The Netherlands is grappling with a substantial housing crisis, marked by an estimated shortage of 380,000 houses. To address this issue, an annual creation of 100,000 new housing units is deemed necessary. However, the current construction rate stands at only 70,000 houses per year, indicating a considerable gap in resolving the housing crisis. Recognizing the potential of urban densification, especially through vertical extension using Cross-Laminated Timber (CLT), presents a sustainable solution. Nevertheless, challenges arise, such as the unique approach to vertical extension and the structural constraints posed by CLT's lower strength compared to materials like concrete.

This research aims to identify the vertical extension potential of CLT in existing buildings by developing a parametric tool that considers various structural constraints. The ultimate goal is to contribute to informed decision-making practices for sustainable and effective structural design in vertical extensions.

The methodology comprises four phases: analysis, synthesis, simulation, and evaluation. The analysis phase examines existing vertical extensions, structural context, and spare capacity concepts, forming the basis for synthesis. A parametric tool is then created using Grasshopper and Karamba, employed in the simulation phase to conduct a parameter study based on the analysis phase findings. This study assesses the effects of the original structure's base geometry on spare capacity and evaluates the design of the extension itself.

The results of the parameter study reveal that the presence and placement of a stability core have the most significant impact on spare capacity in the existing building. The original construction grid and building height also influence spare capacity, though to a lesser extent. Additionally, wall layouts in the extension, such as core alignment, functional design, and façade-aligned layouts, significantly affect spare capacity utilization in both the original structure and the extension.

Variations in extension grid show differences in spare capacity utilization, with effects smaller in magnitude compared to wall layout variations and displaying less dependence on the original structure's geometry. In the vertical extension itself, failure tends to concentrate on connections between CLT panels and floors, particularly with wall layouts emphasizing functional design.

In conclusion, the research, coupled with the development of a parametric tool, successfully achieves its main goal. The tool's accuracy is validated through extensive assessments of horizontal load transfer from the extension to the original structure. The parameter study highlights the significant effects of various parameters on extension design and the original structure, emphasizing the tool's utility in exploratory design stages for vertical extensions.

Selecting the optimal stability framework for high-rise steel buildings is a critical decision that impact both economic efficiency and sustainability. This decision is not easy since there are many stability frameworks to choose from, such as tube, concrete shear-wall, and outrigger system. Designers and clients aspire to compare multiple structural designs, considering both different frameworks and variations in geometry. Unfortunately, the current process of evaluating multiple designs is time-consuming and relies on the designer's experience and rules of thumb, rather than being driven by data. To address this challenge, predictive models can be used to estimate performance in terms of structural and environmental costs based on the given geometry and framework. However, traditional curve fitting methods often fall short in accurately predicting a complex relationship. In response, this study explores the potential of artificial neural networks to accelerate the decision-making process by predicting the most efficient framework during the early design phase while maintaining sufficient accuracy.

To determine this potential, two parametric models were developed using Rhinoceros software to represent buildings with braced framed tubes and outrigger systems. These models automatically optimised beam and column dimensions by FEM of Karamba, aiming to minimise the mass of these structural elements, across a range of building widths (15 to 60 meters) and heights (48 to 300 meters). The resulting data sets of both braced framed tube and outrigger system reflected the structural and environmental costs for the different designs. Separate neural networks were modelled for each framework. These networks were trained on the different data sets. By comparing predicted structural and environmental costs, the models assisted in the selection between braced framed tubes and outrigger systems.

The artificial neural networks accurately approximated structural and environmental costs for both stability frameworks. The Mean Absolute Percentage Error (MAPE) for the braced framed tube was 14%, while the most accurate alternative curve fit, a third-order polynomial, had a MAPE of 25%. For the outrigger system, the neural network achieved an even lower MAPE of 7%, where the most accurate alternative curve fit, also a third-order polynomial, had a significantly higher error with a MAPE of 31%. The neural networks outperformed traditional curve fitting methods. Additionally, the neural network generated instant results, taking only a second compared to the parametric model’s 5 to 30 minutes. However, achieving overall time efficiency with the neural models will require approximately three months when considering both setup time and output generation time. Optimal stability varied based on specific width and height combinations: when looking at environmental costs, the braced framed tube excelled for lower (50-80m) and higher heights (200-300m), while the outrigger system was more efficient for middle heights (80-200m). As the structure’s slenderness increased, the braced framed tube regained efficiency for the middle heights.

Impact of the stability framework is defined as the relative contribution of embodied carbon of the stability framework to the total embodied carbon of the structure (including superstructure and floors). The impact of the stability framework ranged from 25% to 57% for the braced framed tube and 33% to 66% for the outrigger system, with the impact increasing with the building's height...

The recent developments in the building industry to build more sustainable should result in the use of light constructions with a low environmental impact. Timber is a suitable material for this purpose. To reduce the environmental impact of a building, an improvement in an often used structural element can have a significant impact on the sustainability. Floors are a large part of the material consumption of building. A challenge with lightweight timber floors is the vibrational performance of the floor due to walking humans. Conventional concrete floors are less sensitive to vibrations due to their large weight. The vibrations of the floor have influence on the comfort of the humans residing on the floor. Furthermore, concrete is generally seen as a less environmentally friendly material than timber. This raised the main research question of this thesis: How do vibrational performance levels influence the sustainability of several timber floor systems, considering multiple design configurations, compared to conventional concrete floor systems?

The floors used in this research are a CLT floor, LVL box floor, TCC floor, concrete cast in situ floor and concrete hollow core floor. For the research on the vibrational performance and sustainability of floors some methods for assessment are used. For the vibrational performance the assessment method from the renewed Eurocode 5: Timber structures is used. This assesses the resonant and transient vibration response of the floor and checks them with predetermined vibrational comfort criteria. For the assessment of the sustainability the environmental cost indication is used. This method assesses several environmental impact categories and weighs their impact onto the environment, separately the global warming potential is also assessed by the CO2eq emissions of a material.

The result gathered from the research show that timber floors are more sensitive to vibrational performance than concrete floors. Floors with a high vibrational performance need a significantly higher floor height than low performance floors. The influence of damping and floor configurations is important for the vibrational performance. The environmental impact of timber floors have an advantage when biogenic carbon is taken into account. Concrete floors can reach longer floor spans and for high performance floors have a lower increase of environmental impact than timber floors. For the environmental impact of a floor, reuse or recycling is important for the end-of-life scenario.

To draw a conclusion to the main research question; Vibrational performance of floors do effect the environmental impact of the floors. High performance floors have a significantly higher environmental impact than low performance floors. The environmental impact of concrete floors increases less for higher floor performances than timber floors. Timber floors are more sustainable within their technical feasibility. The floor configurations can mitigate vibrations and can thus reduce the environmental impact of the floors.

Numerous structural failure incidents have occurred in the past years. It was found that current methods, such as NEN 2767, fall short in guaranteeing the structural safety of existing buildings. Although structural failure incidents infrequently result in casualties, there are also social and economic consequences that impact both building user as owner. Interviewed asset managers have noted that the current lack of insight into a building’s structural condition often leads to preventable maintenance and repair costs, and safety risks. When coupled with changes in the outdoor and built environment, such as a focus of continuity in use, these risks become increasingly challenging for owners to manage.
To ensure structural safety of significant public buildings within CC3, mandatory assessment via NTA 8790 must be performed. However, this method is exclusively tailored to CC3 buildings and only considers potential casualties as risk consequences. This strategy neglects CC2 buildings and other potential consequences, exposing them to elevated risks due to a lack of insight into their structural conditions. All the asset managers interviewed for this study, all managing CC2 buildings, reported these issues.
The goal of this thesis is to develop an efficient and effective assessment method to evaluate existing consequence class two buildings on structural safety to prevent incidents with structural failures. As a start (CC2) building typologies within the Netherlands were examined to determine the typologies for which the method should be optimised. Subsequently, structural failure incidents were analysed, resulting in a list of common causes that should be considered during the assessment. However, due to limited data availability, expert interviews and general literature this list is not exhaustive but rather an initial attempt. It can serve as a focus during the assessment but should not be solely relied upon. Finally, existing assessment methods were evaluated based on trustworthiness, effectiveness and efficiency. The findings from this evaluation have been incorporated into the development of an efficient and effective assessment process, which is described in the document.
The assessment process developed in this study was validated by applying it to two existing buildings, leading to the following conclusions. The assessment process developed in this study has proven effective in evaluating the structural safety of CC2 buildings, thereby preventing incidents relating to structural failures. While the necessity for comprehensive risk analyses does impact the time required for the assessment, these analyses have been optimised to concentrate on the most critical aspects. Along with other efficiency-enhancing aspects, it presents an efficient method within the parameters of effectivity and trustworthiness.
However, as revealed during validation, not all deficiencies can be detected using this method. There will always be hidden deficiencies that remain undetected and assessors are made aware of this limitation. Despite this constraint, the method provides an efficient and effective evaluation of the structural safety of existing buildings.

The challenge of global warming is an increasing concern of the 21st century. The concept of sustainability is therefore considered of high importance. A major problem of the Dutch government is the growing housing demand. Also after the WWII, the Netherlands faced a housing crisis, resulting in about 847,000 council houses. The massive number of flats combined with the aforementioned deficiency of houses and the climate problem prohibit large scale demolition and reconstruction, as this would lead to both a further short-term deficit of houses and emission of greenhouse gasses. A timber top-up on council estates constitutes a sustainable approach, which accounts for densification and the huge building stock in city centres. Therefore, this research is aimed to develop a method to optimize timber top-up designs for council estates, considering structural limits and environmental impact.

It is found that the building period impacts the structural variety in council estates. Hence unfortunately no universal structural lay-out can be defined. Based on a norm comparison, two flowcharts are produced to predict the overcapacity of distinct council estates. A modular cross laminated timber (CLT) unit and a non-modular timber frame extension (Dutch: houtskeletbouw) are considered. Material minimalization formed the decisive criterion to determine the most effective variant. Therefore, a 3-step method is developed, which considers the flat characteristics, structural overcapacity and minimalization of material use.

To conclude, it is generally not possible to tell a priori which of the two considered timber top-up methods is the most effective for a particular case. Further, it can be concluded that timber top-ups form a sustainable replacement for combined demolition and reconstruction of buildings. Moreover, these facilitate the realization of a substantial number of houses. Therefore, a vertical extension of council estates forms a sustainable solution to the current housing demand in the Netherlands.

The construction sector plays a significant role in the environment, and concrete structures constitute a substantial portion of this sector. The government is actively seeking ways to reduce the environmental impact of construction activities by promoting a more sustainable approach. In the Netherlands, a considerable number of repetitive cellular residential buildings are constructed using the tunnel formwork building method. Although this method can be enhanced in terms of sustainability by utilizing environmentally friendly cement mixtures, it poses challenges, such as an increase in execution time. This research aims to explore a more sustainable approach to the tunnel formwork building method while devising strategies to maintain the same execution time as before.

The tunnel formwork building method operates with a 24-hour daily execution cycle. During the initial 8 hours, the formwork, reinforcement, and installations are set up, followed by pouring concrete at the end of the day. After 16 hours, the concrete attains sufficient strength for the formwork to be dismantled, allowing it to be placed on the next grid. This approach results in rapid construction, high-quality output, and cost-effectiveness. However, a significant drawback is the reliance on CEM I mixtures, which consist of approximately 100\% Portland cement, contributing to substantial greenhouse gas emissions and environmental impact. Blended cement mixtures, such as CEM II and CEM III, offer more environmentally friendly alternatives by incorporating lower percentages of Portland cement blended with fly ash or blast furnace slag. Despite their environmental benefits, these mixtures exhibit a slower strength development, making it challenging to achieve a hardening time of 16 hours.

In pursuit of a dependable and sustainable approach to the tunnel formwork building method that preserves the 24-hour daily cycle, the research question is articulated as follows: "What concrete mixtures and execution strategies can be applied in the Netherlands to diminish the environmental impact of the traditional tunnel formwork building method, utilizing sustainable cement mixtures, while upholding existing advantages in time, cost, and quality?" This research question will guide the exploration of optimal concrete mixtures and execution measures for implementing sustainable cement mixtures within the tunnel formwork building method, while ensuring the continuity of the daily execution cycle.

In addressing this research question, an Excel calculation sheet has been developed. This sheet serves to compute the material costs, shadow costs, and formwork removal time associated with specific modifications in the design, concrete mixture, and additional execution measures for the tunnel formwork building method. The calculation sheet offers flexibility with three grid sizes: 4.5m, 6.0m, and 7.2m. It incorporates various concrete properties, such as the cement mixture (CEM I, CEM II, or CEM III), w/c ratio (0.45 or 0.55), aggregate types (fine and coarse), Blaine value (300 or 400$m^2/kg$), and admixtures (basic and additional). Additionally, the calculation sheet allows for adjustments in seasonal conditions, with options for summer (20°C) or winter (10°C)...

To stop the depletion of natural resources, reduce climate change and fight biodiversity loss a circular economy in 2050 is pursued. In the upcoming years a challenging opportunity arises. Many existing bridges and viaducts with bridge decks consisting of prefabricated concrete girders have to be replaced. These girders although not designed according to circularity concepts have potential to be reused in a new structure, which is in line with the highest achievable level of circularity. However, the construction market is not ready for this innovation. So, while current research still aims at the feasibility and suitability of the girders for reuse in new structures, this research aims at the next step of preparing the construction market. This is of high relevance because it speeds up the introduction process of the innovation and thereby safes girders from demolition.

In this research the focus is on the adaptions and modifications needed in the traditional design process to ensure a more frequent implementation of reuse of existing bridge girders in new designs. After a literature review into the type of bridge girders in the Netherlands, the structural feasibility, obstacles for reuse identified by the industry, the design process and environmental impacts a design approach is developed. Simultaneously to the development of this design approach a case study is performed to give a more practical view to design aspects. In this way the approach could be verified, adapted and modified.

The design approach consists of roadmaps, possible procedures and recommendations that guides project teams through each step of the system and preliminary design. In the case study a bridge deck for a 107 [m] long bridge, divided over 5 spans with reuse of existing girders is designed. The design approach is suspectable to changes due to experiences, gained knowledge and developments in the construction industry. Therefore, it needs review over time. The design approach concentrates on inverted T-girders but can be extended and applied to other girder types as well.

In conclusion, this research provides the foundations for a changed design approach that is needed to prepare the construction market for reusing existing girders. By giving guidance to project teams, the view shifts from using new girders to reusing existing girders. This is valuable to reach the environmental objective of a circular economy in 2050.

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

The steel sector is responsible for 4-5% of the total greenhouse gas emissions in the world. Reusing structural steel elements can potentially decrease the need for the production of new steel. However, designing a load-bearing structure with reusable elements poses challenges to the design process. The starting point of the process is different due to a limited availability of structural elements. The design of the load-bearing structure should be based on the measurements of the available reusable elements, while traditionally the amount of elements and their measurements were based on the design. However, the freedom in a design is often limited by certain architectural and structural constraints. Therefore, the focus of this thesis is on how to organize an optimization process in which the aim is to design a load-bearing structure containing the least amount of new steel by means of implementing reusable elements, while taking into account the architectural and structural constraints.

In the optimization method developed in this study, a primary design for a load-bearing structure functions as an input. The method consists of four big steps: the definition of the geometry, the assignment of (reusable) elements, structural calculations and the formulation of results. The goal is to assign reusable elements which are respecting the given constraints: the minimum and maximum UC-value allowed and the maximum deviation in length. The output is a modified design in which reusable elements are implemented, in a way that lowers the amount of steel required to realize the design.
By performing a case study, the model is tested and the influence of the constraints and the implemented stock can be determined. Several analyses are conducted, using three different stocks. Stock 1 and stock 2 can be considered more diverse than stock 3. 
The characteristics of the resulting designs are influenced by the relation between the stock and the original design. For the more diverse stock, there are only results whenever the minimum allowed UC-value is set to 0.01. While the required amount of steel lowers (up to 79% for stock 1 and 74% for stock 2), the actual UC-values of the implemented elements can be considered low and the change in design can be considered big (up to 19 out of 24 angles in the beam-configuration changing more than 10%). For the less diverse stock, all analyses give results, independent of the values for the constraints. In this case, the results UC-value are high compared to the results related to stock 1 and 2, and the changes in design are less (0 changing angles). Besides, all elements can be reused, which lowers the amount of required new steel to zero. 
Therefore, applying the optimization method developed in this study to a design for a load-bearing structure results in a modified design in which the amount of new steel required to realize the design is minimized. However, the actual UC-values corresponding to the different elements and the changes in the design are dependent on the available stock and the constraints.

The transition to a circular economy requires reducing waste and rework in construction projects. Thereby, the evaluation of building circularity in the early design phase is of great importance. However, due to the current design workflow, such practice is hindered because there is not enough information to evaluate building circularity in detail in the early design stages. An improved workflow to emphasize circularity more in the early design phase is thus needed. This research explores the current workflow and designs an improved work procedure with limited information available by incorporating an automated decision support tool to assess early design phase building circularity, aiming to improve the working efficiency and efficacy. This tool has been designed based on interviews and literature studies, and verified and validated with practitioners. This study serves as a starting point to rethink the workflow to improve circularity with current technological potentials.

Sustained economic growth based on a linear production model is not feasible on a planet with finite resources and a limited capacity to absorb wastes. By 2050, the world's population has grown exponentially to 9.7 billion and a tripling of the global use of materials can be realistically expected. Therefore, the transition towards a circular economy has become one of the top priorities of the European Union and its national governments. The Dutch government has stated the ambition to achieve a fully circular economy by 2050 at the latest.

Worldwide, the construction sector contributes to approximately 13\% of the global economy and employment of over 110 million workers. However, the construction sector is also responsible for 50\% of the total raw material consumption, 40\% of the energy usage and for 39\% of all carbon dioxide emissions. The construction sector therefore shows excellent potential for the transition to a more circular production model. One of the initiatives in the Netherlands to accelerate this transition is called 'het betonakkoord'. This initiative aims to make the concrete supply chain more sustainable by focusing on high quality application of recycled or reused building materials and on circular design.

Another interesting development is ongoing in the Netherlands. Since 2019, the housing shortage is 300.000 units and is continuously increasing to approximately 400.000 units by 2025. Combined with the economic growth of the past decade has resulted in skyrocketing house prices. One of the most effective solutions to overcome this problem is to simply built new houses. However, taken into consideration the transition towards a circular economy, raises a fundamental question of how to design sustainable residential buildings with regard to circular principles. This question is quite extensive and consists of a variety of both structural and non-structural aspects. This thesis project focuses on the circular design of a load-bearing floor system for utilisation as a storey floor.

First, extensive literature review is performed in order to identify circular principles and strategies in the design phase of buildings. This thesis project adopted the framework of Cheshire. The framework consist of six nested circles which represent the hierarchy of the framework. Within the framework, Cheshire proposes five design principles in his book: building in layers, designing-out waste, design for adaptability, design for disassembly and material selection. This thesis project expanded the design principles of Cheshire, by defining and providing hands-on strategies or criteria for each design principle. In total, 42 criteria are proposed for transposition into a comprehensive framework for application in practice.

Next, several recent residential and utility building projects are reviewed to determine the state-of-the-art regarding the implementation of circular design principles in practice. The general tendency is that these projects take the deconstructability and, to a limited extent, the selection of materials of the buildings into account. The common denominator in all recent projects, and especially for residential buildings, is the reduction of environmental impact through the realisation of net zero energy buildings.

Concrete floor systems are still widely used in newly built residential and utility buildings, due to their favourable characteristics. Therefore, the four most commonly used concrete floor systems are reviewed and discussed, These four floor systems are primarily designed in accordance with the demands of users and contractors. As a result of this thesis project, a newly designed floor system is proposed which is fundamentally based on the theoretical design framework developed in this report. Implementation of all five design principles was not considered feasible given the current state-of-the-art and regulatory barriers. Therefore, the newly proposed floor system is based on strategies and criteria related to the design principles of adaptability and disassembly. These design principles form the starting point of the multi-criteria analysis conducted in this report. The multi-criteria analysis is conducted in the first place to evaluate the performances of the four most commonly used concrete floor systems in the context of the considered circular design principles and secondly to compare the newly proposed floor system with the four most commonly used concrete floor systems. Based on the weighted rating scale, a maximum score of one hundred can be obtained. Results from the multi-criteria analysis reveal that three out of four commonly used concrete floor systems score well (scoring between 60 and 80) regarding the circular design principles. The newly proposed floor system scores excellent (scoring between 80 and 100).

The structural resistance of the newly proposed floor system is verified in accordance with codes of practice and state-of-the-art research under normal loading conditions. Horizontal wind loading is taken into consideration as well with respect to the stability of floor systems. Moreover, several stakeholder prerequisites are included in the design. Possibilities for recesses, staircases or vertical shafts for example, and building services are provided and suggested. Buildability aspects, such as the fabrication and assembly process are discussed in the report as well.

Global awareness has arisen for sustainable development to reduce the burden of the building sector on the earth’s ecosystems. One of these sustainable developments is the transition towards a 100% circular building economy with high-quality reuse. However, the sector has insufficient knowledge and understanding about the possibilities and opportunities to transition towards a circular economy. In the current linear economy outdated existing buildings are demolished and replaces with new buildings. This research provides knowledge on a new design strategy of giving existing load-bearing components a proper end-of-service life application by reusing them. This research focuses on outdated school buildings in the Netherlands and sees these existing school buildings as urban mines to extract load-bearing components for new school buildings. In this way, the linear building cycle of load-bearing components closes, and the switch to a circular building economy is possible.

This research proposes a quantitative assessment of the potential reclaim and reuse of existing load-bearing components. Determining the degree of reclamation and reusability starts with assessing individual components on several indicators. A literature study, interviews, and surveys with practitioners determine the indicators and sub-indicators that influence reclamation and reusability. Each indicator and sub-indictor influence the reclaim and reuse of load-bearing components from the indoor environment. Moreover, the reuse of existing components takes place in new SE school buildings, and therefore, the component must meet the current technical requirements. Subsequently, this research collects the required information for each reusability indicator, the theoretical knowledge. Afterwards, the reusability indicators are translated into an assessment method. The assessment method can quantitatively measure the reclaim and reuse potential technically by giving each indicator and sub-indicator a score for reclaim and reuse. Each reusability indicator has a score ranging from 0 = ‘not reusable’ to 1.0 = ‘highly reusable’. The reusability indicators are independent and weigh equal. As a product, this research translated the theoretical knowledge and assessment method into a practically usable, rapid supportive assessment tool. In this way, awareness, knowledge and insight can be provided about the reuse of load-bearing components. The assessment of the reclaim and reuse potential can serve as a supportive tool that helps school organisations and the project teams with the initial decision to apply the reuse of load-bearing components in the construction process of a new SE school building. This decision making

Policy makers have set the goal to reach a completelycircular economy by the year 2050 in the Netherlands. This means that theconstruction industry should shift from its current ‘take-make-waste’ approachtowards a circular approach. The number of buildings of more than 100 m inheight are increasing in the Netherlands, due to the lack of horizontal space.This means that strategies should be investigated on how high-rise buildingscan be constructed in a circular manner. It is found that there are currently alarge number of high-rise buildings that are being demolished. The main reasonfor these demolition cases is that building owners want to replace theirbuilding with a new one, with new technologies and perhaps a new buildingfunction. Abuilding that is adaptable to these changes would not have to bedemolished,  which is why the circularitystrategy of Design for Adaptability is interesting for high-rise buildings.There is a lack of research on the measurement of theDesign for Adaptabilitystrategy on the building level. Therefore, in this research a BuildingAdaptability Indicator is created to measure the adaptability of a building. TheBuilding Adaptability Indicator is constructed from a study on how adaptabilitycan be achieved in a building. It is found that building adaptability isgoverned by three sub-indicators: openness, reserved capacity, andfloor-to-floor height. The Building Adaptability Indicator helps structuraldesigners to prove what amount of adaptability can be achieved with a certainextra material use. It is found that the adaptability can be increased with126% by increasing the structural element dimensions by up to 60%, leading to atotal material volume increase of 38%. Additionally, it is found that purelyfrom amicro economics point of view, the investment into a high adaptabilitycannot be justified due to the high initial investment combined with a low rentincome. However, from a macroeconomics point of view, policy makers caninfluence the construction industry to invest in buildings with a lowenvironmental impact, which is already done by the Dutch government throughsubsidies. Currently, adaptability is not considered in the calculation of theenvironmental impact, which means that investors do not have an incentive toimplement adaptability in their buildings. In this research, the BuildingAdaptability Indicator I simplemented in the calculation of the environmentalimpact, which leads to the conclusion that buildings with a high adaptabilityare more interesting from a circularity point of view. It is concluded that atthe moment, only investors with circularity ambitions will invest in adaptablebuildings. Investors that lack circularity ambitions can be encouraged toinvest in adaptable buildings as well. This can be done by implementingadaptability in the calculation of the environmental impact, for which ownersof adaptable buildings will receive subsidies. This will shift the constructionindustry more towards adaptable buildings, which will prevent demolition andlead to a lower environmental impact across the industry.   

The concept of sustainability takes into account a problem of urbanisation which causes a phenomenon of urban sprawl. In order to fight it, the strategy of urban densification is introduced and building upward extensions is one of the methods. However, investigating the feasibility of placing an extension on top requires a significant amount of time and effort from structural engineers. Therefore, this research aims to explore computational tools that would simplify the initial exploration process and make the option of extension more appealing. Theoretical background part of the thesis analyses conditions and limitations for building reuse, upward extension and use of timber. The main impediments that could prevent realisation of such project are found. The practical part of the research aims to explore parametric modelling and machine learning (ML) in order to produce a proof of concept ML tool which predicts how much an existing building can be extended based on its parameters. In order to have a sufficient amount of data, parametric modelling is used. For the first step, information is collected about seven realised upward extension projects in the Netherlands. This data defines the object for the parametric model which is built using Rhino plug-in Grasshopper. One part of the model analyses the existing structures with the goal to establish structural reserve while another part examines extensions. Six parameters defining existing buildings are chosen for iteration, by changing these parameters, a database of 8 652 fictional projects is generated. For the ML, the data is analysed and used for supervised learning where regression task is performed. Multiple linear regression (MLR) and nonlinear regression (NLR) algorithms are applied to make predictions which are validated using 5-fold cross validation (CV) and evaluated by calculating errors. Finally, the research presents a possibility and an example of using ML for extension exploration. The use of ML model during the initial stage of upward extension projects seems very appealing due to the quick feedback with limited information provided. A useful database of realised projects with a selection of structural parameters together with the incorporation of non-structural ones and a customised ML model should provide accurate predictions. However, the current problem of lack of data about realised extension projects needs to be solved.

Innovative solutions for safety and risk management on construction sites are required to reduce the amount of accidents that occur globally, as too many occupational accidents still happen in the Architecture, Engineering and Construction industry. A particular problem is the fall from height (FFH) accidents on construction sites, due to failing barriers with the underlying cause of insufficient planning. In previous research it has been suggested to develop dedicated BIM plug-ins to automate and visualise risk identification and evaluation of construction sites as a means to assist the safety management process. To explore the impact of BIM on FFH accident reduction through automation and visualisation, a digital tool prototype is developed. This prototype focusses on fall from height (FFH) identification on construction sites during early project phases of civil engineering projects. It is programmed in Autodesk Dynamo for Revit, based on technical and functional requirements derived from literature and industry professionals. A simulation of the FFH tool prototype has been conducted through a pilot project. The result of this product development is a working fall from height detection prototype that is to be used as a supporting tool during the safety analysis of construction site design in Dutch civil engineering projects. The developed tool is added to the body of products that can be used for digitalisation and innovation within the construction process, where it digitalises part of the safety management process that is otherwise performed manually. The added value of the tool prototype is the addition of automated risk detection, creating support in the design and planning process and providing added information to group discussion on safety matters in risk identification and evaluation meetings. Recommendation for future use of the tool is to implement the FFH tool prototype during the design phase to provide the designer with insights in the safety of the constructability. Additionally, the FFH tool prototype can be implemented by safety managers to use the results during safety meetings for better discussion and evaluation of the construction site. For the implementation, improvement of the level of detail in the 3D models for the projects and including temporary construction site works is essential. For further development it is recommended to focus on improving the import of linked models into the script and developing alternative operations to determine the height differences. More developments and improvements can be made to the script to increase the applicability on more complex projects. Concluding, the FFH tool prototype is considered to bring added value in digitalising an otherwise manual process regarding safety management. It is suggested to incorporate use of the FFH tool prototype in the design and planning process to proactively engage in digitalising and innovating engineering processes.

Façades within the building industry ore one the most important and expensive aspect of a project. They are the outer skin of a structure and are responsible for improving energy efficiency, while being both innovative and attractive. At the same time, façades need to accommodate requirements to withstand the outdoor environmental conditions.
To meet all of these requirements, there is need for designers to either have knowledge on the different subjects, such as human comfort, sustainability, stability, among others; or work together with different specialist to achieve an ideal design.

Following a traditional design process, once the conceptual design is defined it goes through an iteration process between designing and detailing before reaching the manufacturing stage. This process, even though is already considered within the planning of a building, is highly time consuming.

Considering this process, the idea of bringing the manufacturing knowledge into the early design stages to speed up the design process was taken into consideration. The idea of bringing the manufacturing knowledge upwards in the design process would help designers, focus only on designing, while the considerations for product availability and manufacturing possibilities are already taken into account.

On the other hand, the increasing use of parametric modeling to improve building solutions, has been a growing field. In regards to façade design, the inclusion of free form architecture in the building industry has pushed the need for innovative solutions. It has been proved in these projects that the use of parametric modeling highly increases the speed in which designs are developed. However, the need to adapt existing products and manufacturing techniques to these complex geometries, generates more iteration times and increases the costs of the final product.

Now, imagine that not only the available products are adapted to the conceptual designs proposed, but that these designs include from their conceptual stages knowledge acquired from previous experience. This would help avoid the iterations between designers and manufacturers, plus would improve the possibilities of generating a bigger amount of modularity in the design process.

With these considerations, the proposal for this project aimed to develop a proof of concept tool that would be capable of encoding a manufacturers knowledge in a digital model, and use it to design a façade that is almost ready to manufacture.
For this purpose, the knowledge and information from the façades manufacturer Vianen Kozijnen was used as base for the development of this tool.

Once this was established, the modelling phase for the façade design tool begun. Initially the input parameters were set, the knowledge is gathered from the company's input, allowing the designer to set up a model within the possibilities of the manufacturer. In the back end of the tool, the build-up of the main modular panel is generated. Four main variables were defined to generate the geometry of the panel and these are determined by the input parameters.

Next, with a finalized panel design, the testing phase is set in place. This phase was divided into two processes. First, the replication of the panel throughout an entire façade. This process begins with a conceptual shape that will be filled with the already designed panel. The results from this process determine the total amount of modular panels and the percentage and amount of customized panels needed.

Secondly, the panel is tested for Building Physics aspects relevant in early design stages, which for this case were daylight and sound proofing. The tool then with the geometrical parameters given, includes simulations for both daylight and sound proofing. The results obtained, give information on the performance of the design. For daylight simulations, the results given are for daylight autonomy and daylight factor; and for sound proofing the results obtained give information on the insulation value of the façade, sound proofing of the structure and typical sound proofing. Both results, are information that is useful during early design stages, and can help shape the final project.

To test the functionality of the tool, the Sluishuis building was taken as a case study and the tool was applied to design and test one of the façade surfaces of the building.

The results obtained through this case study led to conclude the feasibility of encoding manufacturing knowledge. It was determined that as a proof of concept approach the tool generates almost immediate results that include the knowledge needed for manufacturing. However, to be applied into a real project further improvements need to be made; with more focus on, first, being able to apply the tool to a completed building and secondly, include more manufacturers knowledge to generate a library of possibilities; making it useful in real life projects.

Uit onderzoek naar de ingestorte parkeergarage bij Eindhoven Airport in 2017 blijkt dat het tot die tijd gebruikelijke detail voor voegen in breedplaatvloeren met krachtsafdracht in twee richtingen onder invloed van een positief buigend moment niet goed werd ontworpen en uitgevoerd. Een breedplaatvloer is in eerste instantie bedoeld om een krachtsafdracht in één richting te realiseren, maar de toepassing werd verruimd naar krachtsafdracht in twee richtingen. Daarnaast werd zelfverdichtend beton en gewichtsbesparende elementen geïntroduceerd bij de toepassing van breedplaatvloeren. Hierbij is niet zorgvuldig onderzocht of de bestaande regelgeving afdoende was voor deze toepassingen. De partijen in de bouw introduceerden hiermee onbewust een systeemfout: de constructie kon bros bezwijken doordat er een bezwijkvlak mogelijk was, zonder dat het door constructieve wapening werd doorsneden. Op dit moment bestaat er nog geen nieuwe regelgeving voor dit detail, maar worden er al wel vast aanwijzingen gegeven in de VARCE-rubriek in vakblad Cement.

Om inzicht te krijgen in hoe verschillende partijen in de bouw op dit moment omgaan met dit voegdetail bij nieuwbouw, is er in dit onderzoek aan de hand van een literatuurstudie en verkennende interviews een enquête opgesteld die verspreid is onder constructeurs en leveranciers. In dit rapport staan de resultaten van dit onderzoek.

Dit onderzoek is in opdracht van VNconstructeurs gedaan.

The infrastructure industry currently deals with two issues: the deterioration of (highway) bridges, and the urge to reduce emissions by the construction sector. Rijkswaterstaat must repair or replace hundreds of bridges in the upcoming decades. At the same time, the impact of human behaviour on climate change becomes more visible and must be reduced. The most structural solution to diminish the human impact on the environment is switching from a linear economy to a circular economy (CE).
This research aims to develop a system for circular highway bridges by both constructing with timber and extending the lifespan. The first contributes to a lower environmental impact as timber is a renewable material that captures carbon during growth. For an outdoor timber structure, protection is crucial to prevent the timber from deteriorating due to weather influences. The lifespan extension is obtained by applying three circular principles: (1) Design for Material Efficiency (DfME), (2) Design for Adaptability (DfA), and
(3) Design for Disassembly (DfD). Variant studies on typology, connections and material optimise for material efficiency. A flexible structure enables DfA: converting in function and expansion in length and width is possible. Furthermore, a modular system is developed to include DfD: connections between modules are demountable to disassemble, adapt and reuse the system. In summary, four design strategies are defined: efficient, protected, adaptable and demountable.
This research aims to provide an alternative for concrete highway bridges with a lower environmental impact.The timber bridge, a circular concrete bridge and a traditional concrete bridge are compared. The comparison includes the production (A1‐A3), construction (A4‐A5) and end of life (C1‐C4) stages. Timber results in a lower carbon footprint for all reference periods and lifespans. The study considers the third scenario most reliable, as the technical lifespans are most substantiated. In this scenario, reductions of 18% and 47% for respectively the circular and traditional concrete bridge are established.
This study concludes that Dutch highway bridges suit replacement with a modular timber alternative. The developed modular system covers 58% of the highway bridges stock owned by Rijkswaterstaat that were built in 1950‐1980. Moreover, timber shows substantial environmental benefits compared to concrete. The alternative reduces the carbon footprint by 47% compared to a traditional concrete bridge. Furthermore, this study observes additional benefits when one considers carbon emissions in time, as the structure
sequestrates carbon during use. Consequently, building with timber lowers the carbon concentration in the atmosphere, reducing the global warming effect. This study recommends Rijkswaterstaat to invest in the development of circular timber highway bridges. By changing the ’business as usual’ from concrete to a more sustainable alternative, the circular and climate goals can be obtained. Furthermore, the recommendation is made to clarify the regulations on quantification of environmental impact, both on data and methodology level.