Timber high-rise buildings have been gaining in popularity. However, due to the low material stiffness of timber the stability systems of these buildings are often made with steel or concrete. To avoid this the material efficiency of the timber stability systems must be improved. The most material efficient stability systems for timber high-rise are the externally braced systems according to literature. The externally braced systems are the diagrid and external braced frame stability systems. In literature the diagrid is concluded to be more material efficient than the external braced frame. Nonetheless, in practice only external braced frame systems are used for timber high-rise buildings. This disconnect could be caused by the steel connections which are often simplified or overlooked in literature studies but have a large influence on the material usage of a timber stability system. The connections can increase the timber element size because the required connection does not fit, and the connections will decrease the global stiffness of the stability system. For this reason, the connections must be regarded when comparing stability systems. One diagrid and two external braced frame designs will be compared with a parametric model. In this model other parameters will be studied as well. These parameters are: plot sizes of 27.2 x 27.2 m & 27.2 x 40.8 m, floor spans of 3.4 m & 6.8 m, permanent floor loads of 3.5 kN/m^2 & 5.3 kN/m^2 & 6.7 kN/m^2 and element widths ranging from 400 mm to 650 mm. The parametric model will first size the elements individually for the ULS checks and afterwards the elements will be sized per group for the SLS checks. The ULS checks start with a regular ULS member check, then a member check in the fire situation is performed and lastly the connection design component used. This connection design component will create slotted-in steel plate connections where the amount of steel per connection is calculated, and the timber element sizes are increased if needed. In the SLS checks the global lateral displacement is checked and the along-wind acceleration. The along-wind acceleration is often normative for the sizing of the elements in timber high-rise. With a higher global stiffness or higher building mass the acceleration decreases. To make a fair comparison in the results the amount of timber and steel of the internal structure is also added to the material required in the stability system in the façade. From the results it is seen that all buildings are sized on the connection design or on the along-wind acceleration. The diagrid designs have a higher global stiffness so they are sized more often on the connection design whereas the braced frame designs are sized more often on the along-wind acceleration. The diagrid designs use 3x more steel than the braced designs. The results for the other parameters are: Plot size: A smaller plot size requires a higher floor load to meet the acceleration requirement, therefore the large plot size is more material efficient. Floor span: The floor span in the external braced frame has a large influence on the designs with a small plot size. That is because the facade with the smaller span becomes normative for the global displacement. When this happens a smaller floor span decreases the material efficiency significantly. In the larger plot size the influence of the floor span on the braced frame designs is insignificant. For the diagrid designs the larger floor span causes higher normal forces in the diagonals. This increases the material usage in the facade. However, considering the internal structure of the building the large floor span is still more efficient. Floor weight: A higher floor weight is more timber efficient for a small plot size, and the lowest floor weight is the most material efficient for a large plot size. With a higher floor weight, the steel usage always increases since the connection designs are sized on the ULS checks only. Element width: The steel efficiency increases when the element width increases. This is a result of the chosen connection design. The timber usage is similar for all the element widths. Some of the designs with a small plot size and low floor weight are unfeasible since the elements in the facade are too large. This is a result of the choice to only increase the timber element heights and not the connection stiffness to improve the global stiffness. Therefore, it is recommended to study how the global stiffness can be improved more material efficiently. Other recommendations for further research are on the stability system design and the connection design. Since in this thesis many designs are fixed in simplified exploratory studies to decrease the design space of the parametric model.

The implementation of timber as a load-bearing and stabilizing material for high-rise structures has significantly increased over the last decades due to its potential of reducing the environmental footprint of a structure. Timber structures present a reduced global stiffness and self-weight compared to structures incorporating traditional construction materials, making them prone to high accelerations caused by wind load which affects the structural integrity and user comfort. The acceleration of a structure is a highly complex parameter that must be determined using modal analysis computed by a full-scale finite element model, and is significantly influenced by the magnitude of the wind and vertical loads, as well as the global stiffness of the structure. During the preliminary design phase, it is the responsibility of structural engineers to determine the feasibility of the design and estimate the amount of material required and the distribution of the structural elements. However, this process must be done under a limited amount of time, forcing engineers to rely on rules of thumb and previous experience, which are not currently available for the design of timber high-rise structures. Therefore, the goal of this investigation is to perform a parametric study to determine the influence of various parameters on the design of timber high-rise structures and assist structural engineers in making well-argued decisions during the preliminary design phase. The preliminary design parameters to be studied in the parametric study are: stability system design, connection stiffness and building height. The ranges for the parameters were selected based on extreme values such that clear trends regarding their influence on design could be visualized. This decision limits the design feasibility of some configurations studied in this investigation. The selected stability systems to be studied are glulam frame, CLT core and glulam diagrid. The design verification for each design alternative is done using ULS and SLS criteria provided by Eurocode, as well as a simplified method to estimate the dynamic response of the structure. Finally, the sizing of the structural elements and data collection was done by the implementation of evolutionary algorithms. From the data collected it was determined that the most influential design parameter for the design of timber high-rise structures is the stability system selection given that it determines the global stiffness, which showed a significantly higher influence on the dynamic response of the structure than its self-weight. Moreover, the efficiency of the different stability systems was assessed based on the maximum slenderness they could achieve compared to the amount of material they required. Based on this definition, it was determined that the glulam diagrid is two times more efficient than the CLT core and three times more efficient than the glulam frame. The efficiency of the glulam diagrid is caused by its high global stiffness provided by the triangular configuration of the diagonal elements. These observations prove that the effect of timber’s low density can be mitigated by the implementation of efficient stability systems. The influence of connection stiffness was determined to be directly related to the ability of the stability system to provide lateral stability to the structure. The influence of this parameter on form stable structures such as the CLT core and the glulam diagrid, proved to be nearly negligible, while for non-form stable structures such as the glulam frame it proved to be highly influential. However, it was also determined that the addition of rotational stiffness in the connections causes an exponential increase of the costs and environmental footprint of the structure, which decreases their design feasibility. Finally, the influence of building height on the design is visualized by its effect on the dynamic response of the structure caused by the logarithmic increase of the wind speed as this parameter increases, as well as a decrease of the global stiffness proportional to the efficiency of the stability system.

During the early stages of the construction process of a building, the potential impact of design decisions is at its greatest. One of the reasons is the lack of computational tools at these stages. The main objective of this research project was the expansion of StructuralComponents by the development of a parametric real-time computational tool prototype to quickly determine the feasibility of mid-rise buildings designs with rigid frames as stability members. A study of rigid frames behaviour was performed to define a range of applicability of the existing analytical representation and to develop two new methods to analytically represent rigid frames behaviour: a correction method for the shear beam representation and a method based on the Timoshenko beam theory. To allow for vertical connections of different rigid frame geometries, an analytical method to consider a different stiffness along the height was developed. The results showed that the analytical shear beam representation of rigid frames has a reduced range of applicability for parametric purposes. This reduced applicability is due to the combined shear and bending behaviour. The correction method follows from the prediction of the error when using the shear beam representation. In addition to the correction of the shear beam representation, the prediction of the error was defined as a parameter to classify the behaviour of a rigid frame as a shear, flexural or combined type. Both, the applicability range and the correction method are based on analytical and numerical comparisons, as well as the performed validations. The implemented software comprises Maplesoft to get the analytical solutions and Grasshopper with Karamba3D (which contains the finite element solver) to get the numerical solutions. The method based on the Timoshenko beam theory comes from the theoretical derivations of a serial system that takes into account both, bending and shear deformations. It was found that it is more appropriate to analytically represent the general behaviour of rigid frames with the Timoshenko beam theory and by additionally considering a different stiffness calculation for the ground floor. Also, it was shown that the vertical connections of rigid frame geometries can be addressed with the calculation of an analytical solution for each different geometry along the height. Both analytical approaches, the Timoshenko beam representation and the method for vertical connections were implemented in the tool prototype. Such a tool consists of a calculation method to assess the structural performance of a building by the simultaneous structural analysis of every rigid frame subjected to a lateral load. The three main characteristics of the tool prototype are the parametric adaptability, the instantaneous display of results and the stacking “Lego-type” connection between components. The validations in this research project showed that the proposed and implemented methods are suitable for preliminary design stages because the error for the most unfavourable geometric configurations resulted in less than 15 percent. It is recommended to conduct further research and tool development. In so doing, more informed decisions can be made during the preliminary design stages.

Theshortage in housing and office spaces, combined with the desire of people tolive in densely populated cities results in a lack of space. A proposedsolution can be found in the usage of high-rise buildings. Nowadays there ismore awareness for the environment, thus this research tries to reduce theenvironmental impact of a high-rise building by optimizing the material used inload-bearing structures. This research aims to give designers and engineersmore insight into the added value of structural optimization; in particular forthe material usage in the load-bearing structure of high-rise buildings. Theresearch objective is formulated as follows: What is the optimal topology for a reinforced concrete load-bearingstructure, situated at the perimeter of a high-rise building when optimizingthe material use?  A building isclassified as high-rise building when its roof is 70 m or more above groundlevel and accommodates work and/or living space. In literature the distinctionis made between three sorts of optimization: size, shape and topologyoptimization. Topology optimization has the most freedom, therefore it is morelikely to find a novel structure which minimizes the material use as much aspossible. In specific the Ground Structure Method (GSM) is used. The initialground structure is constructed by creating members between all nodes (fullconnectivity) which are located in the design space. The cross-sectional areasof the bars are the design variables in the optimization. An option is that thevariables turn to zero, thus elements are deleted resulting in less material.The conventional GSM starts with the full connectivity as initial groundstructure, deletes elements and calculates the new load distribution until athreshold is reached. In the end the load-bearing structure will consist ofcolumns, braces and beams, which are located at the perimeter of the floorplan. Literature indicates that (high-rise) buildings which are mainly loadedby horizontal loads would be optimal if they contain arches in the load-bearingstructure, or resemble the so-called Michell truss. However, the influence ofthe vertical load is often not taken into account, therefore this isinvestigated with the help of a parametric study. To compare the results withreality, a case study (Boston & Seattle, Rotterdam) is investigated.   The core of the research is the furtherdevelopment of the optimization code, based on the GSM, written by He et al.,where multiple load cases and demands for the material strengths are implemented.In contrast to deleting elements, the code uses an adaptive ‘member adding’scheme, which is firstly proposed by Gilbert and Tyas. This scheme solvesproblems faster than the conventional GSM, up to 8 times, and is able to solvelarge problems. This code is extended during this research with new functionswhich implement demands for fire, second-order, buildability, flexural bucklingand stiffness. Also it is possible to add self-weight to the optimization. Thestiffness is implemented by adding a constraint to the displacement of the topof the building, wherefore a recursive resizing algorithm is written based onthe article of Chan. Thus the extended code exists of two optimizations, firsta strength optimization and afterwards a stiffness optimization. The code iswritten in Python and for the purpose of post-processing exporting the data toExcel and Abaqus is possible.  With thehelp of the extended code, two design spaces are investigated. One design spaceis smaller, such that the computational time is low and many variations can beexamined during the parametric study on the total vertical to total horizontalload ratio (v/h-ratio). The other is based on a case study for comparison witha realistic situation. The verification of the code shows that the extrafunctions work properly for the investigated problems. If the functionsconcerning the stiffness optimization, inclusion of self-weight, fire,buildability and second-order are used, the extended code becomes unstable andthe computation time increases enormously when optimizing the case study.Therefore it is chosen not to include during obtaining the results. The resultsof the parametric study shows an expected pattern for the load-bearingstructure, for a v/h-ratio below 4. The pattern consist of arches, originatingfrom the Michell truss. The optimization of the case study, subjected to onerealistic load combination, showed no clear pattern for the load-bearingstructure. Post-processing steps, based on engineering judgement, are taken toclarify the solutions, which showed that the columns above the supports shouldbe large in comparison to the other elements and that the arches are the mostoptimal structure. Therefore an “optimized” load-bearing structure consistingof arches is proposed. The analysis of the “optimized” load-bearing structureshows us that most of the elements meet the strength requirements. To find theoptimal solution an iterative process would be needed, because increasing thecross-section of an element will decrease the stress but increase thestiffness, thus attracting more load.   Thedifference between the optimized load-bearing structure and the originalload-bearing structure of the case study is that the optimized uses archesinstead of (punched) structural walls and uses less material (±3%). From thepost-processing of the results it is concluded that increasing the strengthratio (compression to tensile) to 1.0, decreasing the total v/h-ratio orignoring the rigid-diaphragm working of the floor help clarify the results ofthe optimization.   This research extendsthe current literature with extra insights in the use of the Ground StructureMethod in an optimization code. Also, it confirms that the arches (originatingfrom Michel Truss) is an efficient manner to transfer the loads to thesupports. However, more research in the influence of the supports, the designspace and the material type on the clearness of the optimal solution is needed.  The advice for designers and engineersis to see what the possibilities are for arches to use in their load-bearingstructure, because these are efficient in transferring the loads so materialcan be saved. The current version of the code needs to be made more userfriendly, stabler and faster before it is recommended to be used by designersand engineers. The extended code is a first attempt to implement multiple rulesfrom the Eurocode in a optimization code.  

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 importance of joints in timber structures is strongly emphasized in the existing literature (e.g., Blaß & Sandhaas, 2017; McLain, 1998). The aim of this project is to provide insight into whether the cross-sectional sizes of the member are dictated by the dimensional sizes of the laterally loaded dowel-type connection or the strength and stiffness requirements of the member itself in timber frame structures. In this research project, a parametric study is performed. The parameters in this study represent the global frame structure and the laterally loaded dowel-type connections. Together, these parameters form a parametric model that lays the foundation for the tool that is constructed in this study. This tool is built in order to generate a number of unique configurations that fulfill the design verifications. Using the tool, two analyses are performed. In analysis 1, the effect of different distances between the secondary beams is examined. In analysis 2, the effect of different grid sizes of the column in the frame structure is studied. In both analyses, two member sizes are first selected based on the criteria 'lowest cross-sectional area' (LCA) and 'lowest height beam' (LHB). These two member sizes form the starting point for generating different configurations of laterally loaded dowel-type connections. In this research project, three factors are found to contribute to the largest reduction in the number of unique configurations for all constructed cases examined in analysis 1 and 2. These three factors are small column widths combined with high shear forces, the effect of a 'compact' member, and the effect of 'brittle' failure mechanisms on the LCA-members, which was selected as a design constraint in this study. These factors may be relevant for engineers to take into account when designing the structural members. However, in this study, no constructed case is found in which the member needs to be redesigned in order to fit the connection. This means that one can conclude that the dimensional size of the structural member is dictated by the strength and stiffness requirements of the member itself. Important to note is that, although a large number of parameters was incorporated into this study, not all potentially relevant parameters were taken into account. When incorporating factors such as the horizontal forces in the connection, the effect of shrinkage and swelling, the level of difficultly in terms of assembling the joints on site, and adjustments to guarantee a certain level of fire resistance, certain turning points in the dimensional interaction between joints and members may be found. Finally, beyond allowing for the dimensional interaction between joints and members to be studied, the tool constructed in this study is also valuable to practical engineering. The large amount of data that is generated by the tool allows the engineer to explore the different possible configurations in the process of designing joints. By connecting the output of the tool to the Design Explorer interface, the engineer has the opportunity to search through all the individual characteristics or a specific range and examine different possible connections in an efficient manner. One of the main contributions of this research project, therefore, lies in the tool itself.

Cross-Laminated timber (CLT), and other engineered timber products, are under high demand due to their prefabricated nature and environmental benefits. A key concern surrounding the application of CLT in buildings is its combustible nature and subsequent contribution to a compartment fire. Previous research has shown that exposed CLT, under certain circumstances, can achieve self-extinguishment. This research aims to further experimentally investigate the fire performance of small-scale compartments containing exposed CLT. The focus of this study is threefold, namely to investigate: i) the influence of (commercially available) adhesives used in CLT panels on fire behaviour; ii) the influence of CLT panel configuration on fire behaviour and iii) the ability of design guidelines to predict experimentally obtained fire behaviour. By investigating these aspects, a detailed investigation into fire behaviour of compartments with exposed CLT is presented to characterise the influence of CLT on enclosure fire behaviour and assess the ability of CLT to reliably self-extinguish. In general, it was found that reliable self-extinguishment is promoted when small-scale compartment fire tests reveal the avoidance of burn-through behaviour (and a second flashover), due to the combined effect of CLT adhesive type and CLT panel configuration. The particular observations recorded in this research project (relating to adhesive type and CLT panel configuration) serve as a base on which to conduct further research (especially by conducting experiments at real compartment scales). In addition, the investigation into the ability of a design guideline to predict fire behaviour, namely a Parametric Fire Curve (PFC) calculation method that includes the contribution of exposed CLT to the fuel load, provided mixed results. Further refinement is required to improve the model’s ability to predict compartment behaviour.

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.

The objective of this project is to devise and develop a design tool that lets the user explore different force flows during conceptual design, with the goal to inform different geometries, thereby realizing an integrated design process. Key characteristics that this tool must incorporate to be successful are defined as feedback (the ability to provide rapid and reliable analysis results), guidance (the ability to guide the user towards better designs), design freedom (the ability to allow users to make their own decisions and use their own expertise) and structural overview (the ability to make the general structural behavior clear instantly). Graphic Statics has been identified as a suitable method to model and compute the force flow with, and has been incorporated as the base of the tool. A workflow has been devised where the user first identifies and investigates a design problem manually, creating an initial design that must be used as input for the tool, which includes a definition of joints, members. loads, supports and certain boundary conditions. Due to the nature of Graphic Statics, this initial design must be statically determinate. The tool has been developed for Grasshopper, a parametric and associative modelling plugin of Rhinoceros, which provides a platform that meets the defined development criteria of accessibility, real-time modelling, geometric flexibility, extensibility, and presentation independence. The developed prototype bearing the name of GSDesign consists of custom components scripted in C# containing the main functionality, as well as Grasshopper clusters for specific visualization sequences. GSDesign facilitates the design of 2D truss-like structures, which can be interpreted as force flow designs, whose efficiency is quantified in the total load path. Feedback is generated in real-time, and is presented in a force diagram, form diagram, unified diagram, and/or as numerical values, providing precise and accurate results. Guidance is incorporated intrinsically through Graphic Statics, but also by the incorporation of an optimization process using the total load path value and the genetic optimization component Galapagos native to Grasshopper. Design freedom is ensured through the general setup of the tool, which allows for maximum utilization of the design flexibility that Grasshopper offers. The tool provides a clear structural overview through the visualizations that characterize Graphic Statics, which can be customized to preference by the user. A user experiment has been set up to test the functionality and workflow of the tool in a simple design case carried out by structural engineers to ensure its practical value. Eleven participants were asked to first create an initial design by hand, and subsequently reproduce that design in GSDesign and improve it with optimization. The use of GSDesign visibly led to new insights towards more efficient structural forms, which was supported by an average drop of 31% in structural material volume when comparing the fitness data of the optimized design with the initial design. Also the participants on average rated their own optimized design more than 40% higher on structural efficiency than their initial manual design, importantly without compromising on practical feasibility.

The application of vertical greening systems (VGS) onto building envelopes constitutes an innovative way to implement more green in the living environment. Especially in dense urban areas, where only limited space is available to integrate more horizontal greening at ground level, VGS have the potential to contribute towards creating a greener, healthier, more nature-inclusive and climate resilient urban environment. This by facilitating and contributing to natural ecosystem functioning, hence providing ecosystem services and through those, benefits for society. These benefits include among others an enhanced microclimate, biodiversity and aesthetic appeal, as well as improved physical and mental health, thermal performance, energy efficiency and air quality, and reduction of urban heat island effect and noise disturbance. In order to substantiate the total set of costs and benefits associated with VGS implementation and enhance rational decision-making, in present research the development of a standardised framework and interactive economic valuation tool is proposed. In the end, an economic valuation framework and tool were developed which can support the decision-making process regarding VGS application. The framework is based on Life Cycle Cost Analysis (LCCA) and Social Cost Benefit Analysis (SCBA). These analyses relate to real estate investors and society (resident focus) respectively. To assess and report on the values of the costs and benefits of these innovative systems, distinct themes were established. The cost themes entail financial costs, environmental costs and potential Ecosystem Disservices. Benefits are distributed over the themes health & well-being, climate adaptation & mitigation, real estate, social & recreational & commercial and biodiversity. The current version of the tool is able to perform quantification and monetisation for financial costs, large parts of the environmental costs, reduction of airborne PM10, increased rental incomes (investors) and rental costs (residents), reduced energy usage for heating and MIA & Vamil tax incentives. Based on implemented valuation methods, the case study delivers project specific results. Though, it is explicitly noted that these results do not yet provide a complete representation of all costs and benefits, due to a limited number of (benefit) indicators that are monetised. Hence, this version of the tool should be regarded as initial impetus for further development. This in order to ultimately obtain an all-encompassing VGS Valuation Tool, fit for project specific economic valuation of costs and benefits of VGS. The result dashboard visualises the valuation outcomes and results in clear tables and graphs, generating insights into the contribution of different themes towards the total costs and benefits of VGS. This can initiate further recommendations for a research agenda into distinct aspects of certain VGS. Hence, the VGS Valuation tool could become a conversational mechanism or steering instrument, to stimulate or justify choices for specific types of VGS at given locations. The test panel of anticipated end users was enthusiastic about the comprehensiveness and user experience of the tool and acknowledged its future practical value.

Currently, the settlements of high-rise buildings are calculated based on two methods. The single pile settlements (s1), are generated due to mobilised shaft friction and pile tip resistance. These settlements are determined with analytical methods (i.e. NEN 9997-1, 2017). Settlements related to pile group behaviour in soil layers below pile tip level (s2) are calculated with the equivalent raft approach i.e. Tomlinson (1977). However, an essential aspect for differential settlement calculations is the redistribution of loads by soil-structure interaction mechanisms, which are not currently incorporated in the calculation approach. A missing factor for a soil-structure interaction calculation is the lack of soil- displacement installation effects in the numerical methods for single pile behaviour. Therefore, this research is focussed on the implementation of a soil displacement single pile behaviour in PLAXIS 3D and thereby towards integration of the structural and geotechnical design in one calculation method for appropriate soil subgrade reactions and load redistribution. In this research numerical methods are used in combination with the embedded beam approach applied in PLAXIS 3D. To approximate the NEN9997 load-displacement behaviour of soil displacement single piles, the behaviour of the embedded beam in combination with the multi-linear shaft friction is fitted in PLAXIS 3D. The fit is conducted by increasing the stiffness of a soil volume below pile tip level. Which does account for the residual stresses after pile installation. The solution of this fit consists of two parts: improvements on behalf of the new embedded beam formulation after Smulders (2018) and a soil stiffness fit below pile tip level. Regarding the new embedded beam formulation, improvements have been determined on mesh-dependency and a stiffer load-displacement response. The fit method performs well in combination with the embedded beams while approaching the load-displacement response of soil-displacement piles according to NEN9997. However, the ultimate bearing capacity of the embedded pile should still be calculated with D-Foundations (analytical method based on NEN9997). In the pile group calculation, the behaviour of single piles is extrapolated to all piles in the PLAXIS 3D model. A plate element is modelled on top of the pile heads to achieve a redistribution of loads due to the overlying superstructure. In this way, the single pile behaviour and bending stiffness of the superstructure is implemented in the PLAXIS 3D model, and the soil-structure interaction calculation is possible. However, group effects due to the soil displacement installation method are only partly covered in this approach. The reduction or increase in skin resistance in pile groups is not covered since, the predefined maximum skin friction capacity is manually inserted as an input parameter and it is not an outcome of the PLAXIS 3D calculation. Afterwards, the proposed framework is applied to a practical case study including measurement data of a high-rise project in Amsterdam. The proposed framework turned out to capture soil-structure interaction properly by taking into account a part of the superstructure bending stiffness and single pile behaviour. Compared to current calculation approaches, complex soil behaviour is captured in redistribution of the loads. However, the calculated settlements are still deviating from the measurement data. A probable explanation for the discrepancy is the shift in applied load over time in PLAXIS 3D relative to the real construction process. In conclusion, an improvement in terms of modelling soil-structure interaction has been achieved by incorporating single pile behaviour and superstructure bending stiffness in PLAXIS 3D. Therefore, the possibilities of linking the structural design to the geotechnical design in an early stage of the design process will be feasible. Combining the designs in an early stage, the structural dimensions of columns and beams are calculated with appropriate soil subgrade reactions and load redistributions by the soil. However, it is recommended to apply more investigation on the behaviour of soil- displacement pile (groups) in combination with embedded beams because, group effects are still not completely incorporated.

To mitigate climate change and to reach Dutch targets to reduce greenhouse gas emissions with 49% by 2030, emissions by the construction industry must be lowered. Developments regarding mass timber construction have increased the potential to do so. This thesis addresses the problem that the opportunity of reducing CO2 emissions by constructing in timber is not utilised to its full potential. Timber can contribute because the production of structural timber elements is less carbon intensive compared to concrete, the most used structural building material in the Netherlands. Additionally, timber has the capacity to capture and store carbon. From a literature study it is concluded that one of the main reasons for the reluctance towards timber structures is the perception of higher cost. The goal of this thesis is to qualify and quantify the conditions under which timber structures can be competitive with concrete structures in the Netherlands. For two designs to compete at the same level they must have the same potential profit and serve the same function. Nine interdependent variables are investigated in this research: |1| building use, |2| vertical bearing system, |3| stability system, |4| structural floor system, |5| floor span, |6| building height, |7| CO2 emission costs, |8| additional revenue for timber structures, and |9| the calculation method regarding biogenic carbon. It is found that considering both the costs and the (non-financial and financial) benefits is important when choosing a structural building material. The competitiveness of timber structures increases if CLT is efficiently used with a limited building height and reduced floor span. Imposing a CO2 tax will give the industry an incentive to reduce CO2 emissions and therefore use timber more frequently, which is essential to mitigate climate change.

This thesis examines the load distribution on 60 m long piles under gradual static loading, considering the POST Rotterdam high-rise building as the study project. The research employs fibre optic (FO) instrumentation on site to monitor strain changes in the piles over time and assess load transfer mechanisms. This data is integrated into a Plaxis 3D model of the building's foundation to validate existing approaches on soil structure interaction (SSI), optimize SSI modelling, and assess the high-rise building's impact on nearby structures. Results show that at early stages, the resistance contribution comes from the shaft in contact with the Pleistocene sand layer. However, as loading progresses and the Kedichem clay layer consolidates, most of the resistance shifts to the tip and the shaft located in the deeper sands. The FO strain measurements follow a similar trend to the site stratigraphy, but there is high uncertainty about the results at early load stages. The latter requires further investigation to corroborate once the building is finalised. The piles were incorporated into the Plaxis 3D model by means of EBR with a layer-dependent force distribution. The resulting spring stiffness of various pile groups reveals the significance of the group effect. Regarding the impacts of POST loads on the adjacent Old Post Office building, an angular distortion of 1/555 in 50 years was obtained, which indicates a conservative result of slight damage in the structure. For the Timmerhuis building, a resulting angular distortion of 1/1428 indicates no damage. This study addresses gaps in understanding load distribution in 60 m long piles, offering a practical modelling approach and recommendations for future research. It contributes to optimizing design and safety protocols as the use of such piles becomes more common in Rotterdam. By utilizing advanced sensing techniques like FO, this research may lead to more accurate pile design and criteria, potentially reducing construction costs and enhancing safety for high-rise buildings and their surroundings.

In slender high-rise buildings wind-induced accelerations can become the governing design criterion. These issues can be solved by increasing mass, increasing stiffness, or increasing the damping ratio. The focus of this research is on the last option and investigates the opportunities of supplemental damping in the Dutch high-rise building context. The research report answers the following main research question: In what way can supplementary damping be applied in Dutch, slender, tall buildings to efficiently meet the structural design requirements? A literature research was conducted to the topics of wind-engineering, high-rise structures, and supplemental dampers. To answer the main research question two research methods have been applied. First, a variant study was performed in Karamba, a FEA plug-in for Rhino Grasshopper. Building height, floor mass, outrigger, stiffness limits, and damping ratio were varied. From this analysis charts were generated from which it could be determined which design requirement is governing. In this way opportunities for the application of supplemental damping could be determined. In the last phase of the research the mitigating effects of tuned mass damper (TMD) were modelled with the use of the theory of random vibrations and modal analysis. With a developed python script the reduced accelerations could be computed and the parameters of a TMD could be determined.

The goal of this thesis is to create a decision-making framework for the structural material choice for high rise buildings (between 70 m and 250 m) in the Netherlands. The main research question is: How is the structural material for a high rise building in the Netherlands chosen and how can this process become structured? Currently of the buildings in the Netherlands above 120 m, 86% have only reinforced concrete as structural material. This raises the question if the preference in the Netherlands for concrete comes from a clear decision-making process or if it originates elsewhere? In theory this decision-making process follows an organized cycle called the Basic design cycle. In practice preferences based on experience gained from former projects play a role, which results in deviation from the theoretical decision-making process. By gaining insight in the differences between theory and practice in the decision-making process, this thesis tries to identify the main differences arising in the structural material choice process. Four differences between theory and practice – regarding the structural material choice process of high rise buildings in the Netherlands – have been identified. By conducting interviews, these differences between theory and practice have been further researched and confirmed. (1) Disproportionately less steel is used for the main load-bearing structure of high rise buildings in the Netherlands. (2) Reasoning behind design decisions is often not made clear. (3) Building methods of contractors influence the structural material choice. (4) Arguments and expectation don’t match reality. For example, figures based on the construction time of the buildings in the Netherlands above 120 m show that prefab concrete buildings don’t always have a shorter construction time than cast in-situ concrete. In this thesis Difference 2 and 3 are combined and addressed together by creating an advisory excel-tool. The goal of this excel-tool is to give the structural engineer – early in the design process of a high rise project – insight in the influence of the structural typology on: cost (direct and indirect costs) and sustainability (environmental cost). Early in the design process very little details are available about the design of the high rise building and a lot of things can still change. Because of that, the input of the tool is kept simple: the height of the high rise building. As output a top ten of structural combinations is given. The structural combinations are a combinations of (1) stability system, (2) structural material and (3) floor type. This top ten is determined by calculating the (direct and indirect) costs and the environmental cost (sustainability) of twenty-six different structural combinations at all heights within the height range of that stability system. Eventually the top ten shows which out of the twenty-six structural combinations have the lowest (direct and indirect) costs and the lowest environmental cost (sustainability). This way a structural engineer can explore early in the design process what the influence of his or her design choices are on the final result and take the top ten structural combinations into consideration.

In the field of structural and geotechnical engineering, a uniform approach to predict and model foundation settlements during the design phase of a high-rise building appears to be missing. In the Netherlands, pile foundations of tower structures underlain by compressible soil layers are challenging to model due to different stiffness and load distribution effects. As a result, the Dutch building code currently used for foundation design, the NEN9997-1, does not include realistic soil-structure interaction (SSI) effects. Instead, the NEN defines a simplified approach for high-rise buildings as the sum of two types of foundation settlements: individual pile head settlements (s1) and pile group settlements (s2) due to compressible layers below pile tip level. Numerical models were used in this thesis to predict the individual contribution of different soil layers to measured subsidence of tower structures. By running several simulations using Tomlinson’s load spread method and the new embedded beam formulation (EB-I) in Plaxis 3D, it was found that approximately 65% of the total (s2) settlements are caused by the compression of clay layers below foundation level. Moreover, the effects of different pile factors (αs, αp) on the load distribution (more pile shaft resistance versus base resistance) from superstructure to subsurface were investigated. This research concluded that updated pile factors - in accordance with recent pile load tests on the Maasvlakte (Gavin, 2020) - influenced the predicted and modelled pile head settlements (s1) slightly for a Fundex 560 pile. Nonetheless, the change in load distribution due to different pile factors did not affect the vertical effective stresses or resulting (s2) settlements at depth. Further, to accomplish a more uniform modelling approach for high-rise building settlements, this thesis provides insights for an automated soil-structure interaction mattress methodology as illustrated in Figure 1. A model verification is proposed for the mattress model approach using finite element software commonly used by geotechnical (Plaxis 3D) and structural engineers (SCIA Engineer) in daily practice. In essence, it is based on a simplified (s2) settlement analysis from Plaxis 3D (step 1) and mattress fit model in SCIA Engineer (step 2) consisting of multiple springs with linear stiffness (k_bedding) connected by a plate (E_plate) and a simplified surface load on top. The surface load represents the quasi-permanent building loads. An apparent limitation of the Plaxis 3D model (step 1) was the missing building stiffness or load redistribution within the superstructure due to differential settlements over time. However, a modelling discrepancy of only 1% was found for both the peak and differential settlements between SCIA Engineer (step 3) and Plaxis 3D (step 4) for a theoretical, symmetric high-rise building of 69 m in the North of Amsterdam. Thus, a model verification was accomplished by comparing the settlements from Plaxis 3D with the building on top of EB-I embedded beams (step 4) to the deformations of the fitted mattress model (k_bedding + E_plate) representing the compressible soils underneath the structure in SCIA Engineer (step 3). Altogether, this thesis provides a solid foundation towards a more universal design methodology between multiple stakeholders while including SSI effects for settlement predictions of high-rise buildings in daily practice.

The isostatic slab was developed by Pier Nervi and his colleague Aldo Arcangeli to create an elegant and easy to produce floor system, with efficient use of material. These slabs are designed with ribs aligned to the principal bending stress lines that support a flat deck. Concrete isostatic slabs are no longer constructed due to their expensive formwork. However, this system could be advantageous when made from timber as the grain direction will be aligned to the optimal flow of forces. Additionally, isostatic slabs can be designed for any support conditions, so an isostatic timber slab may be more desirable than the typical one-way spanning timber systems. The isostatic timber slab is a new concept and has not been previously used. Therefore, before the system can be applied, there needs to be a greater understanding of the design process. This research achieves this goal by splitting the process into two parts. Firstly, the rib geometry is created by generating the principal bending stress lines. Secondly, the system is designed and analysed for a case study. The aim is achieved by creating a functional design and identifying the critical areas in the design process. An approach for measuring the accuracy of stress lines is developed and used to test different methods for improving the stress line generation process. The improved process uses a more advanced integration method and a holistic seeding method. Additionally, a novel method for interpolating the principal stress trajectories from finite element analysis (FEA) results is established by utilising the shape functions from the theory of FEA. An iterative approach used to select stress lines to create optimised truss geometries in in-plane-loaded plates is tested for its applicability to out-of-plane loaded plates (i.e. slabs). The rib geometry produced was measured by the approximation error and the deck elements' span lengths. This iterative approach does not apply to slabs as it creates clustered areas and excludes symmetries. Analysis of principal stresses under different load cases shows that the most considerable difference from the primary load case is when half of the slab is loaded with a maximum load and half with a minimum load. (The primary load case is the condition used to create the stress lines for the rib geometry). Using FEA to calculate the stresses under each load case shows that uneven loading of the slab does not produce higher stresses than the primary load case. A functional isostatic timber slab design is made for the case study using laminated veneer lumber (LVL) for the ribs and plywood for the deck. Linear elastic FE modelling of the structure shows that increasing the deck thickness and decreasing the rib depth, causes the deck to carry more load and the ribs to carry less and vice versa. Increasing the rib thickness has a small effect on the force distribution due to the available LVL thicknesses. The FE modelling also showed that the torsional load transfer mechanisms are reduced by increasing the rib slenderness. The design is made based on the ultimate limit state (ULS) stress requirements for the elements and three critical connections, and the deflection under the serviceability limit state (SLS). The rib-to-deck joint requirements determine the deck thickness, and the deck has a low utilisation for the stress conditions, meaning that the deck span lengths are not critical. The ribs' depth is heavily dependent on the rib-to-rib moment connection as a large lever is needed. The cross-sectional properties of the ribs are also dependant on the standard LVL sizes. This system is compared to several conventional one-way spanning alternatives based on the total material volume, the structural weight, and the structural depth. The isostatic timber slab has a reduced volume and weight compared to a flat cross-laminated timber (CLT) slab, a Kerto-Ripa slab, and a concrete hollow-core slab; however, the isostatic timber slab has a larger structural depth. A ‘T’-beam equivalent to the two-way spanning isostatic slab has less volume and weight while maintaining the same structural depth, but has a larger average deflection. Timber isostatic slabs are complex to design with a highly connected network of parameters. The system should be designed by minimising the peak moment forces at connections, curating the support conditions to reduce stress line clustering, and selecting stress lines for the rib geometry which ensure sufficient stiffness at the peak deflection location. It is advised to produce a parametric model of the slab that can quickly assess the design performances and efficiently complete design cycles.

The demand for high-rise building has been increasing over the past decades which has induced new developments such as modular construction. Modular construction has advantages in terms increased speed, safer construction and less construction waste. Applying modular construction in high-rise however brings about great complexities for the structural design of the building. Therefore, a design aid is created which generates a structural model from any arbitrary shape and uses structural optimization techniques to explore a range of designs for the early design stage. Existing optimization techniques have been studied, including Cross-Section (CS-) optimization (size) and BESO (topology). CS-optimization adapts the size of each member, considering utilization and displacement conditions whereas BESO removes or adds elements from the model based on stress level and Target Ratio (TR). Performing the methods successively further decreases the structural weight at certain TR. Generally, weight increases as more elements are removed. By developing the two-way coupled ESO<>CS-optimization method, elements are removed by lowest strain energy density, while the cross-sections of the remaining members are updated in each iteration, thus coupling ESO (topology) and CS-optimization (size). This results in a logical load path and additional weight reduction especially in the braced frame structures loaded by lateral loads when displacement is governing. In multiple load case design, the removal of elements is somewhat hard to interpret, however the method consistently results in the lowest structural weight for the considered cases. In order to create a modular structural design, boundary conditions are assumed by standardizing column and beam dimensions and considering multiple realistic load cases (wind+vertical load). By transforming arbitrary shapes into structural models and optimizing these, a range of solutions for the structural design is presented in which the number of elements and the structural weight are generally negatively related. For the considered rectangular buildings, the results are more efficient than core or outrigger structures and almost as efficient as mega frame structures, with the added benefit that it can be applied to any shape. Exploration of these solutions is a useful contribution to the early design stage of modular high-rise buildings, while the coupled ESO<>CS-optimization method could also be useful in other optimization problems.