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In design against fatigue, a lower bound stress range vs. endurance curve (S-N curve) is employed to characterize fatigue resistance of plain material and structural details. With respect to the inherent variability of the fatigue life, the S-N curve is related to a certain probability of exceedance, a percentile of the fatigue life. This paper is concerned with modelling and estimating uncertainties in fatigue resistance of welded joints under constant amplitude loading. A new S-N curve format is proposed and fitted to fatigue test data by using the Maximum Likelihood Method. The results have been compared with the Random Fatigue Limit Model and the Bilinear Random Fatigue Limit Model. The proposed S-N curve appears to be more accurate in describing the S-N relation in high-cycle fatigue: it presents a smooth transition from finite to infinite-life regions and, differently from previous non-linear S-N relations with fatigue limit, this transition is controlled by an independent model parameter. Thereby it provides more flexibility for statistical fitting. In addition, a Bayesian framework is defined to fit the proposed relation including informative and non-informative prior distributions. © 2017 Elsevier Ltd

Creating a driving cycle (DC) for the design and validation of new vehicles is an important step that will influence the efficiency, functionality and performance of the final systems. In this work, a DC synthesis method is introduced, based on multi-dimensional Markov Chain, where both the velocity and road slope are investigated. Particularly, improvements on the DC synthesis method are proposed, to reach a more realistic slope profile and more accurate fuel consumption and CO2 emission estimates. The effects of using synthesized DCs on fuel consumption are investigated considering three different vehicle models: conventional ICE, and full hybrid and mild hybrid electric vehicles. Results show that short but representative synthetic DCs will results in more realistic fuel consumption estimates (e.g. in the 5%-10% range) and in much faster simulations. Using the results of this proposed method also eliminates the need to use very simplified DCs, as the New European Driving Cycle(NEDC), or long, measured DCs.

We introduce a new way to look at the combined lateral and longitudinal control problem for platooning vehicles by studying these problems separately. The lateral control problem is approached as a path following problem in the spatial domain: based on the path of the preceding vehicle we determine a path for the following vehicle which converges to the given path of its predecessor. In particular if the following vehicle happens to be on the path of its predecessor, the generated path of the follower equals the path of its predecessor. This approach not only overcomes the problem of corner cutting, but also achieves appropriate following behavior in case of large initial errors. As a by-product of solving the lateral control problem, we obtain a mapping from the path of the follower to the path of its predecessor. Using this mapping we can consider the longitudinal control problem as controlling two points on the same path towards a required inter-vehicle distance, which is comparable to CACC, i.e., the problem of controlling two points on a straight line towards a required inter-vehicle distance. We illustrate our approach by means of simulation. We introduce a new way to look at the combined lateral and longitudinal control problem for platooning vehicles by studying these problems separately. The lateral control problem is approached as a path following problem in the spatial domain: based on the path of the preceding vehicle we determine a path for the following vehicle which converges to the given path of its predecessor. In particular if the following vehicle happens to be on the path of its predecessor, the generated path of the follower equals the path of its predecessor. This approach not only overcomes the problem of corner cutting, but also achieves appropriate following behavior in case of large initial errors. As a by-product of solving the lateral control problem, we obtain a mapping from the path of the follower to the path of its predecessor. Using this mapping we can consider the longitudinal control problem as controlling two points on the same path towards a required inter-vehicle distance, which is comparable to CACC, i.e., the problem of controlling two points on a straight line towards a required inter-vehicle distance. We illustrate our approach by means of simulation.

For conventional buses, based on the decades of their operational knowledge, public transport companies are able to optimize their cost of operation. However, with recent trend in the usage of electric buses, cost optimal operation can become challenging. In this paper an offline optimal charging strategy is developed to minimize the energy cost. This is done by exploiting the periodicity and predictable operation of the city buses. For effective usage of the developed offline strategy, the actual energy demand of the electric bus must be known a-priori, which can be demanding. In order to address this issue, a predictor is designed. The neural network based predictor is able to estimate the energy demand for the next day. Using this, three different optimal charging strategies are implemented. Initially, only the operational constraints are considered to ensure the completion of a trip, later, a more involved problems consisting of battery state of charge (SoC) constraints and temperature constraints are included for the second and third optimization problems, respectively. All the three approaches result in significant energy cost minimization when compared to the non-optimal strategy of charging the electric bus to the full capacity at every available opportunity. Additionally, for the second and third formulations, namely, SoC and temperature constraints, by using a qualitative aging approach, some enhancements in the battery health is observed when compared to the non-optimal charging strategy.

In this paper a Vehicle State Estimator is developed and validated on experimental data from a 2012 Toyota Prius. The estimator is capable of estimating both planar vehicle velocities and the tyre-road friction parameter. Emphasis is placed on the comparison of the commonly used Extended Kalman Filter and a novel application of the State Dependent Riccati Equation technique. The State Dependent Riccati based estimator relies on a factorization compared to linearization in the case of the Extended Kalman Filter. This factorization is non-unique, therefore the construction of this factorization, is also presented. A comparison is for both estimators is presented for experimental data. For estimation of the tyre-road friction parameter, simulations are used, due to absence of a reference value in the experimental set-up.

Nowadays, there is an increasing societal demand for smart mobility solutions which can increase the throughput, comfort, and safety of driving on a road. As one of these solutions, vehicle following technologies like cooperative adaptive cruise control (CACC) are introduced. with the help of vehicle-to-vehicle (V2V) communication, CACC can reduce the safe minimal inter-vehicular distance. Additionally, sharing the vehicle intentions through V2V, enables multi-vehicle maneuvers to be cooperatively executable. In this paper, using the concept of artificial potential fields, a longitudinal control scheme for performing a cooperative merging maneuver will be suggested. Artificial potential fields are powerful enough for modeling and solving such a complex problem, where in addition to vehicle following other objectives such as merging should be addressed. The designed algorithms for vehicle cooperative maneuvering are verified through simulations.

The optimal design of a hybrid electric vehicle (HEV) can be formulated as a multiobjective optimization problem that spreads over multiple levels (technology, topology, size, and control). In the last decade, studies have shown that by integrating these optimization levels, fuel benefits are obtained, which go beyond the results achieved with solely optimal control for a given topology. Due to the large number of variables for optimization, their diversity, and the nonlinear and multiobjective nature of the problem, a variety of methodologies have been developed. This paper presents a comprehensive analysis of the various methodologies developed and identifies challenges for future research. Starting from a general description of the problem, with examples found in the literature, we categorize the types of optimization problems and methods used. To offer a complete analysis, we broaden the scope of the search to several sectors of transport, such as naval or ground.

This paper considers local buckling of perforated square aluminium plates. Plates of various slenderness with simply supported edges and subjected to uniaxial compression are studied using the finite element method. Different perforation patterns are investigated, from a single circular hole to 25 circular holes distributed over the plate. A number of aluminium alloys are considered and compared to steel grade A36. Results show that the resistance of the plates containing a single central cut-out is higher than that of plates with more holes and of equal total cut-out size. A further refinement beyond 5 holes does not influence the resistance.

This paper presents a battery peak power shaving strategy for battery electric buses. The developed strategy restricts the battery charge/discharge power when the propulsion power demand is high to avoid high deterioration of the battery capacity during operation. Without reducing the propulsion power, the developed strategy optimizes the power demand of the passenger cabin air conditioning system while guaranteeing the passenger temperature comfort. An equivalent consumption minimization strategy (ECMS) technique is extended to include the thermal comfort of the passenger in the energy management system of the bus. The developed strategy is analytical, real-time implementable and verified via hardware-in-the-loop test. Simulation results demonstrate the capability for satisfying the propulsion power demand and passenger temperature comfort while reducing the battery peak power (up to 20% during acceleration) to restrict the battery degradation significantly.

This study deals with ductile fracture prediction of a marine steel using new damage functions. The stress triaxiality and Lode angle are known to be governing parameters on the ductile fracture. Recent research has reported that loading path is also one of the important parameters. A three-dimensional fracture strain surface for EH36 steel was developed based on a series of tension/compression tests subjected to the tension, shear, shear-tension, and compression. To account for the non-proportional stress effects, the linear and non-linear damage evolution models were presented with a combination of the fracture strain surface. The material constants associated with the damage evolution were identified from calibration with the experimental data. Validation of the damage-based fracture models was conducted by comparing predicted fracture initiation with the results of structural test results. The fracture model with the nonlinear damage evolution predicts slightly more improved predictions than the linear damage-based fracture model.

It’s hard to imagine life without smartphones. In many ways, they make our lives easier, more convenient and more productive. But when it comes to smartphone usage while driving, it is clear that sensible solutions are needed to make roads safer for us all.

It’s hard to imagine life without smartphones. In many ways, they make our lives easier, more convenient and more productive. But when it comes to smartphone usage while driving, it is clear that sensible solutions are needed to make roads safer for us all.

De Afsluitdijk is op dit moment ruim tachtig jaar oud en heeft ons al die jaren goed tegen de krachten en invloeden van het zeewater beschermd (foto 1 en 2). Rijkswaterstaat gaat de Afsluitdijk nu een grote opknapbeurt geven, zodat hij tot ten minste 2050 mee kan. De dijk wordt zodanig versterkt dat hij bestand is tegen het stijgende zeewater. Bovendien worden de sluizen versterkt en verhoogd en wordt de waterafvoer verbeterd. Om dat te kunnen realiseren, was het noodzakelijk de betonnen kunstwerken, onder meer de spuisluizen, te laten inspecteren

The current theory of ASR gel formation in concrete between silicic acid anions with cations and is unable to explain the differences in concentration required for gel formation between e.g. potassium and sodium or the effect of calcium on the gel formation. In this paper, a new gelation mechanism is explained by means of a condensation between silicic acid anions. The role of salts on the ASR gel formation and gel time is described by their charge screening capacity of the silicic acid, resulting in the decreasing concentration range for gelation: Ca < Mg < Cs < Rb < K < Na < Li. A Cation Gelling Strength (CGS) is defined to assess the cation strength when different cations are present. Silica gel formation will moreover in many cases form a calcium silica precipitate rather than a gel that will be difficult to distinguish from CSH formed during hydration.

The current theory of ASR gel formation in concrete between silicic acid anions with cations and is unable to explain the differences in concentration required for gel formation between e.g. potassium and sodium or the effect of calcium on the gel formation. In this paper, a new gelation mechanism is explained by means of a condensation between silicic acid anions. The role of salts on the ASR gel formation and gel time is described by their charge screening capacity of the silicic acid, resulting in the decreasing concentration range for gelation: Ca < Mg < Cs < Rb < K < Na < Li. A Cation Gelling Strength (CGS) is defined to assess the cation strength when different cations are present. Silica gel formation will moreover in many cases form a calcium silica precipitate rather than a gel that will be difficult to distinguish from CSH formed during hydration.

Frisse lucht zorgt voor een goede en diepere slaap. Dus bieden veel kinderdagverblijven de mogelijkheid om kleintjes buiten te laten slapen. Kan dat onder alle weersomstandigheden? En waar let je op als het bijvoorbeeld pijpenstelen regent of vriest dat het kraakt?

Frisse lucht zorgt voor een goede en diepere slaap. Dus bieden veel kinderdagverblijven de mogelijkheid om kleintjes buiten te laten slapen. Kan dat onder alle weersomstandigheden? En waar let je op als het bijvoorbeeld pijpenstelen regent of vriest dat het kraakt?

Design methods for marine structures have evolved into load and resistance factor design, however existing partial safety factors related to berthing velocity and loads have not been verified and validated by measurement campaigns. In this study, field observations of modern seagoing vessels berthing in Bremerhaven, Rotterdam and Wilhelmshaven were used to evaluate partial safety factors for berthing energy and berthing impact loads. Various types of vessels and navigation conditions were statistically examined. The results show that characteristic values of berthing velocity with a return period of 50 years are in line with design recommendations in literature. Design values of berthing velocity are sensitive to the number of berthing operations during the lifetime of a marine structure. Typical partial safety factors for sheltered and exposed navigation conditions were derived by extrapolating distribution fits and applying extreme value theory. Differences in structural response due to soil stiffness and the type of berthing system installed influence partial safety factors for berthing impact loads. The probability of an uncontrolled berthing event was higher for exposed navigation conditions (strong tidal currents). In these circumstances, higher partial safety factors for berthing velocity should be considered in the design of marine structures. When berthing aid systems are used, the probability of extreme berthing velocities is lower, resulting in lower partial safety factors. The key findings of this study could be beneficial for the structural design of new and lifetime extension of existing marine structures. © 2017 Elsevier Ltd

Onze buitenlucht is schoner dan de lucht in woningen. Deze treurige constatering werd onlangs gedaan tijdens de 'Dag van de Binnenlucht', die werd georganiseerd door onder andere de VLA en Isso. Klopt het wel? We belden TNO-onderzoeker Piet Jacobs op om hem hierover aan de tand te voelen.

This study deals with ductile fracture prediction of a marine steel using new damage functions. The stress triaxiality and Lode angle are known to be governing parameters on the ductile fracture. Recent research has reported that loading path is also one of the important parameters. A three-dimensional fracture strain surface for EH36 steel was developed based on a series of tension/compression tests subjected to the tension, shear, shear-tension, and compression. To account for the non-proportional stress effects, the linear and non-linear damage evolution models were presented with a combination of the fracture strain surface. The material constants associated with the damage evolution were identified from calibration with the experimental data. Validation of the damage-based fracture models was conducted by comparing predicted fracture initiation with the results of structural test results. The fracture model with the nonlinear damage evolution predicts slightly more improved predictions than the linear damage-based fracture model.

In this paper, identification of energy dissipation in the joints of a lab-scale structure is accomplished. The identification is carried out by means of an energy flow analysis and experimental data. The devised procedure enables to formulate an energy balance in the vicinity of the joints to obtain local energy dissipation. In this paper, a damping matrix based on the locally identified damping coefficients is formulated. The formulated damping matrix is later used in a five-degrees-of-freedom (5DOF) system for validation. The results obtained with the proposed method are in good agreement with the experimental data, especially in the low frequency range.

Cooperative Adaptive Cruise Control (CACC) employs wireless intervehicle communication to allow for automatic vehicle following at small intervehicle distances while guaranteeing string stability. Inherent to the CACC concept, however, is its vulnerability to communication impairments, among which latency of the wireless link, which compromise string stability and, hence, safety. To investigate the sensitivity of the string stability property with respect to communication latency, two controllers are developed by means of H8 controller synthesis, employing a one-vehicle look-ahead and a two-vehicle look-ahead communication topology, respectively. The string stability properties of the controlled vehicle platoon are investigated, based on which it is proposed to switch from one-to two-vehicle look-ahead when the latency exceeds a certain threshold, thereby creating robustness against increasing communication delay by retaining string stability at the lowest possible time gap.

The last decade has seen a growing interest in cohesive zone models for fatigue applications. These cohesive zone models often suffer from a lack of generality and applying them typically requires calibrating a large number of model-specific parameters. To improve on these issues a new method has been proposed in this paper based on the Thick Level Set approach. In this concept, material degradation due to cyclic loading is the result of interaction between damage evolution and fracture mechanics. The Thick Level Set formulation has been extended to interface elements, in order to allow for separation of strain energy in the bulk and energy required for surface creation. Global fracture parameters, derived from a free energy description governing the interface elements, are used as input for the empirical crack growth rate relation (Paris’ equation). It must be emphasized that in contrast to existing fatigue models, the Thick Level Set approach does not require the definition of a damage evolution law. Instead, damage is updated automatically by a continuously moving damage front. It is shown that applicability is not limited to fatigue behavior of linear elastic materials; elastic-plastic materials such as steels can be analysed as well. The sensitivity of model parameters is investigated and discussed and the practical relevance is explored for standard test configurations.

Traditionally, a failure strain criterion is used in crash simulations in the maritime and offshore industry. More sophisticated methods for multi-axial stress states are based on the Forming Limit Diagram and the Fracture Forming Limit Diagram (FFLD). The diagrams are derived for the steel sheet forming industry, such as car parts. Few tests are performed on specimens with plate thickness repre-sentative for maritime application. Full thickness effects can not be neglected. In this paper, full thickness material failure tests are described. S355 and S690 samples have been subjected to lateral impact. Round specimens, fully clamped, simulate an equi-biaxial strain state. Apple core shaped specimens simulate the plane strain conditions. Tests results are analyzed by Digital Image Correlation techniques, acceler-ometers and ultrasonic thickness measurements. The failure of the specimens are depicted in the FLD diagrams, showing the relevance of these tests for updating failure criteria for maritime and offshore impact analysis.

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made., Materials and Structures, 50 (2), ISSN:1359-5997, ISSN:1871-6873

In a BIM data flow, an essential part of the coordination between disciplines is the agreement on recesses and openings in building elements. Different disciplines will request recesses and openings in elements that are managed and maintained by others. Using the full dataset of the elements has proven to be inoperable because of the information overload, interoperability problems and contradictions in the commonly used downstream dataflow. A group of companies has been experimenting with the exchange of data that only consists of the requested openings and recesses in IFC. Coordination is being done using BCF. This approach has been fine-tuned and adjusted during several projects. This paper describes the current status of that initiative and discusses the challenges that are still open.

Tuffstone elements with a large length/width ratio, as e.g. mullions, often suffer damage in the form of cracks parallel to the surface and spalling of the outer layer. The response of tuff to moisture might be a reason for this behaviour. This research aimed at verifying if a differential dilation between parts with different moisture content (as outer and inner part of partially encased mullion) can lead to damage. The effect of moisture on the degradation of Ettringen and Weibern tuff has been investigated. A purpose-made weathering test was carried out to simulate the wetting-drying process. Despite no cracks developed during the test, existing cracks widened up and the flexural tensile strength of both materials decreased. The moisture transport properties of the stones were determined as well as their porosity and pore size. Ettringen tuff has a considerable amount of very fine porosity, resulting in slow moisture transport and significant hygroscopic adsorption. Both tuffstones have an extreme hydric dilation. Environmental X-ray diffraction analyses showed that Ettringen tuff undergoes (reversible) mineralogical changes when subjected to RH cycles, whereas this does not occur for Weibern. All results support the hypothesis that moisture gradients in tuff elements may enhance decay in this stone.

Risk Based Asset Management (RBAM), or rather Asset Management based on both a perfor-mance requirement and a supporting Risk Analysis, is a beneficial Asset Management methodology for a number of industries, including the Asset Management of infrastructure. In the implementation of RBAM at Rijkswaterstaat a number of challenges have been faced. This paper focusses on three major challenged and the solutions adopted: 1) how to RBAM into the existing asset management processes. 2) how to communi-cate effectively about the performance and its constraints with all levels within the organization, including the communication with decision makers, maintenance engineers and operators and 3) how to scale RBAM scope into manageable implementation

Beschreven onderzoek in dit rapport wordt uitgevoerd in het kader van het Kennisplan Natte Kunstwerken 2017. Het Kennisplan is de praktische concretisering van de NKWK1-onderzoekslijn 'Toekomstbestendige Natte Kunstwerken'. In deze onderzoekslijn werken momenteel Deltares, TNO, Marin, RWS en NLIngenieurs samen aan onderwerpen op het gebied van natte kunstwerken (stuwen, sluizen, gemalen en stormvloedkeringen). Een groot deel van deze kunstwerken bereikt komende decennia einde technische levensduur. Er dient zich dan ook een aanzienlijke vervangings- en renovatieopgave van deze kunstwerken aan. Een opgave die niet alleen technisch van aard is, maar die ook rekening moet houden met het functioneren van het kunstwerk in het netwerk/systeem/regio.

An investigation is presented to determine the wind loads on external solar blinds on two 60 m high towers. This investigation was performed some years after the construction of the towers, with the sun blinds in place. A combination of wind tunnel tests and full scale measurements was done. The shape of the towers, and the unique design of the solar blinds, make that this design is not covered in any wind loading code. However, during the design stage, a simplified approach was adopted to construct the solar blinds and its load bearing structure. During operation of the building, damage occurred to some of the hangers of the structure and doubts were raised whether the wind loads on the external blinds were properly estimated. The results of the current investigation are being used for a re-analysis of the structure, and may lead to replacement of parts of the structure.

Modeling the stochastic evolution of a large-scale fleet or network generally proves to be challenging. This difficulty may be compounded through complex relationships between various assets in the network. Although a great number of probabilistic graph-based models (e.g., Bayesian networks) have been developed recently to describe the behavior of single assets, one can find significantly fewer approaches addressing a fully integrated network. It is proposed an extension to the standard dynamic Bayesian network (DBN) by introducing an additional dimension for multiple elements. These elements are then linked through a set of covariates that translate the probabilistic dependencies. A Markov chain is utilized to model the elements and develop a distribution-free mathematical framework to parameterize the transition probabilities without previous data. This is achieved by borrowing from Cooke's method for structured expert judgment and also applied to the quantification of the covariate relationships. Some metrics are also presented for evaluating the sensitivity of information inserted into the covariate DBN where the focus is given on two specific types of configurations. The model is applied to a real-world example of steel bridge network in the Netherlands. Numerical examples highlight the inference mechanism and show the sensitivity of information inserted in various ways. It is shown that information is most valuable very early and decreases substantially over time. Resulting observations entail the reduction of inference combinations and by extension a computational gain to select the most sensitive pieces of information. © 2017 Computer-Aided Civil and Infrastructure Engineering

The Province of Zuid-Holland encourages the development of innovations to make the provincial road network more energy efficient. This is one way the province can contribute to reducing energy consumption and CO2 emissions in accordance with the Dutch energy agreement. To this end, the Province of Zuid-Holland, Strukton Civiel and TNO have conducted joint research on road surfacing that reduces rolling resistance and hence reduces fuel consumption and CO2 emissions. This document sets out the objective of the research, as well as the methods used and the research results (both in the laboratory and the field). It also looks ahead at the impact the results could have and how the construction of such energy-saving road surfacing could best be put out to tender by road authorities

In this paper a Vehicle State Estimator is developed and validated on experimental data from a 2012 Toyota Prius. The estimator is capable of estimating both planar vehicle velocities and the tyre-road friction parameter. Emphasis is placed on the comparison of the commonly used Extended Kalman Filter and a novel application of the State Dependent Riccati Equation technique. The State Dependent Riccati based estimator relies on a factorization compared to linearization in the case of the Extended Kalman Filter. This factorization is non-unique, therefore the construction of this factorization, is also presented. A comparison is for both estimators is presented for experimental data. For estimation of the tyre-road friction parameter, simulations are used, due to absence of a reference value in the experimental set-up.

Risk Based Asset Management (RBAM), or rather Asset Management based on both a perfor-mance requirement and a supporting Risk Analysis, is a beneficial Asset Management methodology for a number of industries, including the Asset Management of infrastructure. In the implementation of RBAM at Rijkswaterstaat a number of challenges have been faced. This paper focusses on three major challenged and the solutions adopted: 1) how to RBAM into the existing asset management processes. 2) how to communi-cate effectively about the performance and its constraints with all levels within the organization, including the communication with decision makers, maintenance engineers and operators and 3) how to scale RBAM scope into manageable implementation

Owing to the unique molecular structure and high ion exchange capacity, hydrotalcites are believed to have a potential to be modified and tailor-made as an active corrosion protective component of reinforced concrete. In this paper, two types of modified hydrotalcites (MHT-pAB and MHT-NO2) were tested both in alkaline solution and mortar for their possibilities as chloride scavengers and inhibitor release agents for application in concrete. The test in alkaline solution showed that ion exchange occurred between free chloride ions in solution and the intercalated inhibitive anions in the MHTs. The results in mortar validated that MHTs could be promising alternatives for preventing chloride-induced corrosion when an appropriate dosage is adopted and applied in a proper way, in particular, either incorporation of a certain amount (MHT-pAB to replace 5% weight of cement) in the bulk mortar or as a coating of the reinforcing steel (MHT-pAB or MHT-NO2 at 20% weight of cement).

Borax has been identified as a possible crystallization modifier for sodium sulfate. Understanding the effect of borax on factors influencing transport and crystallization kinetics of sodium sulfate helps to clarify how this modifier might limit crystallization damage. It has been observed that the addition of borax to sodium sulfate solutions has no influence on the wetting properties (contact angle on glass, surface tension, or evaporation rate) and therefore will not influence solution transport. Additionally, the influence of borax on the crystallization kinetics of sodium sulfate was studied under controlled environmental conditions. This was carried out in mixtures in glass microcapillaries, and sequentially in droplets on glass plates. Under the here studied precipitation conditions, the addition of borax has no influence on the supersaturation ratio at the onset of crystallization, but it significantly affects the crystallization pattern of anhydrous sodium sulfate crystals (thenardite). Using RAMAN spectroscopy, two different hydrates of borax were identified after precipitation, depending on the initial concentration of the solution. Each hydrate has a different effect on the subsequent crystallization of sodium sulfate. The decahydrate polymorph of borax leads to the precipitation of hydrated sodium sulfate crystals (mirabilite) and the pentahydrate form favors the precipitation of the anhydrous sodium sulfate crystals (thenardite) with an altered crystal habit. Using X-ray diffraction, overdevelopment of the (111), (131), (222) and (153) faces of thenardite was identified. Additionally, the ratios between several peaks are reversed. These results confirm the deviation of the grown crystals of the equilibrium crystal shape of thenardite as observed with optical microscopy.

In-situ load testing of reinforced concrete (RC) structures is often performed to confirm the presence of the required resistance for the intended use (Conformity Load Testing) or to support the assessments of the residual capacity by models (Supplementary Load Testing for Condition Assessment). When performing an in-situ load test, one of the main concerns is the avoidance of irreversible damage to the structure, since that may impair the structural performance after testing and eventually reduce its residual service life. Therefore performance indicator are needed to recognize the development and/or to prevent failure during an in-situ load test of real structures. For many of the existing RC structures without transverse reinforcement, shear failure is one of the governing mechanisms. Due to its brittle character, this failure mode is difficult to sense at an early stage of its development. Up to now no good performance indicator is available for shear. In the presented study, a smart key performance indicator for in-situ load tests has been developed, with particular focus on shear failure. Results of several laboratory tests on full-scale shear beams have been examined, confirming that a change in structural behaviour at an early stage during testing can be traced by the proposed indicator. With the proposed performance indicator, performing measurements only on the top or bottom of the tested specimen is necessary, which is of importance for the applications to existing structures, with limited access for measurements. An algorithm for data analysis has been developed, which can be used to control the proposed performance indicator in real time during testing. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra

Different analytical models exist to predict the shear strength of reinforced concrete members. Generally, each of these shear strength models consists of a formulation based on certain underlying theory and fitted model coefficients. The model fitting parameters are usually established from the comparison with test data. Hence, the predictive value of a shear strength model depends, to some extent, on the quality and representativeness of the used test data. This work investigates the predictive capability of several shear strength models for reinforced concrete beams without shear reinforcement. Particular attention is given to the application domain of relatively low reinforced and high depth concrete beams where limited shear test data is available. The predictive capability of the models for this area of interest is analyzed with Bayesian Inference. This probabilistic technique calculates the posterior distributions of uncertain parameters, given a set of measured test data and some prior knowledge. The predictive capability of each shear strength model is quantified by means of a calculated model uncertainty. Furthermore, the influence of the uncertainty in model parameter values on the calculated model uncertainties is evaluated. Bayesian Inference is also used to estimate the model evidences conditionally on the used data.

Instantaneous insight into the structural damage sustained by a ship running aground, can be of great aid in the decision making following such a disaster. It should be possible to distil the extent of structural damage from acceleration measurement data of the entire vessel. Such measurements could possibly even be done using a simple smartphone. This paper describes experimental research exploring the detection of plate rupture in a raking damage scenario by merely looking at acceleration measurement data. Drop tower experiments were performed, which reflect a realistic raking damage scenario and also aim to gain better understanding of both friction and failure in such a scenario. In total four drop tests were performed. Ductile fracture occurred without precedence of necking. A calibration method for a failure criterion, using only one single strain-state, was successfully applied. Separate friction tests showed that static Coulomb friction seems to be a proper model to be applied for the energy dissipation through friction. Moreover, the transition to plate rupture can readily be detected from the experimental acceleration data. When accurate calibration of both the failure and the friction is performed, it is envisaged that the extent of raking damage can indeed be derived through real time acceleration measurements on board of a vessel.

In this paper simplified expressions for assessing fundamental frequency and modal damping of high-rise buildings taking into account the soil-structure interaction (SSI) are proposed. To this end, several steps have been followed. First, a 3DoF model is formulated making use of dimensionless parameters. Second, the 3DoF model is simplified into an equivalent 1DoF system. Finally, cancelling high-order and cross-terms and making some mathematical manipulations a simplified expression for fundamental frequency and modal damping is obtained. Results of the equivalent 1DoF are compared with those of the 3DoF to check the accuracy. Furthermore, the influence of the foundation in the overall system is studied making use of several pile configurations and foundation layout.

In the Netherlands civil engineering structures, such as overpasses, bridges and tunnels are generally built using blast furnace slag cement (BFSC, CEM III/B) concrete, because of its high resistance against chloride penetration. Although the Dutch experience regarding durability performance of BFSC concrete has been remarkably good, its resistance to carbonation is known to be sensitive, especially when the used slag percentage is high. In a field investigation on a highway overpass damage was found in sheltered elements such as abutments and intermediate supports, which was attributed to chloride induced corrosion enhanced by carbonation that occurred prior to the chloride exposure. Many structures built using BFSC could be prone to this mechanism, i.e. carbonation enhanced chloride induced corrosion, negatively affecting their durability. Focus of the research was given on the influence of carbonation on the chloride penetration resistance of BFSC mortars with varying slag content. In light of the characteristics from the overpass case, it was assumed that first there is a period of carbonation during sheltered exposure, and subsequently joint leakage causes exposure to chlorides. In order to identify the influence of slag content on carbonation, chloride penetration resistance and their coupled effect, mortars with twelve cement blends in a range of 0-70% slag were evaluated based on chloride migration coefficient, accelerated carbonation and electrical resistivity. This study shows that carbonation of BFSC mortars increases the porosity, consequently decreasing the chloride penetration resistance. Binders with 50% or more slag were found to have a significantly lower resistance after carbonation. Consequently, the chloride penetration resistance of a given concrete cover strongly depends on the duration of carbonation and the resulting carbonation depth, hence influencing its lifespan. The service life was estimated using a simplified model for the chloride penetration time of a combined carbonated and uncarbonated layer. It was found that mortar with a slag content between 35 and 50% that was carbonated before chloride exposure show the lowest influence of carbonation on the chloride penetration resistance. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra

Path planning of an autonomous vehicle as a non-holonomic system is an essential part for many automated driving applications. Parking a car into a parking lot and maneuvering it through a narrow corridor would be a common driving scenarios in an urban environment. In this study a hybrid approach for dynamic path planning is presented which deals with the limited degrees of freedom of a non-holonomic system, as well as the real-time constraints and limited computational power. Furthermore, it takes into account ride comfort of the passenger by generating smooth path. The proposed method has been evaluated in simulation environment and is implemented and tested on a Toyota Prius test vehicle with an active steering system.

An investigation is presented to determine the wind loads on external solar blinds on two 60 m high towers. This investigation was performed some years after the construction of the towers, with the sun blinds in place. A combination of wind tunnel tests and full scale measurements was done. The shape of the towers, and the unique design of the solar blinds, make that this design is not covered in any wind loading code. However, during the design stage, a simplified approach was adopted to construct the solar blinds and its load bearing structure. During operation of the building, damage occurred to some of the hangers of the structure and doubts were raised whether the wind loads on the external blinds were properly estimated. The results of the current investigation are being used for a re-analysis of the structure, and may lead to replacement of parts of the structure.

Although the steel–concrete interface (SCI) is widely recognized to influence the durability of reinforced concrete, a systematic overview and detailed documentation of the various aspects of the SCI are lacking. In this paper, we compiled a comprehensive list of possible local characteristics at the SCI and reviewed available information regarding their properties as well as their occurrence in engineering structures and in the laboratory. Given the complexity of the SCI, we suggested a systematic approach to describe it in terms of local characteristics and their physical and chemical properties. It was found that the SCI exhibits significant spatial inhomogeneity along and around as well as perpendicular to the reinforcing steel. The SCI can differ strongly between different engineering structures and also between different members within a structure; particular differences are expected between structures built before and after the 1970/1980s. A single SCI representing all on-site conditions does not exist. Additionally, SCIs in common laboratory-made specimens exhibit significant differences compared to engineering structures. Thus, results from laboratory studies and from practical experience should be applied to engineering structures with caution. Finally, recommendations for further research are made.

In the Netherlands civil engineering structures, such as overpasses, bridges and tunnels are generally built using blast furnace slag cement (BFSC, CEM III/B) concrete, because of its high resistance against chloride penetration. Although the Dutch experience regarding durability performance of BFSC concrete has been remarkably good, its resistance to carbonation is known to be sensitive, especially when the used slag percentage is high. In a field investigation on a highway overpass damage was found in sheltered elements such as abutments and intermediate supports, which was attributed to chloride induced corrosion enhanced by carbonation that occurred prior to the chloride exposure. Many structures built using BFSC could be prone to this mechanism, i.e. carbonation enhanced chloride induced corrosion, negatively affecting their durability. Focus of the research was given on the influence of carbonation on the chloride penetration resistance of BFSC mortars with varying slag content. In light of the characteristics from the overpass case, it was assumed that first there is a period of carbonation during sheltered exposure, and subsequently joint leakage causes exposure to chlorides. In order to identify the influence of slag content on carbonation, chloride penetration resistance and their coupled effect, mortars with twelve cement blends in a range of 0-70% slag were evaluated based on chloride migration coefficient, accelerated carbonation and electrical resistivity. This study shows that carbonation of BFSC mortars increases the porosity, consequently decreasing the chloride penetration resistance. Binders with 50% or more slag were found to have a significantly lower resistance after carbonation. Consequently, the chloride penetration resistance of a given concrete cover strongly depends on the duration of carbonation and the resulting carbonation depth, hence influencing its lifespan. The service life was estimated using a simplified model for the chloride penetration time of a combined carbonated and uncarbonated layer. It was found that mortar with a slag content between 35 and 50% that was carbonated before chloride exposure show the lowest influence of carbonation on the chloride penetration resistance. © Springer International Publishing AG 2018. Bam; Cement and Beton Centrum; et al.; Rijkswaterstaat - Ministry of Infrastructure and the Environment; Van Hattum en Blankevoort; VolkerInfra

The wind loads on solar energy systems are crucial for the engineering of the panels, substructure and fixings. There is a demand for aesthetically more acceptable solutions such as frameless solar systems. For these frameless systems, the wind loads are carried by the panels themselves. Combined with the increase in the size of photovoltaic (PV) panels, reducing the wind load is becoming more important. The wind loads on building integrated PV panels depend on the external pressures and the pressures in the cavity under the panels. The magnitude of these pressures and the resulting wind loads on the panels are to a significant extent determined by the pressure equalization caused by the openings between the panels. An in-situ experiment has been carried out to assess the influence of the openings on the external and cavity pressures, as well as on the overall wind loads

Clause 6.2 of EN 1993-1-1 covers the cross-sectional resistance of steel sections. The bending-shear interaction design rules for I-shaped cross-sections make use of a reduced yield stress for the web area. On this basis, a reduced design plastic resistance moment allowing for the shear force is presented. The effect of shear on the bending resistance may be neglected if the shear force is less than half of the plastic shear resistance of the cross-section. Plasticity in the Eurocode is described by the well-known Von-Mises yield criterion, however, the formula used for the reduced yield stress deviates from this criterion, resulting in sometimes greater and sometimes smaller values. The background of the Eurocode formula for reduced yield stress can be found in a publication by Drucker. The purpose of the present research is to investigate the influence of shear on the bending resistance of I-shaped steel cross-sections with as result a possible reconsideration of the Eurocode design rules. At Eindhoven University of Technology an experimental investigation on bending-shear interaction in rolled steel I-shaped sections was performed. A numerical model was developed in Abaqus Finite Element software to simulate the experiments. With the validated numerical model a larger database of numerical ‘test’ results was generated, which was subsequently used in a statistical analysis following Annex D of EN 1990 as further developed in the RFCS project Safebrictile. The statistical distributions of the steel properties recommended by Safebrictile were adopted. This paper presents the results of the statistical analysis and safety assessment of the strong axis bending-shear interaction design rule currently present in Eurocode 3. The parametric test group consists of HEA, HEM and IPE sections in the steel grades S235, S355 and S460: in total 180 numerical simulations with increasing amount of shear. A stress-strain model including strain hardening was used in the numerical simulations, since the influence of strain hardening is also largely present in the experimental test program. Based on strain hardening material behavior it is show in this paper that the current partial factor is un-conservative for shear dominated beams and should be increased. Alternatively, the design rule should be modified.

De Noordersluis bij IJmuiden is één van de grote infrastructurele werken in vooroorlogs Nederland, uitgevoerd in beton (Fig. 1). De bouw van de nieuwe sluis was onderdeel van een reeks verbeteringen aan het Noordzeekanaal: In 1909 was een staatscommissie ingesteld '(om)dat opnieuw de vraag rees of de belangen van Nederland in het algemeen en van Amsterdam in het bijzonder in de toekomst wel voldoende waren gewaarborgd door een maritiem kanaal, dat toegang uit- en naar zee verleende voor bootee van 220 m lengte, 24 m breedte en ongeveer 92 dm diepgang. In het bijzonder was op het stellen van deze vraag van invloed het feit, dat sedert 1906 de werken van het Panamakanaal met kracht waren ter hand genomen, die na de voltooiing - welke inmiddels in 1914 heeft plaats gehad - doorvaart zouden bieden voor schepen van 305 x 331/2 m bij 1261/2 dm diepgang. Ook een verbetering van het Suezkanaal was inmiddels ter hand genomen. In die omstandigheden werd het noodig geacht een onderzoek in te stellen naar de wenschelijkheid van het nemen van verdere maatregelen om op den duur een geregelden toegang tot Nederland door het Noordzeekanaal te verzekeren ...' (Gelinck 1924). Op 2 Januari 1917 publiceerde Het Staatsblad een wet die verschillende verbeteringen aan het Noordzeekanaal van Rijkswege mogelijk maakte, waaronder een nieuwe schutsluis. De sluis werd ontworpen door een team ingenieurs onder leiding van Johannes Ringers (1885-1965), de latere Directeur-generaal van Rijkswaterstaat, Regeringscommissaris voor de Wederopbouw (een benoeming een week na de Duitse inval in 1940), verzetsman en als partijloos minister na de oorlog 'Vader van de Wederopbouw' (Van der Ham 1998, Pollmann 2006ab). Het team bestond verder onder andere uit de ingenieurs J.P. Josephus Jitta, C. Tellegen, F.E. Mulder en B. Peiser. De bouw trok van begin af aandacht in binnen - en buitenland (Fig. 2), -zo bracht onder in juli 1924 een gezelschap Duitse hoogleraren een bezoek aan de bouw (anoniem 1924a)-, en ging gepaard met uitgebreid toegepast-wetenschappelijk onderzoek. De ontwerpers publiceerden hun resultaten en overwegingen in De Ingenieur (Ringers 1924, Tellegen et al. 1924, Ringers & Peiser 1925, Jospehus Jitta 1928) en Ringers kreeg er in 1930 een eredoctoraat aan de TU Delft voor.