For the first time since the 1970s, concrete plans are in motion to bring humans back to the Moon through the Artemis programme. The dawning era of space exploration aims to set the groundwork for long-term off-Earth settlement, with sights on bringing the first humans to Mars. In order to provide a safe means of inhabiting extraterrestrial (ET) environments, a self-supporting habitat shield concept has been developed by the Specialist Modelling Group at Foster + Partners, which is based on the use of mechanically interlocking masonry manufactured from in-situ resources. Significant progress must still be made in the structural design and validation of such systems, however, before they can be safely implemented. Due to the novelty of the proposed structure, existing research does not provide numerical evidence of its stability under self-weight, or under seismic loading. Research in this direction is valuable, as it explores alternatives to popular design concepts based on monolithic additive manufacturing and addresses research gaps related to the analysis of mechanically interlocking structures.

The aim of this project is to provide novel insight into the stability of self-supporting dry-stone vaults under the influence of microgravity and ground motions. This is achieved through a three-part analysis approach, which starts with an investigation into the fundamental structural behaviour of dry-stone, Nubian-type vaults based on a series of parametric studies. Key geometric parameters of the vaults are varied, and the resulting distinct element models are subjected to quasi-static pushover-type analysis in 3DEC. The parametric studies indicate what configuration of the vault geometry can maximise seismic capacity. This optimal vault geometry is modelled in Rhino using geometric constraint solving, which is used to produce a model which can be assembled from mechanically interlocking components. Through pushover-type testing and dynamic time history analysis, the performance of the resulting vault model is assessed with respect to possible moonquake loading. The final part of the design process accounts for uncertainties in material properties by conducting sensitivity studies, which indicate what degree of variation in performance is possible.

After completing the three mains sets of analysis needed to design a moonquake-resistant vault, several comparative analyses are carried out to provide context to the structural performance of the Nubian-type vault. The first of these additional investigations models an equivalent monolithic vault geometry in DIANA and conducts finite element analysis to determine its capacity for lateral acceleration. The second comparative study determines how covering the vault in loose regolith may influence its structural performance. The third study investigates how the variation of gravity affects the stability and seismic performance of the vault.

Several key findings are obtained in this project, leading to an understanding of the structural behaviour of Nubian-type vaults and how they may be a possible solution to shielding demands in ET contexts. The final vault model was shown to remain stable under a uniform lateral acceleration equivalent to the PGA for a possible moonquake with a 475 year return period. Dynamic analysis conducted using an artificial ground motion record obtained for the same return period produced less favourable results, resulting in partial collapse of the outermost six courses of the vault. Computational constraints necessitated the implementation of an undamped analysis, however, so these results are considered to be conservative. Further analysis is needed, but these results suggest that with minor adjustments, the vault may be able to safely resist moonquake loading. The comparative monolithic vault analysis demonstrates that an additively manufactured vault may provide slightly better resistance to static lateral acceleration than a component-based vault. When considering the structural redundancy and energy dissipation necessary for safe seismic design, however, the discrete vault is expected to perform better. Results show that covering the vault in loose regolith is expected to reduce its overall stiffness. Conclusions about changes in stability cannot be made with confidence due to modelling issues at the interface between the regolith and the structure. By studying the influence of gravitational variation on the vault, results indicate that it may perform favourably on the Earth or on Mars, though the possibility of material damage must be studied further.

Satellite radar interferometry (InSAR) is a powerful technique for monitoring deformation phenomena. While deformation phenomena occur in a three-dimensional (3D) world, one of the limitations of the InSAR phase observations is that they are only sensitive to the projection of the 3D displacement vector onto the radar line-of-sight (LoS) direction. To uniquely estimate the three displacement components, we would require at least three sets of spatiotemporally coinciding independent (STCI) LoS observations, (i.e., scatterers on an object that is not subject to internal deformations, observed at the same time) available over the same Region of Uniform Motion (RUM). More importantly, the system of equations needs to have a full rank coefficient matrix. Unfortunately, in most practical situations at most two sets of STCI LoS observations are available, resulting in an underdetermined system with an infinite amount of possible solutions.

Within the InSAR literature we encounter different approaches to address the underdeterminancy problem, unfortunately often with either mathematical or semantic flaws. We concluded that the InSAR community has no uniform way of addressing the underdeterminancy problem. We developed a taxonomy for the different fallacious approaches that can help by evaluating InSAR results and reviewing InSAR papers.

Moreover, using the east-north-up (ENU) reference frame for decomposing the LoS observations provides results that are not tuned to the needs of the end-user of an InSAR product. Therefore, we developed an alternative solution to the underdetermined problem, in the form of a `strap-down' approach, which uses a local strap-down reference system that is fixed to the deformation phenomenon with transversal, longitudinal, and normal (TLN) components. For many practical cases, such as line-infrastructure, landslides, or subsidence bowls, analysis of the main driving forces supports the assumption that significant deformations in the longitudinal direction are unlikely.

We found that using the strap-down approach gives physically more relevant estimates. Moreover, it results in more relevant estimates since it properly includes all uncertainties. We can further conclude that the conventional way of communicating (PS)-InSAR results by means of a `dot distribution map' is sub-optimal when considering the quality of the estimates. For many cases, `vector arrow maps', or traditional geodetic vector-based visualizations, including error ellipses are a viable and more optimal alternative.

The gas production in the Groningen gas field of the Netherlands has caused a significant amount of shallowhuman induced earthquakes. Among various building typologies, Groningen is home to many Dutch historical churches constructed by unreinforced masonry which has shown to be highly vulnerable to these earthquakes. From the perspective of conservation and prevention of loss of our historical and cultural heritage, the structural assessment of these churches and their monitoring is of importance. The assessment of the seismic performance of historic churches is a challenging task because of their unique design, governed by macro element behaviour and nonlinear material behaviour. An accurate and reliable earthquake resistant assessment with appropriate numerical modelling of the structure and proper assumptions of all the uncertainties is crucial. The structural monitoring cannot be applied to all historical churches. By selecting representative case studies, indepth study regarding both numerical modelling and structural monitoring are possible. This information can then serve engineers and professionals to evaluate similar structures. The research gap lies in accurate modelling of historical churches to achieve reliable and faster results by linear dynamic modelling. The fundamental modes, eigenfrequencies and modal shapes, geometry and material properties, boundary conditions, connections between structural elements and loading variations are studied using 3D models with shell elements of the casestudy. Although, the models described cannot closely represent the real structure. Firstly, a regular thickness has been assigned to masonry walls and piers despite their irregularities. Secondly, the material properties have been estimated from similar structures in Groningen, and may not represent the actual material characteristics of this case study. Thirdly, the cavity ties has been disregarded because they have been assumed to be corroded (no actual information was available). Finally, the concrete slab at the entrance of the church is disconnected to the foundation, which was an approximation from the drawings but could not be verified. For the casestudy prior structural retrofitting (models 15); Numerical Model 3 with eliminated foundation and timber flooring and a rigid base at the ground level is expected to give the best approximation of dynamic response of the church. The fundamental frequency in X direction of the casestudy prior structural retrofitting can be approximated between 2.30Hz to 2.75Hz and the fundamental frequency in Y direction between 3.0Hz to 3.45Hz. The fundamental global modes in this model show maximum deformation in the timber roof of the mainstructure and tip of the belltower in globalnd Y directions. This indicates weakness of the casestudy prior structural retrofitting. The Old Church has undergone structural retrofitting in July 2018, to prevent further seismic damage on the structure. From the survey of the casestudy and the retrofitting measures, the recent findings (eg., cavity walls, installation of steel frame, steel and timber columns) are incorporated into the finite element model of the casestudy and various modelling variations are presented in models 6 to 10. From comparing the results of these models post structural modifications, Numerical Model8 (or Model9 which has almost similar results) with degraded material properties of masonry and timber diaphragms, a shallow masonry step foundation and a rigid base at the foundation level are predicted as the closest approximation of the dynamic properties of the church. The fundamental frequency of the casestudy post structural retrofitting can be predicted to lie between 1.5Hz2.6Hz in global X direction and between 1.1Hz1.65 Hz in global Y direction. It can be observed that the implemented measures make the church stiffer and the weakness of the structure post structural retrofitting is localised at masonry facade walls of the belltower, cavity wall between the belltower and mainstructure, tip of the belltower, lateral walls and timber roofing of the mainstructure. This research on simulating a numerical model that closely represents the dynamic properties of the Old Church in Garrelsweer for achieving reliable, computationally effective and faster results. This can be used as a basis to compare the results of ambient vibration testing and operational modal analysis, and a relevant guide to study how the numerical models can be defined for modelling similar structures.

The lack of insight regarding the stability of many dolmen in the Netherlands is problematic. In 2019, a capstone fell down dolmen D14, greatly damaging this cultural heritage. In order to decide on whether it would be wise to reconstruct this dolmen, it is useful to understand the stability of potential reconstruction scenarios without having to perform invasive tests that could damage the structure. To this end, this research has focused on the application of non-destructive, digital methods to analyze the stability of dolmen D14. Laser scanners were used to obtain point cloud data from the zone around the dislocated capstone, with which 3D meshes were created. Furthermore, tests were conducted to estimate the relevant parameters to quantify the shear strength of the rock contact areas. This was done in the field using the Equotip and Barton’s comb and by performing tilt tests and Golder shear box tests in the laboratory. For the rock parameters, a basic friction angle of 33° was found with tilt tests and a residual friction angle of 31.2° and 30.5° was found for the Golder shear box on a flat sample. The meshes and rock parameters were used as input to conduct stability analyses in 3DEC. Two different models were analyzed, one based on the rock configuration as it was in 2019 (Model 1) and the second model with a rock configuration as it was in 1925 (Model 2). In the stability analysis, it was found that Model 1 is much more unstable compared to Model 2. The minimum pushing force for instability of the structure was 2 kN for Model 1 and 94 kN for Model 2, for the conditions under research. Furthermore, it was found that the number of cycles used in the analysis, mesh coarseness and rock joint friction angle all have a significant impact on the model results. All in all, this research has demonstrated the potential for using digital and non-destructive methods to analyze the stability of megalithic structures.

This research looks at the workings of three design methods for piles loaded in compression and tension by modelling capacity for different soil profiles, varying parameters and load tests. Compared methods are from the NEN 9997-1 (NEN), CUR 2001-8 report (CUR) and a newly developed international standard (ISO). It is generally accepted that the NEN is overly simplistic and research shows the CUR to be generally over-predicting capacity, but the implications of these flaws are not in detail investigated. Per method, the behaviour of shaft and base resistances/capacities and total axial capacity were modelled for constant cone resistance, real CPT's and applied to case studies. Case studies, where possible, are focused on Dutch soil condition to see how the ISO would apply. The capacities were modelled over the whole domain of the CPT to get insight in general behaviour of the methods and to see where potential weaknesses lie. Also an evaluation on installation effects as residual stresses and pile ageing was done.

The CUR and NEN both have demonstrable flaws that negatively impact their capacity predictions, and most notable are their approach on shaft friction that translates to non-optimal shaft capacity profiles. Also, their response on increasing diameters of concern, as design methods are in enormous disagreement on capacities for piles with diameters larger than 1 m. Predictions compared to each other can vary threefold and differ with 8.5 MN.

The CUR generally over-predicts capacities in looser sands but under-predicts for deeper tests. The NEN generally under-predicts for denser sands but is sometimes largest of three for looser sands. General under-prediction does not necessarily mean the method is conservative. The ISO performs in most cases best, and uses a predictive plug length to influence both shaft and base capacity. The NEN is poorly suited for design, the CUR is in particular unsuited for longer piles or diameters larger than 1 m. The ISO is an improvement on current design guidelines for the Netherlands and a good step in incorporating plugging in the design of open-ended piles.