Comportamento de nós viga-pilar

Mestrado em Engenharia CivilDa observação dos danos provocados por sismos recentes, verifica-se que o comportamento cíclico dos elementos de betão armado é fortemente influenciado pelo mecanismo de aderência aço-betão. A degradação progressiva da aderência, com a consequente ocorrência do escorregamento das armaduras, é uma das causas comuns de dano e colapso de estruturas de betão armado sujeitas a ações severas, como as induzidas pelos sismos. Em muitos países, este fenómeno assume particular importância nos edifícios construídos até aos anos 70, com armadura lisa e sem dimensionamento específico face à ação sísmica. Este tipo de estruturas são geralmente caracterizadas por pormenorização deficiente da armadura, confinamento inadequado e fracas condições de aderência. A conjunção destes fatores, associada à elevada concentração de esforços verificada nas ligações viga-pilar, faz com que nestas zonas se concentre o dano em edifícios de betão armado devido a ações sísmicas. Nesta dissertação são apresentados os principais resultados dos ensaios cíclicos de quatro nós viga-pilar, com a mesma geometria e igual pormenorização da armadura, representativos de nós interiores de edifícios de betão armado construídos até meados dos anos 70, sem pormenorização adequada face à ação sísmica. Dois dos nós foram executados com armadura lisa (às quais estão associadas fracas condições de aderência) e os outros dois nós com armadura nervurada. Para melhor compreender a influência da aderência aço liso-betão no comportamento cíclico dos nós é estabelecida a comparação entre os resultados experimentais obtidos nos provetes com armadura nervurada com os alcançados nos provetes com armadura lisa. Esta comparação permitiu concluir que o fenómeno do escorregamento condiciona significativamente o desempenho das estruturas com armadura lisa quando solicitadas por ações cíclicas. Por outro lado, os provetes foram sujeitos a diferentes níveis de esforço axial no pilar de forma a perceber a influência deste parâmetro no comportamento global destas ligações.The observation of the damage caused by recent earthquakes reveals that the cyclic behavior of concrete elements is strongly influenced by the mechanism for steel-concrete adhesion. The progressive degradation of the grip, with the consequent occurrence of slip reinforcement, is one of the common causes of damage and collapse of concrete structures subjected to severe actions, such as those induced by earthquakes. In many countries, this phenomenon is particularly important in buildings constructed until the 70s, with plain armor and no specific sizing due to the seismic action. Such structures are generally characterized by poor detailing of reinforcement, inadequate containment and weak adhesion. The combination of these factors, coupled with the high concentration of efforts observed in beam-column connections, makes these areas concentrate the damage in reinforced concrete buildings due to seismic actions. This thesis presents the main results of the cyclic tests of four beam-column knots, with the same geometry and the same detail of the armor, representative of interior knots of reinforced concrete buildings constructed until the mid 70s, without adequate detailing in view of seismic action. Two knots have been executed with smooth armor (which are associated with poor grip conditions) and the other two knots with ribbed armor. To better understand the influence of grip, smooth steel and concrete structures of knots in the cyclic behavior, it was established the comparison between the experimental results obtained in specimens with ribbed armor with those achieved in specimens with smooth armature. This comparison allowed us to conclude that the phenomenon of slipping affects significantly the performance of structures with smooth armor when requested by cyclical stocks. On the other hand, the test specimens were subjected to different levels of axial load on the pillar in order to understand the influence of this parameter on the overall behavior of these connections

Innovation of Textiles through Natural By-Products and Wastes

Nowadays, the competitiveness of the textile industry and the consumers’ interest have been increasing the demand for innovative and functional textiles. Allied to this, sustainable developments are playing an increasingly important role in the textile industry. Such concerns led to a new development strategy based on the valorization of bio-based wastes and by-products of different industries, inserting this in the circular economy paradigm. These bio-based wastes and by-products come from several industries, as the agri-food industry. These resources present an enormous potential for valorization in the textile finish due to their intrinsic properties (antimicrobial, prebiotic, antioxidant activity, among others). This chapter will review the latest innovation and textile product development through different by-products and wastes, their main properties and characteristics and the advantages that they offer to the textile industry

2 nd Brazilian Consensus on Chagas Disease, 2015

Abstract Chagas disease is a neglected chronic condition with a high burden of morbidity and mortality. It has considerable psychological, social, and economic impacts. The disease represents a significant public health issue in Brazil, with different regional patterns. This document presents the evidence that resulted in the Brazilian Consensus on Chagas Disease. The objective was to review and standardize strategies for diagnosis, treatment, prevention, and control of Chagas disease in the country, based on the available scientific evidence. The consensus is based on the articulation and strategic contribution of renowned Brazilian experts with knowledge and experience on various aspects of the disease. It is the result of a close collaboration between the Brazilian Society of Tropical Medicine and the Ministry of Health. It is hoped that this document will strengthen the development of integrated actions against Chagas disease in the country, focusing on epidemiology, management, comprehensive care (including families and communities), communication, information, education, and research

Chapter Innovation of Textiles through Natural By-Products and Wastes

Nowadays, the competitiveness of the textile industry and the consumers’ interest have been increasing the demand for innovative and functional textiles. Allied to this, sustainable developments are playing an increasingly important role in the textile industry. Such concerns led to a new development strategy based on the valorization of bio-based wastes and by-products of different industries, inserting this in the circular economy paradigm. These bio-based wastes and by-products come from several industries, as the agri-food industry. These resources present an enormous potential for valorization in the textile finish due to their intrinsic properties (antimicrobial, prebiotic, antioxidant activity, among others). This chapter will review the latest innovation and textile product development through different by-products and wastes, their main properties and characteristics and the advantages that they offer to the textile industry

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved