Due to global warming, in the construction sector there is aimed for a transition towards the circular economy. The past years, many utility buildings were demolished, consisting of a concrete structure. This results in concrete rubble which is often down- or recycled. For new construction projects, new concrete elements will be produced. However, instead of producing new concrete structural elements, potentially concrete structural elements can be reused. Therefore, this research focuses on the reuse potential of in-situ concrete elements whose can be dismantled from demolition projects of utility buildings. In order to stimulate structural engineers to reuse concrete structural elements in practice, this research presents the Reusability Tool. This tool assesses the reuse potential of in-situ concrete structural elements based on structural safety, environmental impact, and economic impact. Based on an extensive desk research, interviews with experts from the field, and a case study, the processes of three circular strategies are analysed: reusing, upcycling, and downcycling. These processes are made operational in the Reusability Tool. Based on input information about the analysed structural element, the Reusability Tool assesses the element on structural safety, environmental impact, and economic impact. This assessment result in an advised circular strategy for the element: reuse, upcycling, or downcycling. The Reusability Tool is validated by a case study and feedback sessions with structural engineers. The Reusability Tool is a user friendly tool which can be used to assess the reuse potential of in-situ concrete structural elements from utility buildings, and will prevent valuable elements to get lost. The tool can give insight in the reuse potential in an early design stage of a future project, and can form the basis for further investigations.

Over the last years the critical state of existing quay wall structures have gained a lot of concern. With the focus on urban quay walls in Amsterdam, a lot of aspects could play a role which limit the possibilities for both the design and the construction. The focus in this research is placed at the structural efficiency of the design for renovation projects. By using a parametric approach (with Grasshopper/Rhino) in the preliminary design phase, a design solution with the lowest use of material can be found. From the total of embankment within the management of the municipality, a scope has been defined focusing on the most critical quays with respect to the limited design space and high expected loads. Within the assumptions made, the developed parametric tool can be used to indicate an efficient design solution for which the positioning of the piles, the diameter of the piles and the thickness of the floor follow from the location-dependent input. The indication of the effect of geometrical properties with respect to the defined objective (minimizing the material use) could help in the consideration of the design requirements. Apart from indicating the savings that can be made on the material use by improving the structural efficiency of urban quay wall design, this research also contributes to proof of the power to be found in a parametric approach. The repetitive character in especially large-scale assignments as the renovation of Amsterdam's quay walls makes it a highly appropriate method.

Waste generation is one of the main environmental problems and is a result of the current linear economy. Materials/elements are used whereafter they are wasted which is a problem considering the finite material supply on earth. Therefore, the current linear economy needs to move towards a circular one in which materials are reused and thus kept in the circle. However, reuse is still not a common practise. This is due to the fact that there are no insights in the structural feasibility, potential savings on environmental impact, and costs related to reuse. Besides the lacking knowledge about the different aspects there is no clear image where the potentials for reuse are located within the sector. The goal of this research is to give insights in the reuse potentials and to find opportunities within the sector. This research started with a material flow analysis to find promising material flows in the sector. In this material flow analysis it was found that the demolition of office buildings is responsible for a big portion of the outgoing material flow and the majority of the ingoing material flow is related to the new construction of serial houses. In the analysis it was found that the elements with the highest ECI and mass are floor elements. Next the available floor elements coming from office buildings and the floor elements needed for the construction of serial houses were examined to check possible matches. It was found that new plank- and hollow core slab floors used in serial houses can potentially be substituted for reused monolithic- and hollow core slab floors out of office buildings. Thereafter, two different tools were developed. One related to the reuse of monolithic floors and one related to the reuse of hollow core slab floors. These tools are means to give insights in the reuse potentials considering the structural feasibility, potential savings on environmental impact, and costs. Different cases were checked using the tools and the following results were found: -In all cases it was structurally feasible to use reused floors coming from office buildings in the new construction of serial houses. -When reused floor elements are used it is possible to save 40-90% on environmental impact. -Reused floor elements can be cheaper or more expensive as new floor elements. These results are promising and hopefully contribute to an acceleration of reuse in practise. The research states where the potentials for reuse are located in the sector and presents two tools which check the reuse potentials considering structural feasibility, environmental impact, and costs.

The building industry consumes a lot of material, which causes depletion of material stocks, toxic emissions, and waste. Circular building design can help to reduce this impact, by moving from a linear to a circular design approach. To reach a circular build environment, all disciplines should be involved, including fire safety design. However, there is a contradiction between the objectives of circular and fire safety design, either affecting the aim of protection of material sources, or protection against fire risk. Timber is a material that has high potential in contributing to a circular building industry, as it is renewable, recyclable and can store CO2. However, timber is combustible, which increases the risk of fire. Therefore, mass timber building design has traditionally been restricted by building regulations. To enhance mass timber building design research on timber buildings has increased, to allow understanding of the risks. However, yet general guidelines or understanding on the fire behaviour and risk in timber buildings is lacking. This is a problem for the fire safety design and the potentials of timber contributing to a circular building industry. Until now, there was no specific method available that quantifies this relation between material use and fire risk in mass timber buildings. This limits the possibility of fire safety design and mass timber design to contribute to a more circular building industry. By creating a method that allows comparison between the economic and environmental impact of material use and fire risk, a well-founded choice of building materials is easier to make. The design tool created in this research quantifies the impact on material use for fire safety measures relating to CLT, encapsulation and sprinkler availability and their effect on the fire risk in mass timber buildings. This way insight is provided between the balance of material use and fire risk. By the sum of the impact on material use and fire risk, the total “circular fire safety impact” value is calculated. This value represents the total economic and environmental impact of the design based on the choice of building materials. By changing the fire safety design, the most optimal design variant can be determined. This is the variant with the lowest total impact value. This way, a circular design approach is used to steer fire safety design in mass timber buildings towards a design solution that does not only provide sufficient safety for people, but also provides maximum economic and environmental safety from a material point of view.

Wind turbines are decommissioned when they reach their endoflife. The reason for reaching endoflife varies per wind turbine, but they all have in common that the wind turbine blades can not be recycled and thus end up as waste. Since a growing amount of wind turbines will reach their endoflife the coming decade, the waste problem will increase. To solve or limit this problem, the lifetime of a blade can be extended, or a sustainable endoflife treatment can be established. This is currently not available yet. This research focuses on repurposing wind turbine blades. The objective is not to find one application, but rather to propose a method that enables large scale processing of wind turbine blades, for applications in the construction industry. Since to date it is uncommon to repurpose wind turbine blades, Two processes are proposed to give guidance on how to repurpose wind turbine blades. The first process is meant to repurpose as many blades as possible, by sawing the blade in plates and beams that can be applied to construction projects. The second process gives guidance to a project team that wants to incorporate wind turbine blades in their construction project, which can raise awareness for the waste problem. Both processess are supported by a grasshopper script. This script enables the user to either find an efficient mapping of elements that can be extracted from the blade, or gives design freedom depending on the aim of the repurpose project. The first process is further worked out. A geometry model of an actual wind turbine blade is analyzed and categorized in panels with a homogeneous material layup. On this panels, a nesting pattern of plates and beams, as commonly used in the construction industry, is projected which can later be sawn into relative flat plates and beams. With this, almost half of the blade panels can be turned into useful construction elements. The cross section of a blade consists of various functions, and thus various material structures. Three categories are distinguished: Spar caps, shell panels and the shear web. For each of these categories, the material layup and properties are analysed, which has led to an advice on possible applications. Spar caps are strong, stiff and have a homogeneous cross section. They can be repurposed as structural beams. Shell panels are light and stiff and can be repurposed as partition walls, formwork or flooring. The shear web is light, stiff, and entails good insulation properties. This can be repurposed as building cladding. Although this research does not contain sample tests, the material properties of the blade are provided and are of significant value, despite their 27 years of service.

Awareness about our planet is more important than ever before. Thereby, the transition towards a Circular Economy (CE) aims to keep products in use and to design out waste. In the construction industry, one way of reducing the use of raw materials is by transforming waste residuals from demolition projects into resources to be reused. By implementing these resources in new buildings, the supply of harvested (structural) elements and the demand for resources in new buildings can be matched. Due to the high amount of embodied carbon in superstructures, this research focuses on the reuse potential of harvested concrete (structural) elements in the design of new buildings. The demolition and construction of buildings are analysed from the point of view of structural engineers with an extensive literature study, interviews and a case-study. This resulted in the process of ‘Deconstruct & Reuse’, which includes all information required to assess the reuse potential. The assessment is made operational in the Decision Support Tool, which makes this research the first of its kind. For use in practice, the Decision Support Tool is validated and verified with a test-case that considers the disassembling of De Nederlandsche Bank (DNB) in Amsterdam. In the Decision Support Tool, the test-case is executed by the researcher and by experts resulting in remarks, opportunities, challenges and further research. In conclusion, the Decision Support Tool has a high practical value as it stimulates the reuse of concrete elements through an operational method. The output provides valuable insights with which a structural engineer can decide if a harvested (structural) element can be reused and implemented in a new building. Hence, the assessment of the reuse potential is considered to be a step towards circularity in the construction industry.

Very little research has been done on the potential use of glass bottles in a structural system. Knowledge gathered from past projects showed that individuals or communities usually tend to create structures with glass bottles with a cementitious material, which is usually concrete or mortar. Under vertical compressive loading, the corresponding failure mechanisms should predominately be fractures in either the heel or the shoulder. Using two different finite element models and Weibull Analysis, a characteristic tensile strength of abraded container glass of 20 MPa was found. When structures are created out of glass waste, designs should be made with the abraded state in mind. Connections concepts are created to connect glass bottles together, i.e. 'Masonry', 'Stacked' and 'Bundled'. The 'Stacked' concept was considered the most suitable for this thesis. Eight different configurations of the Stacked concept were created, of which four were tested in a hydraulic displacement controlled compression machine in Stevinlab. These four configurations were called 'Whole-Up', 'Whole-FF', 'Whole-BB' and 'Cut-Double-BB'. The results showed that the Whole-Up had the highest vertical failure loads, followed by the Whole-FF and Whole-BB configurations, and the Cut-Double-BB have much lower failure loads, which is most likely due to the imperfections at the cut surface. Following these results, two different design options were created. The final prototype contains a demountable glass bottle column with intermediate plates and plastic elements. A proposed design formula for the vertical compressive design load was created based upon collected data and safety factors. The limitations of the bottle column are mainly the tolerance issues due to the different bottle heights and connections, the costs of the connections and the capacity in comparison with more conventional materials. The bottle column could however be an interesting options for smaller or temporary projects.

Vertical greening systems (VGS), i.e. vegetated building facades, can harness the benefits of nature to contribute to resilient and healthy cities. A lack of guidelines for the early selection and design of VGS currently limits implementation. Based on a literature study and expert interviews, this thesis proposes a multi-criteria framework and tool to assist architects and engineers in the holistic selection of multi-purpose VGS. The research compares the performance of different system types on 18 impact criteria, ranging from urban noise reduction to installation costs. Depending on project-specific input about environmental conditions and building project objectives, the framework provides a ranking of the most suitable VGS. Design recommendations ensure a VGS that is fit for purpose. Subsequently, sensitivity analyses, a case study and testing on sample projects validate the usability and results of the tool. The thesis extends current perspectives on evaluating the impact of VGS on the built environment. The tool enables users to make holistic and justified decisions on the application of a VGS.

Politicians, scientific researchers and companies all know; the transition to a Circular Economy [CE] should start now, or actually should have started yesterday. The CE is an economic system that replaces the current take-make-waste linear system and replaces this with the reduction, reuse and recovering of resources. The challenge is to build with limited emissions, depletion and pollution of the living environment. Looking more specifically to a building, the load-bearing structure is responsible for a significant part of the material related environmental impact. In order to reduce the environmental impact of a building, more guidance is needed as the implementation of the CE principles requires a new approach for designing. The principles of the CE are safeguarded in various circular design strategies. Which circular design strategy is most beneficial for the project depends on the requirements and ambition of the project. The resulting difference in environmental impact caused by the design choices should be illustrated. Unfortunately, the current determination methods for the environmental impact do not include the design principles of the circular design strategies. Besides, the environmental impact is assessed at the end of the design process. Once the design is final, adjustment to improve the environmental impact are too difficult or costly. In this research a design tool is developed that makes the practitioners in the building sector aware of the environmental impact of the design choices. Three circular design strategies are presented in the tool that can be followed to stimulate the development of a circular building project. The design tool can be used in the preliminary design phase to create and explore varying structural design variants in line with the chosen circular design strategy. The structural design variants can be compared on their environmental impact expressed in five indicators: the MPG, the environmental performance value (in Dutch: Milieu Prestatie Gebouwen [MPG]), the produced amount of CO2 emission, material usage, expected service life and building costs. The research shows that based on literature review, expert judgement and open databases a design tool can be built, which gives insight in the environmental impact and more design parameters to support the implementation of circular solutions in the preliminary design phase. To meet the unique project specifications different solutions are required. Therefore, the design tool supports the design process with a uniform approach. The outcome of this research highlights three main influential aspects for the determination of the environmental impact; (1) the expected lifespan of the design assumed in the calculation method, (2) the quality of the environmental database of materials and (3) the total applied materials in the load-bearing structure. For the practitioners of the design process it is extremely important to be aware of the effect of changing the expected lifespan and thus the determination method for the environmental impact and the quality of the environmental database used.

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.

Many countries such as Brazil, have a low percentage of recycled container glass due to multiple factors, such as inadequate waste collection and recycling infrastructure, low public awareness about recycling’s significance, and insufficient laws to promote it. In addition, the country faces high levels of homelessness and inadequate housing. As a result, an increasing number of builders are exploring repurposing glass bottles as a construction material for walls, occasionally incorporating them into traditional earthen building techniques. Therefore, this thesis investigates the potential of repurposing glass container bottles for the construction of load-bearing walls for affordable housing in Brazil while at the same time reducing pollution, enhancing aesthetics, and promoting environmental friendliness. The main research question is formulated as follows: How can the structural feasibility of re-purposing beer bottles in Glass Bottle Earth Bricks (GBEB) for wall constructions be ensured? The report consists of four parts, which are created for each research area: state of the art, experimental investigations, numerical investigations, and finally the discussion, conclusion and recommendations section. The literature review underscores a rising trend of incorporating glass bottles into earth-based constructions, driven by their shared advantages of environmental friendliness and affordability. Nevertheless, challenges emerge in connecting glass bottles when constructing walls with mortar due to their irregular shapes. To enhance construction efficiency and quality, innovative methods entail pouring mortar between the bottles rather than applying it manually. This approach is complemented by creating bricks while using molds where the bottles are placed inside, facilitating easier stacking and faster execution. The direct integration of glass bottles into bricks further expedites the process. Prefabricating these blocks with pre-placed glass bottles in controlled environments further optimizes efficiency. During experimental investigations, a self-compacting earth-based mortar mixture is formulated using local Dutch soil from Emmen. Five different mixture designs are explored, utilizing both artificial and natural soil. The mechanical properties of the earth-based mortar mixtures are evaluated through compressive and flexural strength tests, as well as a mini slump flow test to assess workability. The selected earth mixture is anticipated to achieve an average compressive strength of 12.1 MPa after 28 days, an average flexural strength of 3.67 MPa after 7 days, and a flow diameter of 23.05 mm. Subsequently, a prototype glass bottle earth brick containing a horizontally aligned longneck beer bottle is produced, revealing a compressive strength ranging between 8.21 and 11.40 MPa after 28 days of casting. Upon failure, a fracture analysis indicated that the origin of failure lies at the bottom of the bottle, with breaking stresses at failure measuring 608 kg/cm² and 431 kg/cm² for two samples. Results from SEM-EDS analyses reveal iron and aluminum residue at the fracture origin in the glass bottle. The earth mortar cast around the bottle showcases a similar composition, suggesting that scratches were likely introduced during brick manufacturing by the earth mixture. Additionally, an initial evaluation of the thermal behavior of the Glass Bottle Earth Brick (GBEB) indicates that the mortar acts as a heat sink, suggesting that the GBEB could contribute to thermal comfort. Through numerical investigations employing Finite Element Methods (FEM), a comprehensive understanding of stress propagation and behavior within a Glass Bottle Earth Brick is achieved. Modeling the brick with the bottle from laboratory experiments aligns with expected peak stresses. However, the Finite Element Method (FEM) model's simplification disregards knurls, the ribbed patterns commonly present on the outer bottom surface of the bottle. Simplifying the model by removing the knurls lowers the computational complexity but potentially overestimates the strength of the GBEB. This underscores the importance of considering knurls to accurately predict peak stresses. Based on these findings, it is inferred that repurposing glass bottles for constructing walls capable of supporting small-scale structures is feasible. However, since this represents a novel building approach, it demonstrates potential while also highlighting the need for further investigation and clarification. Increasing the number of samples tested and expanding the range of factors examined can enhance confidence and provide insights into the material results and assumptions made.

A large number of offshore wind turbines have been installed in recent years, and even more are being erected in current and future projects. The majority of these turbines have been or are being built of monopile foundations. Eventually, both the turbine and the foundation have to be decommissioned. However, decommissioning options for monopile foundations are limited, especially for complete removal of the foundation. This thesis aims to study a new removal method patented by the company Iv-Consult, which could potentially make entire monopile removal possible. The method uses deformation of the monopile wall by a clamping tool to generate a vertical force. Since the thesis served as a preliminary study into the removal method, it was chosen to limit the scope of this study to the monopiles that are expected to be decommissioned in the near future. With this information, a single case of monopile with dimensions that are representative for these monopiles was presented. To analyse the removal method on the case monopile the finite element method was used. In order to ensure results obtained using the finite element method are accurate and representative, a convergence study was carried out. To determine the element type and the mesh size that was the most suitable, two different models were used: a ring model and a small cylinder model. Each was studied using different combinations of inputs. After the results from the convergence were obtained, these results were used on the models with which the removal method was studied. Different configurations of the removal method were analysed with the aim of maximizing the force that can be generated by the method to overcome resistance forces. As a final step, the resistance forces that need to be overcome were calculated for different soil types and compared to the results obtained from the removal method models to verify the feasibility of the method. From the results of the convergence study, it was shown that it is possible to model the removal method using the finite element method and obtain representative results. The final results of this thesis showed that clamping the monopile multiple times does not have a positive influence on the vertical force that can be generated. This is because clamping the monopile only once caused the highest vertical force. However, the forces generated using the different setups of the clamping method were not sufficient to overcome the resistance forces. This shows that the removal method in the current configurations is not feasible, without applying any soil resistance reducing methods.

A large number of offshore wind turbines have been installed in recent years, and even more are being erected in current and future projects. The majority of these turbines have been or are being built of monopile foundations. Eventually, both the turbine and the foundation have to be decommissioned. However, decommissioning options for monopile foundations are limited, especially for complete removal of the foundation. This thesis aims to study a new removal method patented by the company Iv-Consult, which could potentially make entire monopile removal possible. The method uses deformation of the monopile wall by a clamping tool to generate a vertical force. Since the thesis served as a preliminary study into the removal method, it was chosen to limit the scope of this study to the monopiles that are expected to be decommissioned in the near future. With this information, a single case of monopile with dimensions that are representative for these monopiles was presented. To analyse the removal method on the case monopile the finite element method was used. In order to ensure results obtained using the finite element method are accurate and representative, a convergence study was carried out. To determine the element type and the mesh size that was the most suitable, two different models were used: a ring model and a small cylinder model. Each was studied using different combinations of inputs. After the results from the convergence were obtained, these results were used on the models with which the removal method was studied. Different configurations of the removal method were analysed with the aim of maximizing the force that can be generated by the method to overcome resistance forces. As a final step, the resistance forces that need to be overcome were calculated for different soil types and compared to the results obtained from the removal method models to verify the feasibility of the method. From the results of the convergence study, it was shown that it is possible to model the removal method using the finite element method and obtain representative results. The final results of this thesis showed that clamping the monopile multiple times does not have a positive influence on the vertical force that can be generated. This is because clamping the monopile only once caused the highest vertical force. However, the forces generated using the different setups of the clamping method were not sufficient to overcome the resistance forces. This shows that the removal method in the current configurations is not feasible, without applying any soil resistance reducing methods.

Traditional approaches to noise barrier design often rely on outdated techniques and resource-intensive materials like concrete and steel. However, with sustainability gaining prominence, aligning noise barrier design with green construction principles becomes crucial. Structural optimization, aimed at minimizing material usage, emerges as a promising strategy to mitigate environmental impact. This study focuses on determining the optimal geometry of a noise barrier composed of low-tensile strength material, under the influence of self-weight and uniformly distributed lateral load. The methodology employed addresses this question through a series of key steps. Beginning with a two-dimensional analytical form-finding process, optimal cross-sections are derived for the noise barrier. The application of uniform strength theory, known for its efficiency in generating material-effective structures, results in constant stress shapes. These solutions are validated using Finite Element Analysis (FEA) to ensure conformity with predefined stress criteria. Subsequently, numerical structural optimization is conducted to achieve minimum weight geometries that adhere to stress constraints, utilizing a penalty function. The validation process involves comparing numerically optimized geometries with analytical solutions, confirming their reliability and mutual consistency. This validated optimization approach is then extended to three dimensions, exploring the optimal combination of longitudinal profiles and varying cross-sections along the barrier. Analytical solutions for 2D uniform strength cross-sections of the noise barrier differ based on load conditions. For self-weight, an exponential function describes constant stress, ensuring uniform compressive stress across the structure. Conversely, under uniformly distributed lateral load, a linear function depicts constant maximum bending stress along the height. The interaction between self-weight and lateral load results in symmetric geometries defined by specified constant tensile stress. A square root geometry guarantees constant zero tensile stress, offering advantages like reduced need for additional structural elements and practicality in real-world scenarios. A significant distinction arises between 2D cross-section and 3D structural optimization regarding bending capacity. In three dimensions, the entire structure contributes to bending resistance by shaping itself. Releasing the rotational degree of freedom at the bottom support enables the generation of a corrugated longitudinal profile, enhancing bending stiffness. This corrugation distributes bending moments over longer spans, reducing stress and material requirements. Notably, the optimized corrugated profile exhibits enhanced bending stiffness, minimizing the impact of practical constraints. In summary, this research provides insights into optimal geometries for free-standing structures, highlighting the efficiency of analytical and numerical approaches. The numerical optimization framework proves highly effective and efficient, contributing valuable insights to noise barrier design within a sustainable framework.

This thesis report provides an analysis of the structural behavior of façades made of CLT panels with openings. These openings will have a significant influence on the transfer of forces in the panels, as well as the stiffness of the façade. The connections required to transfer the forces between the panels are designed. Deformations of the connections introduce addition deformation of the façade itself. The components that influence the force transfer and deformation of the façade have been identified in this research. Their contributions have been investigated. The theoretical calculations have been compared to computer results. The resulting conclusions aid designers in an early design phase regarding the feasibility of a CLT façade structure. The main focus of the research has been on the mechanical fastener connections that are required for the CLT façades. The research question is stated as: “What is the influence of mechanical fastener connections on the strength and stiffness of CLT façades that function as the main stability system?” The research started with the goal to find the limitations of CLT façades for multi-story timber buildings. In order to find these limitations, a complete understanding of the structural behavior of the façade was required. Since connections were found to be of great influence the research focused on this topic. The structural behavior of the façade was defined as the top deformation of the structure and the force transfer and resulting stresses in the panels. The dynamic response of the structure has not been analyzed. Seven components were identified that influence the stiffness and force transfer in the structure. Bending of the façade Shearing of the façade Bending of lintels Bending of piers Sliding of connections Rocking of connections Additional bending deformations due to connections Computer models were used to verify the overall behavior of the façade as found with the theory. The computer model did not verify each individual component. Peak shear forces in the CLT panels near the corners of openings determine the required panel thickness. When these shear forces are reduced (for example by applying a concrete core in the structure) the required panel thickness can be reduced. Top deformations of a façade with a width of 20 meter limit the maximum height to 45 to 55 meter, depending on the connection stiffness. The main contributor to the top deformation is the connection stiffness of the connections between the vertical edges of the CLT panels. These influence the collaboration between the panels, hence significantly affect the bending stiffness and corresponding bending forces in the panels. The lintels of the façade panels highly influence the load distribution in the façade. There is no accurate method to calculate this influence on the load distribution.

The current understanding of auxetic metamaterials in structural engineering applications is limited. Auxetic materials exhibit lateral contraction under compressive loads, possessing a negative Poisson's ratio. The research addresses this gap, focusing on the use of auxetics for steel reinforcement in structural concrete elements to enhance sustainability by reducing material usage without compromising safety. The research goals include: Describing the state of the art in auxetic materials for concrete structural elements. Investigating auxetic behavior under different loading conditions (compression, tension, shear, and bending). Developing a geometrical design for auxetic steel reinforcement, considering practical aspects like manufacturability and mortar flow. Performing numerical analyses on proposed beams under various loading conditions, comparing Young's modulus and Poisson's ratio. Exploring upscaling solutions for architected metamaterials. The research follows a systematic approach: Literature Study: Examines the use of auxetics in concrete structural elements. Selects a bow-tie architecture for its adaptability and manufacturability using Laser Powder Bed Fusion (LPBF). Geometrical Study: Focuses on a cantilever beam subjected to rotation, ensuring pure bending with a linear geometry. Chooses a range of unit cell angles for desired structural behavior. Designs unit cells and beams, considering compatibility, continuous lattice, and manufacturability. Numerical Study: Utilizes FEM software (ABAQUS) to analyze effective Young's modulus and Poisson's ratio. Validates models against literature using Euler-Bernoulli beam theory. Studies the influence of boundary conditions on results. Upscaling Technologies: Explores technologies for upscaling auxetic lattices beyond current LBPF methods. Proposes multi-robotic fabrication for automated assembly using conventional rebar. Findings and conclusions include: Selected Architecture: Chooses bow-tie architecture for its modifiability and manufacturability. Proposes "single cells" and "three angle" units for different loading conditions. Design Expansion: Develops a stacking sequence for a 3D lattice, considering dimensions and relative density. Creates beams with auxetic, cubic, non-auxetic, combined, and gradual behaviors. Numerical Model Conclusions: Affirms constant moment and zero shear in designed beams. Emphasizes the dominance of effective modulus in lattice geometry. Validates Poisson's ratio behavior in different beams under pure bending. Upscaling Proposal: Recommends multi-robotic fabrication for full-scale lattice construction. Uses software like Rhinoceros 7 and COMPAS FAB for design and control. In summary, the research contributes to understanding auxetics in structural applications, providing insights into their behavior under various loads, proposing practical designs, and exploring upscaling possibilities. The proposed approach and findings aim to advance the use of auxetics in steel reinforcement for sustainable and safe construction practices.

According to the European Commission, buildings are responsible for approximately 40% of the EU energy consumption and 36% of the CO2 emissions, resulting in the largest energy consumer in Europe. Especially, the reduction of energy consumption for heating of residential dwellings has gained more and more interest in the last decades. Although some reduction has been achieved by implementing passive or active strategies and improving the thermal performance of new or renovated dwellings, the decrease is found to be lower than predicted by the energy performance models. One possible reason is that the existing thermal comfort models, the PMV and the adaptive thermal comfort model, are not appropriate for all different types of buildings and climates, resulting in inaccurate predictions of thermal comfort and leading to amounts of energy use different than the actual ones. In addition, the occupants’ behaviour, which is determined by their thermal comfort preferences might play a significant role on the energy use which needs to be explored. Therefore, the main topic of the current thesis is to explore the relationship that different parameters such as dwelling and installation characteristics, indoor and outdoor climate parameters, household and physiological characteristics as well as occupants’ behaviour have with thermal comfort and energy use. A measurement campaign took place within the context of the OPSCHALER project and data related to thermal comfort perception, indoor climate and energy consumption was collected for 96 dwellings in the Netherlands during periods ranging from two to twelve months over a one-year period (2017-2018). The gathered data included both quantitative and subjective data. The quantitative data included the indoor climate data (air temperature, relative humidity, CO2, presence), the gas use and the electricity use collected through smart meters and sensors. The subjective data related to comfort was gathered by a comfort mobile application where users recorded their thermal sensation and other comfort related parameters (thermal preference, clothing, metabolic activities, actions), while questionnaires and inspections did also take place. This data was analysed using different types of graphical representation (bar charts, pie charts, stacked bar plots, scatterplots) as well as statistical tests such as chi-square tests, regression analysis, Kruskal-Wallis and correlation tests. Due to limited or unavailable data only 78 dwellings were included in the analysis, while the reliability and generalisation of the results entails some uncertainty due to the number of dwellings and data points available. All in all, it was found that the thermal sensation is correlated with the four comfort related factors (thermal preference, clothing, metabolic activity, action), the indoor air temperature as well as the energy labels and the ventilation types, while only age was resulted in not being associated with thermal sensation. Indoor air temperature was found to be related with the energy label of the dwellings, but not with their ventilation type. In addition, the results indicated that the heating energy use is related with the outdoor air temperature as well as with the indoor-outdoor air temperature difference, but not with the indoor air temperature. Energy labels and ventilation types were found to be related with the heating energy use, while thermal sensation, actions and income did not show any correlation with it. Based on the findings it is concluded that the adaptive thermal comfort model is more accurate and closer to the reality of a residential environment in comparison with the steady-state PMV model, where no adaptations take place. However, it is highly recommended that instead of improving the existing thermal comfort models, personalised comfort models could be developed for each single person separately by gathering data using sensors. This would help to trace all different parameters that influence the thermal comfort and the energy use as well and lead to more accurate prediction and lower actual energy use.

The starting point of the thesis relates to the “Rotterdam Mountain” Project, envisioned by the Rotterdam Dreamers, which proposes an artificial mountain in the otherwise flat landscape of the Netherlands, supported by a cable network that is spanning between multiple high-rise towers. This network has the double function of supporting the weight of the mountain and connecting and stabilizing the towers. With the “Rotterdam Mountain” Project as a starting point, the thesis aims to investigate the structural feasibility and performance of a new typology for the design of high-rise towers, where a cable network interconnects and stabilizes them. The goal of the thesis is to investigate the design of such a system with respect to relevant parameters, as the relative position of the cable-net (RPC) or the spacing between towers (SBT). Such, a core system to which the cable-net is connected is used throughout the thesis. To understand the relative influence of different parameters, a parametric approach (in Grasshopper) is used, that allows for a rapid change of the initial properties of the system. The Grasshopper script is linked to the Robot Structural Analysis (RSA) software, where a non-linear analysis is performed. The outputs of the RSA analysis refer to both the serviceability limit state and ultimate limit state, as both the core and cable-net are designed to meet the stability and strength requirements imposed by the Eurocode. Based on the Eurocode checks, conclusions are drawn on the preliminary design of the system, by identifying multiple design zones with respect to the two relevant parameters: a zone where the stability of the core is governing (for a SBT of up to 90 meters, and an RPC of up to ~0.6), a zone where the strength of the core is governing (for a SBT higher than 90 meters or an RPC higher than ~0.6), or a zone where the influence of the cable-net is negligible (for an RPC lower than ~0.1). Conclusions are further drawn on the performance of the system, by comparing it to the simple core and outrigger systems. It is observed that the proposed core + cable-net system performs (at least) as good in terms of stability and strength with less material usage. A concrete weight reduction of the core of up to 50% is observed when compared to the simple core and a steel weight reduction of up to 20% is observed when compared to the outrigger. From an economic point of view, preliminary calculations have shown a reduction of the total weight of the structure of up to 14%, due to the increase in slenderness when the cable-net is placed. This is equivalent to a number of up to 5 extra floors that can be constructed with the same amount of material. With these remarks in mind, it is concluded that, based on this preliminary study, the cable-net stabilized towers can pose a feasible alternative to the design of high-rise towers, and they can be efficiently used for the ambitious “Rotterdam Mountain” project.

The application of vertical forests in the building industry is a popular development with promising advantages regarding sustainability. However, placing trees along a façade gives additional loads which often results in extra material use. This is undesired concerning building design, costs, and the environment. To mitigate these adverse effects, trees could be used as load-bearing structural elements. To increase the stability of such elements, it might be advantageous to connect the trees to each other. Such connections can naturally be created with inosculations: self-growing connections in which the bark and inner tissue of two trees merge. Applying living trees as structural elements requires a deeper understanding of both the botanical and structural behaviour of trees. Likewise, more must be known about the botanical and structural behaviour of self-growing connections. This research expands the knowledge on the topic of using living trees as structural elements, both as single tree elements and self-growing interconnected tree elements. This aim is reached by proposing a structural model of (interconnected) trees, which is verified by comparing the outcome of the model with the outcome of winching tests. Furthermore, a design is made in which living trees are used as structural elements in a vertical forest case study. This lays the groundwork on how to approach a living tree design, both from a structural and botanical point of view. The structural model is verified by carrying out winching tests on the Living Tree Pavilion, including one single tree, one pair of cross-connected trees and one pair of parallel-connected trees. Additionally, winching tests are performed on a tree in an airpot, in which boundaries constrain the root system. During the winching tests, a force is applied to the tree system, and the elongation is measured on several locations of the tree, providing insight into the strain distribution. Additionally, the displacement of the trees is measured at the height of the force application. Based on geometry measurements, the trees are modelled as solids in a finite element software. From the models of the interconnected trees, a compound solid is created which behaves like a single solid. The winching load is applied to the models to allow for a comparison between the results of the winching tests and the models. The geometry measurements show indications that leaning trees create an oval cross-section, which is influenced by the presence of inosculations. The winching tests show that an unconstrained root system is stiffer than a root system constrained by an airpot. Furthermore, the tests show that interconnected trees do not have favourable stiffness qualities compared to single trees. A comparison between the model and test results indicates that the finite element model is a plausible representation of reality for the single tree, the parallel-connected trees, and the out-of-plane results of the cross-connected trees. The finite element model fitted poorer with the in-plane winching test results of the cross-connected trees. More research is needed to determine whether diverging tree characteristics, in the direction that is rarely subjected to loads, could explain the discrepancy in measured and modelled behaviour. Two designs are created in which living trees of the Wonderwoods vertical forest carry the loads of a plant container. There are three reasons why cross-connected trees are not favourable over a design with single trees. First, the single trees can bear the plant containers at a younger age. Second, the risk of trees not creating suitable inosculations is high. Third, as interconnected trees share one container, the competition for space can become fierce. This research concludes that a system of interconnected trees as structural elements is not favourable over a system of single trees. This is mainly because no clear advantages in terms of strength and stability could be found in both the winching tests and the design for Wonderwoods.