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The treatment of uncertainty in the long-term planning of infrastructures in general and of mainports such as airports and seaports is a key challenge for decisionmakers. Moreover, these uncertainties have increased over the last decades due to changes in owner structure, changes in rules and regulations, and the ever increasing connectedness of the world. This dissertation explores how the treatment of uncertainties in airport planning can be improved. Currently, the treatment is limited to one or a few forecasts for the future. Such an approach limits the exploration of the multiplicity of futures to those that are judged to be most likely. However, if the last decade has taught is anything, then it is that the future will be substantially different from the one we are anticipating now. The implication of this for decisionmaking is that any plan or policy optimized for one or a few forecasts is likely to perform poorly. An alternative approach that is capable of handling the multiplicity of futures and accepts the limits on predictability is needed. Such an approach should result in a plans consist of time-urgent low regret options that can be taken immediately, while establishing a framework for guiding future actions. Thus the decisionmaker is able to adapt the plan to the way in which the future unfolds. This dissertation presents such a dynamic adaptive planning approach, tailors this approach to the specifics of airport planning, and provides computational evidence for the efficacy of plans that are designed utilizing this approach.

In order to turn a brittle cement matrix into a ductile composite different types of man-made fibres such as steel, glass and polyvinyl alcohol are currently used as reinforcement, as well as some natural fibres. Compared to synthetic fibres, natural fibres are more easily available worldwide and they are friendlier to the environment since less energy is needed to produce them. They are also a renewable resource. In this project natural fibres from wood were chosen as reinforcement for cement-based materials. Three softwood species: larch, spruce and pine were studied. In the matrix, cement was partially replaced with other binders to achieve a low environmental-impact matrix as well as a matrix with a tensile strength compatible with the chosen wood fibre’s strength. The wood fibre-cement matrix interface was studied. This thesis contributes to a better understanding of its properties. A lightweight cement-based composite reinforced with pine fibres was designed to exhibit deflection-hardening behaviour. This material developed multiple cracking prior to failure under bending stress. Due to this improved behaviour it can be considered for applications such as low-budget housing in countries subject to seismic risk, where ductility and low weight are desirable characteristics of the building material.

Concrete is a composite construction material, which is composed primarily of coarse aggregates, sands and cement paste. The fracture processes in concrete are complicated, because of the multiscale and multiphase nature of the material. In the past decades, comprehensive effort has been put to study the cracks evolution in concrete, both experimentally and numerically. Among all the computational models dealing with concrete fracture, the lattice fracture model wins at several aspects, such as being able to capture detailed crack information, high computational efficiency and stability. The lattice fracture model also enables to investigate how the fracture properties of concrete depend on its material structure. This can be achieved by projecting the lattice network on top of the original material structure of concrete. In this thesis a parallel computing code is described, which is implemented for the lattice fracture model, in order to reduce the computational time and to enable the analysis on even larger lattice system. The fracture properties of cement paste, mortar and concrete are highly related in nature. In this thesis the lattice fracture model is coupled with the parameter-passing multiscale modeling scheme to study the relationship of the fracture processes in cement paste, mortar and concrete. A multiscale fracture modeling procedure is proposed and demonstrated. Three levels are defined, including micrometer scale for cement paste, millimeter scale for mortar and centimeter scale for concrete. The lattice fracture model is applied at each scale respectively. The inputs required at a certain scale are obtained by the simulation at a lower scale. At the lowest scale in question, the micrometer scale for cement paste, inputs are determined by laboratory experiments and/or nanoscale modeling from literature. Besides the multiscale lattice fracture model, another highlight in this thesis is the development of the Anm material model, which can simulate a material structure of concrete with realistic shape aggregates. Compared with classic concrete material models, the shape of aggregates is changed from spheres to irregular ones, which is closer to reality. The aggregate particle shape is represented by spherical harmonic expansion, where a set of spherical harmonic coefficients is used to describe the irregular shape. The take-and-place parking method is employed to put multiple particles together within a pre-defined empty container, which can be interpreted as the material structure of concrete. The key element in this parking algorithm is to check whether two particles overlap, as no overlap is allowed in the resulting simulated material structure. The multiscale lattice fracture model and the Anm material model, proposed and established in this thesis, can be used by researchers in concrete community, to study the various factors which influence the mechanical performance of cementitious materials. They can also be adapted with other computational models to form a complete fully multiscale modeling framework, from nanoscale to macroscale.