This study investigates the behavior of interacting surface cracks at the circumferential weld toe of monopile-supported offshore wind turbines. Relying on a numerical model that explicitly considers weld profiles, we explore the impact of crack interaction and loading scenarios on crack propagation. Our findings reveal that, initially, surface cracks grow independently, resembling single crack behavior. However, a pronounced interaction effect accelerates their growth as cracks propagate further, potentially leading to crack coalescence, high stress intensity factors, and reduced fatigue life. Consequently, this work highlights the need for integrating specific weld geometry representation in numerical models, as neglecting this can lead to significantly inaccurate fatigue life estimates in typical practical applications. Moreover, this study points out the challenge in accessing representative crack growth material parameters, vital for accurately evaluating the fatigue life of structural connections in offshore wind turbines.@en

Efficient planning of inspection and maintenance (I&M) actions in civil and maritime environments is of paramount importance to balance management costs against failure risk caused by deteriorating mechanisms. Determining I&M policies for such cases constitutes a complex sequential decision-making optimization problem under uncertainty. Addressing this complexity, Partially Observable Markov Decision Processes (POMDPs) provide a principled mathematical methodology for stochastic optimal control, in which the optimal actions are prescribed as a function of the entire, dynamically updated, state probability distribution. As shown in this paper, by integrating Dynamic Bayesian Networks (DBNs) with POMDPs, advanced algorithmic schemes of probabilistic inference and decision optimization under uncertainty can be uniquely combined into an efficient planning platform. To demonstrate the capabilities of the proposed approach, POMDP and heuristic-based I&M policies are compared, with emphasis on an offshore wind substructure subject to fatigue deterioration. Results verify that POMDP solutions offer substantially reduced costs compared to their counterparts, even in traditional problem settings.@en

The river network in South America (S.A.) is extensive and consists of some of the largest river basins in the world. However, despite these natural features, inland navigation is underutilised and still plays a marginal role in the transport of commercial goods in the region. South America has not yet taken full advantage of its extensive system of navigable waterways and there are many opportunities to better integrate inland navigation into the region’s transport network in order to cater for the ever-increasing demand for cargo and passenger transport. Although the international shipments of cargo utilizing inland waterways has increased over the last decade, this transportation mode is less than one percent of the total value and volumes of goods that are shipped internationally. Inland waterways are not only used for transport between the South American countries who share the rivers, but the waterways are also the first leg of international transport with other regions of the world. Examples of the latter are the natural resource exports (soybean products, aluminium, and petroleum products) from the Paraguay-Paraná, Amazonas, Plata, Orinoco and Magdalena river basins that are destined for Europe, the US or Asia. In these cases, seagoing vessels are directly deployed from the ports along these river systems. While the values of these international exports have more than tripled since 2002, in some waterways the volumes have shown a decreasing tendency over the past several years. Other waterways, such as the Paraguay-Paraná, Madeira, Tapajós, and many others have experienced significant growth in their utilisation for the transport of commercial goods in recent times. In South America, there are several independent inland waterway systems, which currently have varying levels of development and investment. From a macro perspective, the uses of the inland waterways in the S.A. regions/countries are challenged by various factors. These factors include: a low level of investment in the construction and maintenance of waterway infrastructures and inland ports; incomplete, outdated or absent national and regional[1] norms and regulatory frameworks; poor administrative structures and institutional capacities; limited use of navigational services and technologies, such as aids to navigation, updated maps, electronic charts, AIS (automatic identification system) and other RIS (river information services) technologies; lack of qualified labour and institutions for capacity building and formation/training of quality labour These challenges have limited the potential of inland navigation, affecting not only the direct use of this mode of transport, but also its integration with other modes. These limitations also lead to inefficiencies within the overall transportation sector, such as higher costs of transport at local, national, and sub-national levels, as well as reductions in the production of regional goods due to the economic and environmental impacts associated with a high dependency on roadway transport. A common inland waterway classification for South America could be a tool to support the development of inland navigation in South America. Given the experiences in other regions of the world (EU, USA, China, etc.), such classifications can be a powerful and dynamic way to support and implement inland waterway policies and projects as it enables the identification of the limitations and the economic potential of navigable waterways in the region and can encourage and monitor the development of their capacity for transport of goods and people [Jaimurzina et al., 2016 ; Jaimurzina and Rigo, 2018]. In October 2016, at the occasion of an ECLAC/PIANC/ANTAQ ‘Seminar on Inland Navigation and a More Sustainable Use of Natural Resources: Networks, Challenges and Opportunities for South America (Rio de Janeiro, Brazil)’, the representatives of the South American countries with interest in inland navigation and the PIANC experts from Europe, Northern America and Asia, supported the idea of elaborating a regional classification for inland waterways in South America and recommended the creation of a dedicated Working Group on the issue. As a consequence, in 2017, PIANC (InCom) and ECLAC launched the WG 201 for the elaboration of a common classification for South America which would promote a more efficient, transparent and sustainable use of inland water transport and logistics services, in general. In 2018, the preliminary PIANC-ECLAC WG 201 report ‘Development of a Proposal of Inland Waterway Classification for South America’ was published. Then, the applicability of the proposed classification has been further discussed among local experts and governments representatives. Those discussions led to updating the former document and the enhancements are included in this final report (which replaces the PIANC WG 201 2018 report).@en

The fluvial network in South America is known for having one of the highest densities and widest geographical coverages in the world, but, despite this natural endowment, inland navigation still plays a rather marginal role in the transport of goods and passengers in the region. South America has not yet taken full advantage of its extensive system of navigable waterways and needs to better integrate them into the region’s transport network in order to cater for the ever-increasing demand for cargo and human mobility. Although the evolution of international transport in inland navigation has been positive over the last decade, the modal shares of inland shipping in the region’s international transport are less than one percent in terms of value and volume. Inland waterways are not only used for transport between the countries of the region, located along the river basins, but also are the first leg of international transport flows with other regions of the world. Examples of the latter are the natural resource exports (soybean products, aluminium, and oil related products) from the Paraguay-Paraná, Amazonas, Plata, Orinoco and Magdalena river basins that are destined for Europe, the US or Asia. In these cases, seagoing vessels are directly deployed from the ports along these river systems. While the values of these exports have more than tripled since 2002, in some waterways the volumes have shown a decreasing tendency over the last years but hopefully not everywhere as in Paraguay-Paraná IW. In South America, there are several independent inland waterway systems, which have different levels of development. For some of these systems and from a macro perspective view, the uses of the inland waterway systems in the region are challenged by various factors.@en