Robustness of corroded reinforced concrete structures

Short Term Scienti c Mission, COST ACTION TU-0601The deterioration of existing structures has been a growing concern in the last decade. Signi cant attention has been paid to the deterioration of bridges, since signi cant costs in repair and replacement are expected in the next decades. At the same time structural robustness seems to be an emergent concept related to the structural response to damage. At the present time, robustness is not well de ned and much controversy still remains around this subject. This report intends to be a contribution to the de nition of structural robustness especially in the analysis of reinforced concrete structures subjected to corrosion. To achieve this, rst of all, several proposed robustness de nitions 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 damage scenarios, a robustness de nition is proposed. To illustrate the proposed concept, some example of corroded reinforced concrete structures will be analyzed using nonlinear analysis numerical methods based on a continuum strong discontinuities approach and isotropic damage models for concrete. Finally the robustness of the presented examples will be assessed and compared

Effect of non-structural masonry brick infill walls on the robustness of a RC

Western countries are increasingly demanding for robust structures, i.e., structures capable of withstanding local damage caused by unforeseen extreme events without triggering a progressive collapse, thus reducing the magnitude and proportion of the resulting consequences. In this paper, the robustness of framed RC buildings is analysed by comparing the reliability of the damaged structure with that of the original structure and considering (or not) the contribution of the masonry infill walls. To validate the adopted methodology, this is tested on a residential RC building severely damage due to a landslide, herein considered as case-study. A numerical model of the original, as well as, of the damaged structure is defined using force-based finite elements with distributed plasticity. Masonry infill walls are modelled as equivalent internal struts. Monte Carlo simulation and FORM coupled with artificial neural networks and response surface polynomials are used in parallel to perform the reliability analyses of both original and damaged structures. Obtained results show that the masonry infill walls are fundamental to contain damage progression after the failure of a couple of columns. In fact, without these non-structural elements, the structure would lack in robustness, and the probability of failure would be above 99%. On the contrary, by considering the structural contribution of the masonry infill walls, the robustness of the structure would be circa of 30% corresponding to a failureprobability of 6%

Mechanical performance of eco-efficient hollow clay bricks incorporating industrial nano-crystalline aluminium sludge

In this paper, mechanical properties of a new structural and eco-efficient hollow clay bricks are investigated. The principal goal was to recycle residual sludge from aluminium anodizing industries by incorporating it in the raw material of bricks, thus contributing for the sustainability of the construction sector. It was also an objective to enhance thermal properties of the bricks, contributing to improve the energy efficiency of buildings, and maintain their mechanical properties. A large set of mechanical tests was conducted. A comparison between traditional, structural, and the new eco-efficient bricks is established. Results show that the mechanical properties of the new bricks and masonry are not significantly affected by the aluminium sludge, thus allowing their use without strength limitations, and taking advantage from the thermal improved performance

On the robustness to corrosion in the life cycle assessment of an existing reinforced concrete bridge

Management of existing structures has traditionally been based on condition assessment, based on visual inspections, disregarding the susceptibility of different structural types to aging and deterioration. Robustness, as a measure of the effects of unpredictable damage to structural safety can be a complementary information to the results of inspection. Although robustness has mostly been used to evaluate the consequences of extreme events, a similar framework can be used to investigate the result of aging, allowing a better understanding of the potential effects of deterioration and allowing a better allocation of available maintenance funding. In this work, a probabilistic structural robustness indicator is used to quantify the susceptibility of structures to corrosion. The methodology is exemplified through a case study comprising an existing reinforced concrete bridge deck, heavily damaged due to reinforcement corrosion, and finally demolished due to safety concerns. Robustness measures the bridge deck safety tolerance to reinforcement corrosion. The principal effects of corrosion, including loss of area and bond between concrete and steel are modelled using a non-linear finite-element model, coupled with a Response Surface Method to compute the bridge reliability as a function of the corrosion level, and finally used to assess robustness. Results show that the redundancy of the bridge allows significant redistribution of loads between elements with different corrosion levels. As a result, the bridge presents significant robustness and tolerance to reinforcement corrosion

Behavior of reinforced concrete frame with masonry infill wall subjected to vertical load

The effectiveness of masonry infill wall on behavior of a Reinforced Concrete (RC) frame subjected to a column failure is studied experimentally. For this reason, one full scale RC frame designed according to Eurocode is statically tested to investigate the behavior of the frame with and without masonry infill wall. The obtained results show that infill wall can significantly increase the load carrying capacity of RC frame and thus serve as an important robustness reserve in the case of unpredictable extreme events (i.e. local impact, blast or earthquake). A photogrammetry analysis is carried out to study the behavior of the structure. Results give valuable information about the alternative load path, transfer of the applied load to the column and beams, and interaction forces between RC frame and infill wall. At the end, the experimental program is simulated by the OpenSees software to study the behavior of the frame. After having demonstrated that this model can predict the load deflection with good accuracy, a parametric study is conducted to evaluate the effect of the percentage of longitudinal reinforcement ratio of beams and columns on the load carrying capacity of the infilled RC frame

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

O Trompe l’Oeil em Cozinha: Criando “ilusionismo culinário” através da utilização de aromas

Mestrado em Ciências Gastronómicas. Universidade de Lisboa, Instituto Superior de Agronomia. Nova School of Science & TechnologyAtualmente a gastronomia tem evoluído muito, e o crescimento do diálogo entre gastronomia, artes e ciências é constante. Esse diálogo permitiu a introdução de diversos equipamentos e ingredientes, nunca utilizados em restauração. Com isso, para além de surgirem novos desenvolvimentos e abordagens no mundo da gastronomia, tais como a cozinha molecular, surgem também produtos inovadores altamente criativos capazes de satisfazer as atuais exigências dos consumidores. Determinante no sucesso de qualquer empresa, a inovação é um fator muito importante para se obter vantagem competitiva e criar valor acrescentado. Considerando o que foi referido anteriormente, este trabalho teve como objetivo desenvolver dois produtos inovadores (BOLOnhesa e Quasí-brownie) capazes de criar uma experiência multissensorial inovadora ao evocar diversos sentidos e emoções. Esses produtos, para além de iludirem o sentido da visão, também iludem o sentido do olfato. No desenvolvimento destes produtos utilizaram-se diversas metodologias da cozinha molecular (o uso do sifão e hidrocoloides, por exemplo) como também uma técnica de Trompe l’Oeil culinário. Para iludir o sentido do olfato, realizaram-se extrações por destilação dos aromas naturais de Bolonhesa e de Brownie, num evaporador rotativo. De forma a completar a componente científica, analisou-se por cromatografia os produtos obtidos pela destilação, ou seja, o extrato antes de ser destilado (original) e o produto e resíduo da destilação (destilado e concentrado), de forma a compará-los e a averiguar a complexidade aromática dos componentes voláteis em cada um. Na análise cromatográfica da Bolonhesa propuseram-se 32 compostos, tais como p-cimene, eucaliptol, linalool e o nonanal, compostos que estão presentes em diversas especiarias utilizadas. Já no Brownie foram propostos 18 compostos, confirmando assim a complexidade dos aromas. Os produtos desenvolvidos foram submetidos a avaliação por um grupo de foco.Gastronomy has evolved in the last decades, the dialogue between gastronomy, arts and science became stronger. This dialogue allowed the introduction of various equipments and ingredients, never used before in gastronomy. As a result, in addition to new developments and approaches in gastronomy, such as molecular cuisine, innovative and highly creative products were also developed, which satisfy current consumer demands. Innovation is a very important factor in the success of any company, allowing to get a competitive advantage and creating added value. Based on the previously mentioned aspects, this work aimed the development of two innovative products (BOLOnhesa and Quasí-brownie) capable of creating an innovative multi-sensory experience by evoking several senses and emotions. These products, besides eluding the sense of sight, also elude the sense of smell. For the development of these products, several methodologies of molecular cuisine were used ( siphon and hydrocolloids, for example) as well as the culinary Trompe l'Oeil. To delude the sense of smell, distillation extractions of the natural aromas of Bolognese and Brownie were carried out in a rotary evaporator. To complete the scientific component, the products obtained by distillation were analyzed by chromatography, i.e. the extract before distillation (original), and the product and residue of distillation (distillate and concentrate) in order to compare them and to ascertain the aromatic complexity of the volatile components. In the chromatographic analysis of the Bolognese, 32 compounds were proposed, such as p-cymene, eucalyptol, linalool and nonanal, compounds that are present in various of the spices used. On the other hand, only 18 compounds were proposed in Brownie, thus confirming the complexity of the aromas. The developed products were submitted to evaluation by a focus group.N/

Robustness of corroded reinforced concrete structures. A structural performance approach

Structure and Infrastructure Engineering, 1-17The aim of this work is to provide new contributions in order to define more accurately the structural robustness concept, particularly when applied to corroded reinforced concrete (RC) structures. To fulfill such task, several robustness indicators are analyzed and discussed with special emphasis on structural performance based measures. A new robustness definition and a framework to assess it are then proposed, based on the structural performance lost after damage occurrence. The competence of the proposed methodology is then tested comparing the robustness of two reinforced concrete foot bridges under corrosion. The damage considered is the longitudinal reinforcement corrosion level and load carrying capacity is the structural performance evaluated. In order to analyze corrosion effects, a finite element based on a two step analysis is adopted. In the first step a cross section analysis is performed to capture phenomenons such as expansion of the reinforcement due to the corrosion products accumulation; damage and cracking in the reinforcement surrounding concrete; steel-concrete bond strength degradation; and effective reinforcement area reduction. The results obtained are then used to build a 2D structural model, in order to assess the maximum load carrying capacity of the corroded structure. For each foot bridge, robustness is assessed using the proposed methodology

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.COST Action TU-0601; Fundação para Ciência e Tecnologi

Ideas for intervention in abandoned urban spaces: experiences from Eastern Lisbon and Barreiro

Este livro é um desafio para pensarmos novas viabilidades para os espaços urbanos abandonados da cidade. Esse repto que I. Solà-Morales (1995) fez inicialmente há mais de duas décadas ganhou entretanto especial urgência. As transições cada vez mais rápidas e inesperadas entre ciclos de expansão e de retração da economia mundial, a crescente mobilidade do capital e a volatilidade dos investimentos relacionados com a globalização, e o encolhimento urbano, para o qual pesa grandemente o envelhecimento demográfico de extensas regiões do Globo, convergem para que a presença de terrenos vagos nas cidades se tenha vulgarizado. Por outro lado, vivemos cada vez mais agudamente a aceleração do tempo de que falava Hartmut Rosa (2013), e essa é uma variável que obriga a repensar profundamente os horizontes temporais do urbanismo. Essa aceleração tem consequências na mutabilidade da cidade, na velocidade da ocupação e desocupação dos seus espaços, nas dinâmicas de arruinamento, e, logo, na própria temporalidade do planeamento. Historicamente, a lógica do urbanismo sempre foi a de planear o fixo e o estável, projetando preferencialmente para um longo prazo e para um tempo que se esperava durável. A aceleração do tempo na época em que vivemos vem colocar ao urbanismo contemporâneo o desafio novo de planear também o mutável e transitório, projetando para o curto prazo e para um tempo incerto e breve. Neste livro, pretendemos abrir esse debate sobre a possibilidade de um urbanismo mutante e temporário e sobre a utilidade da sua aplicação aos terrenos vagos das cidades.This book challenges to imagine new viabilities for abandoned areas in the cities. This feat that I. Solà-Morales (1995) made over two decades ago has recently become particularly urgent. The ever quicker and unexpected transitions between cycles of expansion and retraction in the global economy, the rising capital mobility and volatility of the globalization related investments, as well as the proliferation of shrinking cities in large regions of the world partly due to the population ageing, converge towards the trivialization of empty and derelict sites in cities. Still, we are living more and more acutely the time acceleration mentioned by Hartmut Rosa (2013), which forces us to rethink about the time-bound limits of urbanism. Time acceleration has consequences for the changeability of the city and, thus, for the urban planning’s temporality, since the rhythms of occupation and abandonment of the built structures in cities as well as ruination became more unpredictable and faster. Historically, the logic behind urbanism has always been about planning for what is fixed and stable, developing preferably long-term and longlasting projects. The acceleration of time places a new challenge upon contemporary urbanism, compelling us to invent new ways of planning for what is changeable and transient through short-term projects designed for an uncertain and brief time. In this book we aim to open the debate about the possibility of an urbanism that is both changeable and temporary, and about the utility of its application on the urban derelict areas in particular.info:eu-repo/semantics/publishedVersio