AbstractCivilian structures and fortifications are primarily composed of reinforced concrete elements. The development of methods suitable for blast-loaded structural concrete elements requires experimental data for validation and an understanding of the structural response. Previous studies have focused either on variations in geometry and material properties or on realistic boundary conditions. This study complements existing experimental datasets on reinforced-concrete wall panels. In total, 29 shock-tube and 9 quasi-static tests were performed on geometrically half-scale wall panels with different load intensities, geometries, reinforcement configurations, and boundary conditions. The results showed that static and dynamic failure modes were similar: panels with stirrups failed in flexure, while panels without stirrups failed in flexural–shear. Significant arching action developed for both loading types, with flexural damage resulting in the wall retaining a large portion of its initial axial load after the test. Comparison of static and dynamic resistances showed that for panels without stirrups, dynamic resistance exceeded static resistance, whereas failure initiated at the same midspan displacement. This suggests that the deformation level should be considered when assessing the risk of flexural–shear failure. For panels with stirrups, dynamic resistance was initially governed by the direct compression strut capacity but converged with static flexural resistance at larger deformations. Predictive models for axial load, displacement, and reaction forces were evaluated and further developed. A simple spring model, based on rigid-body kinematics and static axial stiffness, was developed to predict axial loading due to arching action and showed good agreement with the tests. Simplified single-degree-of-freedom models and a multi-mode elastic model predicted displacement and reaction forces with good agreement. The experimental results were used to develop a novel closed-form model for predicting reaction forces. Conventional methods and the proposed closed-form model were used to derive iso-damage curves, which were then compared with experimental data. The results showed that the iso-damage curves provide satisfactory early approximations of the blast response.

Hydropeaking, resulting from flexible hydropower operations, causes rapid hydraulic fluctuations and disrupts downstream ecosystems, posing significant ecological challenges. This study develops an enhanced ecohydraulic modeling framework to assess the responses of fish habitats to different hydropeaking scenarios for the European grayling ( Thymallus thymallus ) and brown trout ( Salmo trutta ). A two-dimensional hydrodynamic model was coupled with a novel habitat module that introduces a machine learning-based habitat suitability computation method. This method effectively captures the nonlinear and coupled effects between flow velocity and water depth, outperforms traditional habitat suitability approaches (e.g., geometric mean and fuzzy logic), and yields stable, ecologically consistent habitat suitability results. To complement local habitat assessment, a habitat connectivity index (HCI) was also developed to quantify longitudinal connectivity and migration pathways across life stages under dynamic flow conditions. Results demonstrated that hydropeaking frequency was the primary driver of habitat variability, while spill gate closing time played a secondary role. Lower frequencies increased temporal variability but expanded opportunities for accessing high-quality patches; higher frequencies stabilized conditions but reduced ecological flexibility. Longer closing times enhanced short-term stability, but their effect was relatively minor compared with that of frequencies. The HCI approach enabled the prediction of migration pathways and the identification of critical corridors under extreme flow regulation. The proposed framework offers a valuable tool for evaluating habitat quality and connectivity dynamics under hydropower regulation, providing practical insights for adaptive ecological flow management in regulated rivers.

Fiberarmerad sprutbetong har sedan slutet av 80-talet använts för att förstärka svenska bergrum. Med några få undantag är all sprutbetong armerad med stålfiber. Detta är även situation idag trots att flertalet alternativa fibermaterial finns på marknaden. Trots att det strukturella beteendet efter uppsprickning skiljer sig åt mellan fibertyperna har forskning visat att fiber av glas, basalt och polypropylen alla kan uppfylla de idag ställda kraven på bärförmåga. En stor anledning till att alternativa fiber inte används är att det finns osäkerheter kring hur bärförmågan för fiberarmerad sprutbetong påverkas efter lång tids exponering i tunnelmiljö. Tidigare forskning har ofta fokuserat på nedbrytning av individuella fiber i lösningar med höga salthalter eller pH värde. Sprutbetongens energiupptagande förmåga efter uppsprickning beror på fibertyp och styrs av en kombination av utdragning av fibrer från betongmatrisen samt deformation och brott i fibern. För att studera förändringar i bärförmåga över tid är det därför lämpligt att utsätta fiberarmerade provkroppar för exponering i olika miljöer och därefter testa bärförmågan. Detta har studerats i ett nyligen avslutat BeFo projekt där accelererande åldringsförsök har genomförts varefter bärförmågan utvärderades med Barcelonametoden.

Svenska bergrum förstärks oftast med fiberarmerad sprutbetong i kombination med bergbult. För trafiktunnlar används uteslutande stålfiber trots att flera alternativa fibermaterial idag finns tillgängliga på marknaden. Tidigare forskning har visat att dessa fibrer kan uppfylla de strukturella kraven som vanligen ställs på bärförmåga. Dock kvarstår det osäkerheter gällande fibrernas bärförmåga över tid och hur denna påverkas av exponering i tunnelmiljö. Syftet med denna rapport är att undersöka lämpliga metoder för att genomföra sådana studier med fiberarmerad sprutbetong. Det säkraste sättet att undersöka effekten av åldring hos sprutbetong är att genomföra långtidsprovning. Eftersom tekniska livslängden på svenska tunnlar vanligtvis är 120 år är dock detta både kostsamt och tidskrävande. Denna rapport sammanfattar kunskap från tidigare långtidsförsök och vad framtida långtidsförsök bör ta i beaktning. Ett snabbare sätt att studera åldring är att genomföra accelererad provning. Medan tidigare genomförda studier ofta fokuserar på åldring av betong och fibrer enskilt fokuserar denna rapport på att hitta en metod för att studera åldring av fiberarmerad betong som ett sammansatt material. Efter genomförandet av en provserie där fler än 80 provkroppar med fyra olika fibertyper exponerades för olika miljöer visas att Barcelonametoden, som är ett spräcktest av fiberarmerade kuber eller cylindrar, kan användas för att utvärdera förändringar i betongens energiupptagande förmåga. Metoden kan inte användas för att bestämma orsaken till förändringen men anses lämplig för att ge indikationer på vilka miljöer som vissa fibertyper är lämpliga eller mindre lämpliga för.

In hard rock tunnelling, the bond between the shotcrete (sprayed concrete) lining and the rock substrate is critical for structural safety and long-term performance. With a complete bond, composite action between the shotcrete and rock exists, which reduces cracking and fallout risk. Despite its importance, a predictive function for tensile bond fracture energy as a function of tensile bond strength remains unclear. In this study, experimental data from a range of literature were compiled, standardised, and analysed to investigate this relationship. The dataset includes results from multiple quasistatic direct uniaxial tensile and three-point bending tests across different surface roughness levels, curing conditions, and shotcrete compositions. A statistically significant correlation between tensile bond strength and fracture energy was identified. A linear relationship is proposed, motivated by the observed data distribution, providing a simple function for an initial estimate of the fracture energy when bond strength is known. The model was compared to and agreed with finite element simulations that reproduced experimental data. The proposed function is therefore suitable as an initial estimated input for numerical modelling of rockshotcrete interfaces and for energy-based analytical formulations.

Previous research on statically loaded reinforced concrete beams has shown a clear influence of the shear span-to-depth ratio on the resulting shear failure mode. Large shear spans relative to the depth typically lead to capacities governed by the breakdown of beam action, whereas low ratios result in capacities governed by the remaining or full arch. Experimental tests with static loading have determined limits for these ratios and the corresponding failure mode. However, no corresponding limits exist for reinforced concrete beams subjected to high strain rates. This is especially true for deep and short beams, for which test data remain scarce. Impact tests were conducted to study shear span-to-depth ratio limits and corresponding shear-type failure modes at high strain rates. Deep, short, and slender beams were tested to study differences in response. Crack development and deformations were analysed using high-speed photography and digital image correlation (DIC). The series consisted of 27 scaled beams tested under static and impact loading, with varying amounts of transverse reinforcement. Results indicated similar shear failure modes for static and impact-loaded beams across the tested shear span-to-depth ratios. For slender beams, inertial forces and undamaged direct struts dominated early, resulting in higher reaction and internal forces for impact-loaded beams. As deformation developed, the response during both load types was similar, with stiffness dominating and flexural and flexural-shear capacities governing the resistance. Strut and tie models generally aligned with the experimental results, while sectional models were over-conservative. A design procedure based on strut and tie modelling was proposed to capture both early transient and quasi-static phase capacities.

Shotcrete is a widely used construction material known for its rapid application and high strength. It contains high amounts of cement, a source of greenhouse gas emissions. SCM can be used to reduce the environmental impact of shotcrete by replacing amounts of cement in the mix. This can affect the strength properties of shotcrete. A pilot study is set to investigate the effect of replacing cement with slag on compressive strength for the first 24 hours. Using the stud driving method and cast cubes, the study showed reduced compressive capacity for the first few hours.

This dataset [1] contains results from structural testing of cast and sprayed fibre-reinforced shotcrete with steel, synthetic and basalt fibres. This includes testing residual flexural strength on beams according to EN 14488-3 [2] and the energy absorption of round determinate panels tested according to ASTM C1550 [3]. For all tests, the compressive strength was evaluated according to EN 12390-3 [4]. Four different fibre types were tested, and for each fibre type, three dosages were tested. Beams were produced by casting, while panels were produced by casting and spraying. This resulted in a total of 36 beams and 72 panels and cubes. Structural testing was performed at an accredited laboratory by certified personnel using standard equipment found in a commercial laboratory for structural testing. The dataset contains a summary of the standard parameters evaluated for each test method but also contains the raw data from the test machine for tests on beams on panels. One unique property of this dataset is the variation in fibre types, i.e. testing includes steel, synthetic and basalt fibres. The standard test parameters summary is useful for directly comparing and evaluating the structural performance for each fibre type and dosage. This could be used to get an indication of the required dosage of each fibre type to fulfil structural requirements. The raw data from the test machine is valuable for the numerical modelling of fibre-reinforced shotcrete. This data contains the relationship between external force and vertical displacement of the specimen and can be used to calibrate a material model for finite element simulations.