This research investigated how climate change may affect characteristic values for precipitation, snow, and wind loads on structures in the Netherlands and assessed the implications for structural design. Historical observations from KNMI weather stations were analysed and compared with the current characteristic values prescribed in the Dutch National Annexes. Future changes were assessed using the KNMI'23 Climate Scenarios.

For precipitation, recent Dutch depth-duration-frequency studies indicate that the current 50-year return level for 5-minute precipitation events is already approximately 20% higher than the value prescribed in the Dutch National Annex. The climate projections indicate a further increase in extreme precipitation, resulting in an estimated factor of change of approximately 1.06 for a 50-year return level under 1.1°C global warming relative to the 1991-2020 reference period. Combined, these findings imply that emergency drainage widths may need to increase by approximately 27% compared with current practice.

Historical snow depth observations showed decreasing trends in annual maximum snow depth, while estimated 50-year return levels were generally lower than the current characteristic ground snow load. Although quantitative snow projections are unavailable, multiple climate indicators consistently suggest that conditions favourable for snowfall and persistent snow cover will become less frequent under future climate change.

For wind, estimated 50-year return levels of the 10-minute mean wind velocity were generally comparable to or lower than the values prescribed in the Dutch National Annex. Furthermore, the KNMI'23 Climate Scenarios project only minor changes in extreme wind velocities relative to the associated model uncertainty, indicating no clear need to revise the current characteristic wind loads. ... Read more

The structural state of several cast iron lighthouses in the Netherlands has been deteriorating, as cracks have formed in the cast iron plates of the columns. Current assessment methods of such large cast iron plate structures require a very detailed finite element model, which is time consuming to create and analyse. In this thesis, the use of an orthotropic continuum damage model, the Engineering Masonry Model (EMM) of DIANA FEA in this case, for the structural analysis of cast iron plate structures is explored. The thesis focuses on a specific case: the lighthouse the ‘Lange Jaap’, located in Den Helder, the Netherlands.

First, to obtain the required input parameters for an orthotropic continuum damage model,
detailed models of small plate structures are created. Different loading conditions are applied, and the resulting force-displacement curves are analysed to derive constitutive laws for the structural analysis. Next, a sensitivity study of the size effect of the structure is performed, which resulted in some changes in the failure modes for some of the loading types. This resulted in quite a difference in strength and ultimate strain between the small and large structures. For each load case, a unit structure size should be defined, which should have the same failure modes as those expected to occur in the large structure the study focuses on. After obtaining the input parameters, they are verified and calibrated by using them in equivalent EMM models of the small plate structures.

The final, calibrated input parameters were used in an orthotropic continuum damage model for the cast iron plate structure of lighthouse the Lange Jaap and it was concluded that very similar results were obtained as from a detailed model, when all strains were in the linear-elastic regime. As the obtained values of the bed- and head-joint tensile strengths that were quite low, the tensile stresses exceeded the tensile strength of the material quite quickly in the model of the lighthouse. Once plastic deformations occurred, cracks started to form and the analysis of the model quickly became unstable, so the results were no longer accurate. This shows that, after the calibration of the parameters, the linear-elastic behaviour of the structure is accurately captured in the model, while the plastic behaviour is not.

It is concluded that, by using an orthotropic continuum damage model, the complexity of a structural analysis of a cast iron plate structure is reduced in the following way: reduced total modelling time, reduced complexity of geometry and reduced running time of analysis. The last point is achieved by using regular curved shell elements instead of structural solids, which is the result of the simplification in geometry. Using an orthotropic continuum damage model for similar structures is a very suitable modelling method for studies in which many finite element analyses have to be made for a structure, where small changes are made in every analysis. For the lighthouse structure, a study of the effectiveness of different strengthening solutions for the columns is a very good example. ... Read more

The method of Macaulay makes use of singularity functions to describe the integrations in the Euler-Bernoulli beam equation in a single equation, instead of splitting the structure into parts with equal load situations. In this report, an expansion for this method is derived, which makes it possible to solve structures with multiple stiffnesses and varying stiffness slopes using this method as well. ... Read more

In Huisduinen, a small town next to Den Helder, there is a cast-iron lighthouse called the Lange Jaap. Due to corrosion and improper construction in some places, as well as neglected maintenance, the lighthouse has lost its structural integrity. Many bolts have critical damage and can no longer withstand further tension. There are also several critical cracks in the walls and floors. A solution is therefore needed to reinforce this lighthouse. Recent research shows a promising development in using structural glass to reinforce historical structures. Glass can be used to reinforce the structure, without drastically altering its appearance. This research aims to expand the existing knowledge on reinforcing with glass to an application with iron. This then leads to the best method to reinforce a tall iron structure, like the Lange Jaap, using structural glass.

For this research, the specific case study of the Lange Jaap was examined. Based on the existing proposed solutions for this case study, as well as solutions related to existing research on structural glass, 21 variants were proposed. The ideas range from simple, practical solutions to more experimental concepts, ensuring that a wide range of possibilities was considered.
In the first round, impractical designs were eliminated based on sketches and initial estimates on their effectiveness. A variant was taken to the next round if it could be verified structurally, did not drastically alter the appearance of the lighthouse, and had realistic construction potential. Eleven variants met these criteria and were evaluated further.
The second round included simplified hand calculations and digital renders to assess feasibility and obtain preliminary, conservative dimensions. From these analyses, three variants remained for detailed evaluation. The final round evaluated these three variants and involved more accurate calculations, including load combinations. These were used to estimate required material quantities and assess performance under wind and temperature loads for a variety of cross-sections. Each variant was then rated in a multi-criteria analysis (MCA), based on constructability, effectiveness, and preservation of heritage value.
From this analysis, the 'glass fin variant' was identified as the best-performing solution. The 'glass fin variant' uses vertical glass fins attached externally to the Lange Jaap to reduce deflection caused by wind and temperature. The detailed final design specifies that the fins are formed from prefabricated float-glass panels which are laminated with a PVB-interlayer and glued to steel plates. The steel plates are bolted to the tower at regular intervals. This configuration achieves a 59% reduction in deflection of the tower, and a 41% reduction in stresses inside the floors under wind loading. The total estimated material cost is approximately €2.56 million.
In the Netherlands 12 cast-iron lighthouses were built, of which 10 exist to this day. These lighthouses were evaluated based on their current condition, as well as three tall iron structures in other countries. From this, only two cases were found that had any problems and required a reinforcement solution.

Overall, this research demonstrates that it is possible to reinforce a tall iron structure using structural glass. There are however not many structures in the world where this solution can be applied, as properly maintaining the structures is usually preferred. For the structures where maintenance is not possible, the 'glass fin' solution can be applied, though further research and testing is required before it can actually be implemented.
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This study investigates the seismic performance of the Adıyaman Grand Mosque, a historical masonry mosque in the East Anatolian Fault Zone, with emphasis on its response during the 2023 Kahramanmaraş earthquake sequence. The two main objectives are: (i) to evaluate the mosque’s inherent seismic vulnerability in isolation, and (ii) to assess how the collapse of adjacent buildings may have aggravated damage.
The work combines nonlinear static and dynamic analyses in DIANA within a macro-modelling framework using a Total Strain Fixed Crack model calibrated from literature. Pushover analyses establish direction-dependent capacity, drift limits, and mechanism trends; nonlinear time-history analyses capture transient response under recorded ground motion. Neighbouring building collapse was examined through an exploratory numerical study in which a simplified sustained lateral pressure was applied to the south wall during the strong-motion window. The representation is non-calibrated and used to indicate trend-level shifts in demand rather than predictive values.
In isolation, results indicate moderate lateral capacity with strain localisation at openings and roof–wall/dome–drum junctions. Dynamic peaks remain within the pushover plateaus, and control-point drifts lie in a range consistent with no indications of triggering full collapse scenario, noting that principal-strain maps reflect upper-bound transient demand because cracks open and close cyclically. A simplified interaction case was included only as a sensitivity check; because it neglects contact transients, friction, eccentricity and vertical load transfer, no quantitative findings are reported from it. At most, the check suggests that adding a sustained lateral pressure could redistribute demand toward out-of-plane action on the loaded façade. These indications motivate future, higher-fidelity interaction modelling rather than supporting a firm conclusion here. Taken together with field evidence, this supports the interpretation that neighbouring collapse plausibly acted as a trigger for the most severe local failures, while the mosque alone would likely have sustained repairable damage.
The findings clarify seismic risk for historical masonry located in dense urban settings and motivate interaction-aware assessment, including explicit contact or bounded pulse models, to study cascading failure mechanisms.
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This thesis investigates the impact of confinement on the structural performance of Concrete-Filled Steel Pipe (CFSP) pile to concrete cap connections in the absence of dedicated force transfer provisions such as dowels or shear rings. Current Eurocode guidelines provide no explicit framework for confinement in partially loaded areas, resulting in uncertainties in design. The research combines theoretical modelling, drawing on Mander’s confined concrete model and the Dual–Wedge Stress Field (DWSF) approach of Markič et al., with a finite element case study to evaluate confinement mechanisms. A quasi-non-linear analysis was implemented to approximate peak concrete strength, supported by analytical formulations and parametric scripts. The findings confirm that confinement significantly enhances bearing capacity and stress transfer in CFSP pile–to–cap connections, with the FEA substantiating several features of the DWSF model while also highlighting limitations in reinforcement activation and stress redistribution. Overall, the study demonstrates that confinement effects are decisive for structural performance and should be explicitly considered in design practice to achieve reliable and efficient CFSP connections.
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This research focuses on comparing Accoya® with unmodified wood and investigates Accoya®’s structural performance in environments with varying relative humidity levels. The wood’s moisture content, and consequently its swelling and shrinking behavior, fluctuates on an annual basis due to these varying relative humidity levels, especially when exposed to outdoor conditions. FEM analyses were conducted to investigate physical properties and the performance of moment-resistant connections, with their implementation aimed at incorporating rotational stiffness into a structural portal frame. Accoya® demonstrates excellent moisture resistance and an increase in dimensional stability of approximately 80%, based on Dutch climate conditions. The reduction in swelling alleviates internal stresses within the connections, enhancing the strength and stiffness of moment-resisting connections. Specifically, a clamped connection and a circular dowel connection were analysed using a linear elastic static FEM model, revealing internal stress reductions of 81% and 52%, respectively. This reduction was observed during the simulated initial annual swelling cycle that the wood may undergo. With the use of Accoya®, significantly less plastic deformation is expected in connections due to swelling issues compared to unmodified wood and reduced deflection in structures is expected. An increase of 219% and 58% in rotational stiffness was observed for the respective cases. To evaluate the impact on overall stiffness, these observed values were implemented in a portal frame structure. A reduction in horizontal displacement was observed ranging from 31% to 66%. This opens up new possibilities in structural wood design, allowing for slimmer and lighter wood constructions. Due to Accoya®’s lower property degradation and more stable structural performance in high-humidity conditions, an adjustment of the kmod and kddef factors is suggested; however, this is not sufficiently substantiated in the current study. Future research could explore long-term performance factors with experiments such as creep and fatigue to validate Accoya®’s structural reliability further. ... Read more

Subsidence is a significant geohazard affecting many areas globally, including the western part of the Netherlands. Subsidence is the lowering of the ground relative to the surface level, and it occurs both on the scale of a single structure and larger areas. The shallow subsurface in these areas, characterized by compressible soil, contributes to subsidence, which may be initiated or intensified by additional drivers. Subsidence can cause damage to buildings, leading to increased costs and social concerns

In the current state of the art, less distinction is made regarding the difference in effects between different subsidence drivers. This study aims to provide insights into the relative influence of different drivers on the damage to existing buildings with a shallow foundation. More specifically, it aims to understand how various conditions and factors influence the damage parameters associated with soil deformation. This approach allows for analysing the interactions between the soil and the structure, ultimately contributing to a better understanding of the relative influence of the different drivers.

Numerical models in PLAXIS 2D have been carried out to compute settlements for various scenarios, involving different soil scenarios, building scenarios, and subsidence drivers. The primary emphasis of numerical modelling lies on the soil rather than on the structure itself. Various damage parameters have been established based on the numerically calculated settlements. The purpose of this analysis is to determine the impact of settlements on the building based on these damage parameters.

Several aspects related to settlement occurrence and its impact on buildings were investigated. The study provides multiple outcomes regarding the interaction between soil scenarios, different drivers of subsidence, and the presence of an existing building with and without a partial basement. This was achieved by considering the influence of each of these variables on the damage parameters, with emphasis placed on the relative influence of the different drivers. The approach includes a method that compares the influence of the situation with the existing building and the situation without the existing building (greenfield situation). This comparison shows the settlement behaviour caused by the presence of the building load and its interaction with the soil. Additionally, the combined effects of the soil scenarios, different drivers, and building scenarios on the resulting damage to an existing building are considered.

To conclude, for the soil scenarios considered in this study, the soil scenario with a weak spot (SS3) has the most unfavourable effect on an existing building. For the drivers considered in this study, when evaluating the relative influence of the different drivers, the global groundwater lowering (D2glo) has the most unfavourable effect. Considering the combined effect, the soil scenario exerts the greatest influence on the resulting damage parameters for the evaluated scenarios, followed by the type of driver and the building scenario. ... Read more

The city of Amsterdam faces the challenge of monitoring and assessing 200 kilometers of historic quay walls, of which much is deemed to be in poor condition. A key monitoring technique used is photogrammetry resulting in deformation testing. The fundamental data source forming the basis of this deformation analysis is a collection of overlapping images acquired of the masonry quay walls. Solely focusing on deformations overlooks a potential wealth of information which could be retrieved from this imagery, like the existence of cracks in the quay walls, a key sign of potential deformation of the structure.
As manual visual inspection of this imagery is very time-consuming, this work proposes a methodology based on fully-supervised deep learning-based segmentation techniques with the goal of detecting and localizing cracks in the masonry quay walls. For this purpose, two neural networks are trained, one for the segmentation of quay walls in images, and one for the segmentation of cracks.
The neural network architectures which are considered in this work are DeepLabV3+, FPN, MANet and LinkNet, together with different encoders and loss functions. For quay wall segmentation, we adopt transfer learning on a network trained on masonry walls and fine-tune it for quay walls specifically. Here, DeepLabV3+ with ResNeXt-50 was found to be most effective, achieving a F1-score of 96.3 % on the test set. For crack segmentation, FPN with ResNeSt-50 performed best, resulting in a test set F1-score of 78.8 %.
The inference of the crack network is done with a multi-level scheme to detect cracks at different image scales and increase output confidence.
The inherent photogrammetric properties of the imagery have proven to be vital for further post-processing steps, like aggregating overlapping predictions, resulting in more prediction confidence.
Photogrammetry also enables converting pixel-wise predictions to crack length and crack width in the units of meters and millimeters respectively. The methodology additionally proposes photogrammetric image processing methods to transform neural network predictions to a 3D representation and a true-to-scale orthographic 2D image.
Additionally a concise visual evaluation has been conducted to assess the prediction performance on an otherwise unlabelled dataset.
This thesis presents an engineering effort for fully-supervised crack localization within the context of photogrammetric processed images, with generalization in mind for automatic assessment. ... Read more

he growing demand for renewable energy sources has led to the deployment of wind turbines worldwide. One of the most critical parts of a wind turbine is the foundation, which plays an important role in maintaining the structural integrity and reliability of the towers throughout their service life. This research project is a case study that focuses on validating the numerical model against the experimental values from an operational onshore wind turbine foundation present at Riemst, Belgium, while considering the effect of hydration heat during the concrete curing process. The main aim of this research is to study and compare the behavior of the steel stresses in the on-site foundation with that of the numerical analysis and to see whether an adequate match can be obtained.

The study begins with the development of a three-dimensional symmetrical finite element model that captures its intricate geometrical and material properties. The structure’s behavior is simulated under realistic loading conditions to assess its structural performance and identify potential areas of concern. To validate the accuracy of the numerical analysis, experimental data obtained from fiber optic sensors are used. After converting the measured strains into stresses, they are carefully compared with the finite element analysis results to identify any variations and fine-tune the model. The validation of the FE model is performed using a 2D plate model in SCIA Engineering.

The research investigates the effects of hydration heat along with the structural analysis in FEA on the stresses experienced by the steel elements in the mass structure. This further extends to the effects of bedding and inclined piles combined with the thermo-mechanical analysis, where properties such as stiffness are varied in the simulations to study their influence on the structural response. It is imperative to note that utilizing the FE model with solely non-linear structural analysis can lead to a significant overestimation of the expected field results, up to 87 times. To mitigate this issue, the variant with thermo-mechanical analysis is implemented, reducing this estimation to a maximum factor of 58 compared to the field data.

It is crucial to achieve a satisfactory level of the project through iterative modifications. Implementing soil bedding on all sides in the thermo-mechanical model is one such step to effectively reduce steel stress to an acceptable level. The model shows steel stresses that are approximately 26 times higher than the actual experimental values. Along with reducing the steel stresses, the crack widths have decreased considerably from 3.4 mm to 2.35 mm. Hence, the effective way to perform the numerical simulation is to consider thermo-mechanical coupling along with minimizing assumptions and ensuring sufficient stiffness of the structure for reliable assessments of steel stresses and structural integrity of onshore wind turbine foundations.

The findings contribute valuable insights into the foundation’s structural behavior under varying operational conditions, highlighting areas of strength and potential advancement. Moreover, the outcomes from this investigation can assist engineers and designers in making informed decisions during the planning and construction phases of wind turbine foundations, leading to more cost-effective and robust structures. Additionally, the methodologies presented here may serve as a framework for future research in this field. ... Read more

Dit onderzoek richt zich op het verminderen van trillingshinder in CLT- en betongebouwen, zodat ze voldoen aan de richtlijnen en er meer naast het spoor gebouwd kan worden. De centrale vraag van het onderzoek is hoe specifieke ontwerpmaatregelen kunnen leiden tot een vermindering van trillingshinder in overeenstemming met de richtlijnen. Een voorspellingsmethode is ontwikkeld om trillingshinder te voorspellen op basis van trein-geïnduceerde trillingen, waarbij voorwaarden gesteld worden aan de trilling en het frequentiespectrum. Ontwerpmaatregelen zijn bepaald voor zowel CLT (variërende dikte, totale vloerdikte, overspanning, permanente belasting) als beton (variërende vloer- en wanddikte, overspanning, stramienconfiguraties, starre vloerverbindingen). Analyse toonde aan dat ontwerpmaatregelen met betrekking tot vloer- en wanddikte en overspanning het meeste effect hadden op de eigenfrequentie van de vloer. De methode omvatte ook het gebruik van een eindig elementen model voor dynamische analyses, waaronder een frequentieresponsanalyse en een lineaire tijdsafhankelijke analyse. De methode werd toegepast op een casus in Arnhem en vergeleken met de SBR richtlijn-B voor het bepalen van hinder voor personen in gebouwen gedurende de nachtperiode. De methode bleek effectief in het voorspellen van trillingshinder bij verschillende ontwerpmaatregelen, hoewel er een onderschatting was bij maatregelen met resonantiepieken rond 10 Hz en 12 Hz. Voor zowel het CLT-model als de betonmodellen waren vergroting van de overspanning en toepassing van doorlopende tussenwanden effectieve ontwerpmaatregelen om aan de richtlijnen te voldoen. Verder onderzoek op meerdere locaties wordt aanbevolen, waarbij het gebruik van een spectrum met de volledige frequentie-inhoud van trein-geïnduceerde trillingen wordt aanbevolen en het middelen van de frequentie-inhoud wordt afgeraden. ... Read more

Mining activities at the Groningen gas field are causing earthquakes which result in building damage. This has started a discussion on what type of damage is caused by earthquakes. These discussions are typical in the forensic engineering field, especially in complex cases. The problem is the lack of regulations, in terms of standardizations and uniformization.
To solve that problem, experts can be provided with an independent tool which can contribute to the investigation of the cause of building damage. The tool can help to indicate potential damage causes. This will support the findings of experts. Also, it can draw attention to overlooked damage causes.
The tool is based on relations found in a database of damage cases that have been determined earlier. The database consists of damage cases in the Groningen province. Not all available damage cases were incorporated in this thesis, because processing the damage reports to a database was a labour-intensive job. The analysed dataset consists of 1830 damage cases in 49 buildings. Experts were able to determine the cause of damage in 1180 of these damage cases, which results in a ratio of 64.4% known cases. Only the known cases where applied in the analysis. The buildings were located in seven different areas in the province of Groningen.
Each analysed damage case consists of a damage cause and a description. A description has been structured in 191 characteristics. These characteristics have been categorised into three types: building characteristics, context characteristics and damage characteristics. Building characteristics say something about the function, materials and size of the building. Context characteristics explain the sub soil, vibration sources and external forces in the surrounding of the building. Damage characteristics describe how damage is presented in terms of position, location and shape of damage.
Whether the found relations can be deployed in practice, depends on how useful those relations are. Useful is defined as reliable and meaningful. Reliable is how a found pattern performs according to a test, mostly measured in terms of accuracy or coefficient of determination. Meaningful is whether the found relations are logical to be explained by literature or plausible damage situations. The pattern recognition can introduce some relations and can provide them with a reliability value. However, if the relations are not explainable, they do not mean anything for use in practice.
The relations in these data were found by deploying pattern recognition methods. Two algorithms were utilized as a pattern recognition method: decision tree and linear regression. A decision tree algorithm splits the data into groups by applying thresholds on case characteristics. These thresholds can be made visual in a decision tree figure. Linear regression tries to obtain a target value by means of a linear relation of characteristics. Therefore, the linear regression algorithm determines the slope value of each characteristic.
Classification analyses were done with decision trees on six damage cause categories. The results of that type of analysis were capable of determining if or which damage was caused by a certain cause. Linear regression was performed in order to find regression relations where the technical attributability of a damage cause could be calculated for each case. In the more complex task of regression analysis, only three damage cause categories were suitable for finding a relation.
To determine whether damage was caused by earthquakes, earthquake load in terms of PGV is an important characteristic. Also, the age of a building and trees has a possible significant influence on the occurrence of earthquake damage, according to the found pattern. A relation between those last two characteristics and earthquake damage is not described in literature. Besides that, this decision tree pattern seems to be the most useful pattern for in practice.
Another interesting finding is that hindered deformation mostly occurred at the inside of a building. Combined with other characteristics, a pattern on this damage cause performed with the highest score in this thesis. It has an accuracy of 77%. This means that 77% of the cases in the test set were correctly predicted by the produced classification decision tree. However, the found relation with the characteristics is not always explainable or meaningful so as to be applied in practice. More conclusions of classification analysis are shown in Table 1.
<Table 1, See abstract in report>
The presented findings above are classification relations. Regression analyses were difficult to execute. A desired positive coefficient of determination (R2) could not be reached without subjective interference in the pattern recognition. The best regression result was obtained on damage caused by earthquakes. It had a R2 of 0.48. Which means that 48% of the data was describable in a linear relation. More conclusions of regression analysis are shown in Table 2.
<Table 2, See abstract in report>
It has been interesting to study the relation between characteristics and damage causes. However, the results are not of decisive importance. The building and context characteristics supported by literature were not always selected or applied properly by the pattern recognition. Also, the potential of damage characteristics was not recognized by the algorithms. Nonetheless, the results of earthquake related damage seem promising. They even indicate characteristics which may be worth investigating more closely.
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Due to global warming and the subsequent rise of the sea level, scarcity of land to build on, the continues increase of the world’s population and a shift in population from rural areas to the city, there is a need for innovative projects to tackle or deal with the increase of needed liveable area. One of the solutions is floating cities. A component of a modern city is high-rise buildings. High-rise is an advantageous option to deal with the limited availability of ground surface on the floating platforms. The question is whether it is possible to realise these floating high-rise structures.
This research investigates whether it is possible to realise high-rise buildings on floating platforms with limited dimensions on the sea or ocean regarding stability. And if it is feasible, what the requirements are for the general dimensions of both the platform and the high-rise building. For this purpose, conditions were used from three representative locations. At these three locations, the floating high-rise is tested for four different wave situations: Tsunami, Growing waves, most extreme wave. And an Irregular wave field. The platform and building are tested whether the structure could meet the various requirements and regulations. These are divided into three forms of stability: Buoyancy, static stability and dynamic stability.
In this study, for both the platform and the building a square cross-section is used and both are prismatic in the direction of the height. The platform and the core of the building are made of concrete. Apart from the four parameters: height of the building and width, height and depth of the platform all other parameters are based on these four parameters. No stability systems in the building were used (except the core), nor methods to keep the platform in place, such as mooring systems.
For the buoyancy, mainly the relation between the mass and the depth of the platform is determined. This is a relationship that has been used extensively in static and dynamic stability. The mass of the building and platform pose few problems for staying afloat. In fact, extra ballast water can easily be used to make the platform heavier in order to achieve the desired mass or depth.
For the static stability a combination of hand calculations based on the GM-method and a model that can include deformations in the calculations as well is used. A linear relationship was found between the height of the building and the width of the platform for which the floating high-rise is stable.
The model is used to determine the minimum platform depth and height, as well as the rotation for different building heights and platform widths. It follows that there are platform widths for which the vertical force is minimal. This is when the width of the platform is equal to the wavelength of the wave or a multiple of it. In addition, there are platform widths for which the moment due to the wave force on the platform is minimal. These values are called "zero moment widths" because for these widths the wave moment, regardless of position or time, is approximately equal to 0 kNm. Therefore the rotation is minimal when these zero moment widths are used for the platform width. These widths are only optimal for the specific wavelength for which they are calculated. If the wavelength is different, the zero moment widths will be different.
For the dynamic stability, a model consisting of three point masses distributed over the height connected with a beam was used. The three point masses each have three degrees of freedom: vertical and horizontal translation and rotation. With this model the accelerations of the three possible motions for different heights of the building, platform widths and platform masses (this can be adjusted by including ballast water) are calculated. It follows that: The tsunami and the growing wave are not a problem and the most extreme wave or the irregular wave field is normative; The vertical acceleration is minimal when the width of the platform is equal to the wavelength or a multiple of it; The vertical acceleration is only normative for small building heights and platform widths, whereas it is the biggest cause of seasickness; The horizontal acceleration at the top of the building due to both the horizontal motion and the rotation is almost always normative. It is largely caused by the rotation of the platform; If the zero moment widths are used for the width of the platform, the rotation and thus the horizontal acceleration is minimal. This does not mean that the accelerations are below the limit.
In order to avoid resonance in the motion, and thus extreme accelerations, of the floating high-rise with an irregular wave field, graphs are made were the combination of the height of the building and the width of the platform that result in resonance are shaded.
Using the results of the static and dynamic analysis and a few case studies, it can be concluded that with the design choices and simplifications used, it is not possible to realise floating high-rise buildings on platforms with limited dimension at the North Sea and the North of the Atlantic ocean due to too extreme condition causing too high accelerations, especially in the horizontal motion. The static stability and the buoyancy are less of a problem. If one of these locations is chosen, platforms over 600 m wide are required that are so stable that the rotation of the platform is minimal and no resonance occurs in the rotation motion. In this case, the conditions are similar to those on land and the wind force becomes the governing factor. In those cases, the same approach and measures should be used as for high-rise buildings on land. Even with these sizes, it is advised to use the zero moment widths to limit the rotation as much as possible.
The location on the Atlantic Ocean around the equator is the only location that is promising. The results show that several building heights are possible on different platform dimensions for the highest wave, as long as the platforms have the zero moment widths dimensions. However, it appears that the accelerations become too high when these sizes for the building and platform are tested with different wave frequencies with lower wave heights. Therefore, this option might not be suitable either, but it is not excluded in this research. One option is found that meets the regulations for all possible wave frequencies is a 50 m building on a platform 223 m wide (a zero moment width) and 22.7 m deep for the location around the equator. This proves that it is possible to construct high-rise buildings on platforms of limited size with the design choices used, but that it is very difficult and the options are limited.
Despite the conclusion that it is almost impossible with the design choices, floating high-rise buildings on limited platforms are still expected to be possible as the design can be improved. The first next steps to investigate are other, better shapes for the platform and building to increase stability and reduce overall forces. In addition, it is recommended that other methods of increasing stability and reducing motion, such as building stabilisation systems and tuned mass dampers, are investigated. With these improvements floating high-rise is more feasible than found in this research.
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With the rising demand for renewable energy sources the amount of wind turbines which are built on land are growing rapidly. Because of the repetitive nature of the foundation small design improvements can add up to large savings in material usage and building cost. The most critical part of the foundation is the connection between the metal mast and the concrete foundation. This connection is made by implementing an anchor cage. The application of an anchor cage results in complex multiaxial stresses in the surrounding area. Confinement plays a large role in the compressive strength of the concrete subjected to the partially loaded area created by the anchor flange. The main goal of this thesis is investigating the best way of modelling the concrete surrounding the anchor cage at confinement levels being present in the wind turbine foundation. This is done by investigating the theory regarding confinement and the effects of it. But also the way this is captured by analytical models. To make a comparison between DIANA and the analytical models the present stress situation in the wind turbine foundation is analysed. Looking at the stress distribution and the confinement levels. Next a comparison of the ideal case of confinement is made. This is later expanded to a larger scale model, to compare the effects of confinement. The confinement present will enhance the concrete strength and strain properties. The concrete specimen can resist larger loads and reacts more ductile. These properties are captured in analytical confinement models, these are compared to the way DIANA approaches confinement. The anchor rods between the anchor flanges are prestressed, this prestressing results in a permanent stress situation. Within this stress situation there is a small part beneath the anchor flange subjected to confinement. With increasing pressure, originating from the moment load which results from the wind on the tower and it’s blades, the confined area increases to the top half of the foundation. With significant confinement in the pedestal. Comparing the DIANA compressive behaviour models with the analytical confinement models and experimental data within a one element model. It is seen that compressive behaviour models do react on the confinement. Although they show a lower peak strength than the analytical models. A larger difference is noted in the underestimation of the peak strain. This difference in outcomes is the result of the different approaches between DIANA and the analytical models. As well as some assumptions that DIANA makes concerning the strength and strain increase factor. The Parabolic compressive curve is most suitable for modelling the confinement in this ideal case. A case study is conducted to further investigate how the confinement is represented in a total non-linear model. Modelling the top part of the foundation and checking the effect that confinement has on this model. For this model the prestressing of the anchor rods is increased until failure. Without confinement the concrete elements directly beneath the anchor flange fail in compression. Running the model with confinement it is noticed that the underlying weaker concrete is failing in compression first. This is the result of the confinement being present surrounding the anchor flange. The model with confinement is also able to resist a 30% larger load than the model without confinement. The parabolic compression curve is the most suitable curve currently available inside the strain based crack model for modelling the effects of confinement. Overall DIANA is able to capture the effects of confinement well enough to see the positive effects in the case study. Due to limitations in the analyses performed and in their interpretations, it is not possible to give an unequivocal answer on the effect of confinement within the foundation of the wind turbine. ... Read more

Many quay walls in Amsterdam have surpassed their structural lifetime and have started showing signs of damage. The city of Amsterdam is currently tackling the problem and have published a plan of action. This plan includes the renovation of hundreds of kilometres of quay walls. Given this enormous amount, it is necessary to prioritize certain quay walls over others based on the severity of their damage. Some quay walls have reached total collapse, of which the most recent case involves the "Grimburgwal" quay. The municipality has no accurate view of the current condition of quay walls in Amsterdam. On top of that, the vast majority of quay walls have not been assessed on their safety. It is known that the most vulnerable quay walls types consist of masonry walls, supported by wooden foundation structures. Given that the quay wall renovation project requires prioritisation, it is necessary to gain more information on how the most vulnerable walls are recognised. Preferably, a method should be developed in which only visual cues given by the masonry wall are required, as it is quick and relatively cheap. To gain information on what these visual cues might be, a three-dimensional finite element model is made to run simulations on possible behaviours of quay walls. In this thesis, it is attempted to model a quay wall as realistically as possible. Several different deterioration conditions will be applied to see how the masonry responds. The 3D model is built using a parametric model coded in Python. This code can be used to run simulations in the finite element software DIANA FEA. Many behavioural aspects have been incorporated into the model, with the purpose to make the model more realistic. The model consists of a masonry wall, planks on which the wall rests, and supporting piles. The behaviour of each component has been applied in the code and have been obtained through other literature and European norms. The model is loaded by simulating the weight of the soil and its effect on the quay wall structure. The masonry is simulated using a smeared cracking model (macro-model). Long-term deterioration of quay walls is simulated by changing the material properties of each respective component. This thesis focuses on three deterioration conditions: 1. Non-uniform pile degradation: application of broken piles, simulated by removal of those piles from the model. This is subdivided into two categories: removal of entire rows (a row consisting of a front, middle and end pile) and removal of front piles only. 2. Non-uniform soil removal: formation of soil pits at the foundation level, which result in decreased bedding around the foundation piles. 3. Uniform degradation: application of uniform deterioration along a stretch of quay walls. The simulations yield fairly consistent cracking patterns, in which the same crack fields appear in each simulation depending on the chosen case mentioned before. Displacement patterns are also documented and presented in all cases. The quay wall model is able to display in-plane and out-of-plane movement simultaneously. The effect of each parameter on the crack/displacement patterns are analysed as well. This includes masonry and wood quality. The results show that the largest in-plane settlements are reached by damaged piles, while the largest out-of-plane displacements are caused by a loss of soil bedding around the piles. The results can be used to provide better insight on how quay walls with poor quality present themselves in real life and what their cause might be. This research contributes to the possibility of improving recognition of quay walls which find themselves in critical condition, which can then be prioritized for renovations. For future research, it is recommended to see whether time-dependent simulations can be run, to see if it makes a difference in the outcome of displacement/cracking patterns. Another important recommendation is to look into deterioration rates of materials, which could be used as another indicator for critically damaged quay walls. ... Read more

The city of Amsterdam contains about 1600 bridges and 600 kilometres of quay walls. Of these walls, about 200 kilometres are of masonry walls placed on a timber floor and founded on timber piles. These quay walls are sometimes over 100 years old. Due to the increasing loads in the past century and the degrading of material properties in the masonry wall and timber elements, the quay walls are in bad shape. When designing a quay wall, a cross-sectional analysis is used to calculate the desired dimensions to withstand the loads. When this calculation is performed on a quay wall over a 100 years old, containing a failing pile foundation, the quay wall should fail. However, many of the quay walls under the condition of a partly failing foundation, are deforming, but still standing. During recent years, at 16 locations in Amsterdam, the risk of collapse appeared imminent, and emergency structures are put into place. Possible practical measures are removing trees on the quay walls, traffic limitations in the city centre and placing temporary struts and sheet piles to provide stability. Since the scale of the problem in Amsterdam is large, the time to renovate all the quay walls is lengthy. Therefore, there is a need for knowledge on the state of quay walls at the end of their life phase when partly failing. Different failure mechanisms occur, and various measures are developed to control those and provide (temporary) stability. This research answers the question: How can 2D analyses of quay walls, in multiple directions, under the condition of a partly failing foundation, provide insight into the hidden structural capacity within the masonry work? The study focuses on the severeness and scale of the foundation defects in the quay wall's cross-sectional and longitudinal direction. For the longitudinal models, the effects of the masonry material qualities are studied by using different material properties. Also examined is the effect of the failing foundation pile's post-peak behaviour, modelled as brittle and checked for plastic behaviour. Finally, the relevancy of the timber floor is studied for a stiff continuous floor and most notable, the full removal of the floor. To study this, two 2D regular plane stress, nonlinear elastic, finite element models are created in Diana FEA. The foundation piles are modelled as nonlinear elastic springs via a force-displacement diagram. The foundation piles' defects are modelled by assuming a smaller pile diameter, resulting in a weaker force-displacement diagram and larger displacements in the quay wall system. The foundation defects can be scaled over a small or big area by adapting multiple foundation piles over the length of the quay wall. The masonry's behaviour is researched by using a macro material model using smeared material properties for the brick and mortar, resulting in a continuous material. The material model used is the Total Strain Rotating Crack Model, which can be used in a 3D analysis of the quay wall system in future research. Finally, the interface between the timber floor and masonry is modelled using a coulomb friction interface criterion. This simulates the effects of the mortar layer connecting the timber floor and masonry work in a quay wall. The results conclude that analysing a foundation defect in the cross-sectional direction of the quay wall results in instability of the wall without further horizontal and vertical constraints to keep the quay wall in place. Modelling the pile foundation defects using a reduced pile diameter and consequently, a decreased force-displacement diagram as spring input provides the model with temporary stability. Ultimately, the cross-sectional analyses contribute little knowledge on residual strength and hidden structural capacity. Separately, the longitudinal model implements a vertical constraint in the masonry by using the bending capacities of the material. The results present an expected correlation between the scale of the foundation defects and the vertical displacements. Similar to the cross-sectional analyses, the reduced pile capacity of the foundation piles provides the model residual strength compared to the situation where the total failure of a timber pile is used. The timber foundation pile's failure mechanism needs to be researched in-depth since the results present a notable difference for crack patterns and force-displacement curvatures when modelled brittle or plastically. For brittle failure, a horizontal crack forms at the tip of the central, vertical crack, due to the abrupt enlargement in vertical displacement of the quay wall. The functionality of the timber floor in the longitudinal analyses presents itself when the crack patterns are analysed. The presence of the timber floor results in multiple smaller cracks instead of a single large crack when foundation defects of the quay wall system are analysed without a timber floor. It can be concluded that the masonry quality, most notably the tensile strength, affect the results significantly in terms of maximum values in the force-displacement diagrams and crack development. The material properties are based on Groningen masonry experiments, and it is recommended to perform experiments to the masonry quality of Amsterdam quay walls. Finally, the observed displacements related to the intervention points of the municipality conclude that foundation defects result in cracks for displacements below the marking points of 20 and 25 millimetres. For weaker masonry, the quay wall fails before the indication values. It is recommended to perform more measurements to the quay walls in Amsterdam and study the reliability of the intervention points. ... Read more

When a breakwater is under heavy wave attack, the concrete armour units will occasionally move, causing a collision between two concrete armour units. This process is called rocking, and induces stresses in the concrete, that may lead to breakage of the concrete armour units. This MSc Thesis provides a probabilistic method to predict breakage of concrete armour units, focussed on Xbloc®. The impact velocity is based on the forces on a unit under wave attack. This impact velocity is used as input to determine the impact force, based on an energy balance. The stresses at a critical location in armour unit will then be determined from a strut-and-tie model. With an estimation of the distribution of several stochastic variables, the eventual result is a probabilistic prediction of breakage of the concrete armour units. ... Read more

’De Watersnood van 1953’, the largest Dutch flood in recent history, caused the death of 1795 people in the Netherlands directly from the flood conditions, while in the UK, 315 were recorded. Most of them were among those whose residence collapsed due to high water depth, quick rise rate of the water or strong flow velocity. Based on historical data of floods with similar flood characteristics and comparable buildings, mortality functions were developed to estimate the number of fatalities. These functions are still used, but the correlation between the flood characteristics and the damage observation is not clear according to multiple studies. The current study contributes to improving these functions by investigating which flood conditions may lead to collapse of the residences in the current Dutch building stock. From the BAG-registration (in Dutch: Basisregistratie Adressen en Gebouwen) it is found that 50% of the Dutch live in terraced houses (in Dutch: rijtjeshuizen), which is similar in the areas which are most likely to be affected by flooding. Most of these residences are built in the period of the housing shortage between 1965 and 1975 and the energy crisis between 1975 and 1994, which are considered as ’the typical Dutch residence’. This residence type consists of cavity walls with a load-bearing leaf of concrete or unreinforced masonry (URM), which can be clay or calcium-silicate. This inner leaf is tied to the outer leaf of URM consisting of perforated clay units, wood-based materials, or concrete. Stability is provided by piers in the façades in case of the URM walls or rigid connections between the concrete floor and walls. To define the properties of the building materials, existing experimental research on the masonry is used.
Experiments with a physical model were conducted herein to measure the quasi-steady load in the form of pressures acting on different elements of the residence. This enables the comparison of the quasi-steady flood load and the lateral load due to wind on different elements of a building. Similar to FEMA (2011), it was found that the pressure coefficient decreases when the width-to-water depth ratio decreases. However, higher coefficients are found from the experiments than those provided by FEMA, resulting in higher hydrodynamic loads. Furthermore, the orientation of the residence compared to the flow direction changes the angle of attack. When the flow is perpendicular to the wall, the pressure coefficient is the largest. Decreasing the angle of attack causes a decrease of the pressure due to equal flood conditions. The pressure coefficients obtained from the experiments are used to define the hydrodynamic load due to flooding. The resistance of the load-bearing cavity walls, windows and piers were compared to the acting moment due to different depth-flow velocity combinations. The resistance of out-of-plane bending of the load-bearing wall is the critical failure mechanism for typical Dutch residences. Residences with calcium-silicate masonry walls and system floors have a higher resistance than residences with clay masonry walls and timber floors. Cracks start to develop at a small lateral load resulting in zero tension strength after cracking and an eccentricity of the normal force. This makes the influence of the dead weight carried by the wall, in combination with the compression strength and the thickness, more important than the flexural bending strength.
All types of residences, using design values, already collapse before the hv-product (water depth times flow velocity) of 7 m2/s is reached according to Clausen (1989). A water depth of ±1.2 meters for the older residences (1965-1975) and ±1.8 meters for the newer residences (1975-1994), already cause the design moment resistance of the wall without taking the velocity or wave action into account. If the flood water has a flow velocity of 2 m/s or waves are generated by a wind speed of 29.5 m/s over a fetch of 100 m, the critical water depth reduces to respectively ±0.9 and 1.5 meters. ... Read more

The SBR richtlijn A states threshold values for the vibration speeds causing a 1% probability of failure of masonry structures. These threshold values are very useful for structural designers, because during the construction of new structures or the demolition of existing structures, it is important to know if these structural vibrations can lead to damage to surrounding structures. However, for vibration speeds that exceed those threshold values, it is difficult to calculate the probability of failure of those structures. During this thesis, a procedure is proposed as a guideline to calculate probabilities of failure for masonry façades for vibration speeds higher than these threshold values.

Many factors influence the probability of failure for masonry structures, like soil properties, masonry properties, initial damage, initial loads or the type and frequency of structural vibrations. Also, it is important to know what should be considered damage. All these factors are implemented in this procedure. The proposed procedure is set up using two different models: a structural model, where the loads and façade dimensions and properties are implemented, and a probabilistic model, where the structural results are implemented, as well as stochastic parameters for some properties. This model leads to a probability of failure.

For the structural model, the software package SCIA Engineer has been used in this project. The structural model ensures that after drafting the façade, implementing the masonry properties, and applying the initial loads and the vibration speed and frequency, the maximum tensile stress for this frequency can be calculated. The tensile stress is the property that will determine if the structure fails, since the tensile stress of masonry is generally low. This tensile stress should then be implemented in the probabilistic model, which also takes the dispersion of the tensile strength and Young’s Modulus into account. A Monte Carlo simulation is performed, which results in the probability of failure of the specific façade for a specific vibration speed and frequency.

This thesis’ main focus was the linear-elastic procedure, where no soil-structure interaction was involved. Since masonry does not behave linearly after the first cracks initiate, some assumptions have been made to enable the calculation to be executed in a linear-elastic way, e.g. that failure occurs if the tensile strength is exceeded over a length of 210 mm. Also, in reality, soil-structure interaction will occur and will produce different structural results and following this, different probabilities of failure. Therefore, this study is able to provide a satisfactory statement regarding the probability of failure for masonry structures, but is not able to substantiate this statement completely.

In this thesis, the proposed procedure has also been executed on three different masonry facades in the city of Delft. The procedure is described extensively using these facades to provide a clear example how the reader can implement this procedure in their own projects. Also, because of the execution of this procedure on these façades, comparisons could be made, so the difference in probabilities of failure between façades, but also between different kinds of soil and vibration frequencies could be investigated.

The results show that the proposed procedure gives an adequate approximation for the probability of failure for masonry structures loaded by construction induced vibrations. Also, the results have been compared to a nonlinear case. This comparison shows that the assumptions that had to be made to approach this problem in a linear-elastic way were sometimes too conservative, but some assumptions were also a little too bold. Also, it is demonstrated that soil-masonry stresses have quite some influence on the structural results and therefore on the probability of failure, but more research regarding this topic is necessary to form a substantiated statement regarding the stresses at the soil-masonry interface.

Summarized, for this thesis, an assessment has been computed to determine the probabilities of failure for masonry structures using linear-elastic calculations. By following this procedure, one will be able to gather a good approximation of the probability of failure. However more research has to be conducted to ensure the soundness of this procedure. ... Read more