Da falsa integração do espectador na TV informativa

As actuais potencialidades tecnológicas abrem, perante o (tele)spectador, a promessa de um ilusório empowered user que se vai construindo alicerçado na narrativa mítica da omnipotência, tornada modo verbal e complemento directo da promessa moderna da omnividência. No entanto, os plateaux informativos da televisão portuguesa do século XXI ainda não vêem no telespectador um elemento estruturante do seu trabalho. São escassos os programas que abrem o alinhamento à participação do público e aqueles que o fazem atiram-no para margens que pouco ou nada interferem no desenvolvimento das emissões. Neste artigo, analisamos a integração dos telespectadores em 1673 emissões informativas, distribuídas por seis canais de televisão (RTP1, SIC, TVI, SICN, RTPN, TVI 24). Trata-se de uma investigação que desenvolvemos no âmbito do projecto “Jornalismo televisivo e cidadania”.

O ecrã da (hiper) televisão: novos olhares a partir das emissões dedicadas ao Euro 2012 na TV portuguesa

Dando continuidade a uma série de estudos já realizados no âmbito do projecto de investigação em que se insere, o presente trabalho questiona a evolução do ecrã televisivo como dispositivo supostamente convergente. Contrariando uma tendência discursiva dominante, quer na esfera dos media quer na própria produção académica sobre o medium televisivo, clarificam-se aqui alguns dos desenvolvimentos teóricos mais significativos, resultantes dos anos de trabalho que este projecto de investigação já tem. Propõe-se, pois, uma distinção conceptual entre o ecrã prometido pela cultura da convergência, que designamos como ecrã convergente, e o ecrã verdadeiramente resiliente da instituição-televisão, o ecrã centrípeto, que ainda obedece aos princípios de sequência e fluxo enunciados por Raymond Williams nos anos 1970.

Evaluation of the bond performance in FRP-brick components re-bonded after initial delamination

The bond behavior between Fiber Reinforced Polymers (FRPs) and masonry substrates has been the subject of many studies during the last years. Recent accelerated aging tests have shown that bond degradation and FRP delamination are likely to occur in FRP-strengthened masonry components under hygrothermal conditions. While an investigation on the possible methods to improve the durability of these systems is necessary, the applicability of different bond repair methods should also be studied. This paper aims at investigating the debonding mechanisms after repairing delaminated FRP-strengthened masonry components. FRP-strengthened brick specimens, after being delaminated, are repaired with two different adhesives: a conventional epoxy resin and a highly flexible polymer. The latter is used as an innovative adhesive in structural applications. The bond behavior in the repaired specimens is investigated by performing single-lap shear bond tests. Digital image correlation (DIC) is used for deeper investigation of the surface deformation and strains development. The effectiveness of the repair methods is discussed and compared with the strengthened specimens.

Primusinter (ím)pares - análise da presença dos académicos nos plateaux informativos da TV portuguesa

Os académicos estão a tornar-se uma presença cada vez mais visível nos plateaux informativos da TV portuguesa. Não são um grupo muito diversificado. Pelo contrário. Apresentam-se como uma confraria que é oriunda das universidades de Lisboa e pertence a um reduzido número de campos de saberes. Aos plateaux televisivos portugueses dificilmente chegará o fazer-ciência concreto. O que chega são alguns dos seus actores, o que não significa que o consigam por um efeito de reconhecimento inter pares, mas, antes, por um efeito de verdadeiras imparidades: porque já adquiriram suficiente capital simbólico em zonas exteriores ao campo científico. Zonas mais limítrofes, como o campo institucional-académico, ou zonas mais afastadas, como o campo comunicacional.

A TV do Mundial

No último ano da primeira década do século XXI, quase a entrar na era da televisão digital, importa saber que modelo de TV existe em Portugal. A análise da programação informativa destinada a acompanhar o Campeonato do Mundo de Futebol 2010 ajudará, decerto, a encontrar respostas. Neste artigo, apresentamos um estudo que incidiu em formatos informativos sobre este grande evento mediático, emitidos nos canais generalistas e temáticos entre os dias 11 de Junho e 11 de Julho de 2010 (datas de arranque e fecho do Mundial de Futebol da África do Sul). Essa análise, que incidiu em 604 emissões, procurou conhecer as formas de integração do telespectador nas emissões televisivas e quem foi chamado aos estúdios televisivos para participar nos debates aí promovidos. Os dados apurados demonstram claramente que esta TV do Mundial continua pouco aberta à participação do público e circunscrita a um grupo restrito de convidados, a maior parte dos quais oriundos da classe jornalística. Não é possível falar-se numa terceira fase do audiovisual. A hiper-televisão pode esperar.

Application of acoustic emission technique for bond characterization in FRP-masonry systems

The acoustic emission (AE) technique is used for investigating the interfacial fracture and damage propagation in GFRP-and SRG-strengthened bricks during debonding tests. The bond behavior is investigated through single-lap shear bond tests and the fracture progress during the tests is recorded by means of AE sensors. The fracture progress and active debonding mechanisms are characterized in both specimen types with the aim of AE outputs. Moreover, a clear distinction between the AE outputs of specimens with different failure modes, in both SRG-and GFRP-strengthened specimens, is found which allows characterizing the debonding failure mode based on acoustic emission data.

Numerical Assessment of the out-of-plane response of a brick masonry structure without box behaviour

This paper presents the assessment of the out-of-plane response due to seismic loading of a masonry structure without rigid diaphragm. This structure corresponds to real scale brick masonry specimen with a main façade connected to two return walls. Two modelling approaches were defined for this evaluation. The first one consisted on macro modelling, whereas the second one on simplified micro modelling. As a first step of this study, static nonlinear analyses were conducted to the macro model aiming at evaluating the out-of-plane response and failure mechanism of the masonry structure. A sensibility analyses was performed in order to assess the mesh size and material model dependency. In addition, the macro models were subjected to dynamic nonlinear analyses with time integration in order to assess the collapse mechanism. Finally, these analyses were also applied to a simplified micro model of the masonry structure. Furthermore, these results were compared to experimental response from shaking table tests. It was observed that these numerical techniques simulate correctly the in-plane behaviour of masonry structures. However, the

Effect of environmental ageing on the numerical response of FRP-strengthened masonry walls

Recent durability studies have shown the susceptibility of bond in fiber-reinforced polymer (FRP) strengthened masonry components to hygrothermal exposures. However, it is not clear how this local material degradation affects the global behavior of FRP-strengthened masonry structures. This study addresses this issue by numerically investigating the nonlinear behavior of FRP-masonry walls after aging in two different environmental conditions. A numerical modeling strategy is adopted and validated with existing experimental tests on FRP-strengthened masonry panels. The model, once validated, is used for modeling of four hypothetical FRP-strengthened masonry walls with different boundary conditions, strengthening schemes, and reinforcement ratios. The nonlinear behavior of the walls is then simulated before and after aging in two different environmental conditions. The degradation data are taken from previous accelerated aging tests. The changes in the failure mode and nonlinear response of the walls after aging are presented and discussed.

Survey and dynamic behaviour of the Our Lady of Conception Church, Portugal

The Our Lady of Conception church is located in village of Monforte (Portugal) and is not in use nowadays. The church presents structural damage and, consequently, a study was carried out. The study involved the survey of the damage, dynamic identification tests under ambient vibration and the numerical analysis. The church is constituted by the central nave, the chancel, the sacristy and the corridor to access the pulpit. The masonry walls present different thickness, namely 0.65 m in the chancel, 0.70 m in the sacristy, 0.92 in the central nave and 0.65 m in the corridor. The masonry walls present 8 buttresses with different dimensions. The total longitudinal and transversal dimensions of the church are equal to 21.10 m and 14.26 m, respectively. The survey of the damage showed that, in general, the masonry walls are in good conditions, with exception of the transversal walls of the nave, which present severe cracks. The arches of the vault presents also severe cracks along the central nave. As consequence, the infiltrations have increased the degradation of the vault and paintings. Furthermore, the foundations present settlements in the Southwest direction. The dynamic identification test were carried out under the action of ambient excitation of the wind and using 12 piezoelectric accelerometers of high sensitivity. The dynamic identification tests allowed to estimate the dynamic properties of the church, namely frequencies, mode shapes and damping ratios. A FEM numerical model was prepared and calibrated, based on the first four experimental modes estimated in the dynamic identification tests. The average error between the experimental and numerical frequencies of the first four modes is equal to 5%. After calibration of the numerical model, pushover analyses with a load pattern proportional to the mass, in the transversal and longitudinal direction of the church, were performed. The results of the analysis numerical allow to conclude that the most vulnerable direction of the church is in the transversal one and the maximum load factor is equal to 0.35.

Structural assessment of a masonry vault in Portugal

This paper reports on a structural safety assessment and performance evaluation of the upper choir of the Santa Maria de Belém Church in the Jerónimos monastery, Lisbon, one of the most important cultural heritage buildings in Portugal. The possibility of adding a new 20 t organ to the upper choir and its effects on the church structure's response are presented. A refined and a simplified finite-element model is developed to investigate the structure's performance under self-weight and seismic actions. A sensitivity analysis is performed to investigate the effect of masonry mechanical properties and rib cross-sections on the structural response, given the difficulty in accurately obtaining this information. The results show that the safety level of the structure is acceptable, even in the case of adding a heavy new organ.

Análise sísmica de construções históricas

As construções históricas, em particular os monumentos, apresentam uma elevada importância para as sociedades, que faz com que sejam associadas a uma determinada identidade cultural. É reconhecido internacionalmente que este tipo de edifícios devem ser protegidos para as gerações futuras. Neste sentido, a Carta de Atenas de 1931 e posteriormente a Carta de Veneza (1964) correspondem aos primeiros documentos internacionais que apresentam princípios orientadores para a conservação e restauro de Monumentos e Sítios. Estes documentos originaram movimentos internacionais relevantes e consequentemente fizeram com que vários esforços fossem conduzidos para a conservação e restauro de construções históricas.

Moisture-induced degradation of interfacial bond in FRP-strengthened masonry

Externally bonded strengthening of masonry structures using Fiber Reinforced Polymers (FRPs) has been accepted as a promising technique. Although the effectiveness of FRPs in improving the performance of masonry components has been extensively investigated, their long-term performance and durability remain poorly addressed. This paper, tackling one of the aspects related to durability of these systems, presents an experimental investigation on the effect of long-term (one year) water immersion on the performance of GFRP-strengthened bricks. The tests include materials' mechanical tests, as well as pull-off and single-lap shear bond tests, to investigate the changes in material properties and bond behavior with immersion time, respectively. The effect of mechanical surface treatment on the durability of the strengthened system as well as the reversibility of the degradation upon partial drying are also investigated. The experimental results are presented and critically discussed.

Seismic vulnerability of existing masonry buildings: Nonlinear parametric analysis

Existing masonry structures are usually associated to a high seismic vulnerability, mainly due to the properties of the materials, weak connections between floors and load-bearing walls, high mass of the masonry walls and flexibility of the floors. For these reasons, the seismic performance of existing masonry structures has received much attention in the last decades. This study presents the parametric analysis taking into account the deviations on features of the gaioleiro buildings - Portuguese building typology. The main objective of the parametric analysis is to compare the seismic performance of the structure as a function of the variations of its properties with respect to the response of a reference model. The parametric analysis was carried out for two types of structural analysis, namely for the non-linear dynamic analysis with time integration and for the pushover analysis with distribution of forces proportional to the inertial forces of the structure. The Young's modulus of the masonry walls, Young's modulus of the timber floors, the compressive and tensile non-linear properties (strength and fracture energy) were the properties considered in both type of analysis. Additionally, in the dynamic analysis, the influences of the vis-cous damping and of the vertical component of the earthquake were evaluated. A pushover analysis proportional to the modal displacement of the first mode in each direction was also carried out. The results shows that the Young's modulus of the masonry walls, the Young's modulus of the timber floors and the compressive non-linear properties are the pa-rameters that most influence the seismic performance of this type of tall and weak existing masonry structures. Furthermore, it is concluded that that the stiffness of the floors influences significantly the strength capacity and the collapse mecha-nism of the numerical model. Thus, a study on the strengthening of the floors was also carried out. The increase of the thickness of the timber floors was the strengthening technique that presented the best seismic performance, in which the reduction of the out-of-plane displacements of the masonry walls is highlighted.

Escavações arqueológicas no Mosteiro de S. Martinho de Tibães: campanha de março a dezembro de 1999: relatório científico

Os trabalhos arqueológicos a que este relatório respeita decorreram entre Março e Dezembro de 1999. Conforme se referiu já no primeiro relatório, a intervenção tem por objectivo principal minimizar o impacte das obras de conservação, restauro e adaptação promovidas pelo Instituto Português do património Arquitectónico (IPPAR). Os trabalhos arqueológicos prosseguem igualmente objectivos científicos, orientados para a problemática da evolução arquitectónica do mosteiro e para os diversos modos de organização do espaço envolvente.

Masonry macro-block analysis

The structural analysis involves the definition of the model and selection of the analysis type. The model should represent the stiffness, the mass and the loads of the structure. The structures can be represented using simplified models, such as the lumped mass models, and advanced models resorting the Finite Element Method (FEM) and Discrete Element Method (DEM). Depending on the characteristics of the structure, different types of analysis can be used such as limit analysis, linear and non-linear static analysis and linear and non-linear dynamic analysis. Unreinforced masonry structures present low tensile strength and the linear analyses seem to not be adequate for assessing their structural behaviour. On the other hand, the static and dynamic non-linear analyses are complex, since they involve large time computational requirements and advanced knowledge of the practitioner. The non-linear analysis requires advanced knowledge on the material properties, analysis tools and interpretation of results. The limit analysis with macro-blocks can be assumed as a more practical method in the estimation of maximum load capacity of structure. Furthermore, the limit analysis require a reduced number of parameters, which is an advantage for the assessment of ancient and historical masonry structures, due to the difficult in obtaining reliable data.