The Meaning of Eurocode 8 and Induced Seismicity for Earthquake Engineering in The Netherlands

The Netherlands is one of the few European countries where seismic loading is not a dominant part of the national codes. Only for very special structures, earthquakes are regarded as a separate loading case. Until now, Eurocode 8 (EC8) is not part of Dutch building laws nor is there an official Dutch translation. Tectonic seismicity mainly occurs in the southern part of The Netherlands. The Dutch code NEN 6702 has a zonation map which shows horizontal peak accelerations of 0.01g to 0.1g for a return period of 5000 years. However, this seismic zonation map is yet not coherent with the EC8 National Annexes for Belgium and Germany. Induced seismicity due to the exploitation of natural gas is mainly observed in the northern part of The Netherlands. Induced earthquakes in the Netherlands have been observed at shallow depths with magnitudes up to ML = 3.5. Recorded strong accelerations are usually short in duration but have incidentally reached 0.3g. Currently, a study group is investigating the suitability of EC8 approach for Dutch conditions, the different seismic engineering approaches in Belgium and Germany, the implication of induced seismicity and a uniform engineering approach for sensitive structures, adopting (seismic) risk assessment

A combined risk analysis approach for complex dam-levee systems

[EN] In many areas of the world, dams and levees are built to reduce the likelihood of flooding. However, if they fail, the result can be catastrophic flooding beyond what would happen if they did not exist. Therefore, understanding the risk reduced by the dam or levee, as well as any risk imposed by these flood defences is of high importance when determining the appropriate risk reduction investment strategy. This paper describes an approach for quantifying and analysing risk for complex dam-levee systems, and its application to a real case study. The basis behind such approach rely on the potential of event tree modelling to analyse risk from multiple combinations of load-system response-consequence' events, tested by the authors for a real case study. The combined approach shows how the contribution to system risk of each sub-system can be assessed. It also describes how decisions on risk mitigation measures, at the individual asset scale, can and should be informed in terms of how they impact the overall system risk.This work was supported by Spanish Ministry of Economy and Competitiveness (MINECO) [BIA 2013-48157-C2-1-R].Castillo-Rodríguez, J.; Needham, J.; Morales Torres, A.; Escuder Bueno, I. (2017). A combined risk analysis approach for complex dam-levee systems. Structure and Infrastructure Engineering. 13(12):1624-1638. https://doi.org/10.1080/15732479.2017.1314514S16241638131

Electrically conductive spacers for self-cleaning membrane surfaces via periodic electrolysis

The use of an electrically conductive membrane has attracted significant interest in water treatment technology due to remarkable performance in fouling mitigation domain. In electrochemical systems, when external potential is applied, water electrolysis occurs and the generated gases efficiently clean the membrane surface. However, fabricating and integrating conductive membranes in current water treatment modules is challenging. The present work applies, for the first time, the electrolysis concept at the spacer component of the module rather than the membrane. Two types of materials were tested, a titanium metal spacer and a polymeric spacer. The polymeric spacer was made conductive via coating with a carbon-based ink comprised of graphene nanoplates (GNPs). A membrane system composed of the carbon coated/titanium metal spacer attached to the surface of a polyvinylidene fluoride (PVDF) microfiltration membrane and was assembled to the case of membrane module. The conductive spacers worked as an electrode (cathode) in electrochemical set-up. The membrane system was subjected to fouling and then exposed to periodic electrolysis, wherein in-situ cleaning of membrane surface by hydrogen bubbles generation at the spacer is applied

Upon impact: the fate of adhering <i>Pseudomonas fluorescens</i> cells during Nanofiltration

Nanofiltration (NF) is a high-pressure membrane filtration process increasingly applied in drinking water treatment and water reuse processes. NF typically rejects divalent salts, organic matter, and micropollutants. However, the efficiency of NF is adversely affected by membrane biofouling, during which microorganisms adhere to the membrane and proliferate to create a biofilm. Here we show that adhered Pseudomonas fluorescens cells under high permeate flux conditions are met with high fluid shear and convective fluxes at the membrane-liquid interface, resulting in their structural damage and collapse. These results were confirmed by fluorescent staining, flow cytometry, and scanning electron microscopy. This present study offers a 'first-glimpse' of cell damage and death during the initial phases of bacterial adhesion to NF membranes and raises a key question about the role of this observed phenomena during early-stage biofilm formation under permeate flux and cross-flow conditions.European Research Council (ERC