting along this fault zone (the definition of the present-day narrow graben configuration) and correlative of the atlantic hydrographic incision stage beginning; 4) conglomeratic terraces (middle and late Pleistocene ?); 5) alluvial plains and colluvial deposits (Holocene).

Litostratigrafia do Terciario da região Miranda do Corvo-Viseu (Bacia do Mondego, Portugal)

The lithostratigraphic units (2 groups, 5 formations and 4 members) of the Tertiary of the Miranda do Corvo-Viseu region (Central Portugal) are here described. For each unit the characterization and description (boundaries, diagnostic properties and atributes) were included. The stratigraphic, lithological, sequential and tectonic data allow correlations with other units of the same Tertiary basin located more to west and support the chronostratigraphic attribution. Sedimentologic characteristics of the deposits lead to the interpretation of the influence of tectonism, climate and eustasy during the sedimentary evolution of this Basin.

Miocene marine-continental correlations in the Lisbon area and some discussion related to personnal experience

Sandpit exploitation near Lisbon allowed collecting of many Miocene, non marine fossils. These sands are part of the mostly marine Miocene series in the Lower Tagus basin. The particularly favourable situation led several researchers to deal with marine-continental correlations. Difficulties often concern methodologic aspects. Some poorly based interpretations exerced a lasting influence. A critical approach is presented. Analysis requires data. Methods based upon models often lead to the temptation of fitting data in order to confirm a priori conclusions, or of mixing up data as if of equal statistic value while they have not at all the same weight. Erroneous interpretations' uncritical repetition for many years "upgraded" them into absolute truth. Another point is endemism vs. europeism. Miocene mammals from Lisbon compared well with corresponding French, contemporaneous taxa, while this was apparently not true for Spanish ones. Too much accent had been put on the endemic character of Spanish, or even regional, mammalian faunas. Nationalist bias and sensationalism also weigh, albeit negatively. Meanwhile nearly all the more evident examples as the rhinoceros Hispanotherium are discredited as Iberian endemisms. Taxa may appear as endemic just because they have not yet been found elsewhere. At least for the medium to large-sized mammals, with their huge geographic distribution, faunal differences depend much more on ecology, climate and environmental conditions. Emphasis on differences may also result from researchers that are often in a precarious situation and need very much to achieve short-term, preferably sensational results. Overvalued differences may mask real similarities. Unethic and not scientific behaviour are further enhanced by "nomina nuda" tricks that may simply be a way to circunvent or cheat the Priority Rule. On the other hand, access to communication networks may present as sensational novelties items that are not new at all, misleading the audience. A new class of "science people" arose, created by the media and not by the value of their real achievements. Discussion is presented on sedimentation processes and discontinuities that are often regarded as absolute precision dating tools, as well as on some geochemical and paleomagnetic interpretations. A very good chronologie frame has been obtained for the basin under study on the basis of an impressive set of data, providing a rather detailed and accurate frame for Miocene marine-continental correlations.

Modelação do comportamento dinâmico de sistemas barragem-fundação-albufeira: análise sísmica de uma barragem de abóbadas múltiplas

Trabalho Final de Mestrado elaborado no Laboratório Nacional de Engenharia Civil (LNEC) para a obtenção do grau de Mestre em Engenharia Civil pelo Instituto Superior de Engenharia de Lisboa no âmbito do protocolo de cooperação entre o ISEL e o LNEC

Gestão de operações de um armazém

i Gestão de Operações de um armazém Patrícia Raquel Freitas Gomes Relatório de estágio apresentado ao Instituto Superior de Contabilidade e Administração do Porto para obtenção de Grau de Mestre em Logística Orientado por: Prof. Doutora Maria Teresa Ribeiro Pereira Coorientado por: Eng.º César Emanuel Marinho Carvalho Teixeira

Cartografia de zonamento geotécnico no apoio ao planeamento e valorização da exploração do georrecurso: o caso do maciço rochoso da Curviã (Joane)

Este trabalho centra-se no estudo do aproveitamento expectável do maciço rochoso da pedreira da Curviã N.o 2 (Joane, Vila Nova de Famalicão, no N Portugal), através da obtenção de um bloco unitário tipo que forneça indicações para a exploração do recurso geológico para fins industriais e/ou ornamentais. Desta forma, investiga-se se num dado limite de zona geotécnica do maciço rochoso e propicio a obtenção de blocos com dimensão, avaliados apos o processo de transformação, nomeadamente, para enrocamento em obras marítimas ou balastro em obras ferroviárias. Foram seleccionados diversos afloramentos, tendo-se recorrido a técnica de amostragem linear as superfícies expostas do maciço. Esta técnica e uma das formas mais expeditas de coligir dados geológico-geotécnicos relativos as descontinuidades. Procedeu-se, ainda, a um tratamento estatístico das descontinuidades, bem como dos parâmetros geológico-geotécnicos e geomecânicos a estas associadas, propostos pela Sociedade Internacional de Mecânica das Rochas (ISRM). Todos os dados foram representados cartograficamente numa base apoiada pelos Sistemas de Informação Geográfica (SIG) e utilizadas as ferramentas de geologia estrutural, analise morfotectónica, modelação digital de terreno e cartografia de zonamento geotécnico. O zonamento geotécnico do maciço granítico foi realizado sempre em estreita ligação com o conhecimento das características do maciço ”in situ”. Pretende-se que esta metodologia contribua para um melhor conhecimento da compartimentação dos maciços rochosos em geral e, em particular, do modelo geotécnico comportamental do maciço rochoso da Curviã N.o2.

A framework for robustness assessment in the context of corroded RC structures

Structural robustness is an emergent concept related to the structural response to damage. At the present time, robustness is not well defined and much controversy still remains around this subject. Even if robustness has seen growing interest as a consequence of catastrophic consequences due to extreme events, the fact is that the concept can also be very useful when considered on more probable exposure scenarios such as deterioration, among others. This paper intends to be a contribution to the definition of structural robustness, especially in the analysis of reinforced concrete structures subjected to corrosion. To achieve this, first of all, several proposed robustness definitions and indicators and misunderstood concepts will be analyzed and compared. From this point and regarding a concept that could be applied to most type of structures and dam-age scenarios, a robustness definition is proposed. To illustrate the proposed concept, an example of corroded reinforced concrete structures will be analyzed using nonlinear analysis numerical methods based on a contin-uum strong discontinuities approach and isotropic damage models for concrete. Finally the robustness of the presented example will be assessed.

Robustness of corroded reinforced concrete structures

Short Term Scienti c Mission, COST ACTION TU-0601

A reliability-based measure of robustness for concrete structures subjected to corrosion

This work is a contribution to the definition and assessment of structural robustness. Special emphasis is given to reliability of reinforced concrete structures under corrosion of longitudinal reinforcement. On this communication several authors’ proposals in order to define and measure structural robustness are analyzed and discussed. The probabilistic based robustness index is defined, considering the reliability index decreasing for all possible damage levels. Damage is considered as the corrosion level of the longitudinal reinforcement in terms of rebar weight loss. Damage produces changes in both cross sectional area of rebar and bond strength. The proposed methodology is illustrated by means of an application example. In order to consider the impact of reinforcement corrosion on failure probability growth, an advanced methodology based on the strong discontinuities approach and an isotropic continuum damage model for concrete is adopted. The methodology consist on a two-step analysis: on the first step an analysis of the cross section is performed in order to capture phenomena such as expansion of the reinforcement due to the corrosion products accumulation and damage and cracking in the reinforcement surrounding concrete; on the second step a 2D deteriorated structural model is built with the results obtained on the first step of the analysis. The referred methodology combined with a Monte Carlo simulation is then used to compute the failure probability and the reliability index of the structure for different corrosion levels. Finally, structural robustness is assessed using the proposed probabilistic index.

Geomecânica aplicada à estabilidade de explorações mineiras bench and fill: o caso do jazigo de Feitais, Minas de Aljustrel

Este trabalho pretende abordar a importância de um estudo geomecânico no apoio à otimização e estabilidade de explorações subterrâneas por subníveis, com criação de bancadas e posterior enchimento. O presente envolveu um estudo geológico-geotécnico em quinze galerias situadas a muro, teto e corpo da mineralização com o levantamento das características mais relevantes do maciço rochoso para aplicação das classificações geomecânicas, englobando uma amostragem de mais de 1780 descontinuidades, obtendo um modelo cartográfico subterrâneo com um panorama geral da qualidade do maciço rochoso intercetado pelas escavações nas diferentes zonas. Os dados dos levantamentos de campo levaram à criação de uma base de dados com a aplicação das classificações geomecânicas Q-System, RMR e GSI, por galeria e, em seguida, por zona, com proposta de classe de sustimento a aplicar em cada local, pelo ábaco de Barton, em conjunto com a determinação de parâmetros geomecânicos fundamentais ao refinamento do conhecimento geológico-geotécnico das unidades litológicas em estudo. Na parte final, focando a localização da massa mineralizada de Feitais é efetuada uma abordagem relativa à estabilidade das cavidades geradas pelo desmonte em bancada entre subníveis, com respetivo dimensionamento das larguras admissíveis, em condições de segurança, através da relação entre o número de estabilidade e raio hidráulico, pelo método do gráfico de estabilidade. Com esta metodologia de caracterização geológico geotécnica, é pretendido efetuar um ponto de partida à criação de um modelo geomecânico comportamental do jazigo de Feitais, Mina de Aljustrel, contando com um processo inicial de apoio ao planeamento mineiro aplicado ao método de desmonte em bancada e posterior enchimento por subníveis, atuando nos parâmetros de estabilidade e apoio à extração, favorecendo assim a segurança das operações de trabalho em conjunto com um apoio de otimização da extração.