The transportation industry is constantly developing innovative solutions in order to increase efficiency, sustainability and safety. Truck platooning is one of those emerging technologies with high potential. In one way or another, truck platooning will also have an impact on our current infrastructure and the way in which the motorways are managed and maintained.Trucks have the greatest effect on the occurrence of road surface wear unlike smaller vehicles (Mallick & El-Korchi, 2017). The pavement structure is designed according to the amount of truck axle load repetitions that occurs in the design life of the motorway.The current traffic flow is normally distributed on the traffic lane, which is called lateral wander and has a positive effect on the service life of the road structure. Driving in a platoon will influence the wandering effect of trucks which will have a negative effect on the pavement structure. Lateral wander results in the distribution of pavement damage allowing more load repetitions on the lane.Different professionals from Rijkswaterstaat and TNO (research institute) were approached and search engines like Scopus, Elsevier, ResearchGate, ScienceDirect and the library of Tu-Delft were used to obtain scientific papers on truck platooning, pavement structures and the current maintenance strategies. It can be concluded that little to no research has been done into the impact of truck platooning on the pavement structure. This means that there is a knowledge gap in the scientifically area and in the practical area. This resulted in the following objective of this research, which is to fill the scientific knowledge gap and to contribute to the current practise. The resulting main research question has been developed, based on this objective.What are the potential impacts of Truck Platooning on the road infrastructure and how could this affect the construction and maintenance of asphalt pavements on motorways?Research approachA mix of qualitative methods and quantitative methods were used to find an answer on the main research question regarding truck platooning and the pavement structure. First, a literature study was conducted in order to collect the necessary data to identify the characteristics of truck platooning and to analyse the failure mechanisms of the pavement structure.The literature study identified three failure mechanisms which are effected by lateral wander. The literature study also resulted in three basic models, which are used to analyse the failure mechanisms. During the desk research, the models were adjusted to fit the needed situation of truck platooning on the Dutch motorways. After this, the impact of truck platooning on the pavement structure is determined.Next interviews were conducted with the purpose to obtain and evaluate data regarding the failure mechanisms of the pavement structure in relation to truck platooning and their impact on the maintenance strategy. As such, the obtained data is incorporated into the study.ResultsThree possible platooning scenarios were identified, based on the interviews. The impact of truck platooning will depend on the way on which the platoon will be configurated.• The trucks can be connected to each other only in the longitudinal direction.• The trucks can be connected in both the longitudinal and transverse directions, with an independent leading truck.• The trucks can be coupled in both the longitudinal and transverse directions while the leading truck drives in the exact same track as the previous truck platoons. This scenario applies when the trucks start to drive autonomous.The impact of truck platooning will depend on the way on which the platoon will be configurated. As a result of the interview with the professionals of Rijkswaterstaat, it was concluded that only the third scenario will have an impact on the pavement structure. Today's vehicles are getting smarter and are equipped with a lot of technology. The European Uni encourages the use of Advanced Driver Assistance Systems (ADAS) and even made a number of core systems mandatory for vehicles (Dijsselbloem, Asselt, & Zouridis, 2019).The third scenario represents the most negative setting of truck platooning. The trucks in this setting are coupled in both the longitudinal and transverse directions while the leading truck uses a form of cruise control letting it drive in the exact same track as the previous truck platoon. This situation arises when the trucks start using technology to drive. The strains on the pavement structure can be two times as large in case of fatigue failure. The structural damage on the pavement will increase as a result of rut development and of fatigue.The second part of the literature review resulted in three failure mechanisms and three models were identified.• The first failure mechanism is permanent deformation; using the Rut development model.• The second failure mechanism is raveling; using the Raveling prediction model.• The third failure mechanism is fatigue failure. The Dutch Design Method includes a model in order to predict the acceptable amount of load repetitions on the pavement structure,The following findings have been made with regard to the impact of truck platooning on the failure mechanisms:Permanent deformationA maximum rut depth of 18 mm is commonly used on Dutch motorways. It is generally assumed that this standard will be achieved within 30 years without platooning. In most cases, maintenance is already planned when the rut reaches a depth of 16 to 17 mm. The model used to predict the rut development indicates that the rut depth increases with the amount of platoons on the motorway. This development could impact the current maintenance strategy if more than 50% of the trucks drive in a platoon. The maintenance strategy of Rijkswaterstaat will have to be adjusted, because the critical failure mechanism shifts from raveling to deformations of the road surface. Permanent deformation will have to be maintained in a different way than raveling. The critical point of permanent deformation could be reached within 10 years, if all the trucks that participate in traffic on the highways start to drive in a platoon.RavelingRaveling is the loss of aggregate material from the top layer. Literature research shows that, in case of young asphalt, raveling depends on the asphalt composition and traffic characteristics. However, it was also concluded that the impact of traffic decreases and that the impact of climate increases on older asphalt. It was therefore determined that the characteristics of truck platooning won’t lead to an increase of raveling, which means that the same maintenance intervals as in the current situation can be maintained.Fatigue failureMotorways are designed with a lifespan of 20 years based on a certain number of load repetitions and with fatigue failure as criterium. After this, improvements will be made which will extend the service life by another 20 years and so on. Based on desk research and interviews, it is assumed that, in the current situation without platooning, the pavement fatigue life of motorways approaches 25 year. The results in this research show that the acceptable amount of load repetitions will be exceeded within 20 years if 50% of the trafficking trucks autonomously drive in a platoon and nothing is done. When 100% of thetrucks drive in a platoon the acceptable amount of load repetitions will be exceeded within 10 year.Main findingsOverall, it can be concluded that the scale of damage done to the pavement structure depends on the percentage of platoons on the motorways. The current maintenance strategy will be negatively affected if 50% of all freight transport uses a form of truck platooning. The current maintenance strategy, without platooning, mainly focuses on restoring the top layer of the pavement structure due to the loss of aggregate material or raveling. With truck platooning, the other failure mechanisms like fatigue cracking and permanent deformation will change the current maintenance strategy of motorways. The principal design of a pavement structure is based on the criterium fatigue failure, because this is the most expensive maintenance intervention. Especially because motorways are designed for a lifetime.RecommendationsThe development of truck platooning needs to be dealt with in a timely manner. Data needs to be collected with regard to the failure mechanisms in order to determine the impact and to develop a strategy. This can be done during the first use of the technology and during the regular maintenance intervals used for the current motorways. Rijkswaterstaat lacks the data required for predicting rut development in the current situation, because this failure mechanism has no priority.The impact of truck platooning on fatigue failure will result in maintenance in the form of structural interventions, if no measures are taken. Maintenance interventions in the deeper layers of the pavement structure are the most expensive ones. Applying Smart Lanes could be a solution for simulating lateral wander and organizing maintenance more efficiently.Performing a Cost Benefit Analysis (CBA) to determine whether the required interventions yield more than the costs that must be incurred for upgrading the infrastructure. This not only gives the government a clear overview of future costs as a result of truck platooning, but also a tool to determine whether truck platooning can be permitted on the roads. A positive result of a CBA analysis can therefore be used to get support from various stakeholders, to promote cooperation with different manufacturers and with the Market.DiscussionThree models were used to determine the impact of truck platooning on the pavement structure. The models were obtained through literature research and desk research.The rut development model is based on a number of measuring points generated during the LINTRACK tests on a full scale pavement structures. This tests contains a couple variables like temperature, speed of the tire and wheel load, which differ from practice. A correction has been made for the difference in the variables. The LINTRACK tests produced nine measuring points ,from which a regression line has been developed. More measuring points could be used to increase the accuracy of the regression line.The model which predicts raveling was developed by the New Zealand Transport Agency. As a result, this model does not fit perfectly on Dutch motorways. The model was developed for porous asphalt, but the wheel loads had to be adjusted. This research was conducted for motorways in the Netherlands with limited data. ... Read more

The Netherlands is currently in the process of transitioning from a linear economy to a circular economy, in accordance with the ”Nederland Circulair 2050” policy. To increase the circularity of buildings, several approaches can be integrated. In this research, the so-called Design for Deconstruction and Donor Structural Framework concepts are elaborated as possible approaches. The first concept focuses on taking the future de- and remountability of a building into consideration during the design process. This concept allows buildings that approach their end-of-life phase to be (partially) reused as structural components, on a new location. The second concept can be applied during the construction phase of a building, where structural components of an old building are dismantled and reused in the to be constructed building. The difference between the two concepts thus being the life cycle in which they are applied. Therefore, the resulting benefit of using a Donor Framework can be seen immediately, whereas the benefit of applying the Design for Deconstruction concept can only be stated in the future. Unfortunately, the current procedure to measure the sustainability score of a building, the Life Cycle Assessment methodology, does not take these concepts into account. This makes determining their impact on the environment hardly possible. Also, due to the fact that detailed information about a design is required, a Life Cycle Assessment is made only once the design is final. In this order, all design variables are set such that designing towards sustainability is not an option. This research focuses on solving the introductory problems and aims to enable sustainable material choices for a structural design possible in the early design phase. Both the Donor Structural Framework and the Design for Deconstruction concepts were taken into consideration. This main goal has been split into two sub–questions:- How to assess the environmental impact of a steel, concrete and timber load bearing structure in the early design phase? -How to implement the Donor Structural Framework and the Design for Deconstruction concept into the existing Life Cycle Assessment methodology? The research questions have been answered by executing the following approach: 1.A parametric model is used in which not only the geometry and structural calculations are included, but the Environmental Impact Calculation as well. In the event of a design change, the Environmental Impact Calculation is automatically reiterated, which means different designs can be compared quickly based on their environmental impact. The model constructed for this study is suitable for designs in steel, concrete and timber. For each material a reference design is created. The Bill of Materials of these designs serves as input for the Environmental Impact Calculation on which the materials were compared in a later research phase.2.First, an existing end-of-life allocation method has been adjusted to include reuse during both the construction phase (Donor Structural Framework) as the end-of-life phase (Design for Deconstruction). Secondly, the Building Circularity Index, which recognizes a ”circularity score”, has been implemented in this method. In this study the Building Circularity Index is assumed as the ”probability of future reuse of the building”. The modified method was implemented in the parametric model to enable a real-time Environmental Impact Calculation. This approach has been fully implemented into a parametric visual script, executed in the Grasshopper, a parametric environment plugin of Rhino which enables visual scripting. Input parameters are imported from Excel, the Grasshopper script calculates the environmental impact and exports the results to Excel where they are visualized in a dashboard. Ultimately, the developed parametric model has been divided into a part containing the geometry and structural calculations of the reference designs and a part where the newly developed Environmental Impact Calculation method is implemented. Combining the results of both parts in the total model, it becomes possible to assess whether a design is best built in a certain material in the early design phase. The final model can provide results with or without the use of a Donor Structural Framework and with or without application of the Design for Deconstruction concept. For the purpose of demonstrating the functioning of the model, a reference design in steel, concrete and timber was implemented as a basic geometry. This geometry was assumed equal across all designs and for comparability purposes, dimensions were fixed. Consequently, it can be concluded from the results of these reference designs that using a Donor Structural Framework results in a lower environmental impact than applying the Design for Deconstruction concept by maximizing the remountability of a structure. Until a lifespan of 75 years, using a timber donor framework is the most sustainable solution for the reference design. From 75 until 100 years this is the case for steel and from 100 years onward, a concrete design, whether or not using a donor framework, results in the lowest environmental impact. In the current design practice of a building, the default lifespan has been determined by the function of the building (Functional Service Life). By using the model developed here, this lifespan can be determined on the basis of sustainability requirements instead of functional requirements. The differences in environmental impact for different lifespans can easily be compared. Therefore, it is made possible to steer towards a certain lifespan, in order to determine the most sustainable construction based on the clients requirements. This is currently not possible in the Dutch construction industry. However, these results do have their limitations, as they should not be interpreted as general but rather specific conclusions. The following points of attention apply: -Results should not be interpreted as general results, but these results only apply on the three reference designs as elaborated further in the research. These reference designs are not optimized for every material used. -Changing input parameters can have a significant impact on the results. In addition, a number of important parameters (reuse percentage, material lifespan etc.) have been assumed due to insufficient existing research. -The developed allocation equations include the incineration of timber too favorably. This results in a significant deviation in timber environmental impact for lifespans much shorter than 75 years. This flaw can be either due to the model, or the impact parameters as stated in the NIBE EPD app. Lastly, it is recommended to further research the assumed parameters in this research, especially the material lifespan and the incineration impact parameters. As these parameters can have a major impact on the environmental impact of a specific design. ... Read more

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. ... Read more

New and existing bridges in the Netherlands must abide by structural safety codes, such as the Eurocode. In this code, structural safety is expressed through the reliability index 훽. For certain reference periods a threshold value for 훽 exists. When applying prescribed load models given in the Eurocode, the structure is guaranteed to at least fulfil to this threshold value. However, these prescribed load models are deterministic in nature and can be rather conservative for bridges in urban areas. This thesis focusses on creating a probabilistic load model based on actual traffic loading by making use of a camera system that registers license plates to check whether the vehicle is allowed to enter the inner city of Rotterdam due to environmental zones. From this camera system data, technical information such as wheelbase, legally allowed axle loads, gross vehicle weight and such can be extracted since they are coupled to license plates. This technical information is then used to create load models based on actual registered traffic. This load model represents trucks as point loads with interspatial axle distances. In total, one year of collected data by the camera system is stored, called the LP data. This load model is then used in a probabilistic reliability analysis as a load variable input. When comparing the LP data with available weigh-in-motion (WIM) data from two measurement locations in Rotterdam, it turned out that the LP data does not incorporate under- and overloaded axles and was overestimating the accompanying reliability index. Hence to account for this, an axle load factor 휂௜ is introduced to simulate under- and overloaded axles. This factor 휂௜ is based on the WIM data and is different for each vehicle type. With the use of this factor, a second, improved load model is constructed. This is referred to as the modified LP data. A third and final load model was constructed from the available WIM data, called the WIM model. For each of these three load models the load effects were calculated, and distributions were fitted accordingly for simulating several 25 year periods of traffic. The output of these load models is a loadeffect maxima distribution that can serve as a direct input in a probabilistic reliability analysis. With these three load models, a hypothetical slab with a span length of 10 m was probabilistically analysed where the LP model, the modified LP model and the WIM model resulted in reliability indexes of 4.8, 4.1 and 3.7 respectively. When compared to the requirement in the Eurocode, all load models comply. Concluding from this, the modified LP model suggested in this thesis can be used as a load input in a probabilistic verification for this very considered bridge location. For this load model to be applicable to multiple bridges, more research must be done since only one location was considered in this thesis. However, the suggested approach to construct load models based on license plates can be used verify the applicability to multiple bridges. ... Read more

Due to the alteration in height, the centroidal axis of a non-prismatic beam has a non-linear layout when compared to a prismatic beam. Therefore, in case of a non-prismatic beam, the vertical cross-section cut, on which analysis from the codes are performed, is no longer perpendicular to the centroidal axis, unlike prismatic beam. Moreover, due to the geometry, these beams are prone to shear failure which is mainly due to the vertical component of the inclined cross-section forces. The main focus of this study is to compare the cross-section results obtained on inclined and vertical cut and also to validate the inclusion of the vertical component of the inclined forces in the shear capacity equation.
Different approaches are proposed to calculate the cross-section results on an inclined cut, with the internal forces in the global (horizontal and vertical direction) as well as in the local direction (perpendicular and parallel direction of the cut). From the procedure it was seen that in a prismatic beam, subjected to four point bending test, the cross-section results remains the same irrespective of how the analysis is performed. However, in case of non-prismatic beams, the bending moment resistance obtained on an inclined cut, which is perpendicular to the centroidal axis with the forces in local direction, is greater than that obtained on a vertical cut. Therefore to be conservative it is recommended to perform cross-section analysis on a vertical cut in a non-prismatic beam.
A procedure to calculate the shear capacity of non-prismatic beam is determined in this study. First, the shear resistance contributed by concrete and stirrups are calculated at the assumed critical section. Then the inclined internal forces are determined for each load case and the capacity of the beam is either reduced or increased by the vertical component. This capacity is compared with the applied loading and is checked for failure. Since the shear capacity is influenced by the applied loading, failure of the beam is defined as the load for which the determined capacity is lower than the applied loading. The results obtained from this procedure are in good agreement with the limited experimental data available. Therefore, it can be concluded that the vertical component of the inclined cross-section forces should be considered in the shear capacity equation.
Finally non-prismatic bridge deck is also studied and different errors that engineers make in practice is further analyzed. Due to the non-linear layout of centroidal axis, engineers find it difficult to perform analysis on non-prismatic beams. Therefore, the cross-section of the deck is modified, such that the centroidal axis remains linear. The results determined on a modified deck is equal to that obtained on the original model. Another error engineers make is ignoring the inclination of internal forces, which leads to underestimation of the capacity. This study shows that the vertical component of the inclined cross-section forces, which is considered in the shear capacity, should be determined based on the bending moment obtained for the load combination where applied shear force is governing.
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Nowadays the city of São Paulo has to deal with a lot of traffic jams. Extending the road network is no option and the public transport network cannot keep up with the capacity either. A solution must be found in another type of transport: cycling. The current bicycle infrastructure is not sufficient in terms of connectivity. In this research, a standardised bicycle network is developed for a part of the city, which can be used during future bicycle expansion projects in São Paulo. The development of the bicycle infrastructure concerns the whole city of São Paulo, resulting in a lot of interests being affected. The people behind these interests, the stakeholders, can have an influence over the project decisions, but do usually have conflicting interests. Therefore, these stakeholders are identified and analysed, through literature review and semi-structured interviews. In this case however, most stakeholders did not seem to experience any conflicts. The biggest problem in the development of the bicycle network, is that the stakeholders all work towards the same goal, but do now cooperate towards that goal. Cooperation between multiple stakeholders would result in more power, meaning they could makemore of an impact together. Most of the stakeholder‘s expectations could be met in this case, resulting in a satisfying design for most people. As a result of literature review and the performed interviews, a list of requirements is developed as a basis for the rest of the design of the bicycle network. The conclusion was made that not only a sufficient network needed to be designed, but that incentives for use were also needed. Therefore, the list of requirements is divided into three categories: infrastructure network, incentives for use and long-term guidelines and recommendations. The rest of the standardised design is based on the list of requirements. According to the requirement list, the new cycling network has been designed by greedy algorithm. The new plan can achieve 99.51%inhabitants with 320 metres of the walking distance. And it requires a new bridge for only cyclists and pedestrians’ use to cross Pinheiros River. Due to the demand of a bridge, a structural design is required. A literature review was performed, investigating the existing situation regarding the infrastructure. In the literature study, the different bridge types with their pro’s and con’s are described. Based on the existing situation and the literature study, a sound bicycle and pedestrian bridge design is designed. In this situation, for the standardised bridge, an arch bridge is the best choice. The standardised design allows for an efficient and fast design and execution process. This design process is obtained by using a parametric design in Rhinoceros and Grasshopper, so the design of the bridge can be used for multiple spans. ... Read more

Recycled granular materials such as Recycled Concrete Aggregate (RCA) and Recycled Crushed Masonry (RCM) are widely used in The Netherlands as base layers in asphalt pavements. The lack of natural resources and the growing amounts of demolition waste made that the Dutch industries in the early 1980s started to explore the possibilities to use construction debris in road construction. Recently, the application of recycled materials in pavement structures has also found traction in South Africa. Due to differences in pavement design, however, the mechanical and environmental exposure of these materials will be more severe than in the Netherlands. This results in different challenges with respect to (long term) performance and material durability. Understanding the potential durability issues and the way durability affects pavement performance is crucial to successfully implement these materials in South African pavements.
This research, conducted at Stellenbosch University, South Africa, involves laboratory testing to investigate the performance and durability aspects of recycled aggregates. By means of triaxial testing before and after durability simulation, it is aimed to address the extent of potential material breakdown and the influence this has on performance. Tests are conducted on RCA, RCM, MG65 and MG30. The latter two refer to a mixture of RCA and RCM, with a mass percentage RCA of 65% and 35%, respectively. In addition to the recycled materials, a commonly used crushed rock of G2 quality is tested as well to serve as benchmark. Monotonic triaxial tests, to obtain the shear parameters, are performed on all materials except the pure RCM. Permanent deformation triaxial tests, to gain understanding of the long term response to cyclic loading, are performed on RCA and MG65. Specimens are tested under different confinement and deviator stress levels. For the durability simulation, the South African Durability Mill (DMI) is used. The DMI enables durability testing of the full grading under soaked and dry conditions. After the tests, the milled specimens are sieved out to obtain the change in grading.
The most important findings regarding granulate durability include that the breakdown in recycled materials is significant in comparison with the G2. Mainly the largest particle fractions are affected. Furthermore, for these particular resources of recycled granulates, the RCA suffers more breakdown than the RCM. The breakdown in the blends decreases with increasing masonry content, implying that the RCA is the most prone to mechanical damage. Considering the monotonic triaxial tests, substantial values of shear parameters are measured in all materials. The highest cohesion is measured in the MG30, while the highest internal angles of friction are measured in the pure RCA. The shear parameters in the recycled materials are in all cases higher than those for the G2. Differences in failure type (brittle versus plastic) are observed as well. Durability milling results in a small increase of the internal angle of friction and in a moderate decrease of cohesion. The latter is the most governing for the material’s compressive strength after milling, as this is decreased in all milled specimens. Still, the shear parameters of the milled specimens remain relatively high. In the permanent deformation triaxial tests, a decrease of performance can be observed in both the RCA and MG65. Delayed shear failure is observed in milled specimens tested at a deviator stress ratio (DSR) higher than 30%. Although the number of permanent deformation tests performed in this research is limited, 30% DSR seems the upper limit with respect to cyclic loading. This points out that monotonic triaxial testing alone is not sufficient for an adequate material characterization. A small linear elastic pavement analysis based on the tested materials, however, shows that the occuring DSR levels in a reference pavement caused by standard axles of 80 kN do not exceed 20% DSR, proving the potential of these materials for further studies. ... Read more

The service life of concrete structures depend largely on the durability of concrete. The durability of concrete is influenced by mass transport mechanisms that can have severe deteriorating effects. Transport of water in concrete is of paramount importance as water can act as a carrier of ions such as chlorides which can corrode the reinforcement and reduce the service life of concrete structures. The main objective of this thesis is to study moisture transport through capillary absorption in concrete. Numerical simulation of moisture transport is performed through lattice elements with an irregular mesh configuration. New computational tools are developed and compared with the existing tools in terms of effectiveness to simulate moisture transport in homogeneous uncracked concrete. The existing numerical model uses approximate volume of transport elements to determine the volumetric capacity of elements. During discretization of the governing equation, the variation of diffusivity of the elements is approximated as a uniform mean distribution and an explicit time stepping scheme is implemented which has consequences on the flow equilibrium at each time step. In the proposed numerical model, exact volume of transport elements is considered and during the discretization of governing equations, exponential variation of diffusivity is considered along with an implicit time stepping scheme. Moisture transport is accurately simulated in uncracked homogeneous concrete even by using the existing model as validated through experimental results. Both the models are compared through error analysis by varying mesh size and time step. Moisture flow through different diffusivity coefficients is simulated using both the models and it is observed that the existing model suffers from oscillations in the saturation level during initial stages of flow due to inability of the existing model to maintain flow equilibrium at each time step. The proposed model on the other hand shows no such oscillations due to the flow equilibrium being maintained at each time step. Mesh size, magnitude of time step and diffusivity coefficient are shown to be the parameters limiting the effectiveness of either of the models. A single discrete crack is considered within the domain and its influence on moisture transport is observed. The nature of the crack is considered through two approaches. In the first approach, crack is considered as an additional porous phase in cement matrix and the entire volume occupied by the crack is considered to be a void. In the second approach, in addition to considering the porous nature of crack, moisture surface interaction between the water surface and crack walls is also considered. Horizontal moisture distribution around a planar crack is simulated using both the approaches which show similar results as in the experiment. The vertical moisture distribution is simulated within a wedge shaped crack and the results are compared with experimental observations. The first approach shows a slower rate of saturation of the crack as compared to the experiment. The second approach shows the vertical saturation of the crack similar to the experiment. A comparison between the Delaunay and Voronoi modelling techniques of moisture simulation in cracked domain is discussed. It is shown that the presence of a crack accelerates the moisture transport in concrete as it exposes additional surface of concrete from where water can penetrate in the material and also increases the diffusivity of the concrete material lying in the vicinity of the crack. Moisture transport is simulated in concrete considering its multi-phase nature. Concrete is considered to be composed of three phases i.e. cement paste, aggregates and ITZ around aggregates. Aggregates are considered to be impervious which do not allow the flow of moisture through them which slows down the flow in concrete. The ITZ around the aggregates have higher transport properties and accelerate the flow. A numerical framework is formulated in which spherical aggregates are projected on lattice elements which are assigned transport properties pertaining to the phase of concrete they represent. Moisture transport is simulated and compared with experimental results where an increase of volume fraction of aggregates leads to a decrease of cumulative saturation level. The influence of ITZ is observed on a local and global scale by varying the ITZ diffusivity coefficient. The moisture simulation is also modelled on a finer mesh to see the effect of mesh refinement. Finally, moisture transport is simulated in a numerical model that combines a planar crack along with heterogeneities and flow is observed at different time stages. ... Read more

Several researches have been done in the last decade about the possibility to “give a new life” to the second-hand reinforced concrete elements of a certain building which has been (fully/partly) disassembled. However, not often the actual technical detailing of their reuse practice are addressed. This study is primarily focused on proposing the most suitable solutions to what concerns the reintegration of these structural second-hand parts into a “host” structure, which can contain other reused elements or can be a mixture of new and second-hand parts. The overall approach to the previously mentioned task is structured as follows: -Four structural systems have been considered to formulate the input list of elements for which re-connection approaches need to be formulated; -Connection approaches have been formulated for the elements which have been considered suitable for a potential reuse; -Selected connection methods from the ones formulated above have been studied in detail, assuming to embed them in a hypothetical office building made partially of second-hand elements. From the first part it have been assumed that common columns, shallow beams, load bearing wall panels and one way slabs such as hollow core slabs and plank-floors can be potentially reused. In the second phase several connection approaches have been formulated, highlighting briefly their constructional details and specifying their advantages and drawbacks. Some of these resulted in having different degrees of overall complexity. In any case the proposed designs are requiring more investigation before being actually put in practice, since, for some methods a significantly different design from the one used for traditional connections was used. In the last part, regarding the case study of selected jointing methods, it was chosen to address three approaches: the connection of a second-hand column to the foundation block, a splice joint on a column and a complete study of a columns-to-shallow beams node. In final result it has been deduced that, even if the feasibility regarding the use of second-hand elements requires a careful preliminary assessment and a detailed study about the cost-effectiveness of the details, the proposed connections could be potentially successfully embedded in a new structures. This point has been also confirmed by the positive output results obtained at the end of the analysis of the case-study. ... Read more

Rapid extraction of gas in the north-eastern Groningen province of the Netherlands has led to an increase in the occurrence of induced earthquakes in the region due to subsidence of gas bearing sandstone layers. This process manifests itself in the form of ground motions at the surface. Netherlands, historically being an inactive tectonic zone, has not paid much attention to detail structures withstand lateral seismic forces in the past. This has led to an alarming situation amongst the residents and government authorities since damage has been reported in the form of claims for compensation. The predominant presence of old masonry houses has further aggravated the situation because of quasi-brittle material characteristics weak in tension. A large-scale research campaign was launched after the historical seismic event at Huizinge in 2012 with an aim to assess and safeguard building structures in the region although much of the research has been focussed on behaviour of masonry houses. NPR 9998 which serves as a national guideline in the Netherlands for seismic assessment and retrofitting was published and is continuously being updated with the latest developments. However, it is equally important to address other typology of structures in terms of material and geometry. With this objective, it was decided to start with a fundamental study on the seismic analysis methods with specific regards to steel structures.

The present thesis provides a comprehensive review of the lateral behaviour of affected structure initially and the fundamental differences in the induced earthquakes when compared with deep tectonic earthquakes. This is followed by state-of-the-art of linear and nonlinear seismic analysis methods which forms the basis of guidelines & codes presented in the NPR 9998 and EN 1998 context. Further, an understanding on the generation of seismic action in response spectrum format from recorded ground motions which is the most widely adopted one across seismic design codes worldwide. The case study adopted for this study is a steel office building preliminary designed for non-seismic actions. Global seismic demands are determined using linear-static and linear-dynamic analysis methods with verification of specific criteria to be satisfied for safety of steel structures. Modelling parameters and methodologies are discussed in detail with regards to using simplified numerical models for analysis based on recommendations from Eurocodes and Internaltional codes. A variation model to assess the likely performance level using nonlinear static pushover analysis for a specific intensity of ground motion in terms of peak ground acceleration was made. Conclusions in the form of applicability of analysis methods are made towards the end with affected structures primarily vibrating in the fundamental mode, the present study can serve as a reference guide for a practicing engineer carrying out seismic analysis. Discussions about the background of design principles is made alongside the analysis for a clear understanding.

This thesis is expected to fill the knowledge gap for a design engineer carrying out seismic assessment of structures in the Groningen region of the Netherlands by providing a fundamental understanding of seismic demands imposed on a structure and assessment of capacity deficiency by carrying out non-linear pushover analysis. Recommendations based on NPR, Euro codes and International codes have been made to simplify numerical modelling of the structure. Similar analysis can be undertaken for other types of structures prone to be affected by induced earthquakes by adopting corresponding material nonlinear models and considering level of interaction with the ground in terms of soil-structure interaction where the same may lead to modification of structural response.
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Vanuit Rijkswaterstaat is de wens om een snelle, verifieerbare methode te ontwikkelen voor het controleren van de veiligheid voor meerdere T-ligger constructies volgens huidige normen en inzichten. Hierbij dient rekening gehouden te worden met eventuele wijzigingen in de toekomst, welke door de huidige ontwikkelingen op het gebied van dwarskrachtonderzoek te verwachten zijn. Het is de verwachting dat op basis van verfijnde beoordelingen en verder fundamenteel onderzoek de ‘reserves’ middels een quickscan-aanpassing inzichtelijk gemaakt kunnen worden. Hierdoor zou een deel van de onderzochte kunstwerken mogelijk alsnog voldoen aan de veiligheidsnormen.

Door diverse berekeningsmethoden met elkaar te vergelijken is getracht een methode te vinden welke simpel toepasbaar is, realistische resultaten voor dwarskracht en moment geeft ten gevolge van de verkeersbelasting en tevens conservatief is. Door deze te vergelijken met diverse Scia-berekeningen is een methode gekozen die het best aan de eerdergenoemde punten voldoet. Tevens zijn de invloeden van meerdere uitgangspunten met elkaar vergeleken. Nadat inzicht is verkregen in de manier waarop de belasting over de liggers is verdeeld, is een generiek systeem gemaakt, een zogenaamde quickscan. De quickscan maakt op een snelle manier duidelijk of de gekozen snede voldoende weerstand kan bieden aan de behorende belastingcombinaties. De quickscan is een generieke, eenvoudig toepasbare, conservatieve methode om ‘het kaf van het koren te scheiden’ voor de dwarskrachttoets, zonder dat daarvoor EEM-software nodig is, welke tevens de Scia-berekeningen zo goed mogelijk benadert. Om deze zo goed mogelijk te ontwikkelen is een beoordelingsprocedure gerealiseerd welke zich vormt tot de quickscan.

Om inzicht te verkrijgen in de invloed van de verkeersbelasting op de liggers en om deze conservatief te benaderen, zijn diverse berekeningsmethoden met elkaar vergeleken.
Uit deze vergelijking is gebleken dat de beste benadering voor de verkeersbelasting de ‘verspreide methode’ is. Hierbij wordt de belasting gespreid of is deze niet afhankelijk van de locatie van de dwarsdragers. Met deze kennis is de quickscan Boon ontwikkeld. Deze kan worden uitgevoerd door enkele parameters in te vullen, zoals: de lengte van de ligger, het oppervlak van de ligger, het voorspanverloop, de dwarsdragers en door de ‘kritische’ sneden (belangrijke te toetsen sneden) van de ligger te bepalen. Daarna kan snel en slim inzichtelijk worden gemaakt wat de UC op deze sneden van de constructie is, en wat de consequenties van wijziging van uitgangspunten zijn. Uit het onderzoek is gebleken dat het tandemstelsel altijd op een hoek van 30 graden vanaf het gekozen punt tot hart rijstrook moet staan om de maximale dwarskracht in dat punt te vinden. Deze belastingsposities worden automatisch gevonden, waarna direct de dwarskracht en het bijbehorende moment berekend wordt met behulp van de verspreide methode. Hierdoor kan de constructieve beoordeling van de liggers snel inzichtelijk worden gemaakt.

De quickscan Boon is een eenvoudig toepasbare, realistische, conservatieve beoordeling voor T-ligger constructies, welke inzicht geeft in de maatgevende belastingcombinatie en gemakkelijk te verifiëren is. De kracht van deze methode is dat door te variëren met diverse parameters (zoals capaciteitsaspecten, te toetsen snede en rijwegindeling) direct de invloed van deze parameters inzichtelijk kan worden gemaakt. Waar de resultaten conservatief en toch reëel zijn.
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Wind energy plays an important role in the global energy supply and is obtained by wind turbines placed on- and offshore. The expected growth of offshore wind farms will generate a lot of work in the future. Seaway Heavy Lifting is an offshore company which offers Engineering, Procurement, Construction and Installation (EPCI) solutions worldwide for oil, gas and renewables projects.

Offshore wind turbines are most commonly placed on a monopile foundation. The installation of monopile foundations used for offshore wind turbine farms is the main part of the projects Seaway Heavy Lifting is executing. The installation of monopiles is done using an installation vessel, which needs to be anchored during installation. The anchoring is done in order to cooperate with external forces on the side shell due to the installation of the monopile. The installation of the monopile is done using a frame which is connected to the side shell of the vessel. In order to stay competitive in the business, the company has been doing research to how to decrease the amount of installation time of their projects. It is concluded that profit can be gained by reducing the necessary time to anchor the installation vessel.

To install monopiles without anchoring the vessel, the monopile installation frame (MIF) was designed. The MIF can be placed onto the seabed after which the monopile can be hoisted inside of the frame. The frame will support the monopile during hammering. No external forces will be acting on the side shell of the vessel when using the MIF during hammering, which rules out the need for anchoring the vessel. Instead of anchoring, dynamic positioning will be used. Since the installation of monopiles will occur in different water depths, the MIF needs to be modular. An extension piece will be used in order to change the height of the frame.

The goal of this thesis is to obtain a structural optimized design of the MIF. The connections needed to connect and disconnect the extension piece are critical sections of the MIF. During the lifetime of the MIF, fatigue due to waves, wind and current loading will play a role. Therefore, this thesis has focused on the structural optimization of the connection with respect to fatigue loading. A bolted flange connection will be used in order to connect the members, which will be machined and then welded to the tube end. An initial geometry of the connection was designed with help of design rules stated by ir. M. Seidel.

The finite element program ANSYS will be used for the calculation of stress distributions. The decision was made to verify ANSYS, which was done by studying the accuracy of ANSYS, its way of working and to get used to the program. The verification has been done using a reference project.

The fatigue analysis of the connection started first of all with a global load analysis. This was done with help of the program SACS, which uses wave heights and wind speeds together with currents data as input. A calculation model of the MIF was built in SACS. Once the input was completed, the internal forces of the MIF were calculated. The global load analysis is necessary in order to obtain the loads in the members that will be connected by the bolted flange connection. These loads were used as input for ANSYS.

To check whether the initial design could be used as a starting point, the 3 failure modes of a bolted flange connection have been explained and verified for the initial design. Once it was verified, it was used as input in ANSYS in order to study the stress distribution of the model. The initial geometry has a negligible radius between the tube and the flange of the connection. Therefore, it was expected that a high concentration of stresses would occur in the junction between the tube and the flange of the connection. In order to find the stress concentration factor (SCF) in this junction, the maximum stress occurring in the junction needs to be divided by the stress applied to the tube.

Once the SCF was known the fatigue analysis could be performed. The fatigue analysis was done for two details: the junction between the tube and the flange and the welded connection between the tube and the machined part. Firstly, the amount of actual cycles was calculated for a certain time period with help of the wave scatter diagram, after which the corresponding stress ranges during these cycles was obtained. The stress ranges were multiplied with the SCF for the tube-to-flange junction, the SCF was obtained using ANSYS. Once the stress ranges were known, the amount of cycles until failure was calculated using S-N-curves that fit the two studied details. The actual damage to the structure was determined by dividing the actual number of cycles happening by the amount of cycles until failure. With the damage known for a certain time period, the life time of the structure was calculated.

The MIF will be used for a period of more or less 8 years, so the design lifetime was set at 9 years.
The initial geometry had an extremely low lifetime. Therefore, the connection needed to be optimized in order to improve the lifetime. The optimization of the connection was done by increasing the radius of the tube-to-flange junction to lower the SCF. A lower SCF value resulted in a longer lifetime. The design has been optimized until an optimum radius of 36 mm was found. The final design has a lifetime of 9 years.
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Schiphol Airport and Heijmans are working together on the renewal of the Schiphol runways pavements. Currently the top layer is covered with a synthetic antiskid material called ASK. But the strong weather limitations for the installation of this material have opened the door for alternatives. Heijmans has proposed an innovative asphalt mixture that is able to provide similar and in some cases better surface performances compared with the ASK. This asphalt mixture is called Flightflex R and is a stone matrix asphalt. Consequently it is affected by the variability of the construction process. This thesis project focuses on the analysis of the best quality control procedure for this asphalt. The pavement surface needs to meet specific requirements and it is of interest to define a sampling methodology for the evaluation of the Texture Depth (TD). In particular the research aims to define the minimum number of samples that provides the highest reliability for the definition of the Mean Texture Depth (MTD) of the surface. To achieve this goal a theoretical approach is adopted. Starting from the collection of a consistent number of samples, the properties of the surface are analysed. In this process it is of interest to define the influence of the construction process on the surface quality. The information obtained are used to simulate bigger surfaces on which different sampling methodologies are tested. In particular three different methodologies are analysed: the current methodology called CROW, a Uniform methodology and a random methodology called Hammersley methodology. Thorough testing these sampling methodologies on the simulated surfaces it is possible to evaluate the relative error between the MTD of the simulated surfaces and the MTD of the samples taken. A Monte Carlo type of approach helps to define precisely which methodology performs better. The one with the lowest relative error and minimum required number of samples will be considered the most efficient. The simulation of the surfaces and the analysis of the sampling process highlights a correlation between the manufacturing signature and some sampling methodologies. In case of a correlation the reliability of the methodology decreases. In particular the CROW and the Uniform methodology present a form of correlation and thus have a lower reliability. The Hammersley methodology aims to simulate a random selection of samples and for this reason it does not enter in correlation with the surface patterns. The three aforementioned methodologies are in the last part of the research applied on a 500 m long section of the runway Polderbaan at Schiphol Airport. Although the Uniform methodology is less reliable it provides a 1% of relative error with only 70 samples. The Hammersley instead needs 180 samples to reach the same relative error but with a higher reliability. The CROW is the least performing. In fact it has a lower reliability than the Uniform strategy and it needs 170 samples to reach 1% relative error. The research helps highlighting the correlation between the manufacturing signature left by the construction process and the sampling strategy adopted. It also highlights the fact that a random distribution escapes this correlation and provides more reliable results. To conclude, the companies are suggested to use the Uniform methodology in case of short time available for the quality control measurements. This comes with a lowest reliability that has to be accepted. But in case a high reliability is required and sufficient time is available, the Hammersley strategy is considered more appropriate. ... Read more

The use of synthetic fibres has been reported to enhance the performance of asphalt pavement materials in terms of permanent deformation, fatigue and thermal cracking. However, limited results about the benefits of synthetic fibres in the reinforced warm-mix asphaltic materials, and the exact mechanism of reinforcing the binding part in pavement structures is still unclear. This research aims firstly to examine the material at the warm mixed mortar level using a combination of two synthetic fibres (aramid and polyolefin) to conclude its fracture performance. Several laboratory tests were performed using specially designed experimental tools. Samples of three different fibre contents (0.05%, 0.1% and 0.5% of specimen weight) and two fibre lengths (19 and 38mm) were evaluated. In particular, pull-out tests, whose objective was to explore the interaction of fibre-matrix demonstrated a matrix-type of fracture; meaning that the adhesion of fibre-matrix is higher than the strength of the matrix itself, which implies a benefit of adding fibre to a mixture at high service temperature.
Summary
Moreover, direct tension tests were carried out with both monotonic and cyclic loading to measure the effect of the synthetic fibres on tensile strength, fracture energy and fatigue life of reinforced warm mixes under monotonic and cyclic tension load, respectively. These tension experiments concluded improvements on mechanical characteristics of warm mixed asphalt mortars when fibres were added, mainly applying higher dosages than the recommended by the fibres supplier. Overall, the current results elucidated that implementing dedicated material studies at micro-scales can assist on understanding the material performance and tailoring systems beyond sometimes recommended reinforcement dosages by the suppliers. Finally, a semi-circular bending test was performed as the largest scale of this research using various fibre amount composition as well as fibre length inside the bituminous mix, and the final results mainly correspond with the other examinations that have also been conducted. Therefore, the research methodology utilised in this thesis has been able to examine the reinforcement effect brought by the integration of synthetic fibre to failure performance of the warm mixed asphaltic mixture specifically regarding the cracking resistance extensively. ... Read more

Quidico is a small town, approximately 200 kilometer south of Concepcion. In the bay adjacent to Quidico town, a great number of local fishermen are active. In the current situation, high waves, a strong current and significant sediment transport hamper the effectiveness of the bay as fishing harbour. Also qualitative onshore facilities to support onshore activities of the fishermen, are absent. The Department of Ports of theMinistry of Public Works, developed a preliminary design proposal, to solve these problems. However, after consultation with the fishermen, this proposal was declared unsatisfactory. Therefore, an additional study is performed to develop a new integral design for the bay of Quidico. The desired design consists of onshore buildings, a paved support area, mooring facilities and breakwaters to create shelter for safe mooring of the fishing boats. Furthermore, these breakwaters shouldmitigate the problems related to sediment transport.

To develop a new breakwater orientation and design, wave data is analysed. Waves coming from the south to south-west are most common, but not guiding due to the sheltering factor of IslandMocha, positioned in front of the coast. The guiding wave, which is coming from the north-west, is implemented in models of Delft3D to see what the new orientation of the breakwater should be. Based on the wave analysis, sediment transport analysis and modelling results, a new breakwater orientation is determined, that fulfills all requirements prescribed by the DoP. After defining this new orientation, the influence of the breakwater on sediment and waves is analysed. Due to the new orientation, a new design of the breakwater is made.

The fishing harbour should offer the possibility for the fisherman to unload their goods and berth safely. The DoP proposed the construction of a mooring facility along the south-west shoreline of Quidico Bay. Two types of quay walls for the mooring facilities are proposed, a sheet pile wall and a concrete mass wall. For both types a preliminary design is developed, by making use of the 2D finite element software PLAXIS and hand calculations. The preferred mooring facility design mainly depends on the soil conditions at the specific location. From the boundary conditions it is concluded the bedrock is found at a depth of 60m, the soil above mainly consists of sand. Therefore the construction a sheet pile wall to serve as mooring facility, is recommended.

In the initial design of the Department of Ports, six separate masonry buildings are proposed to accommodate the desired supporting facilities. These buildings cover a large area of the bay and will require a large paved supporting platform. To reduce this paved area, the DoP is interested in a more compact design, that includes all supporting facilities in one multi-storey building. In consultation with the DoP two different designs are developed; a three-storey steel building and a two-storey concrete building. A structural design is developed within the boundaries set by the functional design requirements. Next, a structural analysis is performed by making use of finite element software (ETABS) and a final design is obtained for both buildings. The concrete building is concluded to be the most suitable option for the DoP.

Quick offloading of the boats and smooth transshipment of goods is hindered due to the lack of a good support area and access road. The DoP proposed a design for both pavements in the their preliminary study, but it was requested to evaluate different alternatives. Three different pavement technologies are proposed for the access road: surface treatment, asphalt and concrete slabs. For the pavement in the support area concrete slabs are the preferred solution. To achieve an optimal pavement design that fulfills all structural and serviceability requirements throughout the full design life, slab pavements with different dimensions and thicknesses are evaluated. In conclusion, short concrete slabs are the preferred pavement for both areas. Short slab pavement is an upcoming technology that has great advantages in terms of structural performance and costs.
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This master thesis covers the research into cracking behaviour of slender high strength concrete cantilevering balconies. The research emerged from Pieters Bouwtechniek Delft and Hi-Con Denmark. They cooperatively designed very slender balconies in ultra-high performance fibre reinforced concrete. Other engineering firms tend to recreate these balconies in HSC and insecurities emerged around the cracking behaviour and crack width prediction for these slender HSC cantilevering balconies. In addition to this research an informative report, also functioning as a literature study, on the connection of prefabricated concrete balconies is produced. This report is separately attached.

The research is step wisely conducted starting with a simple fully clamped cantilevering slab. For this slab the cross sectional height, reinforcement diameter and reinforcement spacing are varied to investigate their influence on analytical crack width predictions. First for all variants an analytical design and analysis process is executed, followed by a numerical analysis with DIANA FEA and a comparison of the results. The most important observation is that for a cross sectional height of 120 mm or smaller reinforcement bars are located outside the effective area, making the analytical method unsuitable. Furthermore, a big discrepancy between the predictions of the different analytical models is observed, indicating an unreliability of these methods.

In two steps the fully clamped balcony is transformed into a Hi-con shaped balcony executed in HSC. It appeared that in light of detailing rules from Eurocode 2 an exact reproduction is impossible, but the concept could be reproduced in a less slender way. Furthermore, by comparing analytical and numerical design results for two different balcony designs it is found that the accuracy of the analytical crack width prediction depends on geometric disturbances. In case a geometric disturbance is present in a slender area loaded in tension peak stress concentrations occur, which negatively influence the reliability of the analytical crack width prediction. In case the area is less slender, the effect is less pronounced and the conservative characteristics of the analytical method outweigh the influence of the concentrated peak stresses.

When summarizing, it appears that specific care should be taken when analytically predicting crack widths in slender balconies because it might appear that the reinforcement is not located in the effective area. Furthermore, the more slender the structures become, the bigger the influence of a geometric disturbance can be, increasing the risk of an underestimation of the occurring crack widths because peak stress concentrations are analytically not accounted for.
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Throughout the history of pavement structure, the parallel layer structure has dominated the structural design of pavements. In other words, the entire road pavement share a uniform thickness design regardless how many lanes there are. However, due to traffic regulations and driving habits, the traffic flow most probably does not distribute evenly on a multi-lane road. Modern pavement design methods usually choose the lane that bears the heaviest traffic load as the design lane to determine the thickness design of the entire pavement. Hence there could be a certain over-design in the less trafficked lanes. This study aims to propose and evaluate a new structural design for flexible pavement by reducing the thickness of asphalt layers of the lightly trafficked lanes.
The traffic data of a real motorway in the Netherlands was analysed, based on which a new pavement structural design of a 3-lane road was established. Two finite element models, for both original and new designs, were established in CAPA-3D to calculate the stress and strain responses under different traffic load combinations. Following the Dutch design method the fatigue and deformation performance predictions of the two pavement designs were executed and compared. The results showed that the new design indeed improve the material cost-efficiency without compromising the performance of the pavement structure.
Taking advantage of the finite element models, a real-life simulation was also applied. The strain output of the simulation was used to calculate the rutting depth following the American design method. Both calculated rutting depth and the deformation output of the real-time simulation supported the earlier conclusions. An extra simulation of truck platooning was briefly executed and discussed as well.
Furthermore, the construction and maintenance feasibilities of the new design were explored. It was proved that the new design can be constructed by the existing equipment and machines. The current maintenance methods and procedures can also be applied to the new design. ... Read more

The role of the slab mechanism compressive membrane action is investigated, during the direct loading of a beam integrated in a prestressed deck bridge. ... Read more

Structures are considered safe,when they comply with minimum reliability requirementswhich are expressed by a minimum reliability index ¯ in the Eurocodes (EN1990). However, a complete reliability assessment for every structure would be very time-consuming. Therefore in the Eurocode a partial factor approach is utilized. In this research it is investigated how the reliability of the main bearing structure of a dynamically sensitive building designed within the Eurocode framework can be assessed in a full-probabilistic way for global response to wind loading including both size and dynamic effects. The global response of buildings to wind loading as well as uncertainties in this wind load have been the subject of many research, but few reference has been made to the reliability of structures by linking both aspects. Current research provides
this link and investigates the reliability of these buildings with respect to the target reliability in EN1990. For the purpose of this research the methods were developed for alongwind response at foundation level of the main bearing structure for slender high-rise buildings with a concrete core bearing structure. ... Read more