Artigos de Revista

The morphological evolution of the Tagus estuary inlet in the last century is analyzed in order to characterize its dynamics, explain its behavior and anticipate its future evolution. First, the evolution is characterized through a literature review, complemented by new data analyses. This review synthesizes the present understanding of the inlet

Conservation of the European-built heritage is nowadays closely related to interventions in masonry construction. Since a significant part of these structures are located in earthquake prone zones, designing protective measures that ensure their preservation requires the assessment of the associated seismic vulnerability and the understanding of their degradation mechanisms. However, due to the presence of discontinuities between its constituent elements, the numerical simulation of the non-linear response of masonry structures subjected to strong earthquakes is a cumbersome task, especially when performed using the traditional finite element method. As an alternative, the discrete element method is particularly suitable for the numerical analysis of such structures under large, damaging loads. By allowing discrete displacements/rotations of individual bodies, and by automatically recognising new contacts between bodies, while eliminating obsolete ones, this numerical approach can simulate the complete detachment of discrete bodies initially in contact.The present paper illustrates the use of the discrete element method to assess the seismic vulnerability of stone arches. A probabilistic approach allows to consider the variability of theseismic action and the uncertainties in the definition of the material properties. First, an unreinforced masonry arch is considered. Based on non-linear multi-directional incremental dynamic analyses, five damage states are proposed and the respective fragility curves are elaborated. Toimprove the arch

A seismic assessment study of two historical masonry arch bridges, with different geometries and spans, ispresented. The seismicity of the two locations was analyzed in order to define the seismic action to be applied.Artificial ground motion records were generated accordingly, and real ground motions were also used. The twonumerical models were created with a 3D discrete element code. The accuracy of the deformability of the blockmodels was verified by comparison with a finite element model. In situ measurements of the natural frequencieswere available for one of the bridges, providing further means for model calibration. Time domain dynamicanalyses were performed with each set of ground motions, allowing an evaluation of damage and failure modesunder seismic action. The shorter span bridge was found to withstand the regulatory records with minimumdamage. In contrast, the longer span bridge displayed a significant vulnerability to earthquake action. The studyshows that rigid block models have the ability to represent effectively the dynamic elastic response of the bridgesand can be calibrated by ambient vibration measurements. Furthermore, the discrete element models provide apowerful tool to investigate the nonlinear dynamic response and failure of these structures, which has to be basedon a comprehensive set of dynamic records.

As Europe is faced with increasing droughts andextreme precipitation, countries are taking measures to adaptto these changes. It is challenging, however, to navigatethrough the wide range of possible measures, taking into accountthe efficacy, economic impact and social justice aspectsof these measures, as well as the governance requirementsfor implementing them. This article presents the approachof selecting and analysing adaptation measures to increasingextreme weather events caused by ongoing climate changethat was developed and applied in the H2020 project BINGO(Bringing Innovation to Ongoing Water Management). Thepurpose of this project is (a) to develop an integrated participatoryapproach for selecting and evaluating adaptationmeasures, (b) to apply and evaluate the approach acrosssix case-study river basins across Europe, and (c) to supportdecision-making towards adaptation capturing the diversity,the different circumstances and challenges river basinsface across Europe. It combines three analyses: governance,socio-economic and social justice The governance analysisfocuses on the requirements associated with the measuresand the extent to which these requirements are met at theresearch sites. The socio-economic impact focuses on the efficacyof the measures in reducing the risks and the broadrange of tools available to compare the measures on their societalimpact. Finally, a tentative social justice analysis focuseson the distributive impacts of the adaptation measures.In the summary of results, we give an overview of the outcomeof the different analyses. In the conclusion, we brieflyassess the main pros and cons of the different analyses thatwere conducted. The main conclusion is that although the researchsites were very different in both the challenges andthe institutional context, the approach presented here yieldeddecision-relevant outcomes.

The water availability estimation in large regions is a relevant procedure to define broad water resourcesmanagement policies but may prove difficult due to the lack of data and uncertainty to related regionalhydrological and hydrogeological characterization. BALSEQ, a daily sequential water budget model, wasapplied in a set of twenty-two watersheds in southern Portugal, aiming to understand the possible relationsbetween the model parameters and watershed characteristics that may allow assembling calibration functionsfor non-monitored watersheds. A sensitivity analysis was conducted by comparing BALSEQ results withmeasured surface flow, focusing specifically on the fraction of the potential maximum retention (

Neste quarto artigo (de oito) da série editorial intitulada

Stability analyses of geotechnical structures in rock are traditionally performed using deterministic methods. In Europe, Eurocode7, introduced in the beginning of the 21st century, adopts limit state design and semi-probabilistic methods, using partial factors for the design of geotechnical structures. Meanwhile, reliability-based design, using probabilistic methods, is becoming more common in practical cases. The paper considers an intentionally simple case study?the analysis of a slope in a rock mass with one discontinuity, considered in a discrete way, forming a rock block to be stabilised by anchors?to compare the results obtained with the different methods. The objective is to calculate the force applied by the anchors so that the ultimate limit states of sliding of the rock block is verified. Deterministic-based design optimization considering both the traditional global safety factor approach and the partial factor approach following the Eurocode 7 are first applied. A reliability-based design optimization procedure?which takes geometrical and mechanical properties of the discontinuities as random variables?is then used, and the results are compared to the former ones. A discussion is presented concerning the consistency of the obtained results.

No artigo desenvolve-se uma reflexão, de certa forma, introdutória sobre o interesse da exploração e do subsequente aprofundamento de uma razoável variedade de propostas organizativas para as zonas e subzonas da habitação, numa perspetiva que encara criticamente uma, ainda preponderante, preocupação essencialmente funcional, e que visa a melhor adequação a necessidades e desejos habitacionais específicos num quadro de expressiva qualidade arquitectónica.

TiO2-containing photocatalysts, which combine TiO2 with carbon-based materials, are promising materials for wastewater treatment due to synergistic photodegradation and adsorption phenomena. In this work, TiO2/AC composites were produced by the in situ immobilization of TiO2 nanoparticles over activated carbon (AC) derived from spent coffee grains, using different TiO2/AC proportions. The TiO2/AC composites were tested as adsorbents (dark) and as photocatalysts in a combined adsorption+photocatalytic process (solar irradiation) for methylene blue (MB) removal from ultrapure water, and from a secondary effluent (SecEf) of an urban wastewater treatment plant. All the materials were characterized by XRD (X-ray powder diffraction), N2 adsorption

The subgrade of old railway tracks often exhibits poor geotechnical behaviour, particularly regarding the soils on which the ballast layer rests. Such poor behaviour implies significant maintenance costs and possession times. The reinforcement of subgrade soils by injection of binders may mitigate these malfunctions, but previous applications showed some limitations, and the quality of the results depends on many factors. Herein, the authors present some studies on the development of a subgrade reinforcement method, which minimises the impact on train operation, by using short soil