Structural optimisation problem in support to building retrofitting decision

Various analysis methods, either linear elastic or non-linear, static or dynamic, are available for the performance analysis of existing buildings. Despite its advantages, it must be admitted that non-linear time history analysis can frequently become overly complex and impractical for general use as a first assessment. Simplified models, as the Capacity Spectrum Method, are frequently not able to accurately assess irregular structures. Considering these limitations, it is proposed and evaluated a simplified MDOF non-linear dynamic model, accounting for non-linear storey behaviour and storey damping. Based on the MDOF non-linear dynamic model, were developed optimization algorithms for the redesign of existing non-seismically designed structures. The optimization procedure searches for the optimum storey strengthening distribution (strength, stiffness or damping) in order to meet specific performance requirements, in terms of maximum inter-storey drift for a given seismic demand level. Numerical examples are presented in order to illustrate the capability of methodology

Uma metodologia simplificada para a avaliação de edifícios existentes e dimensionamento do reforço óptimo

Associado ao trabalho experimental, desenvolvido no laboratório ELSA, com vista à avaliação da capacidade original de estruturas representativas da prática de projecto e construção até finais dos anos 70, bem como da validação da eficiência de várias técnicas de reforço, foram utilizados e calibrados modelos numéricos refinados para a simulação dos resultados dos ensaios. Os modelos refinados calibrados com os resultados experimentais demonstraram ser adequados na determinação da resposta não-linear de estruturas existentes. Não obstante as potencialidades destes modelos, é reconhecido que a sua aplicação na avaliação de edifícios correntes pode ser trabalhosa e inadequada face às inúmeras incertezas que podem surgir. Assim, é proposta uma metodologia simplificada para a análise dinâmica não-linear de edifícios baseada no cálculo espectral multi-modal da resposta sísmica. Esta metodologia apresenta a possibilidade de avaliação de estruturas irregulares, e constitui-se como uma ferramenta útil para a optimização do reforço de edifícios existentes. Foi então também desenvolvida uma metodologia, baseada na optimização, para o dimensionamento óptimo do reforço para este tipo de estruturas. Esta comunicação apresenta as metodologias simplificadas desenvolvidas para a avaliação de edifícios existentes e dimensionamento do reforço óptimo

Reforço sísmico do património edificado em betão armado

Sismos recentemente ocorridos em todo o mundo têm demonstrado que a investigação na engenharia sísmica deve ser direccionada para a avaliação da vulnerabilidade das construções existentes, desprovidas de adequadas características resistentes. O seu reforço deve ser realizado, reduzindo a sua vulnerabilidade e consequentemente o risco para níveis aceitáveis. O desenvolvimento de técnicas de reforço adequadas a este tipo de estruturas tem um papel principal. São descritas as causas mais frequentes de dano e colapso em edifícios existentes de betão armado e as técnicas de reforço mais adequadas para este tipo de estruturas. São brevemente apresentados os resultados mais relevantes de ensaios de avaliação do desempenho de estruturas existentes de betão armado, bem como de algumas técnicas de reforço. São discutidas as vantagens e limitações de cada uma destas técnicas

Seismic behaviour evaluation and strengthening of RC buildings

Reinforced concrete buildings constructed until the late 1970’s in most southern European countries were designed and constructed without considering earthquake provisions, constituting a significant risk. Recent major earthquakes around the world have evidenced that this type of existing buildings lacking appropriate seismic resisting characteristics are very vulnerable. Their retrofit or replacement should be made in order to reduce vulnerability, and consequent risk, to currently accepted levels. The development of retrofitting techniques represents a key issue in order to avoid both human casualties and economic losses in future events. Despite the advantages of a refined non-linear dynamic structural fibre modelling, it must be admitted that this approach can frequently become elaborated and costly. This fact sustains the development of less complicated structural models without debasing the essential features of dynamic response. Thus, it is proposed a simplified methodology for non-linear dynamic analysis of buildings based on the multi-modal spectral seismic response. It is also proposed an optimisation tool for the strengthening design of existing buildings

The association of problematic eating behaviours with food quality and body mass index at 7 years of age

Background/objectives: There is scarce evidence of how certain eating behaviours compromise the compliance with dietary guidelines and weight status in school-aged children. This study aims to evaluate the association of children’s problematic eating behaviours with food quality and body mass index at 7 years of age. Subjects/methods: Participants were children aged 7 years old from a population-based cohort study from Porto, Portugal-Generation XXI. Children’s quantity and speed of ingestion, food refusal at the table and food rewards requesting were evaluated by caregiver’s perception. Food consumption was evaluated by a food frequency questionnaire and compared with age-appropriate guidelines. Children’s weight status was assessed by objective measurements and parent’s perceptions. Associations were estimated by logistic regressions (odds ratio (OR), 95% confidence intervals (95% CI)) adjusted for maternal age, education, smoking during pregnancy, birth type, child’s sex, weight-for-gestational age and sports (n = 3801). Results: Children eating small amounts of food, refusing to eat at the table with the rest of the family during meals and asking for food rewards showed a higher consumption of energy-dense foods (OR = 1.51; 95% CI:1.23–1.86; OR = 1.58; 95% CI:1.16–2.16; OR = 1.56; 95% CI:1.14–2.12) and presented higher odds of consuming fruit and vegetables below recommendations (OR = 1.41; 95% CI:1.22–1.64; OR = 1.20; 95% CI:1.00–1.45; OR = 1.28; 95% CI:1.05–1.55). Children displaying these eating behaviours were less likely to be overweight/obese, hence their parents were less likely to show concern with their weight. Including food quality as covariate in the final models with obesity status did not change the associations. Conclusions: Problematic eating behaviours were associated with poorer food quality (more energy-dense foods and low fruit and vegetables), but food quality does not seem to explain the association with obesity status. Parents were less likely to be concerned about their child’s weight if the child ate slowly or poorly, and accordingly the odds of them being overweight or obese were lower.Generation XXI was funded by the Health Operational Programme—Saúde XXI, Community Support Framework III and the Regional Department of Ministry of Health. This study was supported through FEDER from the Operational Programme Factors of Competitiveness (COMPETE) and through national funding from the Foundation for Science and Technology (FCT; Portuguese Ministry of Education and Science) under the project PTDC/SAU-EPI/121532/2010 (FCOMP-01-0124-FEDER-021177) and through the Investigator Programme (IF/01350/2015–Andreia Oliveira and IF/01060/2015–Ana Cristina Santos). It also had support from the Calouste Gulbenkian Foundation

Monitoring process of the re-construction of an ancient structure: the Baluarte do Cavaleiro

The Baluarte do Cavaleiro is part of the stone masonry wall system existing in the city of Chaves of Portugal and it is a construction dated from the XVII century. The Baluarte do Cavaleiro is formed by three walls (North-East, NE; South-East, SE; South-West, SW) and by two junction elements (designated here by cunhais). The SE wall has suffered two collapses recently. The main objective of this research work is to describe the monitoring process adopted to control the stability of the Baluarte do Cavaleiro and the adjacent constructions that could be affected during the last rebuilding process of this wall. Taking into account that this rebuilding process included the total removal of this wall, it was also possible to identify the real geometry of the cross section of the wall, its building solution and the type of the sustained soil. It was also possible to contribute for a better understanding of the structural behaviour of this kind of stone masonry construction

Assessing aerodynamic flutter instability in prismatic structures with rectangular cross sections

Neste artigo estuda-se a ocorrência de instabilidade aerodinâmica por 'flutter' em estruturas prismáticas esbeltas de secção retangular. Considera-se um modelo com 2 graus de liberdade e obtém-se a sua formulação adimensional identificando-se um número mínimo de parâmetros adimensionais que regem a ocorrência de instabilidade por 'flutter' . Obtém-se uma muito boa concordância entre os resultados do modelo de 2 graus de liberdade e os resultados existentes na literatura. Este artigo tem 2 objetivos: (i) definir as condições para as quais estruturas esbeltas com secções retangulares podem instabilizar por 'flutter' sob a ação do vento e (ii) fornecer uma coleção alargada de resultados sob a forma de tabelas ou gráficos prontos a usar, cobrindo um largo número de casos, que proporciona aos projetistas de estruturas uma ferramenta que estes podem utilizar, a nível de pré-dimensionamento, para prever as velocidades críticas do vento que provocam a instabilidade por 'flutter' .This paper is dedicated to the study of the occurrence of 'flutter' instability in slender prismatic structures of rectangular cross section. A two degree of freedom model is considered and its non dimensional formulation is derived so that a minimum number of non dimensional parameters governing the occurrence of 'flutter' instability are put in evidence. A very good agreement has been obtained by comparing the results of the two degree of freedom model with the results available in the literature. The goal of this document is twofold: (i) to summarize the conditions for which slender structures with rectangular cross sections may get unstable by 'flutter' under the action of steady wind conditions and (ii) to supply a broad collection of data in the form of ready-to-use tables or graphics covering a wide range of cases, that provide a basis for designers to predict the critical wind velocities at the onset of 'flutter' instability.Peer Reviewe

Modelos simplificados para a avaliação de estruturas existentes de B.A. e optimização do seu reforço

O estudo e desenvolvimento de metodologias simplificadas para a análise nãolinear dinâmica de estruturas irregulares, e, o desenvolvimento de ferramentas numéricas para a optimização de reforço têm um papel principal na avaliação e reforço de estruturas. Neste artigo é proposta uma metodologia simplificada para a análise dinâmica não-linear de edifícios baseada no cálculo espectral multi-modal da resposta sísmica. Esta metodologia simples fornece bons resultados, mesmo na análise de estruturas irregulares e constitui-se como uma ferramenta essencial para a optimização do reforço de edifícios existentes

A neuroevolutionary approach to feature selection using multiobjective evolutionary algorithms

Feature selection plays a central role in predictive analysis where datasets have hundreds or thousands of variables available. It can also reduce the overall training time and the computational costs of the classifiers used. However, feature selection methods can be computationally intensive or dependent of human expertise to analyze data. This study proposes a neuroevolutionary approach which uses multiobjective evolutionary algorithms to optimize neural network parameters in order to find the best network able to identify the most important variables of analyzed data. Classification is done through a Support Vector Machine (SVM) classifier where specific parameters are also optimized. The method is applied to datasets with different number of features and classes.FCT - Fundação para a Ciência e Tecnologia in the scope of the projects: PEst-OE/EEI/UI0319/2014, UID/MAT/00013/2013, UID/CEC/ 00319/2019 and the European project MSCA-RISE-2015, NEWEX, with reference 734205

O atraso de desenvolvimento nas crianças com anemia por deficiência de ferro. Poderá ser revertido pela terapêutica com ferro?

OBJECTIVE: To compare development of 17 children aged 12 months with iron deficiency anaemia (IDA) and 18 controls without IDA after a 3-months follow-up period and iron therapy in the IDA group. SUBJECTS AND METHODS: Development of all children was evaluated using the Griffith's Scale. Data was collected on parent's social class and education, breast-feeding, number of siblings and clinical nutritional status. RESULTS: At 12 months children with IDA had significantly lower development scores--mean (sd)--than those without IDA: 112(5) vs. 121(7). At 15 months, after iron therapy, there were no significant differences between cases and controls. Non-IDA children showed significantly lower development scores at 15 months when compared with 12 months (121 vs 115). CONCLUSIONS: The study shows that iron therapy can revert some of the adverse effects in the development of children with IDA and therefore both IDA prevention and treatment can be justified.(undefined