Papers

The out-of-plane response of walls in existing stone masonry buildings is one of the major causes of vulnerability commonly observed in post-earthquake damage surveys. In this context, a shaking table (ST) test campaign was carried out on a full-scale masonry façade mainly focusing on the characterization of its out-of-plane overturning behaviour. The structure tested on the ST is a partial reproduction of an existing building from Azores, damaged during the 9 July 1998 Faial earthquake. The definition of the tested specimen as well as the selection of the input ground motion is reported in this paper. A specific emphasis is given to the definition of the time-history to be applied during the tests because it was felt as an essential and crucial part of the work to obtain the desired overturning behaviour. The accelerogram to be imposed was selected from a large set of accelerograms (74) by means of a step-by-step procedure on the basis of several numerical analyses resorting to the rocking response of rigid blocks.

The present work describes a shaking table experimental campaign specifically developed for the characterisation of the out-of-plane response of a full scale stone masonry façade. After the description of the specimen and the selection of the input motion presented in a companion paper (Part 1), the experimental campaign is illustrated and extensively described. The out-of-plane behaviour of the sacco masonry façade is presented in terms of displacements, velocities, and accelerations recorded during the shaking table tests. A one-sided rocking response of the façade was observed prior to collapse. The impacts were clearly identified in the acceleration records. The façade overturning occurred with the expected failure mode, as predicted in the design of the test.Finally, some conclusions are drawn regarding the observed behaviour and particular features of this type of stone masonry constructions, which may influence the global behaviour of the façade.

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Metakaolin (MK) is nowadays a well-known pozzolanic material used in cement-based materials. Its benefits are related to its great pozzolanic reactivity when compared with some others pozzolanic materials, like fly ash or ground-granulated blast furnace slag. When MK reacts with calcium hydroxide, cementitious products are formed. It is known that the main phases produced during its pozzolanic reaction at ambient temperature are calcium silicate hydrates (CSH), stratlingite (C2ASH8) and calcium aluminate hydrate (C4AH13). However, in literature there are several discrepancies regarding these phases stability, namely the transformation of stratlingite and C4AH13 into hydrogarnet (C3AH6) at long term. The consequences of that instability are a reduction in the porosity and a loss of microstructural strength that can induce a complete material degradation. The MK is a material with great potential in Portugal, since there is a large abundance of kaolinitic clays, however its development is not yet achieved. In order to answer this demand a research project was initiated with the aim of optimizing the production of MK in Portugal and enhancing the durability of aerial calcitic lime mortars, to be mainly used in conservation and restoration of historical buildings. With the objective of studying the compounds formed in lime/MK and their stability during time, we have prepared different lime/MK ratio pastes (molar ratios). These lime/MK pastes were stored at saturated conditions (RH > 95%) and 23 ± 2 ºC temperature being analysed at several ages by TGA-DTA, XRD and SEM-EDS. In this paper the results obtained are presented and discussed.

At the National Laboratory of Civil Engineering (LNEC), Portugal, and with financial support from Fundação para a Ciência e a Tecnologia (FCT) given to the research project PTDC/ECM/101810/2008 – Polymer-modified Cement Mortars for the Repair of Concrete Structures, an ongoing study aims to assess the influence of polymers on the degradation mechanism of cement-based materials due to ASR. For polymer dosages in excess of 10% of the mass of cement a continuous network of polymer film starts to form amongst cement hydrates, effectively transforming the cement matrix into a polymer-cement co-matrix (Figure 1). The effect of this polymer network on the expansion and microcracking resulting from ASR was assessed for a variety of polymer-modified cement-based mortars (PCMs) using acrylic-styrene, styrene-butadiene and epoxy polymers and performance was compared to that of an unmodified cement mortar (CM).

The length of the Portuguese coast, the severity of the sea conditions and the concentration of population and economic activities on its coastal zone justify the importance of studying wave-induced risks and, in particular, flooding due to wave action. Indeed, emergency situations caused by adverse sea conditions are frequent and put in danger the safety of people and goods, with negative impacts for society, economy and natural heritage. So, assessing the risk of flooding of coastal and port areas is essential for the proper planning and management of these areas. In this framework, a methodology for the flood risk assessment in coastal and port areas is under development. The methodology is embedded into the HIDRALERTA system, a novel integrated system for port and coastal management, designed to prevent emergency situations, to support their management and to forecast incidental long-term interventions. The present paper describes the methodology, the HIDRALERTA system and a case study, the São João da Caparica beach, on the Lisbon

Within the scope of the repair of concrete structures, localized repair with repair mortars is one of the most used methods, mainly because both the manufacture and the placement of repair mortars are similar to those of conventional mortars. The first part of this paper discusses the importance of repair mortars, as well as the relevant aspects of the concrete degradation, and sets out the principles and methods for repair, which are recommended by EN 1504-9. The second part of this work addresses the need to prove some analytical theories, particularly regarding the need to mix water with the repair mortars and the best way to get the desired workability for each W/C ratio established. The main object of the third part of this work was the development of a software to support the formulation of repair mortars, which resulted from the conjugation of several factors such as: the collection of all the knowledge acquired during the work and the inclusion of normative specifications in use, which are required for a structural repair mortar in articulation with the durability demands for a lifetime of 50 years To conclude, the developed work contributed to increase the knowledge about the repair mortars and the durability of local repairs using mortars. The work is characterized by having as final result a practical application capable of materializing relevant information and confirming the promising results obtained with cementitious mortars modified with polymers.

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Flash flooding is characterised by a rapid flooding phenomenon caused byintense rainfall. Despite being an extreme event with high uncertainty, therainfall-run-off process is often regarded as deterministic (rather than stochastic).In this paper, the Soil Conservation Service (SCS) flood hydrograph uncertaintyis quantified based on the Total Error Framework (TEF), and introducedinto the model by applying perturbation in the input data and model parameters.The random perturbation component is stochastically modelled. A sensitivityanalysis was carried out on the stochastic model parameters, using areal case study in the Azores (Portugal). The results showed that the floodhydrograph uncertainty varies over time, with its largest deviations occurring atthe beginning of the flooding because of the uncertainty associated with the SCSmethod curve number parameter (correlation coefficient R2 of 0.86). Rainfalluncertainty was responsible for the uncertainty in the hydrograph peaks

Railway tracks frequently show higher degradation rates at transition zones from earthworks to bridges, or to other structures. In order to guarantee the safety and comfort of passengers, this aspect results in higher maintenance costs and disturbs railway operations. The behaviour of transition zones is rather complex and its poor performance has been mainly attributed to variations in the vertical stiffness of the track and to differential settlements. These two aspects amplify the dynamic loads of the trains and cause further track degradation. The Portuguese railway network manager has reported the poor structural behaviour of a few transition zones in some of its lines, which constrain train operations and present high maintenance costs. Thus, a research project is currently underway aiming at contributing to a better understanding of the phenomena that occur at transitions, and at optimizing their design for conventional and high-speed railway lines. In this article, we present some aspects of this research project, namely: a review on the design of backfills for transition zones; a comparison between numerical models found in the literature that were used to study the problem; some results obtained during the construction (characterization of materials and layers) and operation of the line.