The offshore wind market is expanding rapidly due to the growing demand for offshore wind energy. This drives the development of larger, more advanced wind turbines and increases the diameter of monopiles. Transporting these massive monopiles presents challenges, particularly in ensuring secure seafastening. Traditional seafastening systems rely on mechanical support to prevent motion, such as saddles for the transverse direction and lashing wires for the longitudinal direction. With the increasing weight of monopiles, these solutions are becoming increasingly impractical, heavy and costly.

During monopile transportation, waves cause the vessel to move and deflect, with the saddles moving accordingly. The monopile, which has separate stiffness properties, experiences different deflections and displacements. Due to these different deflections and displacements, the vertical forces exerted by the monopile on the individual saddles are not distributed equally. In the least favourable conditions, this can result in loss of contact, also called intermittent contact. Longitudinal vessel accelerations generate forces in the monopile’s longitudinal direction, where friction between the monopile and saddles opposes these forces. However, as friction depends on the contact pressure, any reduction of the vertical force, and so the contact force, affects the friction force.

Seafastening arrangements are designed according to DNV-ST-N001 Marine Operations and Marine Warranty standards. Seafastening requirements are based on seafastening design loads calculated for each shipment and cargo item. DNV-ST-N001 set a minimum seafastening capacity based on cargo weight, not considering friction. The latest update (December 2023) allows cargo transport without seafastening if the friction capacity is at least twice the seafastening design loads. Otherwise, seafastening capacity defaults to a weight-based function, creating a gap between the minimum seafastening capacity and calculated seafastening design loads.

Roll Group’s current seafastening designs do not incorporate friction to prevent longitudinal motion, leading to conservative seafastening systems with high equipment- and installation costs. Therefore, there is growing interest within Roll Group in whether accounting for friction between the monopile and the saddles could reduce the required seafastening arrangement, potentially leading to more efficient and cost-effective designs. This knowledge gap leads to the following research question:

”How does friction between a monopile and its saddles affect the seafastening arrangement of a monopile?”

This research aims to determine the friction resistance between the monopile and the saddles when the vessel is exposed to waves, including cases with intermittent contact of the saddles. Based on this information, the seafastening arrangement can be defined when friction is included in the seafastening calculations.

For this research, a coupled fluid-ship model from another research is revised and used to calculate the forces between the saddles and the monopile. This calculation is based on the vertical displacements of the vessel and monopile for all wave heights that can occur during monopile transport. As a result, the loss-of-contact cases were defined. Since this coupled fluid-ship model only focuses on the vertical displacements of the monopile, a longitudinal monopile model is developed. The longitudinal monopile model focuses on the relative horizontal displacement of the monopile caused by heave and pitch motions. This model is a mass-spring system where the monopile represents the mass, behaving as a rigid body to prevent axial vibrations.

An in-depth analysis of the longitudinal monopile model is done for a case excluding friction and a case including friction. The analysis of the longitudinal displacement of the monopile with lashing wires, but without considering friction, resulted in a seafastening arrangement consisting of sixteen lashing wires to prevent all longitudinal motions of the monopile for all wave heights. When friction is considered, the analysis shows that the total friction capacity remains sufficient for all wave heights to prevent the longitudinal motion of the monopile without applying lashing wires.

In this research case, the total friction capacity of the saddles is at least twice the design loads during the whole wave cycle for all wave heights. Based on this, DNV can agree that meeting only the minimum seafastening capacity requirements is acceptable. The last step of executing a friction-based seafastened monopile transport is getting permission from the marine warranty surveyor and the captain.

Offshore wind turbines are complex systems that exhibit intricate interactions among the loads, the environment, and the turbine structure. Therefore, wind turbine design significantly relies on the ability to understand this coupled system and accurately estimate the in-service design loads.

A review of the available literature indicates that most of the current understanding of the structural dynamics of offshore wind turbines stems from research on 5 MW turbines. However, as the wind sector progresses towards taller turbines with larger rotor diameters, the interaction between the rotor and support structure becomes more relevant. In addition, with blades more slender, flexible, and lighter than ever before, the complexity of the turbine dynamics significantly increases. Accentuated geometric nonlinear effects, combined with a more sophisticated blade geometry and anisotropic material behavior, contribute to the challenging structural response of modern blades. Hence, there is a need for further investigation into the influence of modern blades on the turbine response and resulting design loads.

In this context, the present study performs a sensitivity analysis on the IEA 15 MW Reference Wind Turbine to investigate which blade parameters have the greatest influence on fatigue loads during normal turbine operation under turbulence. The sensitivities of different blade parameters are ranked, a reflection on the type of relationship (i.e., either monotonic, quasi-monotonic, or non-monotonic) between each blade parameter and the model response is provided, as well as an indicator of the change caused in the magnitude of the loads. One of the goals of this research is to support blade manufacturers in improving their blade designs by tuning the parameters in new blade models to achieve lower fatigue loads at different positions of the turbine structure. Furthermore, this study aims to highlight parameters that should receive special attention during the manufacturing phase, as slight deviations in their values from the original blade design may considerably increase the fatigue loads.

In this work, aeroelastic simulations are performed with HAWC2, and fatigue loads are quantified using Damage Equivalent Loads, while the first-order Elementary Effects method is employed to assess the parameters’ individual effects on the turbine response. Lastly, two strategies are adopted to ensure that the causes of changes in the dynamic response of the turbine are mainly attributed to variations in blade parameters: turbulence files are generated only once per wind condition and reused in all simulations, and the controller is retuned with HAWCStab2 each time a blade parameter is altered.

The findings reveal a dominant influence of the shear centre on the flapwise moment at the blade root, as well as on the fore-aft moments at the tower-top and tower-bottom across different wind speeds. These moments are critical with respect to fatigue loads since they align with the wind direction and experience a high number of load cycles during turbine operation. This research also unveils that even slight differences in the shear centre position along the chord can have a significant impact on the fatigue loads. For the torsional moment at the blade root - a challenging load component in modern blades due to their increasing length, slenderness, and flexibility - the flapwise bending stiffness, followed by the edgewise bending stiffness, exhibit the highest importance levels at below and near rated wind speeds. In contrast, at above rated wind speeds, the importance of the edgewise swept increases significantly, surpassing the influence of both flapwise and edgewise bending stiffness. Lastly, the torsional stiffness typically plays an important role at near and especially above rated wind speeds in several load components at the tower.

Although the findings may vary based on the size, type, and control of the wind turbine evaluated, the results of this thesis are expected to contribute to the load analysis of other turbines.

Stopping distance is considered to be an important factor for providing a safe roadway network to the road users. Stopping distance is defined as the distance that the vehicle travels before it comes to a complete halt by considering both, the braking distance and the brake reaction/perception distance. With the emergence of Autonomous Vehicles (AVs), new challenges regarding stopping distance are currently posed to the engineering community. Depending on their total computational power, AVs can have a quicker perception as compared to human beings which can be standardized. AVs need a well-defined process to estimate the braking distance as they significantly lack the experience of human drivers. Current AI technology utilized by AVs incorporates a constant coefficient of friction (µ) for estimating braking distance and applies various factors of safety for unfavourable driving conditions. Such practices can overestimate the braking distance or sometimes underestimate it. Either estimates are not good for a smooth travel of the autonomous vehicle. This is because the stopping distance depends on the fundamental friction relationship between tire and pavement. A research study considering input of realistic tire-pavement friction, signified by the variable coefficient of friction into AVs AI toolkits has never been performed. The absence of research with respect to realistic coefficient of friction for AVs can be attributed to the fact that tire-pavement contact is a complex interaction to investigate and model.
The goal of this MSc graduation thesis is to develop a methodology for investigating the variable coefficient of friction between tire-tread rubber blocks and aggregate blocks utilizing a Tribometer. A Finite Element Model (FEM) of the interaction between tire-tread rubber blocks and aggregate blocks is developed to upscale the empirical findings from Tribometer tests to a large range of variables. The data obtained from the scientific methodologies is suggested to be incorporated into intelligent stopping distance algorithms in AVs AI toolkit to improve road safety. Such research involving Tribometer to study the coefficient of friction between tire-tread rubber and aggregates has never being performed. The study also investigated the hysteretic friction in tire-tread rubber which has never been performed previously. Key aspects of the thesis project included studying the effect of varying rubber temperature and frequency on the sliding friction between tire-tread rubber blocks and aggregate blocks. The research studied the varying effect of rubber temperature and frequency on the coefficient of friction for two surface conditions, dry/wet and three types of aggregates: Bestone, Scottish granite, cement concrete. The FEM results offered a preliminary insight on the investigated variable coefficient of friction. The scientific findings from the model and empirical results show a dependence of thermomechanical properties of the rubber material and surface conditions on the coefficient of friction between tire-tread rubber blocks and aggregate blocks. The findings indicate that the coefficient of friction decreases with increase in rubber temperature, interaction frequency and lubrication at the contact.

Bolted steel joints are critical components in steel structures, influencing force transfer, deformation and energy dissipation mechanisms. In traditional analysis of steel structures, beam-column joints are often simplified as either pinned or rigid. While this simplification eases analysis and reduces computational demands, it fails to accurately capture the semi-rigid joint behaviour, underestimating designs, especially in multi-story steel structures where the cumulative effects of joint flexibility and frictional slip can be relevant. The complexity of accurately modelling semi-rigid joints in finite element analysis (FEA) arises from challenges such as geometric and material nonlinearities, frictional contact interactions, and detailed meshing, all of which increase computational demands, necessitating the use of simplified joint behaviour models. This study identifies and attempts to address a persistent gap in efficiently modelling these semi-rigid joints during structural analysis.

The primary goal of this MSc thesis is to investigate the behaviour of semi-rigid joints and propose a relatively cost-efficient approach to incorporating more realistic joint behaviour into structural analysis. To achieve this, the research explores the frictional behaviour and potential relaxation of bolted joints, focussing on the relative sliding of plates in frictional contact. The study specifically examines how these factors influence load transfer, energy dissipation, and overall structural performance. In multi-story constructions, the cumulative effect of small joint relaxations at each story level can lead to increased lateral sway and amplified second-order effects, raising significant concerns about structural integrity.

The research begins with a detailed examination of an individual beam-column joint assembly consisting of top, bottom and web plates welded to the column flange and bolted to the beam flanges and webs. Through numerical simulations in ANSYS, the study analyzed the joint under both monotonic and cyclic loading conditions, focussing on the force transfer mechanisms and relative deformations between various components of the connection. A parametric study, varying friction, bolt pretension, and loading magnitude, was performed to further explore how these parameters influence the stiffness, energy dissipation, and overall behaviour of the joint assembly. Based on the force-displacement response of different components of a beam-column connection, a Component-Based Spring Method (CBSM) is proposed to simplify the modelling of semi-rigid joints in 2-D multi-story frame structures. This method involves creating equivalent spring elements that simulate the load transfer and deformation behaviours observed in various components of a connection. The study then extended the analysis to the global behaviour of a three-story steel frame structure, comparing the performance of rigid and semi-rigid frames. The simplified CBSM approach was validated by applying it to a three-story steel frame structure and comparing the results with those obtained from detailed solid connection modelling.

The investigation into the local behaviour of the beam-column connection identified key components, such as the Top Plate & Top Beam Flange, Web Plate & Beam Web, and Bottom Plate & Bottom Beam Flange, that govern the force transfer and deformation within the joint assembly. The force-displacement curves of each component provided insights into the pre-yield and post-yield behaviour of the connection. The results revealed that the friction coefficient and bolt preload significantly influence the stiffness and energy dissipation capacity of the joints. Higher friction coefficients and bolt pretension enhanced joint stiffness but reduced energy dissipation, indicating a trade-off that must be balanced in design if dynamic vibration is a concern. The Component-Based Spring Method was validated against detailed solid models, achieving accuracy in frame deflection results of 93% to 96% while reducing computational time by 99.5%. The analysis of the global behaviour of joints within the frame structure revealed that semi-rigid frames exhibit significantly higher lateral deflections, up to 40.63% more when compared to rigid frames, highlighting the risks of oversimplified rigid joint models. These findings highlight the importance of accurately modelling the behaviour of semi-rigid joints to ensure realistic structural performance and the safety of steel frame structures.

Unreinforced Masonry, a popular construction material with a rich historical legacy, has been resilient through centuries, despite its susceptibility to failure through various loading conditions such as seismic forces. Understanding the mechanical behaviour of masonry, particularly the cohesion and frictional mechanisms at interfaces between bricks and mortar, is crucial for assessing its structural reliability.
This thesis presents an experimental study characterising masonry frictional interfaces using a tribometer test, a novel approach in masonry research. The study aims to investigate the frictional behaviour of brick-mortar interfaces under varying precompression levels and test frequencies (3 Hz and 0.2 Hz). A novel sampling method was implemented, wherein the required specimens were extracted from a bonded masonry couplet specimen. The couplets were bond wrenched and then subjected to a mechanical extraction. Bond wrenching, through tension, separates the couplets, thereby isolating frictional response from the influence of cohesion by decoupling cohesion between the unit and joint. A tribometer was chosen for the investigation of frictional parameters, tribometers are typically employed with metal surfaces and rarely applied to masonry. Consequently, experiments were conducted using a reciprocating tribometer, featuring a novel specimen extraction procedure and a modified setup. The novel extraction involved mechanically altering a parent brick couplet to extract compatible specimens. Customised holders were procured and used to accommodate the prepared specimen. The obtained specimens were then, fastened into the appropriate sample holders. Tests were performed on the specimen with displacement, tangential force, normal force and time being recorded. Three key parameters, the mean Coefficient of Friction (CoF), the Energy Coefficient of Friction (ECoF), and tangential contact stiffness were analysed from the collected data. The above mentioned parameters were evaluated through two approaches, (i) Mean Curve approach and (ii) Cycle approach. A mean curve is the averaged curve of the measured hysteresis loop, which encompasses the overall behaviour exhibited by the hysteresis loop.
The experimental results revealed a dependency between the coefficient of friction and the applied pre-compression level, showing a non-Coulomb behaviour; this is in contradiction with assumptions of several models used for the analyses of masonry structures. Initially, experiments were conducted at a higher frequency (3 Hz) and followed by experiments at a lower frequency (0.2 Hz), and the results in both cases revealed a non-Coulomb friction behaviour characterised by a nonlinear connecting trend between kinetic and static friction region. The connecting trend between the kinetic and static region demonstrated a reduction in the degree of non-linearityan enhanced symmetry in the hysteresis profile as the precompression levels increased. The mean curve and the cycle approach yielded identical estimates for the coefficients of friction (CoF) and effective coefficients of friction (ECoF).
The evolution of Coefficient of friction (CoF), did not exhibit any clear systematic time dependency, while Energy Coefficient of friction (ECoF) showed a systematic decrease over time. The ECoF related the energy dissipated by friction across each cycle to a hypothetical Coulomb energy dissipation. Therefore the ECoF captures the energy dissipation due to friction during one cycle, while the CoF captured the static friction region. The energy dissipation across different precompression levels were also studied and it was observed that the energy dissipation increased for increasing precompression levels.
Tangential Contact stiffness refers to the tangential force required to effect a unit displacement in the tangential direction. The contact stiffness was calculated from the slope of the region of the hysteresis loop associated with displacement reversal. Contact stiffness was observed to increase with increasing precompression levels. This observation was also validated by the theoretical model which illustrates a proportionality between the applied normal load (precompression) and tangential contact stiffness.
Additionally, the study highlights the impact of frequency on the observed frictional behaviour, noting more prominent static and kinematic components at lower frequencies due to reduced inertial forces. A preliminary study using the LuGre model was used to plot the analytically derived frictional force-velocity relationship, to briefly study the impact of sliding velocity on frictional force. It was deduced that the velocity had an influence over the frictional force at the interface.
In conclusion, the findings provide valuable insights into the frictional characteristics of masonry interfaces under varying loading conditions. The results also shed light on the practical aspects of testing methods and offer considerations for further research in the field of masonry engineering.

In an era marked by the demand for unprecedented levels of precision in engineering applications, the profound impact of friction forces on motion control systems cannot be underestimated. This thesis extensively investigates the frictional behavior of the Proton Motion Stage, an advanced high-precision motion control system developed by Prodrive Technologies. This research conducts both experimental investigations and computational simulations, offering valuable insights into its friction behavior across diverse conditions and scenarios.
The research begins with an analysis of existing models used to describe friction behavior in precision engineering systems. A critical evaluation of empirical models highlighting strengths and limitations is presented, and the LuGre friction model is selected. Subsequently, a simulation work is conducted to identify the viscous coefficients, the stiffness coefficient, the Coulomb friction, the Stribeck friction, and the Stribeck velocity in the LuGre model. The simulation setup is described, including the incorporation of the LuGre friction model and the identification of system parameters. The accuracy of the identification value to the true value is above 99\%. A comparison of the sensitivity of the objective function to the change of parameters is also conducted to enable a comprehensive exploration of friction dynamics. Finally, the research delves into static and dynamic parameter experiments, where cable slab forces' position-dependent impacts and velocity-friction maps that capture the intricate Stribeck effect are presented, and closed-loop and open-loop setups to dissect friction behavior during rapid motion changes are employed. Residual analysis of histogram and 90\% confidence autocorrelation and cross-correlation is also presented to study the quality of identification and shows that the LuGre model does not fully capture the friction phenomena on the Proton Motion Stage. Future research should involve the modification of the LuGre model and data-driven approaches such as machine learning. Overall, this thesis fills the gap in state-of-the-art works by combining theory and practice to enhance the understanding of friction in precision engineering systems.

Friction damping is common in engineering structures for the purpose of energy dissipation and vibration control. Examples of applications are bolted connections and earthquake isolation systems. However, there is a shortage of works that investigate the effects of different contact materials on the energy dissipation performance and friction behaviour of friction dampers, which is valuable knowledge for design optimization.

This thesis uses a numerical approach to explore the time response and energy dissipated by friction of the harmonically excited SDOF (single-degree-of-freedom) system with Coulomb friction contact between the sliding mass and a fixed wall. In addition, for the same SDOF system, an experimental investigation of the friction damping performance in terms of friction behaviour and energy dissipation is carried out for (1) steel, (2) rubber and (3) aramid contact
materials. The aim is to get a better understanding of how different contact materials affect the performance of friction dampers. Various time scales, excitation frequencies and friction forces are considered.

The main findings of this research are: (1) the characterization of the friction behaviour of steel-to-steel, rubber-to-steel and aramid-to-steel contacts; (2) the comparative analysis of the energy dissipation performance of the different contact materials; (3) the assessment of the long-term performance of the different contacts; (4) the comparison between numerical results based on the Coulomb friction model and experimental results. The tests have shown that rubber has the highest energy dissipation capacity and fairly unstable behaviour, steel has the second highest energy dissipation and irregular behaviour and aramid has the lowest energy dissipation performance and very consistent behaviour. Finally, the application of a method that calculates the energy dissipation of friction damping based on direct experimental outputs is an important contribution to the field regarding experimental investigations.

The offshore wind energy industry is quite literally reaching for the sky to meet the increasing demand for renewable energy in Europe. Offshore wind turbines are sprouting out of the waves off the coast of many European nations and their size is increasing rapidly. As the turbines become larger and the waters in which they are placed become deeper, the foundations that carry these behemoths must grow as well. The most frequently used foundation is the monopile foundation. Over the years, both the length and the diameter of these monopiles have steadily increased. Installing monopile foundations has, as a result of this, become more and more difficult.
An important aspect of the installation of monopile foundations that has become more challenging is the upending of the monopile. When the monopiles are transported to the site of installation, they are sea-fastened to the deck in horizontal orientation. When they arrive, they need to be rotated to a vertical orientation for installation. This can be done with the aid of an upend hinge. This thesis focusses on the modelling of such a hinge for operability studies.
The goal of these operability studies is to determine the weather and wave conditions in which the operation can be safely performed. Conventionally, the stiffness of the upend hinge is approximated by several linear springs between the vessel and the monopile. The aim of this thesis is to apply dynamic substructuring to existing Finite Element models of a hinge to more accurately describe its dynamic behaviour within hydrodynamic simulations. Hereafter, the response of the dynamically substructured model can be compared to the response of the conventional model.
The findings of the research show that it is possible to use dynamic substructuring to reduce the Finite Element models of an upend hinge and implement them into hydrodynamic simulations of an upend operation. When comparing the conventional model to the substructured model, it can be seen that there is a significant difference between the high-frequency response of the models. However, the responses of the models to prevailing ocean waves are very similar. For operability studies, this response is most relevant. Furthermore, the required computation time is significantly higher for the simulations employing the dynamically substructured models than for the conventional models. Therefore, it is not recommended to apply dynamic substructuring to model this upend hinge in operability studies. For situations where the high-frequency response is more relevant, however, dynamic substructuring may prove a valuable tool to more accurately describe the dynamic properties of an upend hinge or other marine equipment.

Nautical radar systems are subjected to random vibrations during their service life, which may lead to the degradation of the materials and a possible fatigue failure. Assessing the impact of these vibrations to the structural integrity of the radar is crucial for drafting appropriate maintenance plans and therefore, the development of a new tool is required, which will be capable of evaluating the fatigue lifetime of the radar system.

This thesis examines a 5.7-meter-long radar antenna, supported by a lattice tower with a height of 20 meters, located in Rijkswaterstaat’s test environment in Stellendam. Although the lattice structure and the radar system are coupled, they are treated separately in this study. Firstly, a Finite Element Model of the tower is developed in ANSYS, where the radar is represented by an added mass at the top floor. The aim of the model is to identify the vibrations of the structure under the influence of the incoming wind. The stochastic description of the turbulent wind is taken into account in the evaluation of the wind loads and a random vibration analysis is performed, resulting into the response of the structure in the frequency domain.

Furthermore, a second, simplified Finite Element Model of the radar system is built in ANSYS. Time series of the fluctuating wind velocity are generated and the wind load acting on the radar is approximated by the aerodynamic force in the along-wind direction, considering also the rotation of the radar antenna. In addition, the previously obtained response of the lattice structure serves as input for the radar model, representing the vibrations induced to the radar due to the motion of the structure below. The output of the model is the occurring stress response, which is subsequently used to assess the fatigue damage of the radar antenna.

The results show that the development of stresses at the bottom surface of the antenna mainly occurs at its central area. Given the assumptions used throughout the thesis, the motion of the lattice tower is found to be the governing loading condition for the resulting stresses and the magnitude of the motion significantly influences the fatigue damage of the antenna. Finally, the fatigue lifetime appears to be very sensitive to the construction materials used for the radar system. These results should be verified by future measurements in order to improve the suggested models.

The Circular Arch Bridge is a pedestrian bridge consisting out of four different recycled materials: cast glass, ceramic, circument and geopolymer concrete. Due to an increasing amount of vibration problems in modern pedestrian bridges they should not only be designed for static loads, but dynamic loads have to be considered as well. There are currently no guidelines in the Eurocodes for the dynamic assessment of a bridge like the Circular Arch Bridge. Therefore, this paper provides a research on how the dynamic assessment of the Circular Arch Bridge should be conducted.

The Circular Arch Bridge is considered a dry-stacked masonry arch bridge. A full dynamic assessment is conducted, with the use of finite element software, according to the guidelines for pedestrian bridges. The eigenvalues of the Circular Arch Bridge are not within the critical range for pedestrian induced dynamic loads. It is found that for everyday use the Circular Arch Bridge is within Comfort Class 2 from the Eurocode, thereby providing a medium comfort level. A special load case is added to the analysis representing a group of 60 people dancing on the bridge during experimental testing of the bridge. For this load case the Circular Arch Bridge is within Comfort Class 3 from the Eurocode, thereby providing a minimum level of comfort.

With a sensitivity analysis it is determined that the most sensitive input parameter of the finite element model is the modulus of elasticity of the interlayer. An investigation of the effect of large stiffness differences between the interlayer and the stones on the dynamic properties of the bridge is conducted. It is concluded that the large stiffness differences have a positive effect on the dynamic properties of the bridge. The effect of the dry-stacked assembly of the bridge on the dynamic properties is also investigated. This as a negative effect on the dynamic properties of the bridge.

The development towards a circular economy has many hurdles to overcome. For the construction sector an important step in this process is the transition towards reusing structural elements. Prefabrication of elements is a significant step towards achieving this concept. However, a case where both prefabrication and reuse are limited is the replacement of bridge decks. Headed bolts are welded to the steel supporting elements and encased in grout to connect them to the concrete deck elements. This method prevents reuse of the deck elements and hinders reuse of the steel supporting elements.

Research and literature exists on a number of alternative shear connectors that increase the modularity of these elements. The best alternatives have a single limitation in common: the allowed deviation for the placement of the shear connectors and bolt holes is smaller than is feasibly possible. The variances of element placement during construction add up to make it incredibly hard for these low tolerance connections to be made. The bolt hole diameter can be increased to increase the deviation tolerances. The large nominal hole clearance this results in needs to be considered. This can be done by using either resin injected bolts or High Strength Friction Grip (HSFG) bolted connections. Using HSFG bolted connections is preferred due to the shorter time spent on site and minimal waste, but research on the subject is sparse.

A proposed HSFG bolted connection that implements significantly oversized holes, defined as bolt holes with a nominal hole clearance roughly equal to the bolt diameter, and cover plates was designed together with both a control and regular connection to compare its behaviour with. The control connection is identical to the proposed connection with the exception of its holes which are normal sized. The regular connection has normal holes and does not include cover plates. Finite Element Models (FEM) were made of these connections that were subjected to static loading in a Finite Element Analysis (FEA). Test specimens of these connections were made and subjected to fatigue loading.

The numerical results of the static FEA showed that the use of cover plates reduced the stiffness and slip load of the connection. The second observation was the small impact that the hole size had on the slip load when using cover plates. This small impact becomes negligible at design preload.

The experimental results showed that the impact of larger bolt holes increased the loss of preload by roughly 1% during both short term relaxation and fatigue loading. The effect of the bolt hole size on the slip after fatigue loading was also concluded to be negligible, but the effect of the cover plates was concluded to be detrimental.

It was overall concluded that the use of significantly oversized holes in HSFG bolted connections with cover plates is viable. The negative effects caused by the cover plates and required longer bolt make it preferrable for large disc springs to be used instead of thick cover plates. The viability of the concept allows for further research on the subject.

Pile tip damage due to impact with an object (boulder) during the driving process of monopiles is of main concern in the offshore wind sector. Numerical modelling could accurately describe this failure mechanism and used as a tool in practice but also for the development of appropriate guidelines. In this research project, dynamic Finite Element Analysis is conducted in order to achieve modelling the driving and impact process and properly capture the response of the monopile.

Bridges are exposed to dynamic forces – such as pedestrians crossing a bridge or the wind force acting on a bridge – which cause vibration of the structure. When a structure is forced at one of its eigenfrequencies it deforms into a corresponding shape leading to major deformations, which, in the worst-case scenario, can lead to collapse of the structure, as happened to the Tacoma Narrows bridge in 1940. It is thus very important to know the dynamic characteristics of a structure. For glass structures no specific limit values are defined, this is why it is interesting to investigate the dynamic behaviour of a glass bridge This thesis aims to predict the structural response of TU Delft’s Glass Truss Bridge when subjected to static and dynamic loads. The studied bridge is a footbridge, connecting the TU Delft campus to the Green Village, and is unique in the aspect that glass diagonals have been used in its construction. Through an iterative procedure of modeling, virtual testing and updating the model of the bridge, the dynamic response of the bridge is predicted. The study shows that the response of the bridge is between the European Guidelines’ limits for (steel) footbridges. Maximum acceleration of the bridge is found at 500mm/s and the lowest eigenfrequency is out of range of that of joggers. The sensitivity analysis shows that the parameters having the most influence on the bridge’s response are the diameter of the glass diagonals and the soil density. Using the outcome of the sensitivity analysis a dynamic testing protocol is recommended that outlines the optimal test setup for modal testing of the bridge. Through the simulated dynamic tests ten of the twenty eigenfrequencies of the bridge are found. For each of these frequencies, the damping is approach and modeshapes are reconstructed based on the imaginary plots of the Frequency Response Functions. The latter show a good correlation with the modeshapes obtained from the model.