The aim of this thesis is to investigate and quantify the efficiency of high capacity self-stabilising modules in mid-rise residential buildings. These modules have a higher stabilising capacity than modules that are currently being used in the Netherlands and other countries and can therefore be used for more storeys without requiring an additional stabilising structure such as a concrete core. In the first part, reference projects and case studies are looked at to get a good understanding of the current applications in The Netherlands and the United Kingdom. After analysing four case studies, an assessment is done on the functional efficiency, structural capacity and environmental impact of these modules. By doing so, the load-bearing structure of self-stabilising modules that can be used at a greater height can be identified. Design variants can now be drafted with different bracing configurations, which are later verified on strength and stability requirements. To effectively design a suitable braced frame, it has been researched what the displacement components for braced frames are. This has been done for simple frames without eccentricity as well as frames including eccentricity. Apart from single-cross frames with a relatively large span, double-cross frames are also looked into due to their increased stiffness. As part of the total structure of the building, a design for the foundation as well as the inter-module joint, which is required to be demountable, has been made. These parts of the design are required to calculate the horizontal displacement during lateral loads. A structural assessment is done on the stabilising capacity of each variant at 8 storeys. The design adjustments that are required to further increase the number of storeys up to 10 are looked into as to see whether or not an efficient structure can be maintained. It turns out that each design variant requires adjustments that reduces the efficiency. These changes are the result of a large increase of braced span, resulting in either inefficient use of beam profiles or a too large length when there is more than one braced span along the length. Apart from a structural assessment, the functionality and environmental impact of the design variants has been analysed as part of the overall efficiency of the modules. The functional assessment includes several criteria such as wall-to-floor area and space efficiency factor. Using the required material use in partition structures and load bearing elements, the environmental impact is calculated, resulting in values for the embodied energy and embodied carbon per square meter in each design variant. Since the differences between the design variants are relatively small, they are also compared to four case studies that were done before. On the basis of the results of this research, it can be concluded that self-stabilising modules can be constructed with different possible bracing layouts and an efficient load-bearing structure up to 8 storeys.

The building and construction industry is one of the main polluting sectors contributing to climate change, and is responsible for around 37% of global CO2 emissions. A circular approach is needed to address the global demand for construction materials and resources in a sustainable way. Steel is a commonly used material in construction and fully recyclable. Recycled steel has to be melted in a furnace, which is a polluting process. For reuse of steel only disassembly and transport is necessary. The general shift from recycling to reusing steel can offer environmental benefits. A number of steel bridges in the Netherlands are being renovated or replaced by Rijkswaterstaat in the coming years. Rijkswaterstaat has been investigating the reuse of its bridges on object level, i.e. reusing the complete structure. This has proven to be difficult. Disassembling the bridge and reusing the structure on an element-level has not been thoroughly investigated. As reuse of construction elements in general is relatively novel practice, not much is known about how to determine the reuse potential of structural bridge elements. This thesis aim to identify current knowledge gaps and provide research results that encourages future reuse of steel bridges. As a case study the eastern Van Brienenoord bride is investigated. This bridge is scheduled to be replaced in 2026-2028 and there currently are no plans for reuse. The goal of this thesis is to examine the reuse potential of steel bridges on element-level, focusing on two critical factors: fatigue and corrosion. Fatigue and corrosion are two of the most deteriorating processes for steel bridges. The reuse potential can be evaluated using the remaining service life of the elements. The remaining service life based on both fatigue and corrosion can be determined by implementing the corrosion assessment in the fatigue calculation. Fatigue assessments are based on stress ranges in structural members. Corrosion leads to a reduction in the cross sectional area, increasing the stress and thus stress ranges occurring in the critical structural details. The design, decomposition, loading history and technical condition of the eastern Van Brienenoord are analysed. After critical review of the Van Brienenoord the structural elements of the bridge deck are selected to investigate further. Inspection reports by Rijkswaterstaat and Nebest are used to locate corrosion damage on the Van Brienenoord. The corrosion damage is determined using functions for uniform surface corrosion for steel. The critical structural details of the selected elements in the bridge deck are identified. Using the fatigue assessment procedure described in the Eurocode in combination with the reduced cross section the remaining service life of the structural elements is determined. According to the results of the proposed assessment method in this research, all structural elements of the eastern Van Brienenoord bridge deck have significant service life left and are therefore suitable for reuse after disassembly. However, certain specific details that have a higher calculated fatigue damage may need to be repaired or removed.

To stick to climate change targets and reduce global carbon emissions, the building sector needs to adopt a circular economy. In the steel sector, reuse or elements can reduce carbon emissions which are created in today's steel scrap recycling practices. This thesis contributes to closing the knowledge gap on design, costs, and environmental impact score for working with reclaimed steel elements. The tool Steel-IT is created to research the business-case and environmental impact score of low-rise office buildings. Steel-IT uses a donor element database and new office design, which are specified by the user, and generates new and reclaimed steel design alternatives. Using a weight and activity-based costing method, the costs of these design are estimated. Life-cycle analysis is used to quantify the impact. By generating results and analysing the effect of the input in the tool Steel-IT, the following conclusions can be made regarding the business-case and impact score of reclaimed steel in low rise office buildings. A case study using Steel-IT shows that a 25% impact reduction against minimal cost increase is possible. For this, the match between design and donor elements needs to be good. This match can be searched for using Steel-IT. In terms of design, connection detailing is the most critical factor in the success of a donor steel skeleton. Donor steel elements should be sourced from an existing building to limit storage costs and should not have toxic conservation systems applied to them. Both induce extra costs and make the business case of donor steel less competitive with new steel. In the future, currently suggested emission taxes do not affect the business-case significantly as these taxes are low compared to the total building costs. The most helpful action to increase the business-case is to apply donor steel more often. If the experience with donor steel and its availability grows, reuse will become easier. Steel-IT can contribute to this as it contributes to closing the knowledge gap on costs and impact and can help to match demand and supply.

A series of critical transmission lattice towers failures due to severe ice and wind loads forced German utility companies to reassess the structural stability of their power grid infrastructure. During the structural reassessment process, a problem related to an outdated or even missing documentation of the in-use infrastructure occurred. This issue forced utility companies to gather the data regarding the geometry of the lattice towers on-site, using specialized and labor-intensive geodetic measuring methods. The scale of the required data acquisition endeavor and stability checks to be performed encouraged the use of alternative methods to capture the geometry of the in-situ structures and reconstruct geometric models to be applied during the structural stability checks in a reliable and efficient way. This work presents an innovative method to generate a geometric CAD model using point cloud data captured by a LiDAR scanner. The CAD model can be later implemented for FEA utilized during structural stability assessments. The modeling process defined in this study is fully automatized, enabling to obtain repeatable results and save the time required for manual data processing. For the input point cloud data, two types: Aerial and Terrestrial LiDAR point clouds have been investigated allowing to identify the applicability of both data sets for the proposed method. The model generated with the automatic method proposed in this study is compared in terms of geo-metric discrepancies to an idealized model based on design documentation and a LiDAR point cloud based model manually generated with a commercial software. The two models used for comparison depict a traditional structural engineering approach and a state-of-the-art method within the point cloud processing field accordingly. At the final stage of this work, the automatically generated point cloud based model is used for a non-linear FEA and compared to a FEA response of the idealized mod-el. Results showcase that LiDAR point cloud data is a good source of geometric information to reconstruct a geometric CAD model which can later be implemented in FEA. Obtained results are comparable to the ones of an idealized model based on design documentation in terms of collapse mechanism and ultimate load applied at the failure step. Additionally, the geometrical comparison between the point cloud based models generated with the manual method and the one proposed in this work underline the ad-vantage of the automatic method in terms of permissible level of detail and overall precision of the final geometric model. What is more, the impact of point cloud data usage for FEA modeling is shown. Investigating differences between FEA results of the point cloud based and idealized models allow to showcase the influence of real life imperfections on force redistribution across the analyzed structure and ultimate forces reached by members loaded in compression. The modeling method and analysis results presented in this work can be applied as a set of guidelines for future applications related to point cloud data processing of steel lattice structures used for FEA modeling purposes.

With the building and construction sector accounting for a significant portion of final energy use and emissions, and society’s increasing focus on environmental awareness and improvements, the impor- tance of sustainable construction has never been greater. The utilisation of timber in construction offers clear sustainability benefits and has the potential to replace traditional functions of concrete. One notable replacement is the use of Cross-Laminated Timber (CLT) in composite structures with steel, enabling the potential creation of greatly performing floor systems which has seen a limited amount of research. The research explores the application of Steel-CLT Composite floor systems and assesses composite beam performance as well as predictive methods for analysing their behaviour in hopes of advancing the body of knowledge on this method of environmentally friendly construction. The literature study revealed the current knowledge on steel-CLT composite floor systems and connections. Two particular floor systems, with and without the use of grout, are highlighted as well the potential for future exploration. The steel-CLT composite connection utilised in the floor system significantly impacts performance and composite action as the use of grout is concluded to increase initial-, secondary stiffness and load carrying capacity of the connection. However, restricting the use of grout can promote circular con- struction practices. In this research the behaviour of steel-CLT composite beams is predicted by the use of a numerical finite element model with shell elements and an analytical approach based on the simplified analysis of Eurocode 5(EN1995-1-1): Mechanically jointed beams. The analytical method can predict the bending stiffness with a margin of error just slightly above 10%. However, it should be noted that the analytical method incorporates an incomplete representation of the composite connection used in the beam. On the other hand, the finite element model is able to accurately capture the pre-plasticity behaviour of the steel-CLT composite beam. This is achieved by incorporating the complete load-slip behaviour of the shear connection. A parametric study was conducted to assess the importance of closely spacing composite shear connections in a steel-CLT composite beam to achieve a higher level of composite action. The study also demonstrates that by utilising connections with higher initial stiffness, secondary stiffness, and ultimate capacity, this effect can be further strengthened. As a result, the force resisted at the service- ability limit state experiences a notable boost due to the implementation of both a stronger and stiffer connection, as well as their close spacing. Shear connection position optimisation by concentration of connectors near the supports showed to have a small positive effect on beam deflection. After evaluation of steel-CLT floor systems the research concludes that a steel-CLT composite floor system can be successfully constructed, offering environmental benefits and reduced structural weight while achieving the required structural performance for the set design conditions.

With the effects of climate change being more and more frequent, the European union, and other governments world-wide are looking for sustainable alternatives for processes and products that are part of the daily requirements of people. Among these requirements, the construction industry plays a vital role, as it accounts for the consumption of about 50% of the total raw materials. In line with its targets of 100% recycling by 2050, the industry in Europe, and particularly in the Netherlands is shifting towards the use of circular and sustainable construction products. This thesis investigates into both these aspects: Circularity by addressing the requirements for demountable structural elements, thus providing scope for reusing, and Sustainability by addressing the impact of substituting concrete and steel with timber products. Structural timber products obtained from sustainable forestry are considered as eco-friendly construction products. The benefits are two-fold: First of all, it is produced or grown naturally, and thus avoids the emission of harmful gases during production. Second, growing timber products helps in CO2 storage for the duration of the technical service life of the product. Thus, increasing the market share of timber products in the construction industry can play a huge and decisive role to achieve the targets of sustainability. The focus of this thesis is on steel-timber floor systems i.e., a floor system with timber slabs supported by steel beams. There are many timber products available that can be used as slabs, as a substitute to hollow core slabs and steel-concrete composite slabs, which are the conventional solutions for floor systems in the Netherlands (the former more than the latter). Owing to the disadvantage of timber in stiffness, coupled with the effects of creep, steel beams are considered for traversing larger spans. From the plethora of steel and timber products that can be coupled together to form a floor system, the best solution is obtained with the help of a Multi Criteria Analysis. This is done by scoring the different floor systems on the aspects of utility, circularity and sustainability. The obtained solution is a conventional non-integrated floor system with Lignatur surface elements as the slab, supported by steel I beams. Lignatur elements are box-shaped slabs that can span over large distances typically required for office use. Being made of sawn timber, it boasts the advantage of being more sustainable than other timber products made of cross laminated timber and laminated veneer lumber. I beams were found to perform better than other steel beams, posing as more accessible for demounting, over the other beams. With the help of a case study, the benefits of the chosen steel-timber floor system were evaluated and compared against the hollow core slabs and steel-concrete composite slabs. Owing to the lightweight nature of timber, the chosen floor system was approximately 45% lighter than hollow core slabs, and 25% lighter than composite slabs. They were comparable in terms of floor height, to the composite slabs. The main benefit was the fact that the use of concrete and/or steel could be substituted with the use of timber slabs, and the supporting steel frame could be lighter owing to the lightweight nature of timber. A life cycle analysis was done to compare the different floor systems. Due to the use of sustainably produced timber, the steel-timber floor system had the least environment impact. Considering the effects of carbon storage meant that the total environmental footprint of the floor system could be negative. On further analysis, by excluding the benefit of carbon storage, the steel-timber floor system was still found to have the least impact (39% lesser than hollow core slabs, 31% lesser than steel-concrete composite slabs). Another aspect that was investigated in this thesis was whether the consideration of composite action (similar to that in steel-concrete) could lead to any benefits i.e., composite action between the timber slab and the supporting steel beam. Based on the calculations in the case study, it was concluded that there were no such benefits i.e., the reduction in size of the steel beams was not enough to justify the use of added shear connectors. Another limitation of timber was found to be its lack of reusability. Being a biomaterial, timber is associated with a large reduction in strength for each reuse (although this reduction cannot be quantified using the present state of the art). Other materials such as steel and concrete do not experience this strength loss, and thus assume to have better performance than timber regarding this aspect. The main barrier for implementing a steel-timber floor system would be in terms of costs. Though not explicitly investigated into in this thesis, it is expected to be more than that for its conventional counterparts. Currently, hollow core slabs are the most widely used, in the Netherlands, which is mainly owed to its low costs. Thus, the circulation of a product is closely related to its costs in the market. By showing light on the benefits of the steel-timber floor system, it is expected that the results of this thesis will help the industry shift to the more responsible choice, in the near future. Wider circulation of steel-timber floors can help in reducing its costs, thus making it more desirable.

The development towards a circular economy has many hurdles to overcome. For the construction sector an important step in this process is the transition towards reusing structural elements. Prefabrication of elements is a significant step towards achieving this concept. However, a case where both prefabrication and reuse are limited is the replacement of bridge decks. Headed bolts are welded to the steel supporting elements and encased in grout to connect them to the concrete deck elements. This method prevents reuse of the deck elements and hinders reuse of the steel supporting elements. Research and literature exists on a number of alternative shear connectors that increase the modularity of these elements. The best alternatives have a single limitation in common: the allowed deviation for the placement of the shear connectors and bolt holes is smaller than is feasibly possible. The variances of element placement during construction add up to make it incredibly hard for these low tolerance connections to be made. The bolt hole diameter can be increased to increase the deviation tolerances. The large nominal hole clearance this results in needs to be considered. This can be done by using either resin injected bolts or High Strength Friction Grip (HSFG) bolted connections. Using HSFG bolted connections is preferred due to the shorter time spent on site and minimal waste, but research on the subject is sparse. A proposed HSFG bolted connection that implements significantly oversized holes, defined as bolt holes with a nominal hole clearance roughly equal to the bolt diameter, and cover plates was designed together with both a control and regular connection to compare its behaviour with. The control connection is identical to the proposed connection with the exception of its holes which are normal sized. The regular connection has normal holes and does not include cover plates. Finite Element Models (FEM) were made of these connections that were subjected to static loading in a Finite Element Analysis (FEA). Test specimens of these connections were made and subjected to fatigue loading. The numerical results of the static FEA showed that the use of cover plates reduced the stiffness and slip load of the connection. The second observation was the small impact that the hole size had on the slip load when using cover plates. This small impact becomes negligible at design preload. The experimental results showed that the impact of larger bolt holes increased the loss of preload by roughly 1% during both short term relaxation and fatigue loading. The effect of the bolt hole size on the slip after fatigue loading was also concluded to be negligible, but the effect of the cover plates was concluded to be detrimental. It was overall concluded that the use of significantly oversized holes in HSFG bolted connections with cover plates is viable. The negative effects caused by the cover plates and required longer bolt make it preferrable for large disc springs to be used instead of thick cover plates. The viability of the concept allows for further research on the subject.

Structural joints influence the design strength, material requirement of a structure. Structural joints experience damping dissipation due to friction damping or hysteresis damping. Damping is often used for reducing the vibrations in a structure. However, large amount of energy dissipation leads to deterioration of the material used for constructing the joint. Hence it is important to identify the system parameters like stiffness, viscous damping, friction force as well as the hysteretic restoring force that cause the energy dissipation in the structure. For identifying the uncertain system parameters like stiffness, viscous damping and magnitude of friction force, the SINDy algorithm is extended by using stick and slip temporal constraints. This is done by segregating the data of external forcing and response of SDoF system, applying the existing SINDy algorithm and applying the sticking and slipping conditions in the time domain. The proposed Extended SINDy approach estimates the system parameters more accurately compared to the existing SINDy algorithm. For studying the hysteresis in the structural joints, a pinned column base-plate was considered in an elastic region. Further, the Dahl model with different slope parameter for each branch of moment-rotation hysteresis is employed. The correct values of parameters are estimated using the Bayesian Optimization technique. This procedure yields a functional form representing a resisting hysteretic moment-rotation behaviour in a structural joint with good accuracy.

To align with the objective of the European Green Deal [46] policy of achieving net-zero greenhouse gas emissions by 2050, the construction sector must transition to a circular built environment. Most of the waste in the Netherlands is related to construction and demolition waste, with the industry accounting for approximately 35% of CO2 emissions [89]. The goal of the circular built environment is to minimise waste by reducing, reusing, recycling, and recovering materials throughout the life cycle of a product [66]. Therefore, making an impact in the construction industry can lead to a significant reduction in CO2 emissions and contribute to the achievement of the European Green Deal [46]. This research contributes to the "reuse" component of the aforementioned circular built environment goals. Specifically, the focus is on developing a reusable connection between hollow core slabs and steel frames by implementing increased execution tolerances. Increased tolerances are necessary to allow reuse, as alignment-related problems often occur. The research consists of several parts: the design process, structural verification, experimental research on demountability, and environmental impact assessment. The design process comprises a tolerance analysis supported by a Monte Carlo simulation, variant studies, and a comprehensive qualitative trade-off analysis. After the best scoring alternative is determined, the verification part assesses the structural behaviour of the connection in terms of strength and stiffness. This is done using a combination of analytical and numerical calculations. The purpose of the experimental research is to investigate the demountability potential of the reusable connection. The final part of the research investigates the impact of the reusable connection compared to conventional connections for different lifecycle scenarios. The research demonstrated that incorporating additional tolerances in the connection between the hollow core slab and steel frame is crucial to achieve a reusable construction. Three connection alternatives were generated that can incorporate these tolerances based on a literature review and meetings with experts in the field of building construction. The alternatives were weighted on tolerance inclusion, ease of installation, demountability potential, and costs. The best option was identified as a connection consisting of a square hollow section and a bolted shear stud encased in mortar. This alternative outperformed competitors in terms of tolerances, installation, and costs. However, the demountability potential was identified as a critical part of the connection and, therefore, was further investigated experimentally. The experiments showed an increased demountability potential in situations that include pre-treatment. Vaseline-treated specimens showed no signs of chemical bonding and better lubrication compared to oil-treated specimens, resulting in the lowest resistance and, therefore, the best demountability. The last step of the research investigated the environmental impact of the reusable connection and compared it with the conventional construction technique. Results showed that a marginal addition of 1.3% to the initial environmental impact of the superstructure results in a significant reduction over the full lifespan of the structural elements. This was attributed to the reusability of the connection and the ability to reuse structural elements in another building in a second life cycle. From the results, it is concluded that a reusable and structurally feasible connection between hollow core slabs and integrated steel beams can be created with a small additional investment upfront, resulting in a substantially reduced environmental impact. The purpose of this study is to provide guidance and persuade decision makers, such as project developers, building owners, and government organisations, to consider implementing reusable construction methods in their real estate projects. By doing so, they can contribute to the objective of the European Green Deal [46] policies and the goal of achieving net-zero greenhouse gas emissions by 2050.

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.

The characteristics of the joints play a considerable role in the stability of grid shells. Therefore, the connections are usually assumed to be rigid during the design phase. However, considering the semi-rigid behaviour of connections in the design could be beneficial. This leads to two major challenges. (1) The application of semi-rigid joints increases the indeterminacy of the structure. And (2) the current connection design strategy is not well-equipped for the integration of semi-rigid connections in the design. The following research questions is formulated: How can a semi-rigid approach to steel connection design and considering the semi-rigidity of the joints, be combined in a parametric design strategy for grid shells? To answer this, three objectives have been formulated. Objective 1 focusses on the connection design, creating a design method for connection based on a pre-determined stiffness. Objective 2 focusses on the influence of joint stiffness on the structural behaviour of grid shells. Objective 3 is to design a grid shell, applying the results from objectives 1 and 2. Finally, the method is applied to a case study. Results from objective 1 show that the load ratio can significantly influence the stiffness of connections. Also, design parameters, such as plate thickness and bolt spacing, can be adjusted to achieve different stiffness values. Combining these findings, a design space is generated to enable stiffness based connection design. Results from objective 2 show that the axial stiffness and the out-of-plane bending stiffness of the joints are relevant for the stability of the shell. Depending on the boundary conditions, shape and size of the shell, also in-plane stiffness parameters are relevant. For objective 3, a design workflow is proposed. A design space for the connections is combined with joint stiffness optimisation, resulting in the design of a grid shell with reversible connections. The application is checked with a case study of the C30 Shell. Complexities with increased size of the shell were managed by segmentation of the shell and clustering of the nodes. Resulting in a structure with 58% reversible joints. The following conclusion is drawn: A semi-rigid approach to connection design and the inclusion of semi-rigidity of the joints in the structural design of a grid shell can be combined in the design of a grid shell. This can be achieved by defining a relation between the connection design and the joint stiffness design. This way, a design space can be created that links the connection design to pre-determined stiffness requirements and load ratios in the structural design. Which allows for efficient design iterations and eliminates guesswork in the design of both the connection and the joint stiffness distribution of the shell. For effective application of this method it is important to be aware that the initial design largely determines the efficiency of the end result. The effectiveness of the stiffness optimisation, the segmentation of the shell, and the clustering of the joints all impact the result of the design significantly. Future research could be directed towards a better understanding of these aspects.

In the Netherlands, there are hundreds of operational locks for both recreational and inland shipping. Due to the growing economy, inland shipping is expected to increase in the future. The growing economy causes an increased likelihood of ship collisions with infrastructure, currently estimated at approximately 50 cases per year in the Netherlands. It is necessary to determine the collision energy of a vessel to account for collisions, because this clarifies the potential load. In the context of determining the collision energy for ship collision, the guidelines of the Eurocode, PIANC, and AASHTO involve uncertainties and exhibit variability among them. Therefore, the thesis was initiated to provide more accuracy in the estimation of collision energy in the event of ship-lock collisions. The main objective of this thesis was to enhance the structural design process of lock gates regarding ship-lock collisions. This was done by improving the understanding of the effect of potential loads occurring at a ship-lock collision, and using basic mechanics to estimate the energy absorption capacity of the lock gate.

The demand for offshore wind energy has never been higher, yet the number of ideal areas for wind farm installations is decreasing. As a result, larger wind turbines are being placed in deeper waters, which poses opportunities for floating foundations. However, due to the industry's inability to scale up the production of relatively expensive floaters, companies are exploring alternative foundation methods for offshore wind turbine generators in deep water, including the extension of the use of monopiles, which are now being considered for use in water depths up to 60 meters. However, higher loads in deep water require increased stiffness in the monopile structure, which is typically achieved by using larger thicknesses and diameters, resulting in XXL-monopiles. The steel used for these XXL-monopiles increases exponentially for greater water depths, and the designs cross the production limits. This study investigates the use of a guyed monopile as a more favorable alternative to a conventional monopile for deepwater applications with large wind turbine generators in the range of 60-120 meters of water depth and a rated power of 15 MW. The guyed monopile concept involves adding moorings to a conventional monopile to provide additional stiffness at a certain elevation, reducing the required material within the monopile. A numerical model is elaborated where the structure is represented by a one-direction FEM model having two degrees of freedom. The model is supported by springs that represent the soil and mooring system. The soil is modelled by a series of p-y reaction curves. For the mooring stiffness, a nonlinear stiffness approach is used where the axial stiffness and geometry of the mooring are considered. The method is used to determine the maximum stiffness that a mooring system can bring. After that, the mooring system is included in the FEM model. Static and dynamic analyses are performed to determine the response of the structure. The described methodology also implements requirements based on potential resonance (1P and 3P frequencies), ultimate limit state (yield strength, column buckling, and local buckling), and fatigue limit state (fatigue damage due to wind and waves). The static and dynamic responses are validated using Ansys. It is concluded that the moorings can provide enough stiffness to reduce the impact of the acting loads on the structure. A case study is conducted to compare the use of a conventional monopile and a guyed monopile for a foundation based on realistic wind and wave loads. Data of a reference wind turbine and a reference location is taken to find the advantages of a guyed monopile for a realistic case. The study iterates the process for different water depths and varying numbers of moorings. Greater water depths lead to more issues due to resonance and fatigue, which can only be overcome by increasing the diameter and thickness of conventional monopiles. This can also be overcome for guyed monopiles by increasing the mooring stiffness. The results show that the guyed monopile is favored over the conventional monopile in all cases, with up to a 45% reduction in steel required. The case study's findings are used to identify key parameters in the design of a guyed monopile. The sensitivity of the mooring system stiffness is compared to other key design parameters, including monopile diameter, thickness, and embedded length. The study finds that the moorings have a favourable effect on the system's natural frequency. Also, bending and shear stress may be reduced when moorings are applied.

Tensioned membrane structures are increasingly in demand, because of their ability to cover large spaces with minimum use of material. The material’s mechanical properties play a key role in the design of such structures. The shear behaviour is one of the main influential properties of woven textiles during complex deformations, such as the ones in doubly curved structures where the change in curvature challenges the shear-bearing capacity of the textile during its service life. This study provides a methodology to characterise a novel uncoated woven solar cell integrated textile for tensile structure application. It consists of investigating the limit angle, that avoids damage to the inserted solar strips, and the determination of the shear stiffness of the material. To evaluate the applicability of the material, different mechanical properties are assessed. Mono-axial, picture frame and bi-axial tests were used to determine the strength, elasticity and shear modulus. All results have been validated by comparison with existing experimental data of similar architectural textiles. This research introduces a method of investigation of shear properties of uncoated textiles that can be followed to evaluate other uncoated textiles. In addition, it is now possible to start a preliminary design of a tensile structure with the newly developed material. It is the first step in the introduction ofthe new building material.

The need for sustainable solutions in the energy sector has led to the rapid increase of offshore windfarms around the globe. The areas with ideal soil conditions are gradually being occupied, pushing the offshore wind industry to search for methods of installing wind turbines in hard terrain. So far, the installation of monopiles in weak rock, if successful, required the use of additional casings and grouting. In this thesis project, an alternative installation method is investigated, in which the monopile itself is used as casing, avoiding the waste of extra material. The ‘drill-drive’ installation method under investigation consists of an initial drill-out of the rock from the inside of the pile and its subsequent driving into the seabed with a hydraulic hammer. No casing is used and a cutting toe is equipped in the bottom circumference of the pile, being responsible for breaking through the rock. Through finite element analysis, the structural integrity of both the monopile and the cutting toe during the drill-drive process is assessed. A driveability analysis is conducted for a seabed of different types of rock and the first conclusions on the feasibility of this novel installation method are drawn.

This research aims to investigate the influence of Polyisocyanurate (PIR) insulation on small surface load distribution on corrugated steel roofing sheets. PIR foams are used for thermal insulation in industrial buildings. The distribution of surface loads induced by solar panels support structure might be altered by PIR foams. This is completely ignored in the design calculations according to current standard which might results in overconservative designs. In this study, the following main question is going to be investigated using experimental and numerical methods: ‘’What is the influence of PIR insulation on the transverse distribution of small surface loads on corrugated steel roofing sheets?’’. The methodology involves conducting bending experiments to obtain strains and deflection data, which then are validated using numerical models. The experiments have been conducted on corrugated steel sheets supported by rollers. The PIR insulation is connected to the steel sheet by bolts, and a loading cylinder applies vertical force at the PIR insulation panel side. Two loading configurations are selected to simulate the representative loading conditions in real-life structures. Vertical deflections and strains in the bottom flanges of the corrugated sheet are measured during the experiments. The experimental data are used for the validation of the numerical models that are created by using ABAQUS FEA. First, a linear F.E Model was developed and validated with experimental results up to the initiation of nonlinearities. The results of the linear models shows clearly that the PIR layer influence considerably the stress distribution in the adjacent ribs to the one of load application. A nonlinear analysis is conducted to determine the maximum load that the roof structure can resist. To capture geometrical nonlinearities more accurately, eigen buckling analysis was conducted to implement initial geometrical imperfections. Considering the imperfect initial geometry of the steel sheet and its plastic properties, maximum strength of the roof system could be estimated. As a note, the damage in the PIR insulation material was not considered as it is beyond the scope of this study, the material was assumed to be linear elastic. The experiments demonstrate that the behaviour of the roof structure is primarily governed by the rupture of the PIR insulation, occurring prior to any yielding in the steel sheet. The linear numerical model predicts the behaviour of the roof structure within the elastic phase. The linear model can be used to study the influence of the several influencing parameters such as the dimension, PIR material properties and the loading conditions. Expanding the span from 2 to 6 meters with a single mid-span surface load increases the adjacent rib contribution by 20%, meaning that their normalized strain values relative to the load location's maximum strain grow by 20% in the elastic phase. The nonlinear model is employed to establish the force vs. displacement curve and identify the strength of the roof. The non-linear numerical models show that the ultimate load is found to be 8000 N when a single surface load is applied directly on the steel sheet. The experiments show yielding of the steel at 7300 N after the loading jack ruptures both the PIR surface and layer, then the jack reaches the profiled steel sheeting. For design purposes, it is recommended to exclude the influence of the PIR insulation beyond its elastic phase. Compression tests conducted on the specimen revealed damage within the PIR material at a load of 6250 N, which is considered the upper limit for the PIR's elastic phase.

The motivation of the thesis relates to designing grid shells over existing buildings. Grid shell roofs are a way to enclose an existing space structurally efficiently and have minimal interference with the surroundings from an architectural and environmental perspective. The solution results in less material usage than shell structures, and transparency, allowing for more daylight. Joints play a significant role in the design of grid shells, including structural and economic efficiency. It is common practice in engineering to design rectangular patterned grid shells with rigid joints. A rectangular shape is easy to deform by applying load; hence, it needs stiffness and rigidity. On the other hand, triangular patterned grid shells are designed with pinned joints as the triangular shape is stiff enough and does not need additional stiffness in the joints. Considering these points, the following research question arises: How can connection stiffness in the parametric design of grid shell roof structures lead to more efficiency for existing buildings? To answer this research question, the thesis procedure is divided into five steps. First, a literature study provides a clear understanding of grid shell design principles and their joints. Based on the out-of-plane rotational stiffness, a classification system for joints in grid shells is suggested. The Matrix Method is used to find the boundary for rigid stiffness. The boundary for pinned stiffness is found by studying the influence of the stiffness decreasing in a logarithmic scale over the bending moment distribution. Furthermore, to explore the influence of the stiffness over the design of the grid shell, a parametric model is created. The study investigates the structural behavior of a triangular and rectangular grid pattern. Therefore, a comparison of the influence of the joint between a rigid and non-rigid shape will be made. The design criteria include the Ultimate Limit State (ULS) and Serviceability Limit State (SLS). To quantify the results, a case study is applied. The C30 Shell project, now designed and completed by Octatube, will be used as a reference to apply the theory of this thesis. Based on the Eurocode checks, conclusions are drawn related to the effect of the stiffness. The grid shell with rectangular pattern is significantly affected in both Ultimate and Serviceability Limit State with alternation of stiffness in logarithmic scale. However, the stiffness decrease was proved to have no significant effect over the maximum displacements (SLS) but only over the stress distribution for the triangular pattern. Therefore, to find the optimal solution for a grid shell with a triangular pattern, only the ULS unity checks need to be compared. On the contrary, for grid shells with a rectangular pattern, a balance needs to be found between ULS and SLS unity checks. Following this conclusion, the study is focused on the grid shell with a rectangular pattern. Joints are designed for different stiffness to visualize the difference on how to achieve these stiffness in real-life engineering practice. The FEM software IDEA StatiCa is used to design the joints. The joints follow a similar concept with a rectangular hollow section box in the middle where all the joints are connected. While the required stiffness is decreased approaching semi-rigid and pinned, the dimensions of the joint components are also decreased. The reduction of material used also makes the structure more lightweight and less expensive in terms of material. Finally, to answer the research question, an optimization procedure has been conducted. Octopus, an optimization algorithm within Grasshopper, is used. The optimization procedure is divided into four steps. The first step was to find an optimal cross-section for each of the stiffness studied. This step focuses on where the solution with the smallest cross-section and lower stiffness can be found. By finding the smallest cross-section, the material used is optimized on a global scale, being one step closer to the smaller self-weight of the roof structure. The second step aims to find the lowest stiffness possible for the cross-section obtained in step 1. This objective is related to design considerations. By lowering the required stiffness, also the dimensions of the components in the joint can be reduced. Thus the material used is decreased on the local scale. In step three, two smaller cross-sections are iterated for different stiffness to verify that the solution obtained is optimal. The last step consisted in giving an optimal design solution for the connections. Other aspects are considered, such as fabrication practicality and transport limitations. Two types of connections are designed for the grid shell roof. The first connection is designed using only welding and the second connection uses a combination of bolts and welding. The aim is to avoid welding in situ and prefabricate parts of the roof in the factory within the transportation limitations. The fully welded connections allow the prefabrication of roof components off-site. The bolted ones allow connecting these smaller parts in situ. Based on this investigation, it can be concluded: The final solution results in a reduction of the total weight of the joints by approximately 50% from fully rigid to optimal stiffness design. Furthermore, an 8% reduction of the self-weight of the structure is achieved by optimizing joint stiffness. Consequently, it results in reduced imposed loading over the existing building and foundation. This reduction is also beneficial for economic and environmental purposes by being more sustainable in terms of material footprint.

Rijkswaterstaat aims to build circularly from 2030 onward, with the purpose of having a fully circular economy by 2050. Therefore, the aim of this study is to design a reusable modular superstructure, with a small span, which can replace an existing so-called volstortligger superstructure. This is a structure that Dura Vermeer often uses and it regularly happens that these constructions are demolished after a lifespan of, for example, 10 years. This is a waste of materials and therefore an alternative will be investigated in this research. The following research question guides this study: What is the optimal structure, in terms of shadow costs, mass and financial costs, for a modular superstructure? In order to answer this question, a parametric study is performed using the software Grasshopper, using the Finite Element Model plug-in Karamba3D. In this way, quick structural analyses were performed, to explore multiple options. In total, more than 11.000 bridge design variants have been generated, divided over 12 different runs. The model allowed targeted optimization of shadow costs, weight and financial costs. Optimization is achieved by varying the following input parameters: number of steel girders, steel profile girders, outrigger deck, concrete deck thickness, concrete class, outrigger deck, FRP sandwich panel height, facing thickness, web thickness, and fibre volume. In total, 6 different variants would be developed in this way, 3 with a concrete deck and 3 with an FRP deck. However, the optimization results in only 4 different variants, 3 with a concrete deck and just one with an FRP deck. The results show that the variant with the FRP deck is indicative for Shadow costs, Financial costs and weight. After the four pre-designs had been developed, these variants were weighed against each other by means of a Trade-Off Matrix (TOM). Using this method, a distinction is made between the variants based on the pre-chosen performance indicators. All performance indicators have a weighting that adds up to a total of 100. This study concludes that it can be advantageous to replace the traditional design with a demountable design, with the assumed boundary conditions of this study. All developed variants have an advantage with regard to environmental impact and financial costs compared to the traditional design, assuming a lifespan of 100 years in which it is moved 10 times.

Space frame structures today are a common choice of load bearing system for achieving long spans with minimal interruptions of the floor plan beneath. On top of that, the versatility of space frame structures to conform to any shape makes them particularly interesting today, especially in the context of free-form geometry which is becoming ever more common. In structural design, and especially for space frame design, the creation of a structural model is quite a labour-intensive process, and it is highly beneficial to automate the structural model generation. Furthermore, the design of such structures can benefit from an exhaustive preliminary design space investigation. Thus, this MSc thesis deals with the parametric design, engineering and optimization of space frame structure typologies based on different initial surface discretization of the input free-form surface geometry, and different topological relations of space frame top and bottom layers. These topological relations are based on Conway operators most relevant for the structural patterns occurring in space frame structures specifically, dual, kis and ambo. These operators are always applied on an initial or seed meshing of the desired free-form surface, to create different space frame layouts for them to be compared by their structural performance, primarily in terms of mass. The scope of initial meshing options is kept to tri, quad, and skeleton-based quad meshing. These three different types of mesh options, combined with the three possible Conway operator options, constitute the main nine combinations for each case study example. In essence, every space frame design, due to the linear and geometric nature of the structural elements (nodes and bars seen as points and lines), can be considered as a literal structural translation of the final desired free-form shape. This free-form shape is always tessellated or discretized in certain configurations. The aim was to gain more insight into how the initial tessellation affects the behaviour of space frame structures as well as how the process of optimization of such structures is influenced regarding the initial tessellation. To gain insight into this influence qualitatively and quantitatively a parametric tool was developed to conduct case studies. The tool allows for the generation and cross-section optimization of various space frame structures based on an input surface. This parametric tool was developed using Rhino, Grasshopper, and karamba3D structural analysis plugins for grasshopper.