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.

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.

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 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 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.

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.

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.

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.