In Groningen, seismic activity has increased due to the extraction of gas in the area. A large-scale research campaign has been launched with the aim to assess and safeguard structures in the region. However, an accurate assessment of these buildings turned out to be a challenge, due to the nonlinear behaviour of the masonry and the dynamic nature of a seismic load. A Nonlinear Time History (NLTH) analysis takes into account both these factors, but the computational demand of such a method is considerable. Another method that is widely used to analyse the seismic response of a structure is the Modal Response Spectrum (MRS) method. The computational demand of this method is considerably less compared to NLTH, but nonlinear material behaviour is only taken into account in an indirect manner via a behaviour factor, and the results are considered to be too conservative. A third method is the Nonlinear Pushover (NLPO) method. It takes nonlinear material behaviour into account and compared to NLTH, NLPO is computationally more efficient. Furthermore, an advantage is that it separates capacity from demand. Even though the NLPO method is commonly applied worldwide, its validity still needs to be proven for the Groningen case. Both objectives were studied by looking into a single case study, consisting of a low-rise URM apartment building. The behaviour of the structure is characterised by a weak and strong direction, in which the weak direction is characterised by a relatively low stiffness and lateral capacity compared to the strong direction. The seismic response of the structure is determined according to the MRS, NLPO and NLTH methods. Furthermore, the NLPO analyses are executed using two different computational discretisation methods, namely continuum FEM and macro EFM. DIANA is used as a FEM solver for the MRS, NLPO and NLTH analyses and 3MURI is used for the EFM model. Moreover, a modal and uniform lateral load pattern are taken into account for the NLPO analyses. The conclusions which are drawn from the case study can generally be applied to low-rise URM apartment buildings in Groningen. However, it must be noted that significant alterations in geometry and building materials might influence the results. Furthermore, modelling assumptions have been applied, and it is important to note that the possible influence of these assumptions, may partially limit the extent of the conclusions. Moreover, several limitations are inherent to the studied methods, and cannot be accounted for somehow. All analyses are performed by incrementally increasing the seismic load until one of the near collapse limit state criteria according to NPR 9998 is met. Furthermore, three target displacement methods are evaluated: the capacity spectrum method according to NPR 9998, the regular N2-method, included in the Eurocode 8, and an adaptation of the N2-method which is developed specifically for URM structures by Guerinni. The performance of the structure according to each of the methods is studied subsequently, by looking into the force-displacement behaviour, displacement profile and damage at failure, failure mechanisms and the maximum admissible seismic load. Two significant disadvantages of macro EFM were identified when comparing the results of the NLPO analyses using 3MURI and DIANA. First, the fact that out-of-plane behaviour is not taken into account in 3MURI could significantly influence the behaviour of a structure in terms of base shear capacity, which is especially true when structures are characterised by an extremely low total length of piers in the in-plane direction. Furthermore,DIANA allows for a more gradual softening behaviour, which helps the post-peak force redistribution. As a consequence, the maximum admissible seismic load according to DIANA could be higher. However, despite the two aforementioned disadvantages of the macro EFM method as implemented in 3MURI, all other relevant results of both methods are similar. The fact that the two identified disadvantages of 3MURI can only result in more conservative results, suggests that macro EFM, as implemented in 3MURI, is a suitable computational discretisation method for the seismic assessment according to the NLPO method for low-rise URM apartment buildings in Groningen. However, it should be taken into account that the conservativeness of 3MURI could lead to a significantly larger amount of required retrofitting, in comparison with DIANA. The applicability of the NLPO method is reviewed by comparing the results of the MRS, NLPO and NLTH methods. Similar behaviour of the structure according to the NLPO and NLTH method was captured, which suggests that the NLPO method is a suitable analysis method for the studied typology. The maximum admissible seismic load using the target displacement method according to NPR 9998 is in-line with the NLTH analysis. However, the governing load case made use of a uniform load pattern, which returns a structural behaviour different than that obtained by NLTH analyses, as can be seen from the force-displacement behaviour. If only the capacity curve according to the modal load pattern would be considered, then the allowable seismic load according to NLTH is similar to that of NLPO using the target displacement method of Eurocode 8. Furthermore, from the results of the case study can be concluded that the choice of target displacement method has a significant influence on the maximum admissible seismic load. For the case study, NPR 9998 is more conservative in the strong direction, and Eurocode 8 is more conservative in the weak direction. Regarding the MRS method, very conservative results were found. A reason that was found for these conservative results is that the prescribed behaviour factor by NPR 9998 is too low for the case study when compared to that derived from the NLPO analysis. However, even with a larger behaviour factor, the results according to the MRS method would still be conservative in the weak direction.

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

Building failure incidents are occurring within the Netherlands and these incidents can be a valuable source of technical data regarding improvements in structural safety. This research has attempted to utilize this information gained to develop a tool to aid the building construction sector in identifying hazards during building construction projects. For that purpose, this research has investigated risk assessments and structural failure incidents. To be able to develop a tool, deeper knowledge of risk assessments is required and therefore risk assessments were studied to understand how they should be performed and what characteristics makes them effective. The research of Terwel (2012) on the Cobouw database formed the basis for the analysis of structural failure incidents. This thesis investigated how other research used structural failure databases to improve structural safety and studied the data available from the Cobouw database for developing a tool. The analysis of risk assessments has shown that identifying hazards is a crucial step in the assessment process. It was concluded that it would be beneficial to a project team if it had information on which hazards related to structural failure can occur, the probability of occurrence of hazards and the possible impact they can have. An investigation into structural failure databases showed that no other research could provide a tool that fulfilled the above requirements and in addition it was concluded that the database available to this research was only sufficient to provide information on which hazards can occur. There was not enough data available to make a justified estimate regarding the consequences of a hazard or probability of occurrence. Therefore it was chosen to use a different approach to analyze the database. The Cobouw database has been restructured into a fault tree format, to relate hazards to specific components of a building structure. Afterwards an attempt was made to discover why many hazards have occurred or which building components were prone to hazards. There was not enough data available to draw conclusions on that subject either. Finally this research concluded that the most efficient way of developing a tool, from the data available to this research, is to create a guide which can be used during the design phase to caution the project team about frequently occurring hazards. The method that was used to create the tool can also be used as an inspiration for future research, because this research was limited not only by the amount of available incidents, but also by the source of the incidents, which was from a news site that would most likely not focus on low-profile failure incidents and the reporting of precise technical details. Therefore the most important recommendation this research has, is to introduce a large scale collaboration in the construction industry focused on gathering accurate data on structural failure incidents.

This research investigated in which ways the material environmental impact of the main load-bearing structure of a high-rise building can be reduced. To determine this material environmental impact, the shadow price for each material and product has been determined by using ten environmental impact categories. One of these categories is global warming potential. In this research the material environmental impact of the main load-bearing structure for the building for the European Patent Office has been determined and optimized. The originally designed main load-bearing structure for this building consists mainly of steel columns and beams, and Slimline floors. The optimisation has been done for a design lifespan of 50 years and for 200 years. Additionally, a higher live load that creates more flexibility for the 200-year scenario is examined. The original function for the building is “office” and the other considered function is “meeting”. As alternatives for the beams and columns, steel, concrete, and timber elements have been considered. Hollow core slabs and Lignatur floors were explored as alternatives for the Slimline floors. In this research it has been found that it is beneficial to prolong the design lifespan of building. The environmental impact per year is much lower for a lifespan of 200 years than for a lifespan of 50 years. In order to increase the chance of a longer lifespan, it is wise to create flexibility concerning the function of the building. A higher live load will result in slightly more material needed, but still, the environmental impact per year is much lower than for 50 years. Additionally, there can be looked at choosing the best material for each application. For a design lifespan of 50 years, the difference between the materials is such small, that no preference can be determined. For a lifespan of 200 years the differences are still small, but an entire steel structure or a combination of steel beams and concrete columns result in the smallest environmental impact. For floors, no matter the lifespan, with a big span and where no in-situ concrete can be used, hollow core slab floors proved to be the best choice.

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 aim of this research is to make the early design process more efficient. This is done with a parametric model, which compares high-rise stability systems. The research is focused on the stability systems shear walls, core, outrigger and tube. All systems are executed in concrete cast-in-situ, in the range from 100 to 250 m. The parametric model is executed in Grasshopper and Karamba. Four performance criteria are checked in the model. These are strength, stiffness, foundation design and comfort. An optimisation procedure has been applied to find the most optimal system based on input and optimisation goal. Three optimisation goals have been appointed. These are slenderness of wall and column elements, total weight and carbon emission and flexibility. Flexibility is defined as effective floor area and ratio facade openings. The results of each optimisation goal are plotted with respect to the height to obtain insight in the suitability per system. Input parameters, optimisation procedure and performance criteria have been processed in a tool in Human UI. The model and tool have been applied on De Zalmhaventoren to verify the outcomes. It can be concluded that the model, tool and optimisation results have led to more insight in the high-rise early design process and ease decision making.

Cities like Amsterdam and Rotterdam are located on top of a compressible clay layer. Most of the buildings in these cities are founded on the foundation layer above the compressible layer. Therefore this compressible layer can induce problems when the soil pressure increases significantly due to the weight of the high-rise buildings. This deformation can cause inclination of the floors, damage to the structural and non-structural elements of the building. Therefore the structural design of a building must appropriately be designed to respond or resist these deformations. The deformation, which causes the problems in the building itself, is the differential deformation (sagging). This is unequal deformation over the entire plot of the building. The uniform deformation of the building does not induce problems in the structure itself, but it can damage the adjacent buildings because the soil under these buildings will deform (hogging). The construction sequence decreases the problem for the higher levels because the deformation of the compressible layer start occurring during construction, and these levels are constructed horizontally independent on the amount of deformation of the soil. For this research, the following mitigating measures are considered: changing the construction sequence; increase the length of the foundation pile; application of a camber; increase the stiffness of the foundation slab; increase the stiffness of the superstructure; application of a jack-down system. The primary factors which are affecting the applicability of the mitigating measures are the amount of settlement, the soil structure, and the time-dependent behavior. By a significant settlement of the soil, the mitigating measures of applying a camber and increasing the stiffness of the structure are not possible or less favorable. The soil structure determines if increasing the length of the foundation piles is possible, this mitigating measure put the foundation piles in the second foundation layer, which is situated under the compressible layer. With this measure, the problem of the compressible layer is solved, but it is an expensive mitigating measure. Adjusting the construction sequence depends on the time-dependent behavior of the settlement. It can be an option when the settlement happens mostly during construction. When the settlement of the soil takes longer than the construction time, the jack-down system can be applied to adjust the structure when needed, even when the building is finished. The application of the jack-down system is definitely worth considering when a high-rise building is built on compressible soil. The other mitigating measures can be applied too, however, only under very specific conditions. This makes the jack-down system the most favorable mitigating measure.

In most of city centres in the Netherlands, there is a growing demand for residential housing. However, as most of the land is occupied by existing buildings, developers recur to demolish and build higher buildings, in order to fulfil the urban need. Even though demolition, may be the simplest option in technical and economic terms, it can also destroy architectural heritage, cause noise disturbances and damage the environment. On the other hand, refurbishment can be a sustainable option in building scale, but does not provide extra capacity for the densification demands of the city. Structural extensions can be an attractive alternative that combines the benefits of the last two options, gaining more residential capacity in city centres and respecting the architectural heritage, and at the same time, reduce environmental impact by re-using old structures. Although, an ambitious extension can pose important technical constraints, many successful precedents have been realized. This can be an indicator that some of the complexities will partly overcome in the near future. This work aims at increasing the awareness of structural extension possibilities in existing buildings, as an alternative for ambitious architectural and structural projects, with sustainable considerations.

On April 15th, 2019 a devastating fire burned down Notre Dame de Paris and left the cathedral without its central spire and ancient gable roof, better known as The Forest. The required reconstruction initiated a global debate between architects, engineers, and other stakeholders. The discussion was put to an end by the French authorities, who proposed an identical reconstruction within a timeframe of 5 years. The decision forced the construction crew into a difficult job of finding identical construction materials, eventually leading to environmental and humanitarian suffering in Ghana, where a tropical underwater forest was felled. Besides, the time pressure put the quality of the reconstruction at risk. In the presented thesis, an alternative design for Notre Dame’s roof is proposed. First, the authorities’ reconstruction plans are analyzed to see which practical challenges will have to be tackled. An alternative reconstruction strategy is then developed for the choir and nave of the cathedral. Inspiration is drawn from Notre Dame’s initial construction in the 12th and 13th centuries, during which time pressure also played a key role in the design. The Master Builders’ clever construction strategies like integrated support structures and utilization during construction are indispensable parts of Gothic engineering and are used to tackle current problems. The proposed alternative construction process consists out of three phases: Fast Fix, Field Factory, and Former Finishing. The resulting structure, The Timber Skeleton – named after Professor Jacques Heyman’s book: The Stone Skeleton -, consists out of stabilizing cassettes (Fast Fix), expandable roof segments (Field Factory), covered by a roof cladding with the same external appearance as before the fire (Former Finishing). Notre Dame’s attic is imagined to function as a publicly accessible workshop, dedicated to the constant maintenance of the cathedral and all its Gothic ornamentation. As an alternative to the difficulties the authorities are facing in finding proper timber, modern construction materials and prefabrication strategies are investigated. They are utilized to facilitate a relatively quick construction without obstructing other on-site restoration works. Laminated veneer lumber with cross-plies is used to design openworked members with structural expression. For the particular geometry of the rafters, the boundaries of current analytical engineering tools have been explored. Different verification strategies have been assessed and compared to analyze the structural functioning and feasibility of The Timber Skeleton. A conventional stress analysis is eventually used for the structural verifications of The Timber Skeleton and its most important joints. Recommendations are given for further development of the design, in which mainly the moment rigid connections of the rafters will require numerical and physical testing. A Master Builder’s mentality of prototyping and trial and error will be needed to realize the proposed design. The research shows how an alternative reconstruction strategy for Notre Dame de Paris could result in a good functioning structural design that pays homage to Gothic engineering principles. The design functions as an innovative example for how modern production processes could help to arrive at a contemporary interpretation of The Forest that functionally and structurally better fulfills the contemporary requirements.

In the Netherlands, there are generally two categories of structural forensic investigations. The first category are extensive investigations with the goal to learn from failure by investigating all aspects: technical, human and organisational. The second category are investigations that focus mainly on technical causes and the investigation goal is often determining the failure cause including designing repair measures. For this category, little information is available on used investigation processes. In literature, several investigation methodologies have been described. However, they often describe only a very general process or on the other hand very specific material related laboratory tests. Descriptions and recommended techniques on how to perform the proposed steps of an investigation are scarce. To a client ordering a damage investigation, the most important parts of the investigation are the conclusion and the recommendations. The client expects that the conclusion is correct. Therefore, it is important to ensure that the used investigation process results in a reliable (consistently good quality and able to be trusted) outcome. Basic knowledge of bias may help to indicate possible threats to the reliability of investigations. Techniques used to increase the validity and reliability of case study research can assist in developing strategies to achieve reliable forensic structural investigations. Therefore, the question of this research is: what is a reliable methodology to perform investigations into the technical cause of damages to concrete structures? The research question has been answered by studying available literature on structural forensic investigation techniques, interviewing investigators, researching investigation techniques used for aerospace accident investigations and fire cause determination, studying human error theory and case study research and concrete damage mechanisms. Based on the resulting information from studying all these disciplines the conclusion can be drawn that using a structured investigation process is essential. Therefore, this information has been used to develop an investigation methodology called the ‘investigation process model’. The model recommends the following phases: orientation, data collection, hypothesis generation, hypothesis analysis, conclusion, reporting and follow-up. These phases are split into individual steps that guide the investigator through the process. Each step contains suggestions for specific techniques varying from taking meaningful photographs on location to using a standard layout for reporting in order to execute the step properly. The investigator can select the most appropriate techniques for the project. Special attention has been paid to provide techniques to generate and analyse hypotheses in a reliable way. An example is the tool ‘Concrete Damage Handbook’ to assist the investigator in linking visual damages to possible causes. As a common thread through the model measures have been provided to limit the negative influence of bias (based on the Delft approach). Validation of the model with 1) a test case based on a real damage file, 2) comparison with real investigation reports and 3) scientific papers proved that the model relates to the daily working practice and is usable, practical and functional within the scope of the defined criteria.

High-rise buildings are a potential solution to the environmental impact caused by the built environment and the increasing demand for space in urban areas. As recent developments focus on reducing the impact by operational energy (OE) (heating, cooling, hot water and ventilation during use phase), impact by the embodied energy (EE) (production, construction, maintenance and demolition of materials) becomes increasingly significant. Structural materials account for the biggest part of embodied carbon (EC) in buildings. The number of studies that address the environmental impact of high-rise building structures has grown only recently, research is still limited. Moreover, it is doubtful to which extent these researches are applicable to the Netherlands. This thesis aims to provide insight in the environmental impact of structural systems for high-rise buildings of 150, 200 and 250 meters in the Netherlands. Five different stability and three floor different systems were designed in cast-in-situ concrete, prefab concrete and steel. All of the models contained a concrete core. 2-dimensional static linear calculations were performed in order to determine the cross-sections and reinforcement. Through parametric modelling, an automated design and analysis work-flow was developed and a total number of 146 models was assessed. The environmental impact was calculated by using the fast track life-cycle analysis (LCA) method. A cradle-to-gate analysis (production phase only, A1-3) was performed by using data from the Nationale Milieu Database (National Environmental Database) (NMD) and steel data from Bouwen met Staal, which contain the environmental impact for multiple impact categories, measured in environmental cost (shadow price). The construction and demolition phases were left out of scope. It was found that all steel structures had a 6% to 35% higher cradle-to-gate environmental impact compared to concrete structures with the same stability and floor system. Furthermore, no significant differences were found between the cradle-to-gate impacts of cast-in-situ and prefab concrete models. Differences in impact between the materials are likely to be affected by inclusion of the construction phase (A4-5) and foundation structure. It is expected that the gap in environmental impact between steel and concrete is reduced by inclusion of these aspects. Floors were responsible for 32% up to 73% of the total environmental impact. Regarding the stability systems, results showed that, when subjected to wind loads, systems with axially loaded elements scored significantly better than systems with elements loaded in bending. The outrigger structure decreased the total environmental impact of the concrete models by 5% to 16% and 20% to 26% of the steel models, compared to the tube structure. The braced tube only decreased the impact for the 200 and 250 meter models, with 7% to 12%, compared to the tube structures. The diagrid structure had the best performance at all heights and reduced the environmental impact by 17% to 28% for concrete and 28% to 41% for steel models, compared to the tube structures.

Currently there are a lot of contract types available for building projects. It is not always clear beforehand what type of contract a client should choose for his project. The goal of this study is to solve this problem by advising clients which type of contract to use for moveable bridge projects. Therefore, the following research question will be answered: How does the model look like that predicts which type of contract is best for a moveable bridge project? In order to answer this question, literature is studied and interviews are conducted to show which parameters and characteristics are of influence for this contract decision. This information is used to set up an initial model which advises what type of contract to use. This initial model is verified with the use of case projects in order to get the final model. Due to the wide range of building projects, this master thesis is focused on moveable bridges in the Netherlands only. Moveable bridges are multidisciplinary projects which makes the decision for a specific type of contract ambiguous. Making it the a perfect type of project to test the model. The literature and interviews highlighted eleven criteria that are of influence for the types of contracts incorporated in the model. The contract types that are included in this model are: RAW-bestek, Design & Build, Design, Build & Maintain and Turnkey. The decision to incorporate these four contract types is based on the fact to include traditional and integrated contracts. RAW-bestek is the traditional contract type that is common to use for moveable bridges in the Netherlands. The choice for an integrated contract form for moveable bridges is bigger. Therefore, integrated contracts with different ranges of integration are included. Starting with Design & Build as a conventional integrated contract form followed by Design, Build & Maintain as a more integrated contract form and Turnkey as totally integrated contract form. This initial model is verified with the use of four moveable bridge cases. For three of the case projects the model advised well. These projects went according plan and the advice from the model matched the contract that was actually used or the model highlighted the main headings for which the different incorporated contracts match the actually used contract. For example, case A used the contract type Engineer & Construct, this type of contract is not included in the model. The initial model showed exactly on which statements the Design, Build & Maintain contract and the RAW-bestek scored well for this case project. The statements on which they scored well are exactly the items for which an Engineer & Construct type of contract would be suited. If Engineer & Construct as a contract type would have been incorporated in the model, it would most likely be advised by the model. The verification of case B was not a match between the used type of contract and the advice from the initial model. The project did not went according to plan, but the advised type of contract would probably not have improved the situation. Several improvements are suggested based on comparison between this case and the other case projects. It is concluded that the model is functioning, based on the cases. However, it is recommended to extend the model with more types of contracts, such as the contract type Design & Construct, Engineer & Construct and Bouwteam. The second recommendation comes from the ambiguity concerning the benchmark score for the criterion complexity. The positive correlation between complexity and flexibility was stated in literature, meaning that when the complexity of the project increases the need for more flexibility also increases. However, other literature contradicted this; it was unclear which viewpoint should be preferred. Therefore, the decision was made to adopt the positive correlation for the initial model. After verifying this initial model, the benchmark scores for complexity were adjusted in order to be in line with the other literature. The advice from the initial model and the initial model adjusted for complexity were compared. However, based on this comparison no firm conclusion can be made about which viewpoint is preferred over the other concerning complexity. Therefore, it is recommended to further verify the model for the criterion of complexity. Furthermore, it is recommended to verify this model with more moveable bridges and cases for other types of projects in order to increase the validity, usability and applicability of the model.