P-248 Futility and utility of two-stage hepatectomy

Meeting abstract in the European-Society-for-Medical-Oncology (ESMO) 21st World Congress on Gastrointestinal Cancer.info:eu-repo/semantics/publishedVersio

Modelling the SFRC flexural behavior using a stress-strain relationship

No presente trabalho foi desenvolvida uma estratégia numérica de forma a avaliar a possibilidade de ser definida uma lei tensão-extensão capaz de simular o comportamento fendilhado do betão de custo competitivo reforçado com fibras de aço (BRFA) concebido no âmbito de um projecto de investigação. Essa estratégia englobou dois modelos de complexidade distinta. O primeiro, designado por modelo de secção, foi utilizado para, com recurso a análise inversa e utilizando respostas força-flecha registadas em ensaios experimentais, se determinarem os parâmetros que definem uma lei trilinear tensão-extensão capaz de reproduzir as respostas experimentais com o rigor desejado. De seguida, esta lei foi utilizada para definir o modo I de fractura da lei constitutiva da fenda, no âmbito de um código computacional de análise não linear material de estruturas submetidas a estado plano de tensão, suportado no método dos elementos finitos, onde o processo de fendilhação é simulado por um modelo de fendilhação distribuída. Da aplicação dos dois modelos constatou-se que o modelo de secção não permite definir a lei tensão-extensão pós pico (lei de amolecimento) com o rigor necessário. Enquadrado numa análise inversa, o modelo baseado no MEF foi de seguida utilizado para se determinar a lei de amolecimento do BRFA, tendo-se constatado que essa lei não pode ser explicitada unicamente em função do conceito de resistência equivalente, tal como sugere o RILEM TC 162-TDF.To assess the post-cracking stress-strain relationship for a developed cost competitive steel fibre reinforced concrete (SFRC), a numerical strategy involving two numerical models of distinct complexity was carried out. Inserted into an inverse analysis framework, a cross-sectional-layer-model (CSLM) was used to evaluate the post-cracking stress-strain relationship able of reproducing, with the desired accuracy, the force-deflection relationship recorded in three-point bending tests carried out according to the RILEM TC 162-TDF recommendations. This relationship was used as the strain softening law of the fracture mode I crack constitutive law of a smeared crack model based on the strain decomposition concept, under the framework of the finite element method (FEM). Applying this model it was verified that the CSLM couldn't define a strain softening law able of simulating, with the necessary accuracy, the fracture mode I of the SFRC. Using an inverse analysis and the FEM model, the softening law for the SFRC analysed was evaluated. From the values obtained for the definition of this law it was concluded that this law cannot be exclusively dependent on the concept of equivalent flexural tensile strength, as RILEM TC 162-TDF recommends

Comportamento à tracção directa de elementos laminares de betão armado reforçado com fibras de aço

Quando comparado com o betão simples, o betão reforçado com fibras de aço, BRFA, apresenta melhor comportamento à fendilhação e maior capacidade de absorção de energia. Em consequência, a utilização de BRFA, em determinadas aplicações, pode ser uma mais valia em termos técnicos e económicos. O presente trabalho tem como principal objectivo avaliar a influência das fibras de aço no comportamento à tracção de elementos laminares de betão armado. Os principais resultados experimentais e numéricos são apresentados e discutidos

Assessment of fibre orientation and distribution in steel fibre reinforced self-compacting concrete panels

The benefits of adding fibres to concrete lie, mostly, in improving the post-cracking behaviour, since its ability to transfer stresses across cracked sections is substantially increased. The post-cracking strength is dependent not only on the fibre geometry, mechanical performance and fibre/matrix interface properties, but also on the fibre orientation and distribution. Previous works have shown that in self-compacting concrete matrices, there is a preferential fibre alignment according to the concrete’s flow in the fresh state. Having in mind that fibres are more efficient if they are oriented according the principal tensile stresses, a preferential fibre alignment on a certain direction could either enhance or diminish the material and the structural performance of this composite. In this paper, it is investigated the influence of the fibre orientation and distribution on the post-cracking behaviour of the steel fibre reinforced self-compacting concrete (SFRSCC). To perform this evaluation, SFRSCC panels were casted from their centre point. Two self-compacting mixtures were prepared using the same base mix proportions. For each SFRSCC panel cylindrical specimens were extracted and the post-cracking behaviour was assessed from a crack width controlled splitting tensile test

A mobile sensing approach to stress detection and memory activation for public bus drivers

Experience of daily stress among bus drivers has shown to affect physical and psychological health, and can impact driving behavior and overall road safety. Although previous research consistently supports these findings, little attention has been dedicated to the design of a stress detection method able to synchronize physiologic and psychological stress responses of public bus drivers in their day-to-day routine work. To overcome this limitation, we propose a mobile sensing approach to detect georeferenced stress responses and facilitate memory recall of the stressful situations. Data was collected among public bus drivers in the city of Porto, Portugal (145 hours, 36 bus drivers, +2300 km) and results supported the validation of our approach among this population and allowed us to determine specific stressor categories within certain areas of the city. Furthermore, data collected through-out the city allowed us to produce a citywide ”stress map” that can be used for spotting areas in need of local authority intervention. The enriching findings suggest that our system can be a promising tool to support applied occupational health interventions for public bus drivers and guide authorities’ interventions to improve these aspects in ”future” cities

A METHOD TO ANALYZE SOCCER OFFENSIVE SEQUENCES

There is a range of possibilities to analyze the soccer game in relation to physical-technical-tactical aspects. The importance of going toward the goal rapidly since the recovery of possession was defended by Grehaigne et al (1996). The main technique to analyze soccer attack speed in literature was presented by Yue et al (2008). The aim of this study was to propose a method to analyze offensive sequences in soccer based on goal progression velocity (GPV) and goal progression indicator (GPI)

Tensile stress–crack width law for steel fibre reinforced self-compacting concrete obtained from indirect (splitting) tensile tests

In this work, the fracture mode I parameters of steel fibre reinforced self-compacting concrete (SFRSCC) were derived from the numerical simulation of indirect splitting tensile tests. The combined experimental and numerical research allowed a comparison between the stress-crack width (σ - w) relationship acquired straightforwardly from direct tensile tests, and the σ - w response derived from inverse analysis of the splitting tensile tests results. For this purpose a comprehensive nonlinear 3D finite element (FE) modeling strategy was developed. A comparison between the experimental results obtained from splitting tensile tests and the corresponding FE simulations confirmed the good accuracy of the proposed strategy to derive the σ – w for these composites. It is concluded that the post-cracking tensile laws obtained from inverse analysis provided a close relationship with the ones obtained from the experimental uniaxial tensile tests.The studies reported in this paper are part of the research project LEGOUSE (QREN, project nº 5387). This project is co-supported by FEDER through COMPETE program (“Programa Operacional Factores de Competitividade”). The materials were supplied by Radmix and Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), Omya Comital (limestone filler), and Pegop (Fly ash).The studies reported in this paper are part of the research project LEGOUSE (QREN, project nº 5387). This project is co-supported by FEDER through COMPETE program (“Programa Operacional Factores de Competitividade”). The materials were supplied by Radmix and Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), Omya Comital (limestone filler), and Pegop (Fly ash)

A two-phase material approach to model steel fibre reinforced self-compacting concrete in panels

This work presents an experimental and numerical approach to ascertain the mechanical behaviour of steel fibre reinforced self-compacting concrete in laminar structures. Four-point flexural tests were performed on prismatic specimens extracted from a SFRSCC panel; the specimens’ behaviour was then modelled under the FEM framework. SFRSCC is assumed as a two-phase material, i.e. plain concrete and discrete steel fibres. The nonlinear material behaviour of the plain matrix was simulated using 3D smeared crack model, while the fibre reinforcement mechanisms were modelled using micro-mechanical behaviour laws determined from experimental fibre pull-out tests. The good performance of the developed numerical strategy was demonstrated.FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project SlabSys-HFRC-PTDC/ECM/120394/201

Time-dependent flexural behaviour of cracked steel fibre reinforced self-compacting concrete panels

In the present work are described and discussed the results of an extensive experimental program that aims to study the long-term behaviour of cracked steel fibre reinforced self-compacting concrete, SFRSCC, applied in laminar structures. In a first stage, the influence of the initial crack opening level (wcr = 0.3 and 0.5 mm), applied stress level, fibre orientation/dispersion and distance from the casting point, on the flexural creep behaviour of SFRSCC was investigated. Moreover, in order to evaluate the effects of the creep phenomenon on the residual flexural strength, a series of monotonic tests were also executed. It was found that wcr = 0.5 mm series showed a higher creep coefficient comparing to the series with a lower initial crack opening. Furthermore, the creep performance of the SFRSCC was influenced by the orientation of the extracted prismatic specimens regarding the direction of the concrete flow within the cast panel.This work is supported by the FEDER funds through the Operational Program for Competitiveness Factors - COMPETE and National Funds through FCT - Portuguese Foundation for Science and Technology under the project SlabSys-HFRC-PTDC/ECM/120394/2010. The authors would like to acknowledge the materials supplied by Radmix and Maccaferri (fibres), SECIL (cement), SIKA and BASF (superplasticizers), Omya Comital (limestone filler), and Pegop (Fly ash)

The influence of fibre orientation on the post-cracking tensile behaviour of steel fibre reinforced self-compacting concrete

Adding fibres to concrete provides several advantages, especially in terms of controlling the crack opening width and propagation after the cracking onset. However, distribution and orientation of the fibres toward the active crack plane are significantly important in order to maximize its benefits. Therefore, in this study, the effect of the fibre distribution and orientation on the post-cracking tensile behaviour of the steel fibre reinforced self-compacting concrete (SFRSCC) specimens is investigated. For this purpose, several cores were extracted from distinct locations of a panel and were subjected to indirect (splitting) and direct tensile tests. The local stress-crack opening relationship (σ-w) was obtained by modelling the splitting tensile test under the finite element framework and by performing an Inverse Analysis (IA) procedure. Afterwards the σ-w law obtained from IA is then compared with the one ascertained directly from the uniaxial tensile tests. Finally, the fibre distribution/orientation parameters were determined adopting an image analysis technique.Fundação para a Ciência e a Tecnologia (FCT