1,981 research outputs found
Indirect assessment of the contribution of NSM CFRP laminates for the shear strengthening of RC beams
Near Surface Mounted (NSM) strengthening technique has received increasing attention within the scientific
and technical communities due to the positive indicators that this technique can provide in terms of strengthening
performance. The NSM is especially effective for the shear strengthening of RC beams due to the ease of its application
and the possibility of installing the Fibre Reinforced Polymer (FRP) elements in the most appropriate locations for the
optimization of their contribution in terms of shear resistance. Furthermore, the FRP elements are protected against acts
of vandalism and do not change the geometric configuration of the strengthened components since they are installed
into thin slits opened on the concrete cover. Although either circular or rectangular FRP bars are used, recent research
shows that the latter (herein designated as laminates) are more effective and easier to install. Research carried out in the
area of NSM for the shear strengthening of RC beams reveals that the percentage, inclination and spacing of FRP
laminates have a considerable influence on the effectiveness of this technique. The percentage of existent internal
stirrups, the relative position of stirrups and FRP laminates and concrete strength class are also important aspects for the
performance of the NSM technique. To estimate the influence of these parameters, a new test setup is proposed and an
experimental program has been planned. The test setup is similar to the indirect tensile test (Brazilian test). The
experimental program consists of 27 cylindrical concrete specimens of 180 mm thickness and 600 mm diameter,
grouped in series for evaluating the influence of the aforementioned parameters. The test setup is detailed, and the results of the first series are presented and discussed.Fundação para a Ciência e a Tecnologia (FCT) - POCTI/ECM/59033/2004
Elementos de casca em alvenaria cerâmica reforçados com laminados de fibras de carbono
Este trabalho refere-se a um estudo experimental efectuado sobre elementos de casca em alvenaria cerâmica
com juntas e camada de compressão em betão simples, reforçados com laminados de CFRP para esforços de flexão. No
reforço utilizaram-se duas técnicas: laminados colados sobre a superfície do betão das juntas; laminados inseridos em
entalhes executados no betão das juntas. Os resultados obtidos demonstram a eficiência das técnicas de reforço utilizadas,
dado se ter registado um substancial aumento da capacidade resistente e das condições de segurança dos elementos
ensaiados.Shell elements made by ceramic units bonded by concrete joints and covered by a concrete compression
layer were strengthening by strips of carbon fiber reinforced polymer laminates (CFRP), using two reinforcing techniques:
CFRP laminates externally bonded to concrete joints, CFRP laminates bonded into slits made on the concrete joints. Both
reinforcing techniques have shown to be effective in terms of increasing the ultimate load and its corresponding
deformability, but the last one was more effectiveness. In the present work the experimental research is described and the
main results are presented and discussed
Composite materials for the structural strengthening of reinforced masonry shells
Since the 1950s, the Uruguayan engineer Eladio Dieste designed curved lightweight masonry shells of impressive span width, complex shape and high attractiveness. This structural system is composed of a top mortar cover, a layer of clay bricks, mortar joints, and steel reinforcement. For the permanent loads, this structural system has
been working satisfactory, in spite of rebar corrosion being detected in some shells. However, if submitted to an earthquake of considerable magnitude, damage can be significant, and its rupture can even occur.
In the present paper, an effective strengthening technique, using carbon fibre reinforced polymer (CFRP) materials,
was developed to significantly increase the ultimate load of damaged reinforced masonry shell structures. This
strengthening system is composed by strips of wet lay-up CFRP sheet and prefabricated CFRP laminates. The sheet
strips are bonded, with epoxy resin, to the top cracked concrete surface of the shell to increase its flexural resistance for
the negative bending moments, while laminates are fixed, with epoxy adhesive, to the bottom of the reinforced concrete
joints to increase the shell flexural resistance for the positive bending moments. This strengthening system was applied
to a damaged shell, having resulted a significant increase in the service load and an increase of about 76% in the
ultimate load. A monitoring system was installed to evaluate the applied force, the deflection in critical sections and the
strains in the composite materials and in the steel reinforcement. The experimental research is described and the main
results are presented and discussed
Shear testing of stacked bonded masonry
Report 02-DEC/E-10 - draft versio
Liquid crystal phase and waterlike anomalies in a core-softened shoulder-dumbbells system
Using molecular dynamics we investigate the thermodynamics, dynamics and
structure of 250 diatomic molecules interacting by a core-softened potential.
This system exhibits thermodynamics, dynamics and structural anomalies: a
maximum in density-temperature plane at constante pressure and maximum and
minimum points in the diffusivity and translational order parameter against
density at constant temperature. Starting with very dense systems and
decreasing density the mobility at low temperatures first increases, reach a
maximum, then decreases, reach a minimum and finally increases. In the
pressure-temperature phase diagram the line of maximum translational order
parameter is located outside the line of diffusivity extrema that is enclosing
the temperature of maximum density line. We compare our results with the
monomeric system showing that the anisotropy due to the dumbbell leads to a
much larger solid phase and to the appearance of a liquid crystal phase. the
double ranged thermodynamic and dynamic anomalies.Comment: 14 pages, 5 figure
Testing, analysis and building technology for industrialized reinforced masonry shells
This paper addresses briefly the research carried out at University of Minho, regarding an
industrialized solution for reinforced masonry shells. The aspects of material
characterization are presented, together with a contribution for a full prefabrication process.
Aspects related to numerical analysis and structural design can be found in [1-3].comissão Europeia - projeto GROWTH, GROW-1999-70420 “ISOBRICK”Fundação para a Ciência e a Tecnologia (FCT
Painéis de alvenaria cerâmica com juntas de concreto submetidos a ensaio de cisalhamento
É notável que o mercado da construção civil encontra-se cada vez mais esclarecido e a
concorrência acaba tornando-se um fator estimulante para a área de pesquisa de novas tecnologias. É nesse
contexto que a alvenaria cerâmica está inserida, trazendo uma nova perspectiva sobre a sua utilização nas
contruções, uma vez que tem sido reconhecida como elemento de elevada capacidade estrutural.
O trabalho apresentado neste documento, trata da apresentação e análise de resultados do comportamento de
painéis de alvenaria de cerâmica furada, ligada por juntas de concreto, ensaiados ao cisalhamento, segundo a
Norma Européia EN1052-4.
Os ensaios presentes neste estudo fazem parte de um projeto no qual estão incluídos uma série de ensaios para
a caracterização mecânica de materiais que serão utilizados, posteriormente, na confecção de coberturas em
cascas de alvenaria armada
Soluções industrializadas para cascas de betão com elementos cerâmicos incorporados
A presente comunicação apresenta resultados de um projecto em curso, tendo em vista definir
uma solução competitiva para cascas de betão armado com elementos cerâmicos incorporados.
As soluções tecnológicas consideradas, que incluem pré-fabricação parcial e total são
discutidas, os ensaios experimentais e os seus resultados analisados e os protótipos a serem
construídos são apresentados. Os resultados já obtidos salientam as potencialidades da préfabricação
parcial e do bom desempenho da solução proposta
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