143 research outputs found
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Practical nonlinear analysis of unreinforced concrete tunnel linings
A comprehensive methodology for modelling, analyzing and assessing the structural response of unreinforced concrete tunnel linings is presented. Various modelling techniques are described, considering the plane finite element representation of the lining geometry, material constitutive laws, and boundary and interface conditions. Furthermore, all relevant external loading cases are studied, including gravity, environmental, fire, blast, and seismic loading. Potential pitfalls in the modelling and analysis procedures are identified and properly dealt with. The suggested methodology is finally applied to actual tunnel linings and the interpretation of the analysis results leads to important conclusions regarding the applicability of different analysis methods and the performance of unreinforced concrete linings
Biodegradability standards for carrier bags and plastic films in aquatic environments: a critical review
Plastic litter is encountered in aquatic ecosystems across the globe, including polar environments and the deep sea. To mitigate the adverse societal and ecological impacts of this waste, there has been debate on whether âbiodegradableâ materials should be granted exemptions from plastic bag bans and levies. However, great care must be exercised when attempting to define this term, due to the broad and complex range of physical and chemical conditions encountered within natural ecosystems. Here, we review existing international industry standards and regional test methods for evaluating the biodegradability of plastics within aquatic environments (wastewater, unmanaged freshwater and marine habitats). We argue that current standards and test methods are insufficient in their ability to realistically predict the biodegradability of carrier bags in these environments, due to several shortcomings in experimental procedures and a paucity of information in the scientific literature. Moreover, existing biodegradability standards and test methods for aquatic environments do not involve toxicity testing or account for the potentially adverse ecological impacts of carrier bags, plastic additives, polymer degradation products or small (microscopic) plastic particles that can arise via fragmentation. Successfully addressing these knowledge gaps is a key requirement for developing new biodegradability
standard(s) for lightweight carrier bags
Beneficial reuse of Brest-Harbor (France)-dredged sediment as alternative material in road building: laboratory investigations
Spécification géométrique des produits (GPS) - Concepts, principes et rÚgles - Principes fondamentaux
Recueil de normes françaises 1997: métrologie : gérer et maitriser les processus et les équipements de mesure
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