Masonry bridges are among the most sustainable structures ever to have been built. The long service time, the resilience to carry larger loads than originally intended, and significantly lower life cycle cost compared to other bridge types suggest that we should consider the design and construction of new masonry bridges, even if their initial cost is greater than that of steel or concrete bridges The aim of this work is to understand the structural behaviour and study the collapse of a single-span masonry hydrostatic shell, that is a shell designed specifically to carry a hydrostatic load. Due to the complexity of the masonry shell interacting with fill, it is necessary to use a combination of computational methods and load tests on physical models in their structural assessment. We perform a load test to failure on a physical model spanning 770 mm made from 3D printed blocks and analyse the model using the Discrete Element Method (DEM) in Dassault Systemes Abaqus. ` The physical model behaved well and predicts that the bridge could be used at full scale. The preliminary results from a computational DEM model are found to be qualitatively good, but greatly overestimate the collapse load of the bridge.

This paper reports experimental and finite element investigations conducted to assess the shear strength of corrugated web girders in stainless steel. The steel under consideration is LDX 2101. Four trapezoidal corrugated web girders were tested under shear. All tested girders reached the shear yield strength followed by strain hardening. An imperfection sensitivity study was done with the aid of finite element modelling. It was observed that an initial geometric imperfection based on the first eigen buckling mode with a maximum amplitude of the minimum dimension of the critical corrugation sub panel divided by 200, 𝑎max200⁄, leads to an ultimate shear strength greater than the shear yield strength and close to the test findings. It is concluded that EN 1993-1-5 shear design model for corrugated webs is conservative for stainless steel girders tested in the current study.

In this paper, the shear strength of corrugated web girders made of EN 1.4162/LDX 2101 stainless steel is investigated. Four full-scale trapezoidal corrugated web girders were tested under shear. Before conducting the tests, DIC was used to measure the real geometric imperfections in the web panels. Complementary finite element analysis studies were conducted to assess the sensitivity of the shear strength to initial imperfections. The experimental results indicated that all the tested girders with a local slenderness ratio of λ = 0.7 attained the shear yield strength, which was then followed by strain hardening in the material at a level that was 8–18% higher than the yield strength. This implies that the Eurocode's limit of λ = 0.25 to attain the plastic shear strength in corrugated webs can be quite conservative for stainless steel. According to the findings of the imperfection sensitivity studies, an initial geometric imperfection based on the first eigen buckling mode and with a maximum amplitude of amax/200, where amax is the maximum corrugation fold length, yielded ultimate strength within 3% of the test results. When the amplitude was increased to hw/200, where hw is the web height, the ultimate strength was estimated to be 25% lower on average than in the experiments. In three of the studied girders, initial imperfections with other forms than the first buckling mode were found to be more critical. Further, it was found that regardless of mode number, mode shapes that are more extended over the web panel result in a higher degradation of the ultimate shear strength. © 2023 The Authors

The pan-European “European Plate Observing System (EPOS)” is focussed on Europe and adjacent regions and includes geophysical monitoring networks, local observations (including permanent in-situ and volcano observatories), topographic/surface dynamics information, surface and subsurface geological information, experimental and laboratory data and functions, and satellite data. In 2021 the Swedish Research Council (VR) approved an application for Sweden to join EPOS-ERIC, formally establishing existing collaborations between EPOS and Swedish research infrastructures.

Europe’s low-carbon energy policy favors a greater use of fuel cells and technologies based on hydrogen used as a fuel. Hydrogen delivered at the hydrogen refueling station must be compliant with requirements stated in different standards. Currently, the quality control process is performed by offline analysis of the hydrogen fuel. It is, however, beneficial to continuously monitor at least some of the contaminants onsite using chemical sensors. For hydrogen quality control with regard to contaminants, high sensitivity, integration parameters, and low cost are the most important requirements. In this study, we have reviewed the existing sensor technologies to detect contaminants in hydrogen, then discussed the implementation of sensors at a hydrogen refueling stations, described the state-of-art in protocols to perform assessment of these sensor technologies, and, finally, identified the gaps and needs in these areas. It was clear that sensors are not yet commercially available for all gaseous contaminants mentioned in ISO14687:2019. The development of standardized testing protocols is required to go hand in hand with the development of chemical sensors for this application following a similar approach to the one undertaken for air sensors. © 2021 by the authors. 

Biomethane may contain trace components that can have adverse effects on gas vehicles performances and on the pipelines when injected in the gas grid. Biomethane quality assurance against specifications is therefore crucial for the integrity of the end-users’ appliances. Analytical methods used to assess biomethane conformity assessment must be validated properly and possibly, new methods specifically for biomethane should be developed. This paper provides an overview of the biomethane quality assurance infrastructure and the challenges faced with focus on sampling, analysis methods, reference gas mixtures, and performance evaluation. Currently, requirements for analytical method validation and fit-for-purpose assessments do not exist for biomethane. The industry is in urgent need of a protocol to evaluate the fit-for-purpose of methods in a harmonized manner. Reference gas mixtures to check the accuracy of the instrument and to determine the traceability of the measurement are also urgently required. 

Renewable gases, hydrogen and biomethane can be used for the same applications as natural gas: to heat homes, power vehicles and generate electricity. They have the potential to contribute to the decarbonisation of the gas grid. Hydrogen blending with existing natural gas pipelines is also proposed as a means to increase the performance of renewable energy systems. Carbon capture and storage (CCS) and carbon capture and utilisation (CCU) technologies can be an answer to the global challenge of significantly reducing greenhouse gas emissions. Due to production methods, these gases typically contain species in trace amounts that can negatively impact the equipment they come into contact with or pipelines when injected into the gas grid. It is therefore necessary to ensure proper (and stable) gas quality that meets the requirements set out in the relevant standards. The gas quality standards require the collection and transport of a representative gas sample from the point of use to the analytical laboratory; i.e., no compounds may be added to or removed from the gas during sampling and transport. To obtain a representative sample, many challenges must be overcome. The biggest challenge is material compatibility and managing adsorption risks in the sampling systems (sampling line and sampling vessels). However, other challenges arise from the need for flow measurement with non-pure gases or from the nature of the matrix. Currently, there are no conclusive results of short-term stability measurements carried out under gas purity conditions (suitable pressure, matrix, appropriate concentrations, simultaneous presence of several species). © 2022, The Author(s).

In this study, we evaluated the performances of a custom-built optical feedback cavity enhanced absorption spectroscopy (OFCEAS) instrument for the determination of the composition of energy gases, focusing on methane and carbon dioxide as main components, and carbon monoxide as impurities, in comparison with the well-established, validated, and traceable gas chromatographic method. A total of 115 real sample gases collected in biogas plants or landfills were analyzed using with both techniques over a period of 12 months. The comparison of the techniques showed that the virtual model which allows the measurement, needs to be optimized using real samples of varied compositions. The OFCEAS measurement technique was found to be capable of measuring both the main components and a trace component in different matrices; to within a 2% measurement uncertainty (higher than the gas chromatograph/thermal conductivity detector (GC/TCD) method). The OFCEAS method exhibits a very fast response, does not require daily calibration, and can be implemented online. The agreements between the OFCEAS technique and the GC/TCD method show that the drift of the OFCEAS instruments remains acceptable in the long term as long as no change is made to the virtual model. Matrix effects were observed, and those need to be taken into consideration when analyzing different types of samples. © 2023 The Author(s). Published by IOP Publishing Ltd.

The quality of the hydrogen delivered by refuelling stations is critical for end-users and society. The purity of the hydrogen dispensed at hydrogen refuelling points should comply with the technical specifications included in the ISO 14687:2019 and EN 17124:2022 standards. Once laboratories have set up methods, they need to verify their performances, for example through participation in interlaboratory comparisons. Due to the challenge associated with the production of stable reference materials and transport of these which are produced in hydrogen at high pressure (>10 bar), interlaboratory comparisons have been organized in different steps, with increasing extent. This study describes an inter-laboratory comparison exercise for hydrogen fuel involving a large number of participants (13 laboratories), completed in less than a year and included eight key contaminants of hydrogen fuel at level close to the ISO14687 threshold. These compounds were selected based on their high probability of occurrence or because they have been found in hydrogen fuel samples. For the results of the intercomparison, it appeared that fully complying with ISO 21087:2019 is still challenging for many participants and highlighted the importance of organising these types of exercises. Many laboratories performed corrective actions based on their results, which in turn significantly improved their performances. © 2024 The Author(s)

Agriculture technology is moving toward automation, placing operators in a supervisory role. This change in operator workload may lead to increased stress and higher mental load, resulting in reduced attention and hence greater risk of illness or injury to humans and damage to equipment. This study investigated the use of easily applicable equipment to measure mental load. Three methods were used to measure the mental load on machine operators: heart rate monitoring, two types of electroencephalograph (EEG) evaluation, and an assessment protocol. Three driving exercises (general driving, slalom driving, and loading) and a counting exercise were used in a driving simulator to create different levels of mental load. Due to the number of exercises, a singlescale assessment protocol was used to save time. We found that only the assessment protocol gave clear results and would work well as an evaluation tool. The heart rate and EEG measurements did not provide clear data for mental load assessment. 

Hydrogen fuel cells are an alternative power supply for electric drive trains and could represent 32 % of fuel demand by 2050. To deploy fuel cell electrical vehicles, there is current regulatory barriers (ISO 14687, OIML recommendations) that requires accurate measurements. The European funded project MetroHyVe has provided solutions and improvements in the four measurements challenges (flow metering, quality control, quality assurance and sampling). New challenges arised due to increase of hydrogen economy, therefore a new European project MetroHyVe 2 started in 2020 and its objectives will provide perspectives for the hydrogen economy to solve all regulatory barriers (ISO 14687, ISO 19880-8, ISO 19880-1, ISO 21087, OIML R139-1) and new measurement challenges (flow metering, quality control, sampling and fuel cell stack testing). The presentation will provide a comprehensive overview of the project achievements. The achievements around primary standard for flow metering (light and heavy duty), worldwide inter-laboratory comparison for hydrogen fuel quality, hydrogen sampling intercomparison and fuel cell stack testing recommendations will be highlighted.

The most widespread numerical simulation method for structural response is undoubtedly the Finite Element Method (FEM). However, despite being powerful for modelling continuous structures, it is not fit for handling strong discontinuities. The Discrete Element Method (DEM) simulates interactions between rigid or deformable elements in contact, hence explicitly capturing the discontinuous nature of the structural response, particularly when subjected to extreme loadings. Nevertheless, it requires a time-stepping algorithm even for solving static or buckling problems. The Hybrid Discrete-Finite Element Method, shortly HybriDFEM, was recently introduced in the context of modelling one-dimensional beam-like members. Those members are divided along their longitudinal axis in a series of rectangular rigid blocks, and the deformation is concentrated at the interfaces between adjacent blocks, modelled as distributed nonlinear multidirectional springs. The method, developed within a FEM-like setting, allows for hybridisation with other finite elements (e.g., beam elements). Next to its ability to explicitly model pre-existing discontinuities along the member (e.g. masonry stereotomy), the method can be used for modelling continuous members with satisfactory accuracy by appropriately scaling the interface springs. As such, the HybriDFEM’s formulation can accommodate hybrid discrete-continuous systems. In this paper, the HybriDFEM formulation is extended to 2D, with rectangular blocks in contact on all four faces. First, the algorithm to detect blocks in contact will be explained. Second, specific characteristics of the HybriDFEM applied to masonry modelling are presented. Then, the method is benchmarked against a two-dimensional problem from the literature where the in-plane capacity of walls made masonry blocks is investigated.

Pushover analyses are often used to evaluate the seismic performance of a structure. They give an estimate of the ultimate displacement a structure can undergo, as well as of the residual resisting forces in the post-peak response. When modelling masonry structures composed of multiple blocks, obtaining the post-peak branch of the pushover curve can be difficult with a classic displacement-control strategy. This paper describes a strategy designed to compute this branch for multi-block systems subjected to a given pattern of forces, without the need to apply a displacement-control algorithm. The strategy is general, therefore straightforwardly implementable in different software tools and applicable to complex block assemblies. In the present work, it is implemented in two different DEM software, namely LMCG90 and UDEC, and tested on a benchmark problem for evaluating the in-plane response of masonry walls.

In this paper, a novel numerical method for strucural analysis, called the Hybrid Discrete-Finite Element Method (HybriDFEM), is presented. In this method, a structure is modeled as an assembly of rigid blocks in contact. All the deformation is concentrated at the interfaces, which are modeled as series of distributed nonlinear multidirectional springs. The method shares similarities with the Discrete Element Methods (DEM) in its ability to account for contact interfaces and/or block deformability, and with the Applied Element Method (AEM) in the representation of interfaces as a series of normal and shear springs. However, it is close to the FEM in the way it is formulated, which offers the possibility to readily link both methods for potential hybrid applications. This paper focuses on the modeling of continuous and discontinuous frames with the HybriDFEM. It is shown how the model can do so with a nonlinear material model, and considering (or not) nonlinear geometric effects through large nodal displacements. Different nonlinear solution procedures implemented in HybriDFEM are demonstrated, such as load-control and various displacement-controlled methods. This model is able to simulate contacts between rigid or deformable units, an important feature when it comes to the modeling of, e.g., unreinforced masonry structures, with a reasonable computational cost and a formulation that is cast within the framework of the classical FEM.

This paper introduces a novel formulation, called Hybrid Discrete-Finite Element (HybriDFEM) method, for modeling one-directional continuous and discontinuous planar beam-like members, including nonlinear geometric and material effects. In this method, the structure is modeled as a series of distinct rigid blocks, connected to each other through contact pairs distributed along the interfaces. Each of those contact pairs are composed of two nonlinear multidirectional springs in series, which can represent either the deformation of the blocks themselves, or the deformation of their interface. Unlike the Applied Element Method, in which contact pairs are composed of one single spring, the current approach allows capturing phenomena such as sectional deformations or relative deformations between two blocks composed of different materials. This method shares similarities with the Discrete Element Methods in its ability to model contact interfaces between rigid or deformable units, but does not require a numerical time-domain integration scheme. More importantly, its formulation resembles that of the classical Finite Elements Method, allowing one to easily couple the latter with HybriDFEM. Following the presentation of its formulation, the method is benchmarked against analytical solutions selected from the literature, ranging from the linear-elastic response of a cantilever beam to the buckling and rocking response of continuous flexible columns, and rigid block stackings. One final example showcases the coupling of a HybriDFEM element with a linear beam finite element.

The global impact of anthropogenic greenhouse gas emissions on climate change is undeniable, with carbon dioxide (CO2) identified as the primary contributor to global warming. Urgent action is required to mitigate global warming by reducing anthropogenic CO2 emissions to achieve net-zero levels. Carbon capture and storage (CCS) stands as a proven technology to curtail CO2 emissions from various sources by capturing and sequestering CO2 in geological formations. To address the challenge of deploying CCS on a global scale, it is crucial to accurately quantify the captured, transported, and stored CO2 since quantification underpins regulations and commercial contracts. However, the lack of standardization in CCS projects and measurement methodologies poses a significant challenge, necessitating a common measurement framework to ensure the transparency and reliability of these efforts. This article provides a comprehensive review, with 211 references, of the latest results and operating conditions for current measurement technologies covering the entire measuring system and not just a single instrument. As such, it is a first-of-its-kind effort at establishing a comprehensive framework for CCS measurement. This article serves as a source of references and as a step toward developing an international documentary standard for the transferred CO2 measurement. By addressing measurement challenges and providing comprehensive recommendations for future research, it contributes to the ongoing efforts to mitigate global warming through the widespread deployment of CCS technology.

Non-fossil hydrocarbons are desirable for transport fuels and lubricant oils to reach a fossil carbon neutral economy. Herein, we show the production of such end-products from crude raw materials via the photosensitized dimerization of terpenes. Terpenes are hydrocarbons originating from renewable sources, such as forestry, industrial bio-waste and photosynthetically active microorganisms. Under irradiation at 365 nm, we observed high conversions of terpenes with conjugated diene segments into their dimers (e.g. 96.1 wt%, 12 h for α-phellandrene), and remarkable results were obtained using simulated and natural sunlight (90.8 wt% and 46.6 wt%, respectively, for α-phellandrene). We show that the lower reactivities of some isomeric monoterpenes could be overcome by a cross-photodimerization with α-phellandrene. We also utilized the cross-photodimerization approach to obtain C15 and C30 products, combining mixtures of isoprene, monoterpenes and sesquiterpenes. Hydrogenation of the terpene dimers gave materials with physical properties suitable as high energy density fuels and lubricant oils. Finally, our preliminary analysis based on recent literature points to the commercial viability of this route to produce fuels and lubricant oils, as well as to a potential for reduction of the environmental impact compared to fossil-based routes. 

Novel traceable analytical methods and reference gas standards were developed for the detection of trace-level ammonia in biogas and biomethane. This work focused on an ammonia amount fraction at an upper limit level of 10 mg m-3(corresponding to approximately 14 μmol mol-1) specified in EN 16723-1:2016. The application of spectroscopic analytical methods, such as Fourier transform infrared spectroscopy, cavity ring-down spectroscopy, and optical feedback cavity-enhanced absorption spectroscopy, was investigated. These techniques all exhibited the necessary ammonia sensitivity at the required 14 μmol mol-1amount fraction. A 29-month stability study of reference gas mixtures of 10 μmol mol-1ammonia in methane and synthetic biogas is also reported. 

This investigation delves into the extraction dynamics of 22 per- and polyfluoroalkyl substances from PFAS contaminated firefighting materials. Two distinct test sets were executed: one contrasting a commercial product with water following an elaborate decontamination procedure, and the other assessing seven washing agents on materials from firefighting installations, with one agent examined at 22 °C and 50 °C. A general tendency for improved desorption at the higher temperature was observed. Furthermore, a discernible influence of the cleaning agent's pH on the extraction of specific PFAS species was observed, elucidating the role of chemical environment in the extraction process. PFAS rebound was studied for a period of up to 157 days, this unveiled a gradual escalation in PFAS22 levels, indicative of a protracted desorption mechanism. Intriguingly, PFAS with abbreviated carbon chains (C4–C6) exhibit superior desorption efficiency compared to their elongated congeners, suggesting a chain-length-dependent decontamination potential. A comparative scrutiny between a commercially available cleaning product, featuring multiple washing and flushing steps, and a water-only treatment regimen underscores the potential efficacy of the former. This exhaustive investigation furnishes nuanced insights into PFAS extraction complexities, offering a foundation for informed decontamination strategies

Wave energy conversion is a renewable energy technology with a promising potential. Although it has been developed for more than 200 years, the technology is still far from mature. The survivability in extreme weather conditions is a key parameter halting its development. We present here results from two weeks of measurement with a force measurement buoy deployed at Uppsala University’s test site for wave energy research at the west coast of Sweden. The collected data have been used to investigate the reliability for two typical numerical wave energy converter models: one low fidelity model based on linear wave theory and one high fidelity Reynolds-Averaged Navier–Stokes model. The line force data is also analysed by extreme value theory using the peak-over-threshold method to study the statistical distribution of extreme forces and to predict the return period. The high fidelity model shows rather good agreement for the smaller waves, but overestimates the forces for larger waves, which can be attributed to uncertainties related to field measurements and numerical modelling uncertainties. The peak-over-threshold method gives a rather satisfying result for this data set. A significant deviation is observed in the measured force for sea states with the same significant wave height. This indicates that it will be difficult to calculate the force based on the significant wave height only, which points out the importance of more offshore experiments. © 2023 by the authors.

There are many uncertainties associated with the estimation of extreme loads acting on a wave energy converter (WEC). In this study we perform a sensitivity analysis of extreme loads acting on the Uppsala University (UU) WEC concept. The UU WEC consists of a bottom-mounted linear generator that is connected to a surface buoy with a taut mooring line. The maximum stroke length of the linear generator is enforced by end-stop springs. Initially, a Variation Mode and Effect Analysis (VMEA) was carried out in order to identify the largest input uncertainties. The system was then modelled in the time-domain solver WEC-SIM coupled to the dynamic mooring solver Moody. A sensitivity analysis was made by generating a surrogate model based on polynomial chaos expansions, which rapidly evaluates the maximum loads on the mooring line and the end-stops. The sensitivities are ranked using the Sobol index method. We investigated two sea states using equivalent regular waves (ERW) and irregular wave (IRW) trains. We found that the ERW approach significantly underestimate the maximum loads. Interestingly, the ERW predicted wave height and period as the most important parameters for the maximum mooring tension, whereas the tension in IRW was most sensitive to the drag coefficient of the surface buoy. The end-stop loads were most sensitive to the PTO damping coefficient.

There are many uncertainties associated with the estimation of extreme loads acting on a wave energy converter (WEC). In this study we perform a sensitivity analysis of extreme loads acting on the Uppsala University (UU) WEC concept. The UU WEC consists of a bottommounted linear generator which is connected to a surface buoy with a taut mooring line. The maximum stroke length of the linear generator is enforced by end-stops. Initially, a Variation Mode and Effect Analysis (VMEA) was carried out in order to identify the largest input uncertainties. The system was then modelled in the time-domain solver WECSIM coupled to the dynamic mooring solver Moody. A sensitivity analysis was made by generating a surrogate model based on polynomial chaos expansions, which rapidly evaluates the maximum loads on the mooring line and the endstops. The sensitivities are ranked using the Sobol index method. We investigated two sea states using equivalent regular waves (ERW) and irregular wave (IR) trains. We found that the ERW approach significantly underestimate the maximum loads. Interestingly, the ERW predicted wave height and period as the most important parameters for the maximum mooring tension, while the tension in IR waves was most sensitive to the drag coefficient of the surface buoy. The end-stop loads were most sensitive to the PTO damping coefficient.

Wendelstein 7-X, the world’s largest superconducting stellarator in Greifswald (Germany), started plasma experiments with a water-cooled plasma-facing wall in 2022, allowing for long pulse operation. In parallel, a project was launched in 2021 to develop a W based divertor, replacing the current CFC divertor, to demonstrate plasma performance of a stellarator with a reactor relevant plasma facing materials with low tritium retention. The project consists of two tasks: Based on experience from the previous experimental campaigns and improved physics modelling, the geometry of the plasma-facing surface of the divertor and baffles is optimized to prevent overloads and to improve exhaust. In parallel, the manufacturing technology for a W based target module is qualified. This paper gives a status update of project. It focusses on the conceptual design of a W based target module, the manufacturing technology and its qualification, which is conducted in the framework of the EUROfusion funded WPDIV program. A flat tile design in which a target module is made of a single target element is pursued. The technology must allow for moderate curvatures of the plasma-facing surface to follow the magnetic field lines. The target element is designed for steady state heat loads of 10 MW/m2 (as for the CFC divertor). Target modules of a similar size and weight as for the CFC divertor are assumed (approx. < 0.25 m2 and < 60 kg) using the existing water cooling infrastructure providing 5 l/s and roughly maximum 15 bar pressure drop per module. The main technology under qualification is based on a CuCrZr heat sink made either by additive manufacturing using laser powder bed fusion (LPBF) or by uniaxial diffusion welding of pre-machined forged CuCrZr plates. After heat treatment, the plasma-facing side of the heat sink is covered by W or if feasible by the more ductile WNiFe, preferably by coating or alternatively by hot isostatic pressing W based tiles with a soft OFE-Cu interlayer. Last step is a final machining of the plasma-exposed surface and the interfaces to the water supply lines and supports to correct manufacturing deformations.

This review article analyzes factors affecting emergency response to hazardous events on highways and their bridges, with focus on man-made and natural scenarios: heavy vehicle collision with a bridge, earthquake, heavy snowfall, and flooding. For each disaster scenario, selected historical events were compiled to determine influential factors and success criteria for efficient emergency response, both related to organizational and technical measures. This study constituted a part of a resilience management process, recently developed and demonstrated within the European Union (EU)-funded H2020 project IMPROVER and can be a useful approach in aiding operators of transportation infrastructure to improve their resilience to emergency incidents.

The current paper discusses the contents of the work completed for the project “SERA AIMS – BLIND PREDICTION COMPETITION”. The competition was focused on the prediction of the response of a masonry building composed of two adjacent interacting structural units under earthquake excitation. This research investigates the response of the experimental mock-up by using a numerical model based on the rigid block limit analysis and mathematical programming. The results of the analysis, namely, the failure modes and the corresponding collapse load multipliers, are related to base shear and peak ground accelerations observed for the damage and ultimate limit states using code provisions for the assessment of failure mechanisms in existing masonry structures. Finally, a preliminary comparison of numerical and experiemental results is presented.

Groups of contiguous unreinforced stone masonry buildings are a common type of housing seen in old European downtowns. However, assessing their response to earthquakes poses several challenges to the analysts, especially when the housing units are laid out in compact configurations. In fact, in those circumstances a modeling technique that allows for the dynamic interaction of the units is required. The numerical study carried out in this paper makes use of a rigid block modeling approach implemented into in-house software tools to simulate the static behavior and dynamic response of an aggregate stone masonry building. Said approach is used to reproduce the results of bi-axial shake-table tests that were performed on a building prototype as part of the activities organized within the Adjacent Interacting Masonry Structures project, sponsored by the Seismology and Earthquake Engineering Research Infrastructure Alliance for Europe. The experimental mock-up consisted of two adjacent interacting units with matching layout but different height. Two rigid block models are used to investigate the seismic response of the mock-up: a 3D model allowing for the limit analysis of the building on one hand, and a 2D model allowing for the non-linear static pushover and time-history analysis on the other. The 3D model was built for the blind prediction of the test results, as part of a competition organized to test different modeling approaches that are nowadays available to the analysts. The 2D model was implemented once the experimental data were made available, to deepen the investigation by non-linear static pushover and time-history analysis. In both models, the stonework is idealized into an assemblage of rigid blocks interacting via no-tension frictional interfaces, and mathematical programming is utilized to solve the optimization problems associated to the different types of analysis. Differences between numerical and experimental failure mechanisms, base shears, peak ground accelerations, and displacement histories are discussed. Potentialities and limitations of the adopted rigid block models for limit, pushover and time-history analyses are pointed out on the basis of their comparisons with the experimental results.

Unreinforced brick masonry makes up today a significant piece of the European built environment, including not only residential buildings but also strategically important structures that are not designed to withstand blasts and impacts. Yet, it is difficult to accurately estimate the response of these structures and the extent of damage they sustain during such extreme loading conditions. This paper presents the implementation and discusses the results of laboratory impact tests conducted on natural-scale double-wythe unreinforced brick masonry walls, a typology that is frequently found in Northern Europe. The walls were spanning vertically between two reinforced concrete slabs and were subjected to low-velocity drop-weight pendulum tests in which they were repeatedly hit until the opening of a breach in the centre of the wall. The tests were instrumented with both hard-wired and optical measurements, the latter consisting of high-speed cameras and digital image correlation techniques, to face the difficulty of observing cracks and determining the deflections of the walls with adequate accuracy at the time of the impact. Investigated in these tests were the out-of-plane response of the walls and their capacity to resist the impacts. The axial load applied on the top of the walls was varied for two wall configurations and monitored throughout the tests to study the effect of arching on the failure mechanism produced and number of repeated hits needed to open the breach. Of interest was also the evidence of cracking, more specifically the way it initiated on the undamaged walls and next propagated upon consecutive hits. The data generated from these tests are made available to support further investigations on masonry structures subjected to extreme actions.

Unreinforced brick masonry makes up today a significant piece of the European built environment, including not only residential buildings but also strategically important structures that are not designed to withstand blasts and impacts. Yet, it is difficult to accurately estimate the response of these structures and the extent of damage they sustain during such extreme loading conditions. This paper presents the implementation and discusses the results of laboratory impact tests conducted on natural-scale double-wythe unreinforced brick masonry walls, a typology that is frequently found in Northern Europe. The walls were spanning vertically between two reinforced concrete slabs and were subjected to low-velocity drop-weight pendulum tests in which they were repeatedly hit until the opening of a breach in the center of the wall. The tests were instrumented with both hard-wired and optical measurements, the latter consisting of high-speed cameras and digital image correlation techniques, to face the difficulty of observing cracks and determining the deflections of the walls with adequate accuracy at the time of the impact. Investigated in these tests were the out-of-plane response of the walls and their capacity to resist the impacts. The axial load applied on the top of the walls was varied for two wall configurations and monitored throughout the tests to study the effect of arching on the failure mechanism produced and number of repeated hits needed to open the breach. Of interest was also the evidence of cracking, more specifically the way it initiated on the undamaged walls and next propagated upon consecutive hits. The data generated from these tests are made available to support further investigations on unreinforced masonry structures subjected to extreme actions.

Out-of-plane actions cause confined unreinforced masonry walls (URM) to develop what is known as an arching action. The role of arching is central in the resisting mechanisms of a wall; it contributes significantly to its loadbearing capacity as long as the wall’s deflections are minor, but gradually loses effect with increasing deflections, until collapse occurs. To date, limited experimental data is available on how arching develops in relation to the out-of-plane behaviour of the wall. This study brings new experimental evidence to this aspect. Quasi-static monotonic four-point bending tests were conducted on eleven brick wall strips, with reinforced concrete (RC) slabs affixed below and over the walls to simulate contact conditions of a typical construction system. The walls were tested vis-à-vis three different support conditions: simply supported, rigid, and non-rigid. The influence of these support conditions on the out-of-plane behaviour of the walls was studied on specimens with varying thickness – single and double wythe – and subjected to different levels of axial compression (or overload). While the former support condition was designed not to yield any arching inside the wall (unconfined masonry), the intermediate and latter solutions generated an arching action that was proportional respectively to the elongation of the wall (partially confined masonry), and its deflection (confined masonry). The walls were tested inside a bi-axial test setup that allowed not only the out-of-plane force but also the arching action to be measured, corroborating its central role in the development of the out-of-plane capacity of the walls. To support the observations, deformation characteristics and crack distributions were determined using two optical measurement systems placed in front and to the side of the walls, making use of the Digital Image Correlation (DIC) technique. The results of the tests are discussed in terms of failure mechanism as well as force and displacement capacity of the walls in relation to the investigated parameters. The test data is collected and made available to help with future research on the out-of-plane capacity of URM walls.

This report describes the laboratory work undertaken to characterize the hydromechanical behaviour of a natural rock fracture under varying normal loading. The hydraulic transmissivity of a granite specimen with a sealed (unopened) quasi-planar natural fracture of length 200 mm and width 200 mm was measured. The transmissivity measurements were conducted in the two perpendicular directions of the fracture, repeating them at five different normal compression stress levels, namely, ~0, 1, 2, 4, and 8 MPa, and flow gradients. The fracture was mechanically opened, and the measurements were repeated to investigate the effect of opening the fracture on its hydraulic transmissivity and hydromechanical behaviour. For one direction, the change in transmissivity was explored for high normal compression stress levels, up to ~40 MPa. Laminar flow conditions were ensured at every stage of the experimental campaign by working at very low Reynolds numbers (<1). The equivalent hydraulic aperture of the fracture was derived by resorting to the parallel-plate model theory. The hydraulic aperture was compared to the mechanical aperture, which was obtained by measuring the deformation of the specimen. In addition to the transmissivity tests, the geometry of the lateral walls and surfaces of the fracture was documented and measured by a series of tools, namely, digital scans, high-resolution pictures, optical readings by a stand microscope, and contact pressure-sheet measurements. The results achieved in this campaign shed light on the hydraulic transmissivity of sealed (unopened) and consequently opened natural fractures, and its dependency to the applied normal compression stress at low to very-low flow rates.

There is limited available data on natural rock fractures with low hydraulic transmissivity. In this study, we measured the transmissivity of a granite specimen with a 200×200 mm naturally-induced closed fracture under varying normal load. We repeated the measurements after opening the fracture to investigate how this affects its transmissivity. At each stage, we ensured laminar flows by setting Reynolds numbers << 1. Finally, we resorted to the parallel-plate theory to obtain the equivalent hydraulic aperture, that we compared to the mechanical aperture derived from the observed deformation.

Masonry walls are bulky and heavy and have therefore the potential to act naturally as a protective system to blasts. Yet, they are known to have a limited flexural and torsional capacity, particularly when unreinforced. When exposed to shockwaves, they experience out-of-plane failure mechanisms which may affect the overall stability of the building and engender flying debris inside the building. The out-of-plane response of unreinforced masonry walls to blasts depends on many factors characterizing both the wall and blast action, making any sort of prediction difficult. In this context, experimental tests and numerical models become key tools that can be used to study the wall’s response on a case-by-case basis. This review covers the major experimental and numerical approaches to assess the out-of-plane response of unreinforced masonry walls subjected to blasts. A methodological appraisal is used for the test methods, focusing on the preparation of the test items and test setup, the boundary conditions and failure mechanisms investigated, as well as the commonly employed measurement techniques. The survey on the modelling approaches includes key topics such as level of detail and cost, and reports strategies to model the wall and blast scenario. The review provides a thematic analysis of the available literature, aimed to assist the analyst in selecting a suitable tool for the investigation of masonry in the field of blast engineering. Furthermore, the findings presented herein can support amendments of existing codes and guidelines pertaining to the design of protective masonry structures.

Geotechnical and hydrogeological data are collected during all phases of construction projects. Currently, the collection of such data is not standardized and there is no central, national system for storing the collected data. It is also difficult to evaluate or re-use such data from previous projects which results in collecting the same field data from scratch for new infrastructure projects. Previous studies and this feasibility study have shown the need for clearer, improved methodologies for data collection along with a national portal for access to geotechnical and hydrogeological archives and data from previous projects.

Through two surveys answered by key parties in the rock construction industry, we have identified geotechnical and hydrogeological parameters that need improved methodology and method descriptions and possibly standardization. Existing database solutions, as well as suggestions for the functionality of a future national database have also been analyzed from the survey responses.

Survey results also show that data collection standardization is necessary to ensure data reliability and traceability, and that standardized methodologies should be adapted to project complexity and try to conform to current internationally accepted methodologies. However, the study also shows that industry views are divided on certain issues. How new methodologies and data portals / databases will be developed, funded, managed andimplemented also remains to be clarified.

This feasibility study recommends a national database divided into a searchable document archive and a parameter database. One or more government organizations should be responsible for administration.

The present report serves as a decision basis for initiating and financing projects in the area concerned. It is strongly recommended that any organization(s) that build a document archive and a national parameter database take into account the functional requirements mentioned in this report.

Note that this report is also available in PDF format on Stiftelsen Bergteknisk Forskning- BeFo's website. The links in the report can be easily opened directly from the PDF file and images can be enlarged.

The density and mechanical properties were determined on water saturated specimens from boreholesKFM01A, KFM08A, KFM11A, KFR102A and KFR104 in the Forsmark site investigation area. Therock types in the selected sections were amphibolite (102017) and metavolcanic rock (103076). Somespecimens had a more or less foliated rock structure. The cores were sampled from a depth rangingbetween 196–901 m.The specimens were water saturated using tap water and all subsequent measurements wereconducted at this moisture condition. The density was determined on 30 specimens. The testingended with 20 indirect tensile tests yielding the indirect tensile strength and 10 uniaxial compressiontests including the post-peak response yielded the Young’s modulus, Poisson’s ratio and the uniaxialcompressive strength.Some variation of rock material along the short cores could be seen, which is reflected in themeasured data. The density at a water saturated condition was 2892–3067 kg/m3 for amphibolite, and2697–2763 kg/m3 for metavolcanic rock.The indirect tensile tests were conducted such that every specimen with visible foliation was testedwith the diametrical compression across the foliation planes, with higher values for the indirecttensile strength on the specimens. The strength variation in the amphibolite was large. The indirecttensile strength was 10.8–21.4 MPa for amphibolite and 16.9–20.7 MPa for metavolcanic rock. Twoof the amphibolite specimens had a deviating lower strength, indirect tensile strength 5.7 MParespectively 5.8 MPa, with a ductile failure. Those specimens had a high content of mica.The Young’s modulus obtained from the uniaxial compression tests was 88.6–114.5 GPa foramphibolite and 68.2–89.1 GPa for metavolcanic rock and the Poisson’s ratio was 0.339–0.386 foramphibolite and 0.236–0.313 for metavolcanic rock. The peak values of the axial compressive stresswere in the range 213.1–333.7 MPa for amphibolite and 104.1–283.1 MPa for metavolcanic rock.One of the amphibolite specimens had a deviating lower strength and a ductile failure with Young’smodulus 41.2 GPa, Poisson’s ratio 0.500 and peak axial compressive stress of 44.5 MPa. Thatspecimen had a high content of mica. 

A direct shear equipment for testing rock fractures up to 400×600 mm size, and up to 5 MN force in both normal and shear loading directions, was developed. Normal loading and direct shear tests under constant normal stiffness (CNS) and constant normal load (CNL) conditions were conducted on 300×500 mm specimens, one planar steel joint and two natural and two tensile induced rock fractures. Design targets, e.g. system to maintain undisturbed fractures up to testing and high system stiffnesses to achieve well-controlled shear tests, were verified by the experiments. A new optical system for local deformation measurements was used to accurately determine fracture displacements besides conventional non-local deformation measurements. The determined normal stiffnesses were similar previous results from the literature on smaller fractures, whereas the shear stiffness data are novel. The results provide a new insight into processes at the onset of fracture slip.

The water flow rate through a rectangular granite specimen with a tight unopened natural induced joint of dimensions 200×200 mm was measured in two perpendicular directions. The measurements were conducted at five different levels of stress corresponding to loading from 0 to 8 MPa and unloading back to 0 MPa. The flow was measured at different hydraulic gradients in the range of 10 to 25. The results showed a joint transmissivity between 0.002-0.03 mm2/s and a hydraulic aperture of 8-32 μm. It was shown that the measurements performed in the second orientation displayed smaller transmissivity and hydraulic aperture as compared to those in the first orientation, showing a residual compaction after the first load cycle. The Reynolds number was less than one in all the measurements yielding laminar flow conditions. Deviations from the linear regime relationship were observed for the lowest flow rates (Re &lt; 0.1). A transitory regime was observed when varying the hydraulic gradient. This regime was observed to be longer at the lowest flow rates. © 2023 Institute of Physics Publishing. All rights reserved.

Predictions of fracture displacements are required to support the safety assessments of a deep geological repository for nuclear spent fuel. Laboratory and in-situ experiments are used to estimate these properties. Despite significant contributions in the last decades, there is a knowledge gap in terms of the impact of high normal stresses on the mechanical properties of large-scale fractures under Constant Normal Stiffness (CNS) boundary conditions. Within the framework of the POST project, a cooperative effort was made by SKB (Sweden), NWMO (Canada), and Posiva from Finland (in phase 1) to study these questions. In the second phase of the POST project, a first of a kind direct shear testing machine was manufactured and calibrated that can accommodate samples up to 400 × 600 mm under normal stresses up to 10 MPa, for both CNS and Constant Normal Load (CNL) conditions, with the ability to shear the sample up to 50 mm. Several best practice procedures were developed for fracture characterization pre-, syn-, and post-shear test which utilize high resolution optical scanning, contact pressure measurements, Digital Image Correlation (DIC) measurements, and acoustic emission measurements during the shear test. Natural and tensile-induced fractures of a granitic rock as well as replicas of the hard rock fractures, at three different fracture sizes of 35×60 mm, 70×100 mm, and 300×500 mm, are now being tested. It is hoped that this program will provide a set of high-quality data which will help reduce the knowledge gap in the understanding of fracture behavior. 

Experimental investigations of the shear properties of rock fractures in hard rock have generally focused on tests on smaller fracture s for normal stresses of up to 20 MPa, representative of a nuclear waste repository at a depth of about 400 meters. T he shear properties of large fractures determined at experiments have generally been determined at low stresses , of one or more MPa. To gain an understanding of the effect of the size on the shear properties of the fractures at high normal stresses, it is crucial to perform shear experiments on large rock fractures (> 200 mm) in hard rock under high normal stresses. In the project Parameterization of Fractures, POST (2014 2016), the scale effects were studied by in situ experiments, small scale shear experiments and computational simulations. It was found that laboratory experiments under controlled conditions and on large rock samples are necessary to obtain reliable results. It was also found that in situ experiments are complex with large underlying uncertainties and are at the same time costly. In the ongoing POST 2 project, which started in 2017, rock fractures up to 500 mm have been tested in a new unique laboratory equipment, along with test s on smaller fractures , at high normal stress for both CNL and CNS conditions and with new measurement technology. Techniques for producing replica samples of rock fractures have been developed and tested with the aim of making load parameter studies. The quality of the geometry imaging of the replica samples and the geometries of the fractures has been meas ured by high resolution scanning. This article presents some of the results from the project. The results from the project are applicable to other areas with underground construction, such as the design of tunnels and rock caverns for infrastructure projects and mines.

The scale effect of natural and artifically induced rock fractures and replicas up to a 500 mm length are experimentally studied by direct shear tests in a testing program including a newly manufactured large shear testing equipment. The fractures are chatacterised pre-, syn-, and post-shear test. Combinations of different measurements provide a high-quality dataset enabling deeper understanding of, and constitutive model development for rock fractures used for safety assessment of deep geological respoitories for nuclear waste disposal.

Marine power cables play a crucial role to utilize energy in marine areas, such as offshore wind, wave energy and tidal energy. Marine energy devices are typically grouped into arrays to increase the economic viability, and power cables transfer the energy from the devices to a central hub which is then transmitted ashore. Cables connected to moving devices may experience millions of load cycles per year, and thus they need to be flexible and designed for mechanical loads due to the movements of the cable. In this study, the focus is on the mechanical life of flexible cables connecting devices to hubs, and thus lowand medium voltage power cables is the focus. The reliability design method Variational Mode and Effect Analysis (VMEA) is applied that is based on identifying and quantifying different types of uncertainty sources, such as scatter, model uncertainties and statistical uncertainties. It implements a load-strength-approach that combines numerical simulations to assess the loads on the cable and experimental tests to assess the strength of the cable. The VMEA method is demonstrated for an evaluation of bending fatigue, and it has been found to be a useful tool to evaluate uncertainties in fatigue life for cables in WEC (Wave Energy Converter) systems during the design phase. The results give a firm foundation for evaluation of safety against fatigue and are also helpful for identifying weak spots in the reliability assessment that can motivate actions  in the improvement process. Uncertainties in terms of scatter, statistical uncertainty and model uncertainty have been evaluated with respect to the WaveEL 3.0, a WEC designed by the company Waves4Power, and deployed in Runde, Norway. A major contribution to the overall uncertainty is found to originate from the fatigue life model, both in terms of scatter and model uncertainty. 

Marine power cables connected to moving devices at sea may experience millions of load cycles per year, and thus they need to be flexible due to the movements of the cable and designed for mechanical loads. In this study, the focus is on the mechanical life of flexible low-and medium voltage power cables connecting devices to hubs. The reliability design method Variational Mode and Effect Analysis (VMEA) is applied, based on identifying and quantifying different types of uncertainty sources, including scatter, model and statistical uncertainties. It implements a load–strength approach that combines numerical simulations to assess the loads on the cable and experimental tests to assess the strength of the cable. The VMEA method is demonstrated for an evaluation of bending fatigue, and is found to be a useful tool to evaluate uncertainties in fatigue life for WEC (Wave Energy Converter) system cables during the design phase. The results give a firm foundation for the evaluation of safety against fatigue and are also helpful for identifying weak spots in the reliability assessment, thereby motivating actions in the improvement process. Uncertainties in terms of scatter, statistical uncertainty and model uncertainty are evaluated with respect to the WaveEL 3.0, a WEC designed by the company Waves4Power, and deployed in Runde, Norway. A major contribution to the overall uncertainty is found to originate from the fatigue life model, both in terms of scatter and model uncertainty. © 2022 by the authors. 

There is an urgent need for the development of viable recycling solutions for the increasing waste streams of glass fiber composites (GFRPs) from all sectors i.e. leisure boats, windmills and building constructions. Two potential recycling methods that can separate and recover both the polymers and the high-quality fibers from these kinds of materials are pyrolysis and solvolysis. In this project recycling of an epoxy-based Endof-Life wind turbine blade was evaluated in lab scale using the two methods. In previous literature the main focus has been on the quality of the fibers but in this project the main focus was to compare the chemical composition of the oil products. The produced oils from solvolysis and pyrolysis have been compared with a multianalysis approach by using elemental analysis, GC-MS, pyro-GC-MS/FID, 2D NMR (HSQC) for gaining more information about the chemical structure of the produced monomers (phenols), oligomers and polymers. Almost all the volatile matter in the End-of-Life wind turbine blade was recovered as pyrolysis oil, 36 wt.% yield. The solvolysis oil yield was lower, 17 wt.%, mainly due to a major part of the solvolysis oil ended up in the aqueous solvent. The composition of the oils from both technologies was analyzed based on both their volatile i.e. monomeric and polymeric content. The result point to that both methods produced oils with similar polymeric parts according to NMR and pyro-GC-MS/FID, based on an oxygenated aliphatic network connected with aromatic phenolic structures. Increased information of chemical oil composition will be useful for further processing as raw material in refineries/chemical industries. The monomeric part of the oil produced from pyrolysis was found in relatively large amounts, ~57 wt.%, and can be a future high-value product from recycling of wind turbine blades. The total recovery of phenolics from the pyrolysis was 18 wt.% of the wind turbine blade weight.

Posiva Oy has conducted investigations into excavation damage, including comprehensive laboratory testing of physical properties of rock specimens from excavation damaged rock mass. Laboratory testing was conducted on drill core specimens extracted from the excavated surface of a tunnel located at approximately 345 m depth in Olkiluoto, Finland. A total of 141 drill core specimens of three main rock types, a structurally isotropic coarse-grained pegmatoid (PGR) and structurally anisotropic veined gneiss (VGN) and diatexitic gneiss (DGN), were subjected to petrophysical testing, rock mechanics testing and petrographic analyses. Results from the various tests were subjected to rigorous statistical analysis in order to reveal the effects excavation damage has on the physical properties of the rock mass. Results of the study revealed changes that are credited to excavation damage in resistivity, S-wave velocity and various elastic properties of the rock specimens. Effects of excavation damage and the depth of the excavation damaged zone seem to be different to gneiss compared to pegmatoid. On microscopic level, the extent of excavation damaged zone appears to be 0.2 - 0.4 m depending on the measured property. This means that the deeper excavation damaged layer observed by geophysical surveys may be caused by larger scale fractures. 

Physical and petrographic properties of drill core specimens were determined as a part of investigations into excavation damage in the dedicated study area in the ONKALO® research facility in Olkiluoto, Western Finland. Microfractures in 16 specimens from two drillholes were analysed and used as a basis for fractal geometry-based discrete fracture network (DFN) modelling. It was concluded that the difference in resistivity between pegmatoid granite (PGR) and veined gneiss (VGN) specimens of similar porosity was likely due to differences in the types of microfractures. This hypothesis was confirmed from microfracture analysis and simulation: fractures in gneiss were short and mostly in one preferred orientation, whereas the fractures in granite were longer and had two preferred orientations. This may be due to microstructure differences of the rock types or could suggests that gneiss and granite may suffer different types of excavation damage. No dependencies on depth from the excavated surface were observed in the geometric parameters of the microfractures. This suggests that the excavation damaged zone cannot be identified based on the changes in the parameters of the microfracture networks, and that the disturbed layer observed by geophysical methods may be caused by macro-scale fractures. © 2021 by the authors.

Percutaneous implants are frequently affected by bacterial growth at the skin-implant interface. Integration between implant and surrounding skin is important to prevent bacteria from spreading to the underlying tissue. The standard method to evaluate skin-implant integration is by histomorphometry on samples which have been placed in tissue grown in vivo or ex vivo. In this study, a biomechanical method was developed and evaluated. The integration of implants into porcine skin was studied in an ex vivo model, where pig skin samples were cultivated in a nutrient solution. Cylindrical shaped implants, consisting of polyether ether ketone (PEEK) and titanium (Ti) with different surface treatments, were implanted in the skin tissue and the skin was grown in nutrient solution for 2 weeks. The implants were then extracted from the implantation site and the mechanical force during extraction was measured as a quantitative assessment of skin-implant integration. Implants from each group were also processed for histomorphometry and the degree of epidermal downgrowth (ED) and tissue to implant contact (TIC) was measured. A higher mean pullout force was observed for the PEEK implants compared to the Ti implants. Applying nanosized hydroxyapatite (HA) on Ti and PEEK increased the pullout force compared to uncoated controls, 24% for machined and 70% for blasted Ti, and 51% for machined PEEK. Treatment of Ti and PEEK with nanosized zirconium phosphate (ZrP) did not increase the pullout force. The histomorphometry analysis showed correlation between ED and pullout force, where the pullout force was inversely proportional to ED. For TIC, no significant differences were observed between the groups of same material (i.e. Ti, Ti+HA, Ti+ZrP, and PEEK, PEEK + HA, PEEK + ZrP), but it was significantly higher for PEEK compared to Ti. Scanning electron microscopy analysis was done on samples before and after the pullout tests, showing that the ZrP coating was unaffected by the 2 week ex vivo implantation and pullout procedure, no dissolution or detachment of the coating was observed. For the HA coating, a loss of coating was seen on approximately 5% of the total surface area of the implant. [Figure not available: see fulltext.] © 2022, The Author(s).