The orthotropic steel deck (OSD) is a deck system applied regularly in steel bridges all around the world. It consists of a steel deck plate which is stiffened by structural elements placed in two orthogonal directions. The deck plate can be used as an integral part of the structure, causing OSDs to achieve a high material efficiency and therefore low self-weight. However, this structural integration requires a large number of welded connections between the deck plate and stiffening members, which also make the system susceptible to fatigue. The fatigue evaluation of these connections is complex and time-consuming, hindering the manual optimization of orthotropic deck designs. The use of structural optimization could be a solution for this. With parametric optimization, the best possible ratio between structural dimensions may be searched for automatically, while topology optimization could assist in finding new design concepts that could form alternatives to the traditional deck layout. This thesis investigates how these techniques could reduce the self-weight of the design of a case study (the renovated Van Brienenoord bridge) without reducing its fatigue service life. The two methods are treated in separate parts. In the first part, considering parametric optimization, the traditional OSD concept is maintained and the values of seven selected dimensions are adjusted to obtain a design with a minimized weight. A workflow is developed in which an existing mathematical optimization solver (the artificial bee colony algorithm, a metaheuristic) is coupled to a parametric model, finite element program, and fatigue damage calculator. This enables an iterative process in which designs are generated by the solver and then evaluated in the remainder of the workflow. The information gained from the evaluation is returned to the solver and used to search for lighter designs. In the second part, the deck remains a stiffened steel plate, but the location and orientation of stiffeners may be changed. Two possible leads for finding new structural concepts are explored. The first considers a topology optimization using the ground structure method, which can find the optimal orientation and size of stiffeners in a plate. This thesis evaluates the method’s current applicability on steel bridge decks. The second lead interprets the results of a topology optimization from existing literature. This gives a new design concept in which the crossbeams curve directly towards the supports instead of being indirectly connected by main girders. A weight minimization using the workflow of the first part and a study of the force transfer in the deck are performed to assess the new concept’s potential. The first part showed that a 17,4 percent lighter deck structure (280 kg/m2 instead of 339 kg/m2 ) could be obtained for the case study by breaking with the general trend for designing orthotropic steel decks. The optimized design uses smaller and more rectangular troughs than commonly applied, but the largest differences are found in the deck plate thickness and stiffener spacing. For the latter, a value of 300 mm has been in use since the introduction of OSDs in the 1950’s and is present in almost any bridge using an orthotropic steel deck. When fatigue issues started to appear from the 1970’s onward, it was generally decided to increase the deck plate thickness. The results in this thesis strongly suggest that decreasing the stiffener spacing and trough top width is the preferred option when material efficiency is considered. A cost estimation further showed that the price of the optimized design would be comparable to that of the preliminary design that was suggested for the case study. The topology optimization using the ground structure method showed that the optimal placement of stiffeners for a plate-like bridge deck contains two distinctive zones. Between the supports, the traditional longitudinal-transverse orientation is preferred, while the optimal direction of stiffeners in the middle of the bridge segments is arbitrary. The conventional OSD concept could be seen as optimal based on this result, but for definitive conclusions more research is needed towards a non-linear relation between cross-sectional area and resistance in the applied method. The similar support conditions of decks in other bridges make it likely that these conclusions will apply to those cases as well. The optimization of the curved crossbeam concept showed the versatility of the workflow developed in the first part of this thesis, as only minor adaptations in the parametric model were needed for the application on a significantly different design. Despite the successful optimization, the potential of the new design to replace the traditional OSD concept is considered low. In its optimized form, the concept was 9,8 percent heavier and less than half as stiff as the best found result in this thesis’ first part. The comparable support conditions for plate girder bridges in general again suggest similar outcomes for other cases, while a different setup of the optimization would not tackle the fundamental stiffness problem of the design. Further research towards the curved crossbeam concept should therefore stick to the original application of box girder decks.

Additive manufacturing and 3D printing are rapidly developing digital fabrication techniques. After the first steps in printing of metals and plastics have been made, research from various groups around the world is now also focusing on printing in concrete and moving to larger scales. Using this technique it will be possible to create customised concrete designs in one go at low costs and high construction speeds. Additionally, this new technology will provide opportunities to create more efficient structures. Structures can already be optimised in the early stages of the design for weight and structural performance, but the resulting optimised structures are often difficult to manufacture due to their shape. Additive manufacturing can be the key to make this possible without high costs for moulds and labour. This thesis will present a novel methodology to include material and manufacturing constraints of 3D printed concrete in the optimisation process. The study examines the possibility to optimise concrete structures in the design phase. In order to save material and thus create more sustainable and more cost efficient structures, a topology optimisation tool has been created specifically for 3D printed concrete. Traditional topology optimisation methods consider isotropic and linear elastic material and will not necessarily produce realisable and reliable optimised structures. In the algorithm presented constraints of the printing process and material properties from physical testing of this layered material are both considered in the optimisation. By adopting this methodology more realistic and feasible optimal concrete structures can be designed.

Practical combinations of floor configurations and support conditions are studied for the development of a lightweight timber building method that is suitable for multi-family residential buildings. Classical vibration theory forms the base for a methodology that is developed to assess transmittance of vibrations to adjoining floor fields. Especially when the source is out of sight, humans humans are tend to classify vibrations as annoying for low vibration levels. With the introduction of new engineered timber products made wood a more suitable and used material for residential buildings. Strength- and stiffness variation is reduced by homogenizing the material and regarding soundproofing innovative concepts have been improved, such as floating screeds and resilient materials. Based on these products and acoustic concepts, 32 design combinations are studied. A distinction between forced- and free vibrations is made and related to low- and high-frequency floors. Forced vibrations are in structural dynamics described by the particular solution, and free vibrations by the homogeneous solution of the equation of motion. This solution is found through the method of separation of variables, which multiplies the space- and time-related parts. Mode shapes are studied regarding transmittance and effective measures for prevention. Fundamental frequencies of floors supported either rigid and flexible are determined with one-dimensional undamped continuous systems where supported beams are represented by equivalent springs. All floors are transformed into Single Degree of Freedom systems to include damping. These systems are assessed making use of modal superposition, for steady-state- and transient response. The behaviour of floors under walking load harmonics provides the resonant response, and free vibration of the system due to initial conditions the transient response. Since the perception of vibrations by humans is frequency-dependent, vibrations are weighted accordingly. Eurocodes currently available are found to provide guidance regarding human-induced vibrations of lightweight structures marginally. Non-timber Eurocodes do not provide an assessment method, EN1990 only provides requirements when no assessment has to be done, and current code for timber structures prescribe criteria that are not sufficient as found in the literature. The future revision of Eurocode 5 holds several methods for assessment of vibrations but is generally focussed on rigidly supported floors. In extending to this code methods are developed to acquire fundamental frequencies of flexible, supported floors, and by transformation into SDOF systems an equation is developed for the appropriate determination of modal mass for two-span or beam supported floors using a simple formula. 32 combinations of floor configurations and support conditions are assessed at the excited field and at adjoining floor fields, where both steady-state and transient response are combined. Based on this assessment, transient responses are found to contribute significantly for low-frequency floors, where generally is assumed that the mass is sufficient to neglect this response.

Structures may be subjected to both mechanical loads and imposed deformation. On one hand, the mechanical loads include, for example, the self-weight of the construction work, the action from normal use by person, furniture and movable objects, vehicles, snow, wind, execution, etc. On the other hand, when the deformation of a structure is restrained, imposed deformation occurs. The sources of deformation can be various, not only environmental conditions, such as temperature and humidity changes, but also chemical or physical actions, such as sulphate ingress or creep. If the shortening of a structure is restrained, the structure will be subjected to imposed deformation which results in tensile stress. Since the tensile strength of concrete is relatively low, concrete structures, such as tunnels, bridges and pavement roads, always suffer a high risk of cracking. Even if the concrete structure is prestressed, the tensile stress resulting from imposed deformation would consume the compressive stress in concrete and raise the risk of cracking. If the crack width exceeds the limit, leakage, corrosion and even structural failure may happen. According to the schematized 푁 - 휀 diagram of reinforced concrete, the development of cracking caused by imposed deformation and mechanical load are different. Suppose the cracking is caused by imposed deformation, there is a developing stage for cracking. It means the cracks caused by imposed deformation could be either fully or not fully developed. However, suppose the cracking is caused by mechanical loads, the cracks could only be fully developed. The stiffness of fully or not fully cracked members are different. The stress resulting from imposed deformation in a structure is related to the stiffness of the structure. Therefore, cracking has significant impact on the magnitude of stress resulting from imposed deformation. Therefore, when a structure is subjected to imposed deformation and mechanical load together, it is necessary to take the impact of cracking into account during structure design. The combination of imposed deformation and mechanic loads is referred to as combined actions. It is common to use FEM software to analyze the stress resulting from the combined actions during structure design when cracking has to be taken into account. However, FEM analysis only is not enough. It is also necessary to check the results calculated by FEM software to avoid mistakes, for example a wrong input. There is a project called 'Approach Ring South, Groningen'. In the project, widened deck KW03.01 is subjected to a combination of imposed deformation and prestressing force. FEM software called SCIA is used to calculate the prestress consumption in the widened deck KW03.01. According to the data file of the project, 41% in maximum of the compressive stress resulting from prestressing is consumed when the structure is subjected to combined actions, which is much more than the engineering experience. As a result, a simple approach is required to check whether the prestress consumption in widened deck KW03.01 suits the expectation or not, where the prestress consumption is calculated by FEM software.

Fatigue is an important issue for orthotropic steel deck (OSD) bridges and therefore a design criterium. Cracks will initiate at several locations of the bridge deck. It is likely that a crack at the trough web to deck plate joint at the crossbeam will initiate first. This crack initiates at the weld root and propagates through the deck plate. A crack at this location is harmful because it is not optically visible and therefore hard to detect. The first part of the report focuses on the fatigue assessment of the trough web to deck plate joint at the crossbeam. Fatigue assessment of this joint is possible with different assessment methods which are the nominal stress method and the hot spot stress method as given in the Eurocode, and the effective notch stress method, described by the IIW. A hand calculation using a simple 2D model is made and a finite element (FE) model is used for the assessment. Both a shell and solid element model are build. The fatigue life calculation of the joint for a deck segment is made. Experimental results for the same deck segment are available and used for validation of the FE models. The fatigue life of each method is compared to the determined load cycles to failure from the experiment. There is concluded that the hot spot stress method results in the most accurate fatigue life prediction and a solid element model gives a slightly longer fatigue life than using shell elements. The effective notch stress method results in a conservative fatigue life for this specific joint. Stresses in the zone near the weld root of the rib-to-deck plate joint at the crossbeam are in compression, while fatigue cracks will initiate due to tensile stresses. During welding, residual stresses appear in the joint. Therefore, a fatigue life prediction is made which includes these residual stresses. An approximation of the residual stresses is included in the initial state of the finite element model. Using the Smith, Watson and Topper (swt) parameter, which is a local critical plane based fatigue assessment, the amount of load cycles to failure is determined. The result is comparable to the experimental result. The second part of the report is focused on the geometry of the deck segment. A shell element model and the hot spot stress method are used to analyse different parameters. When the width between the trough webs is larger, a thicker deck plate thickness is required. Four alternatives for a bridge deck are made. The alternatives have a different amount of troughs over the width, which means that the width between the trough webs differs per alternative. The deck plate thickness is chosen so that each alternative results in a damage value just below 1 for traffic category 2 and a design life of 50 years. Fatigue load model 4 is considered. The weight of the alternatives is determined. There can be concluded that reducing the amount of troughs over the width results in a heavier deck. This is because the weight of the deck plate is a large part of the total weight of the OSD and if more troughs are used, a thicker deck plate is applied. There was assumed that the stress in the joint only is affected by deformation of the deck plate. However, the in-plane deformation of the crossbeam has a negative effect on the stress range in the trough web-to-deck plate joint. Besides the geometry, the effect of some assumptions for modeling are investigated. Including a load dispersal through the surface layer by applying a larger wheel contact area results in a reduced fatigue damage value of about 50% and is therefore beneficial to take into account in the design calculations. The stress range in the joint is highest if a wheel load is placed in the center of the trough. A transverse shift of the wheel results in a large decrease in stress. Therefore it is important to take into account the design load cycles per transverse wheel position.

The Netherlands has always been in close proximity to water, whether its rivers or the sea. This proximity to water and the need for land to settle and farm, led to vast amounts of land reclamation by constructing dykes along the water features to prevent flooding of the new earned land. This newly reclaimed land started to subside over the years, increasing the difference between the high water in the rivers and the low-lying land even more. With an expanding population, rising water levels and increasingly severe storms, the consequences of a future flood due to a riverine dyke breach are ever rising. The aim of this thesis follows from these increasing consequences and is to determine the potential structural damage to a masonry house due to a dyke breach leading to a riverine flood.

In the Meuse seven weirs are located in the Dutch reaches, controlling the water level to enable inland navigation through the river. The weirs are being scheduled for replacement, where weir Grave is the first one in 2028. They are reaching their end-of-life time. One of the main issues that became of more importance in the recent years is ship collision. In the past 20 years two major ship collisions happened on two different existing weirs in the Meuse, one at Grave and one at Linne. The place of impact at the weirs was significantly damaged after those collisions. As a consequence, the water level dropped and inland navigation was not possible for one month. In this study an inflatable weir is proposed as replacement of the existing steel weirs in the Meuse. A conceptual inflatable weir design is made for location Grave, for replacement of the existing weir. The design is based on existing literature, such as the inflatable storm surge barrier Ramspol. The design for Grave is considered to be scalable to the overflow (Poirée) parts of the Meuse weirs. One of the aspects that has not yet been considered for those inflatable weirs is ship collision. The theory and formulas found for the existing collision analysis are not fully applicable to the inflatable weir, mainly due to large elastic deformation of the inflatable weir. In literature a standard expression has been found to quantify the ship force on the colliding structure. This expression forms the basis of the analytical model. The inflatable weir in the analytical model is schematized by a two-dimensional plate sheet. An effort was made to validate the strain found in the analytical model by a numerical model in Ansys. However numerical instabilities were found that lead in considerable modification of the desired model and so the results indicated no representative outcomes. To see what happens during the ship collision a physical scale model was made, with scale 1:25 for accurate representation of the physical phenomena. Sixteen experiments were done with four different draughts and four different velocities of the ship. For the experiment with the scaled maximum draught (0.14m) and velocity (1.1m/s). The full video experiments are uploaded to the 4TU-datacentrum (https://data.4tu.nl/portal). The two aspects uplift of the ship and gliding over the weir observed in the experiments are not yet included in the analytical model, therefore the analytical model is extended. The extended analytical model showed a 25% deviation with the uplift of the ship and a 15% deviation with the displacement of the weir from the experiments. With the extended model it was calculated that the limit strain is not exceeded and that the strain is maximum 5% on top of the static strain of 1.9%. Concluding, the first steps have been taken into research of ship collision on inflatable weirs. Further investigation on the ship with V-bow, the propeller of the ship and a more extensive numerical model is recommended for ship collision on inflatable weirs.

The offshore renewable energy market is rapidly growing, particularly in wind and solar sectors. The intermittent nature of these energy sources underscores the necessity for offshore energy storage solutions. Among the techniques being explored, Marine Pumped Hydro-Energy Storage (MPHES) emerges as a promising option. This innovative concept operates similarly to artificial lakes, where water is stored and released to generate electricity. In the MPHES system, a seabed-based reservoir is established, in which water flows, driving turbines to generate electricity. During periods of energy surplus, the system is charged by pumping water out of the reservoir...

This paper presents the development of a feasibility analysis tool for the Architecture Engineering and Construction (AEC) industry called StructuralComponents 5.0. It is the fifth paper in a series of developments starting with Breider (2008), which discussed modelling and analysing 2D tall buildings with an emphasis on quick generation and simple evaluation of designs. This paper expands the concept of bridging the gap between architectural modelling and structural engineering analysis tools used in the conceptual design process, by focusing on mid-rise buildings with three main characteristics. First, it implements a flexible modelling process to support architectural creativity during the conceptual design phase. The conceptual model is composed of building blocks that can be combined and parametrically adjusted to form a whole structure. Second, it helps the users understand the structural behaviour by visualising the force flow in near real-time. Instead of the conventional finite element method, the behaviour results of individual and combined building blocks (super elements) is computed using a symbolic differential equation method. Third, it includes feasibility checks and visualises them for both disciplines to improve understanding and encourage collaboration during the decision making process.

Soil-mix walls are subsoil walls, which are constructed by in situ mixing of soil with cement and water. The technique was initially used as a ground improvement technique and is now being developed as construction method for walls with a structural purpose. Currently these walls are reinforced with large steel profiles, which requires a large quantity of steel. Replacing the profiles with bar reinforcement might lead to a decrease in required material quantity and thus a reduction of material costs. There are multiple aspects which influence the possibilities and limitations of bar reinforced soil-mix walls. These include predictability of the material quality, durability and cooperation between soil-mix and the reinforcement. The aim of this project was to contribute to this research by analysing one of the influential aspects. The specific goal of this research project was to analyse the capacity of a reinforcement detail within a soil-mix wall and define the governing failure mechanism. The research combined an experimental and numerical approach to the subject. The critical detail was chosen based on the Huybrechts et al. (2016), Ganne et al. (2010), Dörendahl et al. (2004) and contact with soil-mix experts. To model this detail in a finite element model, in 2D and 3D, material parameters were derived from Denies et al. (2012a), Denies et al. (2014), Denies et al. (2015a) and performed physical tests. The 2D models represented the most critical sections of the detail based on the theoretical stress distribution. The geometrical parameters of the reinforcement design were varified in the models to provide insight in the influence of the design on the capacity. The model results were used to define an preliminary set of design guidelines for the reinforcement cage, related to the depth of the wall. Since only the capacity of the detail is considered, these guidelines are not suficient for a complete design of a bar reinforced soil-mix wall and can only serve as an initial indication. In conclusion, the reinforcement detail is most sensitive to failure due to vertical splitting and has suficient capacity for acceptable wall depths. As stated before there are multiple aspects relevant to the feasibility of bar reinforced soil-mix walls. The predictability of the material quality, the bond with the reinforcement and the durability of the soil-mix strongly influence the final capacity and behaviour of the wall. Therefore it is important to perform further research on these, and other, aspects to conclude on the total structural integrity of an entire bar reinforced soil-mix wall.

Timber bridges are much applied structures in the Dutch landscape. In contrast to the other two most common building materials, concrete and steel, the use of timber is however almost exclusively limited to bridges for lighter traffic, e.g. pedestrians and bicycles. Examples of timber traffic bridges in Germany, Scandinavia and even in the Netherlands, show however that, at least structuraly, timber can be perfectly used in the construction of bridges for heavier traffic. Although structuraly feasible, there are still a number of doubts and uncertainties that go hand in hand with timber bridges. One of them is the maximum reachable service life. This research focusses on the ability to estimate this service life with the help of so called factor methods. The service life of a timber element in the Netherlands, with respect to biological decay, is in the basis determined by two main factors: the natural durability of the timber specie, and the moisture and temperature levels of the timber during its service life. In the case of timber bridges, where the timber elements are subjected to the weather, this can be broken down in three main influencing factors, namely: 1. Natural durability of the used timber specie 2. Local climate (Temperature, rainfall and humidity) 3. Detailing of the bridge (Protection against water accumulation) With these three main influencing factors in mind, factor methods can be used to estimate the service life of bridge elements. These factor methods estimate the service life based on reference situations, and use modification factors to modify these reference situations into the actual situation of the element. In this research two different factor methods have been reviewed in depth: the DuraTB method, developed in Sweden, and the TimberLife method, developed in Australia. The two factor methods have in this research been compared with each other and after that their usability and accuracy has been tested with the use of two reality checks on existing bridges in Amsterdam. For the reality checks, first an expected bridge condition was determined with the help of the two factor methods. After this the actual condition of the bridge was determined by an in-field visual inspection. Then the expected and the actual conditions were compared in order to obtain insight in the correctness of the service life estimation of the two factor methods. In addition, the role of factor methods in the processes of service life planning and especially during the calculation of the total costs of ownership (TCO) has been discussed. An example of a TCO calculation has been performed for two bridge designs, in which the focus was put on the incorporation of both the DuraTB and the TimberLife factor methods. Even though this TCO example is not representative from a total cost point of view (since the values of the different costs were guessed), it does show how factor methods can be used in the calculation of these total costs.

Orthotropic bridges can be modelled using a grillage model and an orthotropic plate model. The grillage model has some benefits (i.e.: shorter calculation time and easier to apply pre-stressing) compared to the orthotropic plate model. However, during the Blankenburgverbinding project Ballast Nedam experienced that the transverse load-spread of the grillage model can be lower compared to the orthotropic plate model. This potentially results into a less economical reinforcement design. The aim of this study is to investigate the differences in transverse load-spread of the grillage and orthotropic plate model and to make a judgement on the practical usability of the grillage model based upon the differences in reinforcement design. To test the hypothesis that the grillage model has less transverse load-spread compared to the orthotropic plate model and to quantify the impact on the reinforcement design, a case study on the bridge decks of the Blankenburgverbinding is carried out. The results of a grillage model are compared to an orthotropic plate model. In order to be able to judge whether to orthotropic plate model describes the correct behaviour of the bridge, this model is verified using a 3D plate model. In total, 3 different single-span, simply supported bridge deck layouts were modelled (straight, curved and curved with a skew angle). The results of the 3D plate model are almost equal to the results of the orthotropic plate model. Both these models show the same transverse load-spread. The grillage model shows less transverse load-spread compared to the orthotropic plate model and the 3D plate model. This difference in load-spread increases with increasing eccentricity of the applied load. The torsional and transverse shear stiffness has the biggest impact on the transverse-load spread. When these stiffnesses are higher, the transverse load-spread increases. Lowering the stiffnesses results into less load-spread. In case of the curved bridge deck, the grillage model results in about 7.3% more reinforcement compared to the orthotropic plate model. For the curved and skewed deck the grillage model results into up to 4.7% more reinforcement compared to the orthotropic plate model. The differences in design bending moments (Wood-Armer moments) are relatively small. Although the theoretical difference in amount of reinforcement is significant, the practical difference in reinforcement design between both models can be small. For example, the structural engineer is limited by the available space, detailing requirements and the available bar diameters. These limitations and rounding differences make that for some bridges it is possible to reduce for example 5% reinforcement and for some bridges such a reduction can be very hard to realise. In that case, the theoretical difference between the amount of reinforcement becomes very small or completely vanishes in practice. Eventually, it depends on the situation whether the benefits of the grillage model outweigh the theoretically less economical reinforcement design. When there are a lot of repetitive bridge decks it can be beneficial to use an orthotropic plate model. In that case, the orthotropic plate model has to be created only once and a small reduction in the amount of reinforcement of one deck can add-up to a significant reduction for the whole project. When there is only one bridge deck to model, or all spans are unique, the benefits of the grillage model most likely outweigh the practical difference in the amount of reinforcement.

To address the increasing housing demand in Europe and simultaneously tackle the challenge of creating a more sustainable construction industry, timber modular buildings present an innovative solution. However, before multi-storey modular buildings become a widespread practice, various engineering challenges need to be addressed. Ensuring robustness is one such challenge. This study focuses on the robustness of post-and-beam timber modular buildings, particularly through catenary action. The challenge with ensuring robust catenary action lies in designing connections with sufficient resistance and deformation capacity. This study proposes an optimisation process to determine the required mechanical properties of inter-module connections to enable robustness through catenary action. The principle of a catenary relies on the equilibrium between a vertical point load and the vertical component of the tie force in the deflected floor elements. Larger deflections result in a lower required tension resistance but demand a larger deformation capacity in the components. This study introduces a catenary equation to determine the required tensile resistance in a catenary at a specified elongation, creating a catenary requirement boundary. For a timber modular building to form robust catenary action, the axial force-elongation response in a catenary must meet this boundary. The catenary equation and the force-elongation response of the catenary form the basis of the connection optimisation, as the inter-module connection governs the response. To determine the optimised mechanical properties of an inter-module connection in a timber modular building, a case study was performed on a building consisting of twelve post-and-beam modules in width and five modules in height. To determine the effect of a change in the inter-module connection design on the force-elongation response of the buildings, quasi-static numerical analyses were conducted on 2D models, focussing on the frontal view frame of the building, and the floor plane. The load distribution through the floor system and corresponding deformation were added to the frame model by use of spring boundary constraints, after which the catenary could be examined. As a catenary can be formed by increasing the axial resistance, or its ductility, two optimisation methods were formulated, resulting in a high-strength inter-module connection and a ductile inter-module connection with a fuse. The optimisation process is based on iterations of the inter-module connection design. The resulting high-strength connection required a 143% increase in tension resistance, while the ductile connection relied on a 55% increase in resistance and a 550 mm fuse. This study underscores the complexity and critical importance of correct connection design to ensure structural robustness, emphasising the need for sufficient strength and deformation capacity. While the proposed methodology serves as a valuable tool for optimising connections in timber modular buildings, further research is recommended by including dynamic analyses in the optimisation process and experimental testing of inter-module connections to enhance the accuracy of the models.

In het vakgebied van mechanica vormen invloedslijnen een tool waarmee gemakkelijk maat-gevende krachten, momenten en verplaatsingen kunnen worden gevonden. Echter, deze invloedslijnen zijn alleen toepasbaar op balken (één-dimensionaal). Binnen de civiele sector zijn naast balken, ook platen een veelgebruikte constructievorm (twee-dimensionaal). Voor platen is echter geen equivalente methode beschikbaar als invloedslijnen die makkelijk en snel inzicht geeft in een constructie. Dit rapport focust op het ontwikkelen van een ingenieurstool waarmee gemakkelijk invloeds-lijnen voor platen kunnen worden bepaald. Er is een verbeterings- en ontwikkelingsslag gemaakt op het bachelor eindwerk van eerdere studenten die een model hebben ontwikkeld waarbij de plaat wordt geschematiseerd als een groot aantal verbonden balkjes. Dit model is verbeterd en getoetst aan de hand van modellen voor platen. Vervolgens is dit basismodel toegepast in vier modellen voor invloedslijnen. De modellen berekenen de invloedslijnen voor verplaatsingen, krachtsgrootheden volgens de brute kracht methode, krachtsgrootheden volgens de methode dummybelasting en de oplegreacties uit. Het model met de dummybelasting is de verbeterde versie van het model volgens de brute kracht methode, waarbij gebruikt wordt gemaakt van de methode van Muller-Breslau om snel de oplossing te bepalen. Deze invloedslijnen zijn getoetst aan de hand van oplossingen van Guyon & Massonnet en Pucher. Er is een breed inzetbaar, snel en betrouwbare ingenieurstool gemaakt waarmee het gedrag van platen wordt benaderd en invloedslijnen kunnen worden bepaald. Het basismodel voldoet aan alle toetsen, echter ontstaan er fouten rond de randen in de oplossingen voor buigmomenten en dwarskracht door de modellering volgens het balkjesmodel. Het model voor invloedslijnen voldoet aan de meeste toetsen. Alleen bij de dwarskrachten zit er een fout in de oplossing, waardoor deze een factor twee tot vier afwijkt van de oplossing van Pucher. Doordat de plaat als een balkjesmodel wordt benaderd, ontstaat er een grillig effect dat voor fouten in de vergelijking met het plaatmodel zorgt. Dit effect kan nog beter bekeken worden om inzicht te krijgen in hoe het balkjesmodel de plaat het beste kan benaderen. Ook zal onderzocht moeten worden hoe het model het daadwerkelijk gedrag rond de belasting het beste kan benaderen. Er ontstaan in dit punt nu nog grote pieken, die afhankelijk zijn van de detaillering van het model. Als deze punten goed zijn uitgewerkt kan dit model worden gebruikt als basis voor een programma met een makkelijke interface waarmee studenten en/of ingenieurs in de dagelijkse praktijk snel inzicht kunnen krijgen in het gedrag van platen.

In situations with spatial limitations where a bridge is desired, a skewed bridge is a solution. The bridge deck of a skewed bridge has the shape of a parallelogram, in which the angle that remains in the acute corners is defined as the skew angle. This thesis focuses on the design of reinforced concrete skewed slab highway bridges that are simply supported on discrete bearing pads. A parametric tool is created which, based on a set of values for input parameters, generates and analyzes bridge models created in a finite element method (FEM) software program. After analysis, results are summarized, which allows for a parametric study. The goal of this study is to develop knowledge for decision-making in early stages of projects. The influence of main geometric parameters (skew angle, bridge span length, bridge road width) on the load distribution in a skewed bridge is investigated, as well as the influence of FEM mesh element size, applied plate theory, traffic load configuration and support configuration. Another important parameter, being the bridge deck height, is set to be dependent to the span length at first. Skewed slab bridges tend to span from support to support in the shortest direction. This means that loads will concentrate in the obtuse corner. Resultant quantities, mainly bending moments and shear force in the obtuse corner, are studied on their relation with the different parameters. The obtuse corner load concentrations can require the bridge height to become larger than desired. A powerful measure is to add additional triangular sections (ATS) to the side of the bridge, which increases its width. This way, the road skew angle no longer equals the bridge skew angle. Load concentrations in the obtuse corners are reduced, which can result in a lower deck height, less reinforcement, or both. The effect of ATS addition on resultants is studied: great reduction is observed, even for relatively small ATS addition. In order to relate the bridge deck height to bridge geometry, a reinforcement study is conducted. A procedure is described for a certain cross-section, in which the resultants are known from models generated by the parametric tool. Starting point is the longitudinal bending reinforcement based on the crack width criterion, which is usually governing in bridge design. Next, required shear reinforcement is calculated. Following, the ultimate bending moment capacity is checked, which is found to be always sufficient for crack-width-based reinforcement design. Finally, optimization (different bar diameters, add or remove a reinforcement layer, deck height reduction) is investigated and applied if possible. Using the procedure described above, a case study is conducted. A highly skewed bridge (road skew angle of 20◦) is taken. Starting with 0◦, ATS is added in steps of 5◦. For each geometry, a model is created with the tool after which resultants are used for the reinforcement design. For a bridge span of 13.7 m and a road width of 8.3 m, the first bridge (no ATS, skew angle of 20◦) was found to lie beyond the limits of reinforced concrete. Two layers of 40 mm bars required fatigue-sensitive couplers, while detailing and proper anchorage would prove to be unconstructible. Increasing the cross-section also increased governing moments due to concrete self-weight and therefore is not an option. Addition of a 5◦ ATS resulted in a 900 mm high bridge deck, which seems possible to construct. Addition of 10◦ resulted in a 750 mm high deck, 15◦ into 600 mm and further ATS addition reduced deck height even more. Although it should be noted that ATS addition increases deck surface, a significant reduction in deck height can be obtained. ATS addition is shown to be a powerful measure. Depending on project situation, it can provide optimization and cost savings; the parametric tool is proven to be useful in investigating this.

The demand for sustainable high-rise buildings is growing. Such sustainable high-rise could be realized by the use of mass timber for the structural design instead of more conventional building materials such as steel and concrete. Timber is a renewable resource which can be CO2 neutral if reforestation takes place to close its carbon cycle. In addition, the light-weight of timber reduces the loads on the foundation, and the timber could be used as an architectural feature as well. The height boundaries for tall timber buildings are currently extending, as illustrated by the ongoing realization of a 70 metres tall timber building in Amsterdam. However, the light-weight of timber make tall timber buildings prone to dynamic wind loading. In addition, the current trend to design slender high-rise further increases the wind-induced dynamic response of the building. In this thesis, the technical feasibility of a super tall hybrid wood-concrete building was evaluated and its wind-induced dynamic behaviour was optimized. To this end a 300m tall building of timber and concrete was designed for construction in the city-centre of Rotterdam, The Netherlands. Due to the absence of seismic activity in the area, wind loading was identified as the governing parameter for lateral stability design. The structural design was therefore optimized to satisfy serviceability criteria for lateral drift and occupant comfort. Based on these requirements, the structure was designed as a reinforced concrete core surrounded by a glued-laminated timber (GLT) frame and floor slabs consisting of a cross-laminated timber (CLT) panel with a thin concrete top layer. Lateral stability was ensured by an outrigger/belt-truss system at three levels, resulting in a significant increase of the global stiffness in the structure, and in a reduction of the maximum lateral inter-storey drift by a factor two. In order to fully design a 300m tall wood-concrete hybrid building, design aspects such as the floor plan, core layout, lateral stability system and timber frame were designed first. The floor plan layout and storey height were based on a typical office building. The length from the perimeter to the core of the building was set to 9 metres and a storey height 3.75 metres was applied. These dimensions ensured that enough sunlight would fall into the office spaces. The entrance level with double storey height was performed in reinforced concrete to create a more open layout and to achieve a higher safety in the case of accidental blast loading. Stiffness optimization of the structure was carried out in order to satisfy the serviceability criteria for lateral inter-storey drift and displacement. Consequently, a parametric study of the cross-sectional dimension of the columns, of the thickness of the reinforced concrete core wall, and of the outrigger/belt-truss layout was performed. The cross-sectional dimension of the columns and the thickness of the core wall were tapered down over the height of the structure. A diagonally- and orthogonally-oriented layout of the outrigger trusses were compared. For the final design the orthogonally-oriented layout was applied, because it resulted in more lateral stiffness of the structure. Each outrigger level consists of 8 outrigger trusses which are orthogonally oriented with respect to the reinforced concrete core, and a belt-truss surrounds the perimeter of the structure. The outrigger levels were also designed to accommodate the mechanical, electrical and public health system (MEP) facilities. Due to the large tension forces caused by lateral wind loading the connection design of the GLT frame is paramount for the feasibility of a hybrid wood-concrete tall building. The outrigger trusses transfer large tension and compression forces to the perimeter columns, making the outrigger connections critical for the overall stiffness of the structure. Therefore, the connections in the outrigger truss, as well as the belt truss, were designed with two slotted-in steel plates and dowels. Beam-to-columns and beam-to-wall connections were designed with only one slotted-in steel plate and dowels. Column splices were carried out with glued-in rods and bolts. In-between the column splices adjustment devices were installed to compensate for the vertical differential shortening of the reinforced concrete core and mass timber frame. Consequently, an additional steel plate with the required adjustment thickness could be placed between the bolted steel plates of the connection. Continuous columns were applied over a height of 4-storey levels in order to reduce the number of expensive steel-timber connections. Due to transportation constraints, the length of the columns was limited to 15 metres.  Vortex shedding and end-effects of the wind due to lateral wind loading cause peak response accelerations mainly in the across-wind direction. For a return period of 50 years of wind loading to satisfy the serviceability criterion for the occupant comfort, the peak response acceleration should be lower than 0.390 m/s2. This criterion is dependent on the natural frequency of the structure which is equal to 0.130 Hz. To improve the structure's dynamic behaviour, a passive tuned mass damper (TMD) and a chamfered corner modification were applied, resulting in a decrease of the peak acceleration to a level satisfying the occupant comfort criterion. The tall building was considered as consequence class 3 (CC3), meaning that a fire-resistance time of at least 120 minutes should be guaranteed. To this end, the mass timber structural elements were covered with protective cladding and a sprinkler system was applied in the building. The reinforcement bars in the concrete core wall were placed at a 35 mm cover to satisfy the required fire resistance time. The fasteners in the dowel-type connection were sealed with wooden plugs and the slotted-in steel plates are hidden and covered by the timber beam element. Dowels, bolts and steel plates in the column splice connection were protected by a double layer of gypsum plasterboard. During a fire, the protective cladding would eventually fall off and charring of the mass timber element would start. The developing char-layer would protect the rest of the cross-section against the fire load. In the GLT beams, a charring depth of 34 mm developed after 120 minutes of fire loading, and as a consequence all steel plates, connectors, and dowels were placed at a minimum distance of about 40 mm from the outer surface. The designed tall and slender hybrid wood-concrete structure satisfied the serviceability criteria for lateral displacements and accelerations, and the critical connections in the timber frame are able to resist the large forces in the structure. However, a hybrid wood-concrete super tall building required shape optimization and a tuned mass damper to avoid peak acceleration levels exceeding the occupant comfort criterion. Furthermore, the design process established in this case study could serve as a roadmap for the design of future hybrid wood-concrete super tall buildings.

The method of Macaulay utilizes singularity functions to describe discontinuous forces acting on beam structures. This method has been extended to determine internal forces and deformation properties, where the beam is inclined at a certain angle or curved.

Wood is an important building material that has been used for thousands of years throughout the world. It is the most widely used building material and due to its characteristics suitable for a wide range of applications. Still, for the last century steel and concrete have been the materials of choice for large buildings. Part of the reason for this is the lack of knowledge in the industry regarding timber construction. Now that the environmental problems such as climate change get more and more attention, there is an opportunity for timber as a building material and the manufacturers of timber products to increase its popularity. Cross-Laminated Timber, or CLT, is a relatively new product. First introduced in the early 1990’s in Austria and Germany, now gaining popularity in residential and non-residential applications in several countries around the world. The panels normally have 3 or more layers of side-by-side placed boards, that are stacked crosswise at a 90 degree angle. The boards are glued on their wide faces and may or may not be glued together on their narrow faces. The Derix Group, a company with a vast experience in the timber industry, specializes in laminated timber constructions and are interested in developing a new panel configuration. The idea is that by relocating boards from the middle layer of a CLT element, to a more favourable position, material usage can be optimized. A problem definition is formulated and used to derive the research questions that form the direction of the thesis. The research questions are related to the possible advantages and the consequences of the Hollow Core Cross-Laminated Timber (HCCLT) configuration. The first thing that is done in order to investigate the possibilities, is research into the manufacturing process and the structural design of CLT. As a relatively flexible building material with a low dead weight, the design of CLT is often determined by serviceability criteria, such as deformation and vibration. However, the rolling shear properties of the cross-layers can control the design, it influences the effective bending stiffness and stress distribution. It also causes a larger deformation due to shear than for other wood based products. Since there is not one specific design method, the most common methods are researched and described.  The composite theory  The mechanically jointed beams theory  The shear analogy To determine how the existing methods perform and to investigate the structural behaviour of a HCCLT element compared to a CLT element, the methods are used to calculate different configurations in order to compare the results. The knowledge obtained during the research and calculations is then used to model a HCCLT element. Different models are made in order to investigate the behaviour during manufacturing and for when the element is in use.

Over the past years Fibre Reinforced Polymers, or FRP, have started making more of an appearance in civil engineering structures. They have the advantages that they are light-weight, do not corrode and theoretically require little maintenance during their lifespan. Originally they were used to construct reinforcement, cables and small bridges but more and more they are finding uses for larger scale structures. One of these newer applications is in lock gates. Locks are structures which are responsible for enabling water based transport while also retaining high water where necessary and are critical links in the water defence system of a region. Their gates also have a relatively large risk of collision due to the amount of moving vessels passing through them. In order to safely construct these lock gates from FRP laminates it is important that their response to such collision loads is well understood. This is the focus of this study with the aim to construct a model to help better understand the collision scenario. To make the theory concrete a case study is done on the lock gates of Sluis III which is situated in the Wilhelminakanaal in Tilburg. These gates are, at the time of writing, the largest FRP lock gates in the world. With the down stream gates being 13.9 by 6.3 meters. The event in which a Class III vessel collides with these gates will be examined in detail. The collision is schematised as a one dimensional collision using a series of springs and dampers to obtain understanding of the general collision behaviour. From this model it is concluded that the application of a load from the ship’s engine or taking elastic deformations of the ships bow into account has negligible influence of the results (in the order of 2%), simplifying the calculations considerably. This simple model is later advanced in three ways: Two numerical finite element models are used to determine the structural response of the gate elements on a global and local scale and a more advanced analytical model is made to account for non-elastic deformation in the ship’s bow. The gate’s structure consists of multiple overlapping laminates which together form the skins of the gate. The numerical model is set up in two ways, one of which is used to determine the overall response of the gate element and the other to focus on the interlaminar resin layer in the skins. The results show that it is of importance to apply the load in a realistic manner as the results may vary widely depending on bow shape and point of impact. The approximation suggested in the Dutch codes in which the load is applied as a distributed load of a 0.5m2 areas proved to be inaccurate. For this reason a dynamic LS-Dyna calculation is run using a rigid model of the ships bow to apply the load. The outcome of this analysis shows minor damage to the gate over a large area around to point of impact, but the stresses remain under the failure limit of the laminates except for the internal flanges directly under the impact. These flanges will fail, but this will not threaten the water retention of the gate. The stresses in the resin layer also remain under their critical limit. It can be concluded that the gate satisfies the requirements but significant repairs will be necessary to restore it to a fully operational state. The expanded analytical model is based on the fact that the force between the bow and the gate is larger than the failure load of the bow itself. The failure which will then take place will dissipate large portions of energy (in the order of 50%) making the current approach, in which this does not take place, highly conservative. The model suggested here is a segmented failure model in which parts of the ship bow fail completely once their failure load in reached. The results of this model are dependent on a series of inputs based on the ships structure and the damping during collision, but for all input values within their expected regions it shows a significant reduction in the amount of the energy that must be retained by the gate as well as a decreased sensitivity to the, hard to predict, damping factor. This model shows potential to reduce material usage for lock gates in which collision are considered governing. With further refinement this model could be used during the design of future lock gates to come to a cheaper design. Experimental data would serve an important purpose during this refinement.

At the Shonai River around Nagoya, Japan, several flood related problems occur. These problems occur at different locations, each with its own problems or limitations. The desired safety level as requested by the government is that the river should be able to have a discharge which has a probability of failure of once in 200 years. At many locations, the current probability of failure is lower than once in 50 years. This has led to the following research question: How can the discharge capacity of the Shonai River be improved to modern standards? The report has been divided in four phases. The first phase is used to formulate the final research question. This phase focuses on which part of the Nagoya urban area is most prone to flooding. Three kinds of flooding were examined: by peak river discharge, impact by tsunamis and impact by storm surge. The area is already well protected against tsunamis due to the natural shape of the bay Nagoya is situated to. The coastline is well protected against storm surges in the second half of the 20th century. At the river banks however, flood safety is still below the desired level. In the area, risks are relatively high along the Shonai River. Therefore, it has been decided to focus on the threats around the Shonai River. As already described above, there are several locations along the river with safety risks. In phase 2, several locations and solutions are described to increase the capacity of the river. One major problem is the bottleneck around the Biwajima bridges, where four bridges are narrowing the river. At this location, the desired safety level of a flood discharge occurring once in 200 years is still far away. After discussion with officials of the Shonai River office, it was found that this problem was most urgent. Therefore, it had been chosen to elaborate further on this option in phase 3 and 4. In phase 3, several options are described to remove the bottleneck. The first option is to replace the bridges with more clearance and larger spans. The second option is to remove the bridges and replace them for tunnels. The third and last option is to construct a bypass along the river, with flow through a tunnel. The Shonai River office is already working on a plan to raise the bridges, thus the first option has been dropped. The second option required large amounts of space for the tunnels. Therefore, it had been decided to work out the third option of creating a bypass. To minimise the impact of such a bypass and its construction on the surrounding area, the decision is made to construct a bored tunnel. In the fourth and final phase the solution is verified. This is done concerning structural, hydraulic and construction method aspects. All the aspects are found to be possible. In hydraulic aspect, it is found that the required discharge capacity to reach a once in 200 year safety level equals 4250 m3/s. The current discharge capacity is found to be 2850 m3/s. Therefore, the bypass should have a minimal discharge capacity of 1400 m3/s. When using a bored tunnel, it is found that two tunnels with the maximal internal diameter of 16 m should be applied. On top of that, because the concrete surface is to rough in the best circumstances, it was decided to apply an epoxy layer on the surface. Using such a layer, it is found that the total discharge capacity becomes 1490m3/s. The construction of the tunnel would take 137 weeks to complete. The total costs are estimated to be in the order of ¥60,000,000,000, or 60 billion yen, equivalent to 463 million euro. In comparison, the plan of the river office to replace the bridges would cost ¥68,400,000,000. It can be concluded that this option is a reasonable alternative for the current plan.