In the Netherlands, there is a large and widely used railway system that includes numerous railway bridges. This master thesis investigates the problems caused by these railway bridges. Since World War II, continu- ous welded rails have been used extensively throughout the Netherlands. These rails offer several advantages on embankments, such as reduced maintenance due to less vibration, increased passenger comfort, and reduced noise. However, continuous welded rails can cause problems when they run continuously over a bridge, as is the case in the Dutch railway system. Bridges are not continuous structures and have joints between the decks or between the deck and the transition structure. These joints allow the bridge deck to expand and contract due to temperature changes, move due to longitudinal forces from train braking and acceleration, and deflect due to the vertical load of the train, causing rotations at the ends of the bridge decks. This relative displacement between the bridge deck and the continuously welded rails creates addi- tional stresses in the rails. These additional stresses must not exceed the maximum allowable stress of the rail material, as this could cause the rails to buckle or fracture. Fixed points are often used in practice to limit the movement of the bridge deck and keep additional rail stresses within acceptable limits. This investiga- tion, however, focuses on understanding the interaction between the rails and the structure without the use of fixed points. The study assumes a railway bridge in the Netherlands with a ballast bed and uses concrete precast bridge decks.

To gain initial knowledge of the problem and the various railway components and bridges, a literature review was conducted, and two existing railway bridge projects were analysed. It quickly became evident that there are two different bridge types relevant to the study of additional rail stresses: those without embankment influence and those with embankment influence. The study then identified parameters that could influence the magnitude of additional rail stresses to use them as variables in further investigations.

Two longitudinal force models were created in SCIA Engineer: one without embankment influence (Model 1) and one with embankment influence (Model 2). These models are spring models where the stiffness of connections and elements is schematised as springs. The models were validated with hand calculations and used to obtain results for the influence of various parameters such as bridge deck span length, elastomeric bearings, bridge pier length, and foundation stiffness. The results of the two models were compared to understand the influence of the embankment. Additionally, the spring elongations of the non-linear springs between the bridge deck and the rails, representing the ballast bed, were examined to determine if they were in the linear or non-linear part of the spring characteristic to see if the springs slipped enforcing stress redis- tribution. Finally, the models assessed the individual contributions of three load cases (thermal, longitudinal traffic load, and vertical traffic load) to the combined additional rail stress.

The results lead to the following conclusions:
• When a structure is not influenced by the embankment, the magnitude of additional rail stresses depends on the stiffness of the substructure. The stiffness of the weakest component, in this case, the elastomeric bearings, has a significant influence.
• When a structure is influenced by the embankment, the magnitude of additional rail stresses mainly depends on the dominant stiffness of the embankment, with the stiffness of the substructure having little to no influence.
• Structures with embankment influence experience lower additional rail stresses due to the additional stiffness provided by the embankment. Problems with exceeding maximum permissible rail stresses occur mainly in relatively long railway bridge structures without embankment influence.
• The vertical load has the largest contribution to the combined additional rail stresses for both structure types.
• The thermal load has a larger influence on structures with embankment influence because these structures are more constrained by the embankment and thus more vulnerable to thermal deformations.
• Linear summation of individual stress contributions from different load cases generally results in higher or equal stresses compared to non-linear combinations, making linear summation a conservative approach. The stress difference between linear summation and non-linear combination is usually only a few megapascals. If the springs between the bridge deck and the rails slip into the non-linear branch, this difference increases slightly but remains small.


Based on these conclusions, the following recommendations can be made to prevent additional rail stresses from exceeding maximum permissible stresses without the use of fixed points and to streamline the process of longitudinal force analysis for engineers:
• To prevent exceeding the maximum permissible stress in structures without embankment influence, consider using larger elastomeric bearings or less slender bridge decks that are less susceptible to deflection, thereby reducing additional rail stress, especially from vertical loads.
• Since linear summation of individual contributions to additional rail stresses results in conservative and faster calculations, it is recommended to use linear calculations in the initial phase. Then, perform a final design review with non-linear calculations to ensure accuracy. This approach will significantly speed up the design process, as models will not need to run for hours or days each time.
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Efficient recycling and the realisation of a circular economy are essential to meet the growing global demand for metals. This thesis investigates the design and evaluation of a singulation system specifically for brass scraps, addressing challenges in their irregular shapes, sizes, and flow behaviours. Singulation, the process of separating particles, is a critical preparation step for automated AI-driven sorting systems to achieve high-definition recycling of alloys. Experiments revealed key factors affecting particle behaviour, including the impact of shape, size, and flow conditions. A detailed analysis of brass particle properties resulted in a proposed system. With both prototype tests and simulation experiments, the realised system for single file singulation achieved effective particle separation, by focusing on mitigating undesired behaviour like rolling and lateral movement. The findings support potential future developments in smart sorting systems for brass scraps and other materials which need automated sorting. ... Read more

Across the Netherlands close to 70 prestressed concrete T-beam bridges with cast-in-between slabs and transverse prestressing built in the 60's and are still in service. The current code NEN-EN 1992-1-1+C2:2011 assesses the shear capacity more conservatively. In addition, the NEN-EN 1991-2+C1:2015 prescribes an increased traffic load. This results in this type of bridge not complying with the current codes and the shear capacities are considered insufficient. However, upon inspection these bridges do not show signs of distress. This suggests the presence of additional load-carrying capacity, which is not considered in the current Eurocode.

Non-linear finite element analysis (NLFEA) can be used to accurately approximate the structural behaviour. This includes yielding of steel, cracking and crushing of concrete, the development of alternative load paths as well as snap-back and snap-through behaviour. However, performing each load step requires a great amount of computational effort depending on the amount of degrees of freedom of the model. In FEA a continuous shape is divided into discrete elements which together form a mesh. These meshes can be volumes, surfaces or lines.

To describe the geometry of the prestressed concrete T-beam bridges with cast-in-between slabs either volume elements or multiple surface meshes in different planes are required. Using a mesh of solids would result in system with such a high number of degrees of freedom which might even exceed the available computational capabilities or result in a very long duration of the analysis at best. Using shell elements to construct the mesh reduces the number of degrees of freedom by at least two thirds.

In this thesis I investigate to which extent we can simulate the structural behaviour of a prestressed T-beam slab bridge deck using a non-linear finite element model with a 3D non-planar mesh of shell elements. The Vechtbrug bridge near Muiden was a bridge of this type. A team of researchers from TU Delft have performed several collapse tests on this bridge. This includes extensive measurements of all the experiments as well as material testing on concrete and steel samples. For my own research, a single case study is conducted by recreating collapse tests performed on the Vechtbrug in which both isolated beams and unmodified spans have been loaded past failure. The results of the material tests provide accurate material properties as input for my numerical models. The results of the collapse tests allow for verification and validation of the outcome of the performed finite element analyses.\\

The results of the numerical analyses show a close approximation of the true collapse load with an overestimation of 15\% for the isolated beam model and 12\% for the cooperative beams model. The deflection again is overestimated with 18 and 56\%. The deflection of the adjacent beams relative to the loaded beam is too low. The numerical model is underestimating the transverse load distribution by $\pm$ 25\% for the adjacent beams and $\pm$ 34\% for the beams adjacent to those. The Guyon Massonnet method was applied to estimate the transverse load distribution with the supplied material properties and including the two cross beams. By contrast, the results were an overestimation of approximately 70% for the immediate adjacent beams. In the third numerical analysis the complete bridge deck and ultimate limit state verification is performed by applying the prescribed traffic load with all safety factors applied. The bridge can withstand 234\% of the prescribed load which agrees with the lack of damage present on the Vechtbrug after experiencing over 50 years of traffic load.

The results show that a non-planar shell mesh can generate a realistic structural response considering the collapse load approximates the actual one found in the collapse tests. However, this is somewhat limited for decks consisting of multiple beams since the implementation of the transverse load distribution in the numerical model was inaccurate. The structural response of the structure was too ductile in the numerical analysis with the deflection being overestimated and the strain under the loading plate double the value of the collapse test. Both Mustafa and Ensink have performed a numerical analysis of the isolated beam model using a mesh of solid elements prior to my thesis work. The results of the isolated beam model match closely in both the results of the NLFEA performed by Mustafa and Ensink. The solid mesh does yield more realistic cracking patterns. The isolated beam model showed the required evidence to demonstrate the activation of arching action: An increase in the horizontal reaction force required to lateral restrain the beam with the bending crack occurring under the loading plate so the arch action phenomenon could be activated. In the complete deck model evidence of compressive membrane action in the transverse direction was detected. In both the complete deck models, evidence of lateral confinement was demonstrated, increasing the maximum compressive stress of the concrete.

Finally we can conclude that a NLFEA with a 3D non-planar mesh of shell elements yields accurate results when considering a single strip of the bridge deck. However, the model with a the mesh representing the complete bridge deck, the capacity of the transverse load distribution is underestimated and the structure shows overly ductile behaviour. The model is capable of including the load-carrying mechanisms arch-action, compressive membrane action and fixed boundary action as well as the effect of lateral confinement. ... Read more

The offshore monopile decommissioning demand will become definite in the coming years. Our responsibility is to ensure the rights and duties of other legitimate uses by completely removing the ageing monopile from the seabed to continuously redeveloping offshore wind farms within the same location. The growing number of past, present, and future monopile installations opens up the challenges and opportunities to be responsible and lead the decommissioning market. With the goal of complete removal, a novel GDP technique can be the win-win solution for offshore wind operators and contractors to extract the monopiles completely from the seabed using torsional and axial vibration
This thesis seeks to understand the torque and normal force to safely clamp a monopile during a torsional vibration so that the monopile continuously slips over the soil. Gradual soil failure along the pile-soil interface's full depth due to the monopile's torsional motion is a possible theory to explain the failure mechanism. When an upper part of the pile successfully moves relative to the soil, kinetic friction occurs until the soil resistance is larger than the shearing at one point. If more shearing is added by adding more torque, more layers below will be broken while the upper part keeps sliding due to lower friction than static friction. While the linear elastic theory of solid and thin shell bodies is used within a 3D FE modelling in Ansys to couple the soil and pile, the clamping force due to the GDP shaker is decoupled from the analysis. Failure criterion is defined outside the simulation so that the gradual soil failure is done through several simulations assuming discrete soil layers.
The FE model is constructed and verified by analytical calculation through the semi-infinite cavity-pile-soil, wave reflection, and finite cavity-pile-soil-spring-dashpot problems. Several cases of gradual soil failure are simulated and show that the torque amplitudes form a distribution. Firstly, a probabilistic sense is proposed to interpret the torque amplitude and search for the optimum depth of the soil failure. Secondly, a convergence check is made with the help of an analytical shell-spring by considering more soil elements by virtue of good correlation of the shear stress between the analytical and FE model. It eventually suggests that a convergence of the torque amplitude can be achieved, which reinforces the theory of gradual soil failure. The interpretation suggests that the current GDP shaker is one step closer for a monopile extraction test with typical monopile dimensions that correspond to a typical 1 m diameter. A first approximation of the required torque and clamping force is then proposed to benefit the analytical model for larger diameters up to 6 m. ... Read more

Asphalt concrete is the most used material in road construction. Analysing the behaviour and properties of this material is vital for modern day society. Currently, this is mostly done in labs using actual asphalt mixtures. However, this is a very expensive and time consuming process. An upcoming alternative approach is the use of computational models. The finite (FEM) and discrete element methods (DEM) have been used in the past, but both of these have shown significant disadvantages regarding the modelling of discrete particle movement and shape, respectively. An upcoming alternative is the use of physics engines, such as Bullet Physics, to model porous media. This method can have substantial benefits in terms of costs and research time. Also, phenomena can be visualised that cannot easily be observed in experiments.

This research focusses on the utility of Bullet Physics for modelling hot asphalt compaction. Therefore, a complex contact model is implemented which can describe the contact forces of the bituminous mixture. The superpave gyratory compaction process is digitally modelled. The model has been programmed in PyBullet, an open source physics engine, programmable in Python. A parametric study has been performed, which reveals the significance of certain properties, which cannot easily be investigated during laboratory compaction.

Bullet Physics was not initially designed for scientific research in the field of structural engineering. Therefore, alterations are needed to make the software usable. The implementation of a complex contact model is challenging. Although the Burgers’ contact forces can be correctly described, it proves difficult to implement custom contact forces directly in PyBullet. Two attempts have been made. In the case of a custom integration scheme, the computation time proved too long to be applicable for large scale simulations. In case of a direct implementation in Bullet Physics with the application of external forces, instability occurs. The only correct way to implement a custom contact model is by altering the source code.

During the simulations with a simpler contact model, substantial improvements of digital simulations over actual experiments are presented. The consistency proves far better than the prescribed minimum. The influence of inertia and friction can be assessed. It turns out that inertia, as well as the friction of the mould, can be disregarded. Another phenomenon that can be clearly illustrated is the revolving of aggregates inside the mould. Further analysis has shown that the average contact area depends on degradation, but in a typical asphalt mixture does not depend on the size of the individual elements, and could rather be treated as a constant. Further analysis shows that Bullet Physics is incredibly efficient, thus yielding the possibility of performing large scale simulations within reasonable time. ... Read more

This research project aims to implement an elasto-plastic Neo-Hookean Alpha material with a Desai flow surface with hardening and softening in Abaqus via the Continuum Mechanics framework. This is done by first defining the elasto-plastic potato diagram and deriving the corresponding stress tensor definition and dissipation inequality. The elastic deformation gradient is needed in the definition of the stress tensor, which is found by using the Newton-Raphson procedure for the maximization of the dissipation inequality subjected to the plastic flow surface. The Neo-Hookean Alpha elastic material, the Desai plastic flow surface and the definition of the hardening and softening curve are given and are substituted in the stress tensor definition and the corresponding Newton-Raphson procedure, which finishes the derivation of the theory needed to implement this model. This model is implemented in both Abaqus and Python, where the latter is used for rapid prototyping of the model. The methodology of verifying both implementations is presented. The results of the verification of the implementations are given and show that the behaviour of both implementations is as expected and that both implementations correspond to each other; although there are a few small issues. In the end, these issues are discussed, and future recommendations are given to solve them. ... Read more

A new approach to applying the finite difference method for solving the shell model problem. By solving the general shell differential equations (Sanders-Koiter equations) with first-order finite-difference approximation only, a finite difference algorithm called shell code has been developed.

To this end, a 1200-line Python program has been built. In the process many versions of shell code were considered, including
1) Two programming languages (Python and R)
2) Three interpolations for approximating gradients (three-point and five-point with two end slopes)
3) Determined and over-determined systems of equations (square and rectangular matrices)
4) Four solvers for the systems of equations

The final version of shell code has the following features; five-point interpolation with zero end slope, rectangular matrix, solver lm.fit.sparse (R). Approximately 80% of the shell code results match the finite element results with a deviation less than 5%. It has been proved that the selected version of shell code can solve shell model problems by solving Sanders-Koiter equations with finite difference method. Many previously assumed important factor for affecting shell code results, like number of nodes and interpolation methods, were actually less significant. However, the most vital difference in results occurred under different computation methods. Maybe under further research of developing mathematic tools, finite difference method could be a more promising and practical method for solving model problems.
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The earthquake-induced liquefaction is a high-risk phenomenon for dredging industries, which need to set strict requirements in order to avoid potential disastrous effects for the project. Different types of liquefaction exist which can be triggered over a wide range of soil types and for different loading conditions. The liquefaction triggering due to an earthquake event is dependent on the soil behaviour under undrained cyclic loading. The assessment of the liquefaction hazard during an earthquake is mainly based so far on empirical procedures. The most common used in practise is the NCEER method (Youd & Idriss, 2001) which is established according to empirical evaluation of field observations and in-situ testing. However, the NCEER method can be inaccurate for the design primarily due to its empirical nature as it is capturing different soil types and loading conditions. For that purpose, advanced constitutive models can provide more precise assessments as they can be calibrated for specific site conditions. Such a model is the PM4Sand, which is very attractive for practical applications because there are only a few model parameters to be determined in the calibration process.The first part of the current thesis project includes the validation of the PM4Sand model for both earthquake-induced and static liquefaction according to undrained Cyclic Direct Simple Shear (CDSS) tests and undrained Direct Simple Shear (DSS) respectively, performed on Ottawa F-65 Sand. The influence of the model parameters is examined throughout a parametric assessment analysis. It was observed, that the model approximates well the general features of both cyclic and static loading. Regarding cyclic loading, it produced similar responses in terms of excess pore pressures generation and stress paths even though it slightly overpredicts the cyclic resistance for small number of loading cycles and underpredicts the cyclic resistance for large number of loading cycles. Regarding static liquefaction, even if the model had initially overestimated the response, it was able to simulate successfully the static liquefaction behaviour after a recalibration process was established.The next part of the project includes the performance of the PM4Sand model for the prediction of earthquake-induced liquefaction in hydraulic fills, which are analysed for several different seismic motions. The fill is placed over a different range of relative densities and it is modelled in Plaxis software as a 1-D soil column. The fill layers that are prone to liquefy, are modelled with the PM4Sand model while the layers that are not susceptible to liquefaction are modelled with Hardening Soil Small (HSS) model. The PM4Sand layer is calibrated according to factors that are accounting for the in-situ state of the fill and the magnitude of the earthquake motions. The dynamic analyses are performed with and without consolidation and the lateral boundaries used are tied degrees of freedom. The results in terms of excess pore pressures generation are examined throughout the whole earthquake motion. Moreover, the onset of liquefaction in the hydraulic fill is captured when the excess pore pressure ratio has reached a value of around 1.0 (ru≈1). It is shown, that the PM4Sand model is indeed applicable for the prediction of earthquake-induced and static liquefaction in hydraulic fills. The effect of the in-situ state of the fill, in particular the relative density, has a critical role on the liquefaction susceptibility, which is a lot representative to what has been observed in reality. According to PM4Sand model, the loosely-packed fills DR=30% and DR=40%) are indeed more susceptible to liquefaction compared to the densely-packed fills (DR=50% and DR=60%) which showed less or even no liquefaction potential due to the earthquake events. On the other hand, the largest drawback of the NCEER method it its empirical nature, as for the current project it is proved to be conservative for the design. More specifically, it predicted liquefaction for almost all the hydraulic fills (DR=30% to DR=60%) analyzed for all different earthquake motions. Regarding the dynamic analyses with consolidation, the results related to the earthquake-induced liquefaction of the fills are more representative to realistic conditions as there is a better distribution of excess pore pressures along the soil column with respect to the dynamic analyses without consolidation. For the latter type of analysis, in the loosely-packed fills (DR=30% and DR=40%) there is a better diffusion of excess pore pressures more for the signals of low dominant frequencies regardless the peak ground acceleration values of the input signal. In the densely-packed fills (DR=50% and DR=60%) the same phenomenon takes pace more for the signals of high dominant frequencies. However, a localization of liquefied zones is observed in distinct parts along the fill layer for the rest of the signals. ... Read more

Road damage detection is important for road safety and road maintenance planning. Road surface anomalies, like potholes, cracks and ravelling, affect driving conditions, such as driving comfort and safety, noise emission, load loss of trucks, increase of fuel consumption and traffic circulation. Locali- sation of these anomalies allows for targeted road maintenance, which contributes to the improvement of driver safety, comfort and the optimisation of road maintenance.
The current technique to detect road damage is that road inspectors determine road damage in road images. However, the results are susceptible to human subjectivity. An improvement on image based road damage detection is using LiDAR data, because the geometry of road damage is measured too. To mitigate the issue of human subjectivity, an automated method for road damage detection was developed for the profile laser scanner on the IV-Infra car. This laser scanner is mounted at the back of the vehicle so that its profile lines are perpendicular to the driving direction. The proposed method consists of: (I) feature extraction with a sliding window algorithm; (II) K-means clustering to create training data; (III) Random Forest classification and (IV) morphological operations to remove noise and identify larger damage patches. This method was tested on an 800-meter long provincial road with different road defects and road types. Most occurring road damages are cracks, craquel and raveling. The results of this method were validated in two ways: using a road inspectors damage classification and a custom-made validation set based on orthophotos. An overall accuracy of 73% is achieved for the fully automated process. When training of the Random Forest was based on an improved, semi-automated training data, the overall accuracy was 58%, this gives visual clear results. This is explained by more noise are presented in the results based on the fully automatic method, which is overlapped with the coarse road inspector’s data. Optical inspection shows that the semi-automated method identified almost all damages of the custom-made validation set, although a shift between the point cloud and the validation is found. Still, the method has some difficulties with detecting the transverse cracks. This problem can be solved by integrating the two other mounted laser scanners of the Iv-Car, but pre-processing is needed to organise the point cloud. Also, an improvement in georeferencing the validation data would help to optimise the method and training data. Nevertheless, promising results are achieved by this method. ... Read more

Fascicle shear is theoretically a mechanism by which skeletal muscles lengthen. Existing ultrasound based techniques allow measurement of muscle architecture parameters, but not the quantification of shear strain. In this study, an algorithm that tracks the shear strain from ultrasound images using a continuum representation of the muscle was developed. Errors in strain tracking may arise due to misalignment of the imaging plane, movement artifacts and non-uniform strain within the muscle. The goal of this study was to develop and validate the newly developed strain tracking algorithm. Various potential sources of error are investigated. A computer model was created consisting of a three-dimensional (3D) synthetic volume, representing the muscle. Virtual ultrasound images were then sampled from the 3D volume by intersecting the synthetic volume under a known angle of the imaging plane. The measurement error was defined as the difference between the known strain that was imposed virtually to the 3D muscle volume and the strain calculated with the tracking algorithm. The measurement error was determined for conditions of combined axial and shear strain, plane misalignment, plane rotation and non-uniform strain. Conditions were simulated between 30 and 100 times, each time with a different synthetic muscle volume.
The developed strain tracking algorithm provided strain measurement of sub-pixel accuracy and precision when the imaging plane was aligned with the fascicles. Rotation of the ultrasound transducer relative to the muscle resulted in invalid measurements. Axial strain was overestimated when the muscle exhibited a non-uniform axial strain pattern. Largest errors (underestimation of strain by up to 65%) were caused by misalignment of the imaging plane with the fascicles. The large effect of misalignment emphasizes the need for careful transducer placement that requires anatomical information about the muscle structure. Strain tracking methods based on three-dimensional avoid the need for alignment, potentially allowing more accurate measurement of strain. ... Read more

The growing need to understand the behaviour of un-reinforced masonry URM), subjected to
repeated light man-made earthquakes caused by the extraction of gas in the north-eastern part
of The Netherlands has resulted in intense research to determine the exact process of crack
initiation and propagation. The historical masonry buildings and Dutch terraced houses in
Groningen are prone to light damages which become severe upon repeated lateral earthquake
loading. Although there are material models that describe the behavior of modern brick
masonry, they do not accurately represent the mechanical properties of 19th century clay brick
masonry. This led to a large-scale research into the mechanical behavior of un-reinforced
masonry and an orthotropic continuum macro-model called the Engineering Masonry Model
(EMM) was proposed. The existing tension constitutive model in EMM assumes a secant
unloading-reloading branch which does not consider the strength degradation of URM under
repeated loading. Since tension mode-I fracture results in cracking of URM, it is important
to study the effects of repeated loading on the propagation of the crack and its effects on the
capacity of the structure.
This thesis presents a degradation model to represent the strength deterioration of URM
observed during repeated loading. The constitutive model formulated in this thesis is based on
hyperbolic functions along with a secant slope for the unloading-reloading branch. To justify
the model assumptions, a single linear 4-node element is analysed with the new model and the
effect of varying different components of the constitutive equations is established. The window
bank spandrel sample modeled as a 4-point bending test is analysed using the new model for 10,
30 and 100 repetitions. It is shown that the hyperbolic model can predict accurately the stress
reduction within each repetition displacement set and also represent the crack width widening
and crack propagation accurately when compared to the experimental results. The new model
is tested on a wall with a window opening sample and the results closely matched that of the
experiment. Finally, recommendations are provided for further development of the hyperbolic
model and calibration of the material properties. ... Read more

Throughout the history of pavement structure, the parallel layer structure has dominated the structural design of pavements. In other words, the entire road pavement share a uniform thickness design regardless how many lanes there are. However, due to traffic regulations and driving habits, the traffic flow most probably does not distribute evenly on a multi-lane road. Modern pavement design methods usually choose the lane that bears the heaviest traffic load as the design lane to determine the thickness design of the entire pavement. Hence there could be a certain over-design in the less trafficked lanes. This study aims to propose and evaluate a new structural design for flexible pavement by reducing the thickness of asphalt layers of the lightly trafficked lanes.
The traffic data of a real motorway in the Netherlands was analysed, based on which a new pavement structural design of a 3-lane road was established. Two finite element models, for both original and new designs, were established in CAPA-3D to calculate the stress and strain responses under different traffic load combinations. Following the Dutch design method the fatigue and deformation performance predictions of the two pavement designs were executed and compared. The results showed that the new design indeed improve the material cost-efficiency without compromising the performance of the pavement structure.
Taking advantage of the finite element models, a real-life simulation was also applied. The strain output of the simulation was used to calculate the rutting depth following the American design method. Both calculated rutting depth and the deformation output of the real-time simulation supported the earlier conclusions. An extra simulation of truck platooning was briefly executed and discussed as well.
Furthermore, the construction and maintenance feasibilities of the new design were explored. It was proved that the new design can be constructed by the existing equipment and machines. The current maintenance methods and procedures can also be applied to the new design. ... Read more

The search for a transparent, reversible, and reusable consolidation system for monuments led to the ambition to test possible cast glass interlocking brick designs using numerical calculations. The focus of this research is hence the design, simulation and evaluation of a possible cast glass interlocking geometry using Finite Element Analysis (FEA). For this purpose, design criteria are formulated from literature; considering glass, polyurethane (used as interlayer) and interlocking systems. As interlocking systems are determined by their boundary conditions, a case study of a monument is chosen to provide additional design criteria. The goal of the case study is to provide a reversible and reusable restoration and consolidation alternative for the current invalid restorations.
The design criteria obtained then are combined into an initial geometry, whose parameters are varied to test their sensitivity to its shear capacity, using FEA. Christensen’s failure criterion is used to locate prone areas in the geometry, and to evaluate the theoretical moment of failure. This output value combines the three principal stresses into a failure envelope, hence can generate contour plots to envision peak-stress-prone areas. This is important especially for glass structures, as they are prone to peak tensile stresses.
From the results design diagrams are created and applied on a conceptual cast glass interlocking consolidation design for the monument chosen as case study: The Lichtenberg Castle ruin.
The initial design is moreover prototyped to check its interlocking capabilities, residual stresses and deviations introduced by shrinkage.

Being able to evaluate possible geometries using FEA can decrease costs and time when searching for a new interlocking geometry. Prone areas are easily highlighted using the Christensen’s failure criterion output. Hence peak stress sensitive or invalid geometries can be discarded before reaching the prototyping stage, which is time consuming and costly.
The creation of a methodology to predict this behaviour is hence valuable for further research on other cast glass geometries and can moreover be applied in any other field when analysing solid complex geometries.
Another goal is to find a cast glass brick design which not only can consolidate the monument of the case study, but is moreover applicable in other projects or configurations. The brick then is not a one-solution design, but can be reused in other projects.

The geometry hence is varied using Grasshopper plug-in for Rhinoceros. By exporting the geometry using a STEP-file, a solid can be loaded into DIANA FEA, where it can be analysed using their newly implemented output value of the Christensen’s failure criterion.
The geometry of the monument is gained through a 3D laser scan, resulting in a point cloud. The point cloud is adapted using Autodesk Recap, then further processed in Rhinoceros.

The Christensen’s failure criterion output is a proper and fast way to evaluate possible cast glass brick designs. Any compressive stresses on the interlocking brick geometry are beneficial for its shear capacity, as is an increase in interlocking amplitude or brick height. Increasing the amplitude however affects the allowable tolerance negatively, which is also the case for a decrease in brick height. Decreasing the brick height hence results in both negative effects.
The conceptual design for consolidation of the Lichtenberg Castle tower can replace the current interventions with equal or higher capacity, even for all conservative assumptions and simplifications. The design can still be altered less conservative after more experimental results and simulations come available.

The methodology applied can now be further developed and performed on other complex geometry designs. The presented multifunctional cast glass interlocking brick design, and its variations can be further investigated and applied in other projects. ... Read more