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Pure magnesium and Mg-(0.2-0.9 at%) Y rolled sheets were subjected to three-point bending tests to individually investigate the effects of texture and yttrium addition on bending deformation behavior. Yttrium addition increased bending yield stress in both Specimen TR with the neutral plane parallel to the ND (normal direction of the rolled sheets) plane and Specimen TN with the neutral plane perpendicular to the ND plane, resulting from the increase in critical resolved shear stresses (CRSSs) for basal slip and f10-12g twinning with yttrium addition. Bending ductility increased with increasing yttrium addition until 0.5 at% yttrium addition, and then decreased at 0.9 at% yttrium addition in Specimen TN. On the other hand, bending ductility increased until 0.9 at% yttrium addition in Specimen TR since non-basal slip activities increased with increasing yttrium addition. Since the neutral plane in Specimen TN with 0.9 at% yttrium addition moved more to the center than that in Specimen TN with 0.5 at% yttrium addition, resulting in the higher tensile strain at the tension side. Therefore, the bending ductility in 0.9 at% yttrium addition was lower than that in 0.5 at% yttrium addition. [ABSTRACT FROM AUTHOR]

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Piled embankments are becoming widely used to cope with engineering problems (e.g., excessive settlements, bearing failure) caused by soft soil subgrade to maintain the safety and stability of the constructed facilities. This study focused on an international motor-racing circuit currently under construction, where the underlying soft soil substratum characterized by a high void ratio and compressibility may largely influence the long-term performance of the project. Pretensioned high-strength concrete (PHC) pile-supported embankment is designed to improve this project, and its effectiveness remains to be studied. In addition, this study specifically focused on negative skin friction (NSF) and neutral plane (NP) position development, which significantly influence the bearing capacity of the pile foundation and have not been fully understood. As such, two large-scale field tests were performed on the PHC pile-supported embankments to monitor the settlement of piles and the surrounding soils. According to the monitored layered settlements, the NP development with time was quantitatively analyzed, and NP gradually moved up toward the pile top during soil consolidation. Comparison between the measurements of two test sites with and without geogrid reinforcement indicated that geogrids could not only alleviate total and differential settlements of the foundation but also contribute to the shallower final NP position. A numerical model, whose effectiveness was validated by comparing with the field measurements, was established to predict the complete variation of NP positions and explore the effects of various influencing factors through a parametric study. This study enhances the comprehension of NSF and NP development in pile foundations and provides valuable guidance for this motor-racing circuit and other related projects in the future. [ABSTRACT FROM AUTHOR]

This study investigates numerically the impact of the longitudinal location as well as the heat release rate (HRR) of the fire source on the neutral plane and induced flow within a longitudinal sloping tunnel under natural ventilation. Research shows that neutral plane height in longitudinal sloping tunnels is mainly influenced by the longitudinal location of the fire source and the longitudinal slope and is relatively insensitive to the HRR. The nearer the fire source location is to the low entrance and the greater the slope, the higher the neutral plane position at the high entrance of the tunnel will be. In addition, the induced flow between the fire source and the low entrance of the tunnel was compared for all conditions. Results indicated that the induced flow velocity was positively correlated with the longitudinal slope of the tunnel and the HRR, and negatively correlated with the distance between the fire source and the low entrance of the tunnel. Eventually, a non-dimensional model was established to estimate the velocity of the induced flow between the low entrance of the tunnel and the fire source. These conclusions have implications for the field of tunnel fire safety engineering. [ABSTRACT FROM AUTHOR]

Based on a new categorization, significancy and feasibility of vector-acting foundations for offshore challenging substructures are emphasized. A marine challenging status is typically related to loading, investigations, subsurface, environment, construction and sustainability requirements. The issue of the interaction of piles and complex subsoil is discussed in this paper. Three scenarios are studied comprising sensitive deposits at the full depth, the most impressive one, compressible deposits at the top layer and soft soil underlain by strong deposits. The role of CPTu records is addressed in recognition of problematic layers, geotechnical design and embedment depth designation. The effect of soil sensitivity on shaft and toe resistance is quantified through static analysis and reduction factors are suggested. Since bearing capacity, settlement and axial load are interactive, the neutral plane concept is applied, unifying the mentioned aspects. Through the neutral plane approach and considering the downdrag force due to the collapse of sensitive soil, primary design criteria incorporating sensitivity are discussed and quantified. Applying ground modification as a supplement for deep foundations is realized through two case studies, leading to enhancement in geotechnical performance. Overall, the mentioned phenomena must be discovered comprehensively in extraordinary conditions, aiming for a safe, reliable, knowledge-based and optimum design. • Introducing novel classification for foundations based on the form and load transfer mechanism. • Presenting influential factors in marine challenging substructures. • Incorporating soil sensitivity for modifying bearing capacity in undrained condition. • Quantifying and discussing the effect of sensitivity on pile performance via neutral plane concept. • Assessment the performance of ground improvement and deep foundations combination. [ABSTRACT FROM AUTHOR]