Redução do risco sísmico e implicações no imobiliário

Neste trabalho apresentam-se as principais conclusões do debate promovido pela Universidade do Minho, inserido no 6º Congresso Nacional de Sismologia e Engenharia Sísmica, sobre as implicações da redução do risco sísmico no edificado nacional. As conclusões deste debate são precedidas e enquadradas por uma breve descrição do historial sísmico nacional e pela apresentação sumária do Programa Nacional de Redução da Vulnerabilidade do Edificado, proposto pela Sociedade Portuguesa de Engenharia Sísmica e pelo Grémio das Empresas de Conservação e Restauro do Património Arquitectónico, em 2001

Strengthening of masonry vaults with transversal diaphragms: a numerical approach

The compatible strengthening of historical constructions is a critical issue in modern restoration practice. Among others, numerical modelling became a powerful instrument in the practice of checking the suitability and effectiveness of a given structural strengthening solution. In particular, the topic of numerical modelling of masonry arches and vaults was developed by many researchers for several years. This paper is focused on the numerical representation of a traditional strengthening technique, based on the use of transversal masonry diaphragms applied to arches and vaults. Macro and micromodelling approaches were considered in this work as to discuss the adequacy and efficiency of the strengthened method and also compare results between the two approaches. To further define the properties and effectiveness of the strengthening solution, a parametric study was conducted by means of geometrical and mechanical modifications applied to the diaphragms

Numerical modeling of masonry vaults strengthened with transversal diaphragms

Masonry vaults and arches are one of main structural elements present in most of historical constructions. Due to the impact of time, load and other construction features, their strength capacity decreases making them more vulnerable to failure. That is why, to maintain the role of the vaults and arches and prevent them from failure, strengthening is needed. Dur- ing the strengthening evaluation it cannot be forgotten that historical constructions are part of cultural heritage and engineers are required to follow the conservation doctrine of mini- mum intervention, among other relevant principles. This condition involves detailed studies before proceeding with application of strengthening. Within this framework, numerical mod- eling appears as a very useful method to study and define the efficiency of potential interven- tions before its application. The main objective of this paper is the numerical study of masonry vaults strengthened by means of extrados stiffening diaphragms. The idea of transversal stiffening elements is in line with the new trend in restoration practices regarding the use of traditional material and tech- niques while designing strengthening solutions. Preparation and validation of numerical models was done according to experiments carried out at University of Padova, Italy. Based on the experimental parameters and geometry, two numerical models, built up on macro- and micro- approaches, were constructed in DIANA Finite Element Analysis software. The pur- pose of making two models was the comparison of structural response of each one to mono- tonic, incremental load and to conclude on usefulness of macro-modeling approach for masonry arch-type constructions. Further, analysis of the efficiency of strengthening tech- niques throughout the non-linear analysis on both model types was performed. Extrados stif- fening diaphragms were defined to be a valid technique for improving the structural response of masonry arches and vaults, particularly in terms of initial stiffness.Project FP7-ENV-2009-1- 244123-NIKERSAHC Masters Cours

Seismic assessment of a typical masonry residential building in Bosnia and Herzegovina

The paper elaborates the seismic behaviour of a typical masonry building in B&H built in the 60’s without any seismic guidelines. Numerical modelling has been done in two different software packages, namely DIANA and 3MURI. In both approaches, adequate constitutive assumptions were assumed to take into account the nonlinear behaviour of masonry. Seismic vulnerability has been conducted by performing pushover and time history analyses. A comparison in terms of dynamic properties, crack pattern and capacity curves was done and a good agreement has been found between the two software packages. The paper's aim was to assess the seismic safety of this type of construction. A further objective was to investigate if simple software packages could be used for the assessment of these buildings. As a wide stock of this type of buildings is located through the former territory of ex-Yugoslavia, this work would enable a better understanding of this type of structures and quick overview of their actual seismic behavior

Protection of cultural heritage from earthquakes : The NIKER project and the related research at UMinho

The European Commission has recently funded a major research project (NIKER) which aimed at developing an integrated methodology for the systemic improvement of the seismic behaviour of cultural heritage assets. This paper provides an overview of the project and presents the most relevant contributions from University of Minho as partner of the projectEuropean Commissio

Strengthening of masonry arch bridges : research and applications

Masonry arch bridges represent an invaluable architectural and cultural heritage. Often this heritage is insufficiently maintained and subjected to increasing traffic loads, which leads to damage. This paper provides a survey of a dozen bridges in Northern Portugal, recent results in FRP bond and arch strengthening, and selected case studies of repair works in bridges in Portugal.Portuguese Science and Technology Foundation - POCTI/ECM/38071/2001.BETTOR MBT.MAPEI

Comportamento sísmico de edifícios com paredes resistentes

O presente trabalho aborda a questão do comportamento estrutural de edifícios tridimensionais de betão armado, compostos por pórticos reticulados e paredes resistentes de betão armado, sujeitos à acção sísmica regulamentar. Para o efeito, foram considerados os Eurocódigos estruturais, nomeadamente o Eurocódigo 0, Eurocódigo 1 e Eurocódigo 8. As paredes resistentes situam-se nas zonas destinadas às caixas de escadas/elevadores, formando os núcleos resistentes que, perante a ocorrência de um sismo, garantem a estabilidade estrutural e a capacidade de dissipação de energia da estrutura. A consideração destes núcleos teve por base a prática corrente de considerar a zona da caixa de escadas e elevadores em betão armado. A fim de avaliar a importância da localização destes elementos estruturais, elemento fundamental para a caracterização da resposta dinâmica, foi desenvolvido um estudo paramétrico, fazendo-se variar a disposição do núcleo em planta, obtendo-se estruturas com distribuição simétrica e assimétrica da rigidez em planta. Os edifícios considerados neste trabalho foram modelados com base no programa comercial de cálculo automático SAP 2000. A análise sísmica foi realizada de acordo com o preconizado no Eurocódigo 8, e no respectivo Anexo Nacional (em preparação), nomeadamente em termos da definição da acção. Posteriormente, apresentam-se e discutem-se os resultados obtidos, nomeadamente a relação entre a disposição estrutural dos núcleos resistentes, as propriedades dinâmicas e a distribuição das forças sísmicas pelos vários elementos resistentes. Por fim, apresenta-se uma solução estrutural obtida a partir das configurações anteriores e capaz de ultrapassar o comportamento dinâmico/sísmico tido como menos satisfatório

Repair of stone masonry arch bridges

This paper deals with the analysis and design of repair measures concerning two Portuguese masonry arch bridges, carried out at University of Minho. The first example is related with a masonry bridge built in the 19th century, composed of six pointed stone arches and located in the center of Portugal. The second example is a medieval masonry bridge composed of three semicircular stone arches and located in the North of Portugal. Repair measures adopted to re-establish the safety of the bridges are described. These measures were conceived in order to respect the modern principles of structural intervention in architectural heritage

Recomendações para a análise, conservação e restauro estrutural do património arquitectónico

Tradução das recomendações definidas pelo Comité Científico Internacional para a Análise e Restauro de Estruturas do Património Arquitectónico (ICOMOS)