The standard NEN 3215 contains a certain rain intensity for the rainwater drainage from roofs. By making use of the rainfall predictions for 2050, the consequences of this new intensity for the standard are analysed. Based on this analysis, a change of this rain intensity in NEN 3215 is recommended.

When designing a construction pit adjacent to a navigation channel, the event of a ship colliding with the structure is something to take into account in the design of the pit. However, several aspects regarding ship collisions, i.e. the probability of occurrence of a collision, the magnitude of the collision force and the influence on the safety of the pit, are uncertain. The goal of this research is to develop a method to determine the safety of a temporary construction pit. The Blankenburg Connection, which is being built by BAAK, is used as a case study in this thesis. The construction pit in this project is located in the Scheur and has to deal with a busy navigation channel. The end-wall of the pit is a temporary wall, as it has to be removed in order to to be able to float a tunnel element to the middle of the channel.A Bayesian Network is used as a method to take into account all the different parameters influencing the probability of collision. When comparing the outcome of the model with values based on historical data for the Scheur, it can be concluded that the model predicts the probability quite well. A small difference can be noticed, which is probably explained by the fact of under-reporting. To determine the magnitude of the force, a Monte Carlo simulation is used. In this way a probability density function of the magnitude of the force is generated, giving insight in the occurrence of forces on the structure. The resistance of the structure is determined and mitigation measures to increase the safety of the construction pit are examined.

Among the current targets of the building sector, one major goal is to maximize the resource efficiency (in terms of material use and in terms of energy used to produce the buildings); furthermore, the circular economy model aims for maximizing the reuse of the structural elements; thus, minimizing the material waste and avoiding a second production of elements. The high-rise building sector faces the challenge of considering a design that is flexible and adaptable to meet the functional requirements along its life span; and additionally, to consider a design for deconstruction, where the benefits and challenges that arise form reusing and recycling the material can be considered and addressed from early design stages. This research addresses these trends and challenges by evaluating and comparing the environmental impact of different structural systems for a high-rise building in the Netherlands (151m). The comparison of four different structural systems with two core variations provides eight different stability systems. The scope of the stability systems considers foundations, core, columns, beams, bracings and floor slabs. The design of the structural systems was performed by the elaboration of 3D FEM models with parametrical tools to ensure the structural safety and serviceability of the building. Furthermore, the assessment of the environmental impact (global warming potential) was performed by means of a Life-Cycle Aseessment comparing three scenarios of the structure: cradle to gate, cradle to cradle, and cradle to cradle with 100% reuse of the structural elements; with data from the Nationale Milieu Database and with information from a technical report from the Joint Research Center. The analysis of the results demonstrated that the environmental impact of the structural systems with steel core is 21% higher than the one that corresponds to the structures with concrete core, However, this variation is only 4% for the two variants of the diagrid structure. Furthermore, by including the average recycle and reuse rates form the market and current construction practices, the benefits at the end-of-life stage of the building can represent up to 17% of the impacts from the production phase. Moreover, when the reuse rate is considered as 100% the benefits increase up to 42% of the impacts from the production phase. The results indicate that the improvement of the environmental impact of high-rise buildings can be achieved by means of sustainable structural design from the early phases of the design; where the choice of materials and of the structural system play and important role on the outcome of the total environmental impact of the building, which is becoming an important driver for the decision-making of new projects.

More than 50 locks owned by Rijkswaterstaat need replacement or renovation in the coming 40 years. Due to this fact an opportunity for changing the traditional way of building and maintaining navigational locks has arisen. Because of the replacement/renovation of locks in the coming time, implementing a new owning and building strategy is relatively easy. Rijkswaterstaat is interested in how standardization could be applied to (some) lock components to save costs, and increase reliability and availability. The lock gates are the lock components with the highest potential for standardization. A parametric model for several lock gates is made in order to compare these gate types for a range of boundary conditions. The comparison of several gate types which can be made by the parametric model, could lead to a prescription of a standard gate type for specific boundary conditions. With this prescription, standardization could be implemented in the design process for navigational lock gates. The parametric model can also be used to assess the impact of design choices on the standard design. A parametric model is made to assess rolling gates and mitre gates (with and without clearance at the pivots) made in steel. The model has led to a way of optimising one design (in terms of steel volume used) per gate type for these gates for a range of boundary conditions. The model is able to prescribe a gate type for the case study used, the Prinses Marijkesluizen. The model is unable to prescribe a gate type for bilateral retaining gates, since the results of the design are too close to each other to prescribe one variant as the best variant. It is recommended to record more data, since costs can be added as optimisation criteria (instead of material volume) when this data is known.

The re-use of building components and structural elements is an underdeveloped practice which could be an important strategy in the global paradigm shift towards a circular economy. Steel is one of the most important structural building materials which combines incredible strength, favourable mechanical properties and excellent durability characteristics. It is practically infinitely recyclable and raw materials required for the production of steel are abundantly available in the Earth’s crust. This makes steel one of the most interesting sustainable engineering materials. However, the production process requires vast energy investments and produces considerate environmental pollution. To make steel an increasingly sustainable material and a frontrunner in the global transition towards a circular economy, significant investments and process improvements are necessary. The global environmental challenges of the 21st century demand rapid and far-reaching changes from the steel industry but it also poses opportunities for creative thinking and development of alternative strategies. The re-use of structural steel elements could offer great potential in reducing both the embodied environmental impact of construction works as well as the vast waste streams that result from demolition. There is general consensus on the technical feasibility of this circular alternative across academic literature and the idea enjoys widespread scientific support. Actual implementation is however limited, presumably due to the existence of several multi-level barriers. A diversity of actors along the value chain have indicated that various attitudinal, financial, structural, operational, technological and legislative barriers are preventing widespread adoption. Although some of the identified issues are of a practical nature, various perceived barriers have been identified which were found to be rather subjective. It is to be expected that providing additional information on the risks and opportunities, and by quantitative demonstration of the potential benefits of re-use, several of these perceived barriers could be alleviated. This thesis aims to integrate the potential use of circular steel elements in the structural design process for steelworks as a sustainable alternative to the use of new steel. The developed method allows structural design & engineering professionals to assess the environmental impact of structural steel frameworks with increasing accuracy. Furthermore, it improves the current practice by making the design process reuse-inclusive. It thereby provides design professionals with a tool to assess and communicate the possibilities of improving a design with regard to their inherent sustainability. It was found that the currently prescribed ‘fast-track’ LCA method, aimed at quantifying the embodied environmental impact of building structures, is highly sensitive and the current method could be leading to large inaccuracies and spread of misinformation. Two dominant national LCIA methodologies have been extensively compared and a sensitivity analysis has been performed for a variety of data resources. It could be concluded that the prescribed national data for steel products contained in the NMD is unverifiable and inconsistent with other resources. This raises serious concerns with regard to the accuracy and reliability of currently used ‘fast-track’ LCA methods for the Netherlands. It was calculated that the specific LCIA method used and the selection of modules included in the assessment can cause deviations of the estimated shadowprice up to approximately 424%. Subsequently, a tool was developed based on the CML methodology to validate the potential deviations that could arise from selecting a specific data resource. The application analyses and evaluates structural steel frameworks with regard to their inherent environmental impact. Furthermore it allows the engineer to select and substitute new steel elements with remanufactured counterparts found in a circular steel database. A case study was performed for four different scenarios. Both the LCIA method as well as the considered modules were consistent for all scenarios. From the results it could be concluded that the estimated shadowprice is also highly sensitive to the specific data considered. It was indicated that the input data can lead to deviations of the shadowprice of up to approximately 281%. Furthermore, it was calculated what the potential benefits of reuse would be. It was calculated that substituting 25% of the required steel could lead to reductions of approximately the same magnitude by eliminating the required process for production and cutting the transportation requirements. From the results of this thesis it could be concluded that there is serious inconsistency and limited transparency among the various data resources used for quantifying the environmental impact of steelworks. It is to be expected that the actual shadowcosts deviate significantly from the estimations provided by current assessment methods used in the Netherlands. Failure to accurately quantify the impact of primary building products could lead to significant errors as these materials have a relatively large contribution to the total impact of a building structure. Subsequently, this could lead to misinterpretation of LCA results thereby providing a misleading message for policy- and decision makers. However, it was also illustrated that the remanufacturing and reuse of structural steel profiles could offer significant environmental benefits and has the potential to significantly cut the environmental impact of structural steel framework constructions.

A transition towards a circular economy is proposed by initiators like the Ellen MacArthur Foundation and architect Thomas Rau, in order to preserve and enhance natural capital, optimise resource yields, and minimise system risks. A circular economy seeks to ultimately decouple global economic development from the consumption of non-renewable resources, and will eventually result in an economy of services. In this transition, the construction sector plays a major role because it is responsible for 50% of the total resource use, 40% of demolition waste and 35% of CO2 emissions. The design of the façade system of a building which is offered as a service is essential. Assembly and disassembly of components of such a building occurs more often compared to traditional buildings, so the components and elements have to be designed so that they can facilitate this. This is especially true for the components of the façade which, due to the relatively short lifespan of a façade have to be flexible. To help incorporate circular principles in the design, a new method or tool is needed to help making design decisions and compare different alternatives. The main objective of this master thesis is to investigate the suitability of cold-formed steel components for circular façade design and to develop an assessment method to measure the degree of circularity of façades. Current assessment methods for determining the circularity of products either focus on the environmental impact or the flow of materials and protecting existing value, and not on the degree of circularity related to certain design options. Also, there is no method which focusses specifically on façades. A circular economy is restorative and regenerative, and aims to keep products, components, and materials at their highest utility and value at all times. This is achieved by controlling finite stocks and balancing renewable resource flows, circulating products, components, and materials, and designing out negative externalities. Circular design criteria are derived from the design strategies Design for Disassembly, Design for Adaptability and Modular Design. Currently used façade systems do have the potential to be used in a circular economy, provided that the design criteria for circular use are met. During the Case Study two designs are proposed: a traditional façade system which uses sandwich panels, and a façade system which uses façade panels designed based on a concept for roof panels developed by CFP Engineering (two alternatives). The aim of this case study is to investigate the suitability of the newly developed façade element for circular façade design. Additionally, it will serve as input for the assessment method which is illustrated later in this thesis, and set boundary conditions for the comparison of the life cycle costs and level of circularity. The most important design parameters to determine the circularity of a façade system are: the amount of materials used, the possibility for reassembly, the environmental impact of the system, the amount of reused and renewable materials, the availability of information and the amount of toxic materials. These parameters can be measured by calculating the Façade Circularity Indicator which, as the name suggests, cannot be considered an exact value. The Façade Circularity Indicator originates by combining an existing method (Material Circularity Indicator, developed by the Ellen MacArthur Foundation) with research on Design for Disassembly (Durmisevic, 2016). A prerequisite of this method is a Life Cycle Assessment calculation. The method can be used during the design phase to help making design decisions. Based on the Life Cycle Assessment, the environmental costs of the traditional façade system are 22% higher than the environmental costs of the case study alternatives, which makes the traditional façade system less suitable for use in a circular economy. When the mass of the components is used as a weight variable, the Façade Circularity Indicator of the traditional façade system is 9 to 12% lower than that of the case study alternatives. When environmental costs are used as a weight variable, the Façade Circularity Indicator of the traditional façade system is 54 to 60% lower than that of the case study alternatives. This also indicates that the traditional façade system less suitable for use in a circular economy. As an overall conclusion, it can be stated that cold-formed components are suitable for use in circular façade design because of their relatively low weight, low life cycle costs and the possibility to (dis)assemble them with relative ease. Furthermore, an indication of level of circularity of façades can be given based on a combination of the Material Circularity Indicator and Design for Disassembly factors.

For calculation of the resistance of a composite slab against the transverse shear force, the Eurocode 4 (composite structures) simply refers to the calculation procedures of the Eurocode 2 (concrete structures). It is assumed that the composite slab consists out of a consecutive range of concrete ribs in its width direction, which are solely responsible for resisting the transverse shear force. To calculate the transverse shear capacity of these concrete ribs, an empirical formula is used that was originally derived for regular reinforced concrete beams (without stirrups). However, the concrete ribs of the composite slab are created by the profile of the steel deck, making that each concrete rib is accompanied by two steel webs on the sides. According to the Eurocode 3 (steel structures), these webs of the steel deck have their own transverse shear capacity, which is neglected by the current design approach defined in the Eurocode 4. Besides, the interaction between the steel deck and the concrete may lead to an even higher transverse shear capacity of the composite slab. In this thesis, the aforementioned two aspects, which are currently overlooked by the design principle of the Eurocode 4, are further studied by means of non-linear finite element modelling. The validation of this empirical formula of the Eurocode 2 for calculating the transverse shear capacity of the concrete ribs is the first point of interest. From the finite element analysis (FEA) of the concrete section of ComFlor 210, it is concluded that the prediction of the transverse shear capacity by the Eurocode 2 is unnecessarily conservative. The study suggests to use the mean width of the concrete rib (b0) in calculation, instead of the minimum width in the tensile area of the concrete rib (bw), as an improvement to the method of the Eurocode 2. In the next stage, the contribution of the steel deck to the transverse shear capacity of the composite slab is studied. The exact bonding properties between the steel deck and the concrete (at the interface) were not clear when the finite element model was developed, so some assumptions had to be made. When assuming that the steel deck can’t separate from the concrete and the relative slip is restrained in longitudinal direction by the embossments, an increase of 131.6% in transverse shear capacity is found. Because of the assumed interface properties, the steel deck contributes to the total transverse shear capacity in the following ways: it resists a part of the transverse shear force in its webs; it acts as reinforcement to the concrete like a longitudinal rebar; it acts as reinforcement to the concrete like stirrups. However, whether this stirrup-functioning of the steel deck’s webs is representative for the actual transverse shear behaviour of deep composite slabs is being questioned, because it relies on the assumption of no separation at the interface. Therefore, a second FEA of ComFlor 210 is executed in which the interaction between the steel deck and the concrete is neglectable. Still, an increase of 51.4% in transverse shear capacity is found, which can be considered as a lower bound value. At last, from the FEA results of this thesis, it can indeed be concluded that the current Eurocode 4 provides a unnecessarily conservative calculation method for the transverse shear capacity of ComFlor 210. However, using a simple engineering model that adds up the partial resistances of the concrete ribs and the steel deck’s webs, gives a better prediction while still being safe. For the partial resistance of the concrete ribs, the empirical formula of the Eurocode 2 is used, but this parameter bw is substituted by b0 as already mentioned in the foregoing. For the partial resistance of the steel deck’s webs, the procedures of the Eurocode 3 are followed.

Today, society is becoming more and more aware of the environment and the (negative) influence we have on it. Especially the current workings of our economy have a detrimental effect on the environment. To reduce these effects, a transition is being made towards a circular economy. The construction sector plays a big role in the degradation: in the Netherlands the sector accounts for 50% of the raw material use, 40% of the energy consumption, 40% of the waste production and 35% of the CO2 emission. For the construction sector, one of the changes to establish a more circular economy, is the adoption of a circular design method. This method consists of the construction of buildings, building systems and building elements being designed for disassembly and reuse. This reduces raw material use and the expel of harmful emissions. While we see some developments being made in the construction sector regarding circularity, not many developments can be found in the field of reusable floor systems. For the sizable use of raw materials and expel of harmful emissions during the manufacturing process of floors, a more circular design for floor systems can (eventually) contribute to the sectors transition to circularity. Therefore, this research is focussed on developing demountable connections which can be used in such a circular floor system. The result is a system comprising a prefabricated timber-concrete composite (hereafter: TCC) floor slab connected to steel edge beams with toothed-plate connectors. An important aspect taken into account in the development of this design is the efficiency of erecting, disassembling and reassembling the floor. A multi-criteria analysis is conducted to determine floor slabs viable for use in a reusable floor system. A timber-concrete composite floor slab is chosen and designed. The slab is verified using analytical calculations. Design variants are made for demountable connections at the slab-beam positions at the head end and the side of the slab and for the slab-slab position. A choice between design variants is made by reviewing the fabrication and assembly tolerances and by assuring a non-destructive disassembly procedure. Analytical calculations are performed to verify the chosen connections. A case study building is used for the development of the floor system. The TCC floor slab spans 10.8m, has a total height of 510mm and a width of 1800mm. The used edge beam is an L-section. On the web a toothed-plate connector is adhesively bonded onto which the timber beams are placed to enable shear force transfer between the timber beams and the edge girder. At the top of the web a compression bolt is installed which is fastened after instalment of the floor slabs to ensure force transfer between the bolt and the concrete slab. Two angle sections are screwed to the outer sides of the outer timber beams and bolted to the edge girder to guide the slab to its intended position and to ensure structural soundness by vertically fixing the floor slab to the girder. Lastly the limits of the developed floor system are determined by performing a parameter study of the floor slab and the connection. The floor slab can be designed to span 12.6m. The connection still meets the structural requirements when the system is used in a building of maximally 70m high. This is applicable on many combinations of the building length (10m to 70m) and width (6m to 12.6m), if the right cross-sectional dimensions are used.

The standard sign gantries at the highways in the Netherlands have different geometrical and structural characteristics than sign gantries in other countries. The sign gantries have in total four oblique columns instead of two straight columns and have a triangular shaped spatial truss beam. The design loads that are currently taken into account include the effects of the self weight, natural wind and settlements. This research focuses on the structural response to vehicle induced wind loads. The vehicle induced wind loads cause a vibration of the truss beam mainly in its first horizontal mode. The vibration of the beam can be modelled by discretizing a simply supported Euler-Bernoulli beam with rotational springs at the supports that take into account the rotational stiffness of the columns. From literature the vehicle induced wind load is characterized as a pulse load, which is applied to the discrete beam model. The mass, stiffness and damping matrices are used to compute the structural response numerically in the time domain using MATLAB. This numerical calculation model is verified and fitted to the full scale measurements. The measurements were performed with multiple video cameras that were focussed on specific details of the structure and the vehicles that pass the structure. It was found that it is possible to approximate the amplitude of vibration in time using a single pulse load for trailer trucks and trucks. The stresses in the structure are calculated by applying a deformation that was caused by vehicle induced wind loads to a calculation model with bar elements in MatrixFrame. These stresses are compared with the cut off limit for fatigue detail classes. Based on the preliminary measurements and the calculation model it can be concluded that no fatigue damage is caused by vehicle induced wind loads for the newer series of structures (2012). The older series (2005) could encounter fatigue damage, but it depends on the span length of the beam.

The weirs in the river Meuse reach their theoretical lifespan. The weirs were built in the early 1930s and now one is faced with a replacement task. Various studies have been carried out in recent years on the future of the weirs in the river Meuse. This concerns research into the entire weir system, different types of weirs and the way in which the current weirs should be replaced. This study does not focus on one specific task, but focuses on various aspects that are important for the replacement task, both “soft” and “hard” technical aspects. The first aspect is to find a suitable assessment framework that a new weir must meet. This assessment framework has been developed by means of literature research and interviews with specialists from Rijkswaterstaat, resulting in a risk and opportunity plan especially for weir structures. The assessment framework thus forms the basis for finding both a suitable weir type and a suitable solution for construction. A variant study has been carried out into different weir types. The considered weir types are delineated into a conventional variant, the flap weir, and three innovative variants, namely variants with inflatable technology. The steel-rubber gate, also known as the Obermeyer weir, scores best. This weir type consists of air-filled bellows that inflates and deflates the flaps. It is distinctive in terms of discharge capacity, nuisance and ease of maintenance. The next phase is to make a conceptual design. A new weir regime has been developed on the basis of several considered weir configurations. A weir configuration with two weir spans of 50 m weir, each with 5 separate flap-bellow components has been designed. Furthermore, the weir sill has been designed with a length of 34 m. Based on the design loads on the bottom, a soil protection has been designed. A block mattress with a geotextile as a filter proves to be a suitable soil protection. The downstream length of the bottom protection is designed as a total of 50 m. Thereafter the forces in the membrane are determined, after which a suitable type of membrane is designed. The last phase of this research focuses on finding a suitable solution for construction for the new weir in Linne. Three different construction methods have been developed, in-situ, side channel and prefab. For each method, the (global) weir dimensions are verified for the governing load situations. Ultimately, a suitable construction method is selected on the basis of an overall cost indication and assessment criteria, derived from the assessment framework that has been compiled in the first phase. Construction variant C, the prefab solution, scores best. It is an innovative solution in which the entire weir, including flap and bellow elements, is built in a construction dock upstream of the current weir and then transported using pontoons with winches. The major challenges of this construction method are the floating transport where the enormous weir construction must not be damaged, the coupling of the air supply pipes to the compressors in the abutment underwater by divers and the guarantee of a good transfer of forces from the weir sill to the bottom. On the other hand, there is considered to be a great advantage over the other variants in terms of, among other things, costs and construction time. The solution is therefore proposed as the implementation solution for the Obermeyer weir to replace the current weir in Linne. In addition to this study, a strategy has been developed to deal with uncertainty in design as a depth study. The case of the bottom protection for the new weir has been used to apply this strategy. Different stability relations have been compared that come to the required nominal stone diameter. Based on a consideration of the impact in costs, impact on failure and risk mitigation measures included in this strategy, a broadly-based choice can be made for the design of the soil protection.

At this moment hydraulic structures are designed based on a simple method: the Dynamic Amplification Factor (DAF) method. This method does not consider the full dynamic interaction between the wave impacts, structure and water. The research project DynaHicS focusses on the dynamic behaviour of hydraulic structures, taking into account fluid-structure interaction (FSI). The main goal of the DynaHicS project is to develop new design guidelines to identify dynamic behaviour of hydraulic structures, so that more economical designs can be made in the future. The master thesis focusses on improving the current design method, which can contribute to the development of a new design method for hydraulic structures in the future. The present design method, the DAF method, is extended in time and space. This is done by developing a method to determine the force-time signal of multiple wave impacts, whereby the results from scale model tests are no longer required. In this method the spatial variation (height and width) of the wave impact force over the structure surface is taken into account.

A parametric study, using the FEM-software package ABAQUS, validated on experimental results found by Abspoel, was conducted on S690 steel plate girders to address if the results of the previous researches was valid. Using a slightly different analytical model the results show the maximum web slenderness of this steel grade in both 6000 mm2 and 12000mm2 was the same. It was shown that the maximum bending moment was found when the top flange was able to yield, shortly followed by sudden collapse. A new parametric study, to expend the optimizing plate girders using S890 steel was conducted as well to address the usefulness of steels with higher yield strength in plate girders subjected to bending. This study again used the geometry used by Abspoel. The results showed a decrease in maximum web slenderness, but still a significant increase in bending moment capacity compared to the S690 plate girders. It was shown that using an optimized S890 plate girders compared to hot rolled section made also from S890 steel, could reduce the use of steel by more than 80%. After the parametric studies showed increasing capacity, the geometry used to numerically model the plate girders, was critically addressed, using small scale numerical studies using FEM-software. These tests showed that not only the slenderness of the web was a factor in the bending moment capacity of a plate girder, but also the flange geometry plays a significant role. It was shown that increasing the length of the tested part of the girder, the failure mode could change from flange yielding to an instable mode in which the flange rotated around its longitudinal axis, resulting in a much lower bending moment capacity. An extra investigation in using a hybrid steel composition resulted in showing the potential of this optimization. Because by adding lower grade steel, more ductility was shown due to these parts yielding prior to yielding of the compressive flange, resulting in possible safer design.

There is currently increasing interest in making a transition towards a circular economy, to improve resource efficiency and to reduce harmful emissions to the environment. The European Union adopted a Circular Economy package in 2015, while the Dutch government introduced a programme to achieve a circular economy by 2050. The construction industry is regarded in particular, being responsible for the use of about 50% of all raw materials. Innovation in the field of demountable and reusable structural elements is therefore of importance. By connecting composite (steel-concrete) slabs to steel beams using shear studs, composite beams are created. This results in a structurally efficient composite flooring system. However, demounting and reusing this system is very difficult due to the welded connection of the shear studs to the steel beam and the embedment of the studs in the concrete. This research aims to provide recommendations for the design of a demountable composite flooring system in which both the steel beams and the composite slab can be reused, while its structural efficiency is retained. Additionally, the environmental benefits of this system are assessed. To quantify the environmental advantages of a composite flooring system, a Life Cycle Assessment (LCA) has been conducted based on a case study of the Temporary Courthouse building in Amsterdam. For this building, it is found that the use of a composite flooring system instead of hollow core slabs leads to a reduction in environmental impact of 16-37%. For a building with main spans of 16.2 m instead of the original 10.8 m, this reduction increases to 35-51%. This is mainly caused by the reduction in the amount of concrete in the composite slab. Additionally, the weight reduction of 40-50% compared to hollow core slabs is beneficial for the transport-related environmental impact. Furthermore, it is found that the importance of the steel beams for the total environmental impact of the composite flooring system is limited: a reduction in steel section size due to shear interaction between the beam and the slab only leads to a reduction of 2-6% in environmental impact. However, a cost analysis shows that material costs are reduced with €12 - €31 per square metre when shear interaction is achieved. This shows that the use of demountable shear connectors between the beam and the slab can be viable, as long as the costs of the shear connectors are kept below these amounts. The structural behaviour of a composite beam with a composite slab and M20 grade 8.8 bolts as demountable shear connectors has been analyzed in more detail by means of analytical calculations and finite element analysis. It is found that initial slip due to bolt-to-hole clearances must be prevented in order to avoid larger deflections than allowed. A demountable composite flooring system is proposed in which the slab is cast in-situ for the first use, after placing the shear connectors, and reused as prefab elements without the shear connectors. In this way, bolt-to-hole clearances are avoided, while the main advantages of composite slabs are retained. Design recommendations are provided as a framework for the future development of a demountable composite flooring system.

For the design of a steel sheet pile, verification checks should be done on multiple failure mechanisms. One of the failure mechanisms which should be checked is the check on global buckling. This is a mechanism in which the deformation of the pile is enlarged due to the normal or vertical force. With the enlargement of the sheet pile, the soil must be displaced as well, which results in extra resistance against global buckling. However, the check to this mechanism stated by the Eurocode is based on the so called critical global buckling load, which is currently based on the stiffness of the sheet pile. The resistance delivered by the soil is fully neglected in the check on global buckling, which gives that it is thought that this check is too conservative. It is studied how the influence of the soil can be taken into account to the global buckling mechanism. This is done by describing the background of the current check, followed by stating possible methods to determine the influence of the soil. By the use of calculation program’s D-sheet pilling and Plaxis 2D, some examples are calculated in which the proposed methods are compared with the current method. From those examples, it was found that the check on global buckling might be significant lower if the influence of the soil is taken into account.

Limitations in the modern housing market supply and the high demand for city centre living space ask for a robust urban densification way of building. This results in the exploration of innovative vertical extension projects, such as the ’De Karel Doorman’ case in Rotterdam. However, demanding the construction method to be extreme light-weight revealed an unexpected normative serviceability phenomenon. The reducedmass did not dissipate enough vibrational energy induced by human activities such as walking, leading to an excessive and disturbing perception of vibrations. This caused nuisance for both the home situation where the motion takes place as for the neighbouring floor fields. The critical motion-related limit state has to be satisfied to create a comfortable living environment. This thesis aims to further develop the concept of light-weight steel and timber building structures focussing on vibration comfort. This is done by exploring structural measures that can steer the vibrational floor response for both the induced situation as for the transmittance to adjacent fields. Broadening research shows the general impact of the damping, natural frequency and modal mass. From this starting point, new practical building tools are developed to affect and control the path and magnitude of vibrations positively. General guidelines are provided that show the demands for a structural assembly to create suitable apartments. The proposed measures to steer the vibration comfort were researched using both the conventional handcalculation method from the SBR-guideline and by more accurate finite element analyses from SoViST and Autodesk Robot. The resulting OS-RMS90 values indicate the response velocity of the floor and have to meet the limit criteria proposed for the specific function of a building. For the light-weight residential building concept, these criteria were set to 0,8 [-] and 0,2 [-] for respectively the home and neighbouring situation. It was found that for light-weight building structures the implementation of a large amount of stiffness is inevitable in both the floor assembly as in the junction. The consequence of additionalmass and height can be balanced by using efficiently shaped profiles and smart placement of the joists. For the supporting beams, these demands encourage the use of rectangular hollow structural sections whereas for the floor assembly I-joists are recommended. Additional transverse stiffness stretches the clustering of natural frequencies for orthotropic plates but is most effective for two-way span floors. A smaller span will result in improved comfort levels but will complicate the structural assembly by introducing more elements and connections. Besides the overall performance enhancing measures, it was found that the limit criterion for neighbouring apartments is harder to achieve without additional interventions. Introducing more substantial obstacles for the vibrations to overcome along the path, will reflect the transmittance and hence steer the floor response towards improved comfort levels. The use of an alternating floor field can provide in this issue as it avoids the mode-coupling of natural frequencies from adjacent elements. One other recommendation is the differentiation of the home-separating and in-home junctions. This results in maintaining more vibration energy in the home situation and limits the nuisance caused from excitements in a neighbouring apartment. The as-built ’De Karel Doorman’ revealed the impact of additional stiff elements in the wall that substantially increase the bending and torsional stiffness in the junction. It was found that these elements mitigate the nuisance caused by footfalls to imperceptible values for adjacent floor fields. However, these elements do leave a mark on the flexibility of the floor plan. Light-weight building structures face new challenges and acknowledge the shift from strength-design to serviceability-design criteria. Regarding vertical extension projects, not just the building engineering aspects but also the practical implementation was found to contribute in the consideration for structural assembly measures.

Overheight vehicle impact is the impact of a heavy dump truck with a rigid raised trailer on the beam of a light-weighted and flexible temporary overhead sign structure. The structure is initially not designed to resist overheight vehicle impacts and the impacts occurring during construction works with impact velocities up to 40 km/h result in total collapse of the structure and, consequently, high risks with respect to road users’ safety. These serious consequences in combination with the need for revised design specifications and calculations have led to the following main research question: “Is it feasible to create a design for the temporary overhead sign structure which is able to resist the overheight vehicle impact of raised trailers of dump trucks in work zones?” In this research study, a load analysis is performed in order to approximate the impact load for the impact problem analysed assuming viscoelastic behaviour. The analysis demonstrated that the impact response is barely influenced by the dynamic effects in the structure. The mass of the vehicle and the global stiffness of the structure dominate the impact response. The impact load can be approximated based on the quasi-static approximation. The current temporary overhead sign structure is not able to resist overheight vehicle impacts since the tensile resistance of the bolts of the column base plate connection is much smaller than the internal tensile forces it is subjected to as a result of the large overturning moment and the small internal lever arm in the connection. The behaviour of the structure could be improved by redesigning the column structure while focussing on increasing the internal lever arm and simultaneously limiting the transverse stiffness of the column structure and with that limiting the magnitude of the impact load. Some design considerations are analysed demonstrating that it is a challenging task to develop a design for the demountable temporary overhead sign structure which is able to resist the overheight vehicle impact with a mass of 20,000 kg while limiting the structural mass based on the design requirements as provided by Rijkswaterstaat. The possibilities are limited up to an impact velocity of 7.4 km/h after replacing the original column with a lattice column structure. The study is based on viscoelastic behaviour of the structure neglecting the influence of plastic deforming of the structure and vehicle during impact which may be of significance. Moreover, the actions of the driver during impact are not taken into account. Including the influence of these aspects and developing an optimized design for the structure might somewhat increase the currently approximated critical impact velocity of 7.4 km/h.

Sustainability concerns steer the construction sector towards adopting a circular economy philosophy. Steel-concrete composite beams are extensively used in multi-story buildings and bridges due to their competitive construction and efficient material use. Currently the composite action is mainly achieved by headed shear connectors welded to the top flange of the beam, obstructing the non-destructive demountability. Demountable shear connectors can be used in order to open up the composite con-struction for reusability. Demountable shear connectors can take the form of a bolted connection which requires a tight control of construction tolerances. This thesis is fo-cused on studying a bolt coupler connector which is seen as a valuable alternative to the more conventional embedded bolt. The proposed shear connector consists of a bolt and coupler embedded in prefabricated concrete decks which are connected through the top flange of the steel section by an injection bolt. Full-scale experiments have been performed to investigate the feasibility of construc-tion of a demountable car park. The demountable flooring was obtained by large pre-fabricated concrete decks in combination with tapered beams. Experimental research has confirmed the possibility of assembly and disassembly of the system if construction tolerances are appropriately designed. The most influential factors were quantified based on experimental observations, measurements and finite element models. The hole clearance should be designed keeping in mind the deformability of the system during construction, the manufacturing tolerances and the speed of construction. Experiments show that resin injection can be reliably and labour efficiently used for large oversized holes which allow for higher fabrication imperfections and reduced construction while at the same time enabling composite action of the connectors under live load. The reusability of the structure was confirmed by a set of eight four-point bending tests considering uniform and non-uniform connector arrangements. Finite element models closely match the experimental results in terms of deflection, stresses and curva-ture. However, the end slip is overpredicted which is in line with research performed by other authors. The efficiency of the non-uniform connector arrangements was studied experimentally and numerically to reduce the construction costs. Concentrating the shear connectors toward the supports will bring the highest benefit in terms of beam bending stiffness without the need of a large number of connectors to prevent uplift. An extensive cost analysis was performed based on a database of 15500 beam solu-tions generated by a design algorithm develop as part of this thesis. The case study provides a preliminary cost assessment of two demountable steel-concrete composite floorings in order to quantify their economic viability. It was shown that the system constructed with prefabricated solid slabs is more viable compared to the demountable profiled sheeting slab. The most influential contribution to the final cost of the struc-ture comes from the steel work and the labour intensive manufacturing.

Monopiles will be installed in more difficult terrain since space in the 'ideal' locations is reduced by the rapidly increasing development of wind farms in the ideal areas. In difficult terrain, the amount of obstacles or hard layers increase, leading to an increased risk of pile tip damage. Also the ever increasing D/t ratio of the pile leads to piles more vulnerable to damage to the pile tip. Already, damage to the pile tip was encountered in projects such as the Goodwyn A and Valhall projects, resulting in financial burdens. The design codes show close to zero design guidance regarding pile tip deformation when hard driving is expected. There is a demand for research to understand these deformations at the pile tip. The main goal of this research is to obtain insight in the potential deformations at the pile tip as a result of collision with an obstacle. To identify the pile tip deformation, a finite element model is established. Six volume elements over the thickness are required at the contact zone to model the pile-boulder interaction accurately. Axial- and lateral soil support is included in the model by using non-linear Winkler springs. Lateral soil support inside the pile is included by transferring the results of a volume element model into linear springs. A parametric study is performed to investigate the influence of different parameters on damage to the pile tip. It is noticed that a fully geometric- and material nonlinear analyses is required to performs these simulations. Also, it is shown that in contrast with what is frequently done and also mentioned in design standards, the D/t ratio of the pile cannot be used as single parameter to design monopiles. Both D and t should be independently taken into account. Furthermore, it is seen that relatively large pile-boulder contact angles or low steel-rock friction causes the pile to slip over the boulder’s surface. Higher friction or smaller contact angles are likely to result in rippling or local in- or outward (local ovalisation) deformation of the wall. Although the larger contact angles and lower friction causes the pile to slip over the boulder’s surface, the horizontal reaction is shown to be large enough to push the boulder away, reducing the damage to the tip. Based on a pile drive-ability analyses it is pointed out that current offshore hydraulic hammers are able to deliver the load that is needed to initiate the investigated local tip damage. Furthermore, based on Terzaghi's bearing formulation and the Brazilian Tensile Test it is demonstrated that local penetration of the pile into the boulder is likely to happen for softer rocks and that splitting the boulder is not likely to occur. Finally, one dynamic simulation is run to compare the static and dynamic simulation. It seems possible to investigate failure mechanisms using statics. Accurate results and propagation should be obtained in dynamic analyses. Detailed dynamic analyses is left for future work.

For the E39 highway in Norway a project is underway to replace the ferry crossing in the Sognefjord with a fixed crossing. Previous thesis projects have resulted in a design for a 4500 m long buoyancy bridge which consists of 22 concrete pontoons that carry a steel truss superstructure. To reduce lateral movements the pontoons are fixed to a submerged anchoring cable system. In the middle of the bridge a 400 m wide, 70 m high ship fairway is created. In previous bridge designs the superstructure consisted of separate girders for every span which were connected to the pontoons through hinges. The purpose of this research was to investigate the structural feasibility of creating a continuous superstructure without internal hinges for the Sognefjord bridge. After making a design for a continuous CHS steel truss superstructure, behaviour of the whole Sognefjord bridge with the new superstructure was researched for different load combinations. It was found that maximum lateral displacement of the bridge is 27 m, while maximum longitudinal displacement is 46 m. These were deemed acceptable values. A research was conducted into which parameters influence bridge behaviour the most. It was found that of the bridge structure, rotational stiffness of the pontoons influences bridge deformations the most. A two times higher rotational stiffness of the pontoons leads to a maximum reduction in lateral bridge displacements of 44%. The stiffness of the superstructure was found to have only minor effect on bridge behaviour. Internal loads in the superstructure were found to be mainly determined by displacements of the top of the pontoons, upon which the superstructure rests. Internal loads in individual truss members under a ULS storm situation were investigated. Member stress levels under a ULS storm are very diverse in value, with a maximum peak member stress of 590 N/mm², resulting in a unity check for stability of 1.36. Under reduced bridge deformations from double rotational stiffness of the pontoons, member stress in de superstructure on average drops by half. Peak member stress in the superstructure under a ULS storm with double pontoon rotational stiffness is 293 N/mm², resulting in a unity check for stability of 0.67. Preliminary investigations into bridge dynamics and ship collision were performed. Vortex-induced vibrations of structural elements, as well as pontoon displacements and shockwave effects under ship impact are challenges that require more investigation. The results of this research suggest that creating a continuous bridge girder without internal hinges for the Sognefjord buoyancy bridge is structurally feasible. This would require doubling the rotational stiffness of the pontoons, which is expected to come with large material costs. More in-depth research into other load situations is recommended.