Stockholm is built on top of a rare landscape phenomenon: At the ridge of an esker crossing where the sweet water of Mälaren meets the brakish of the Baltic sea. An absolute ecological melting pot, not to be found anywhere else in this part of the world.  Due to the development of Stockholm, the nature of what takes place here has over the past 800 years slowly been lost in the citys urban web. As the citys development continues and generates a land-mass-bi-product in shape of blast stone. -Could the ecology of this rare aquatic environment connecting sweet and brakish be regenerated if the connection was recreated artificially with excess blast stone?

In this work we develop a Blast-Propellant-Facility integrated analysis study, which evaluates, by using two different approaches, the blast-related impact of an explosive accident of the Space Shuttle during the first ten seconds after launch at Kennedy Space Center. The blast-related risk associated with an explosion at this stage is high because of the quantity of energy involved in both multiple and complex processes. To do this, one of our approaches employed BlastFX®, a software system that facilitates the estimation of the level of damage to people and buildings, starting from an explosive device and rendering results through a complete report that illustrates and facilitates the evaluation of consequences. Our other approaches employed the Hopkinson-Cranz Scaled Law for estimating similar features at a more distant distance and by evaluating bigger amounts of TNT equivalent. Specifically, we considered more than 500 m and 45,400 kg, respectively, which are the range and TNT content limits that our version of BlastFX® can cover. Much research has been done to study the explosion phenomena with respect to both solid and liquid propellants and the laws that underlie the blast waves of an explosion. Therefore our methodology is based on the foundation provided by a large set of literature review and the actual capacities of an application like BlastFX®. By using and integrating the lessons from the literature and the capabilities of the software, we have obtained very useful information for evaluating different scenarios that rely on the assumption, which is largely studied, that the blast waves' behavior is affected by the distance. All of this has been focused on the Space Shuttle system, in which propellant mass represents the source of our analysis and the core of this work. Estimating the risks involved in it and providing results based on different scenarios augments the collective knowledge of risks associated with space exploration.

Impulsive loads have been observed to cause brittle shear failure in reinforced concrete elements designed for ductile failure modes under static loads. Brittle failure modes exhibit poorer energy absorption capabilities compared to ductile flexural failure modes due to their limited deformation capacity, leading to premature failure. The discrepancy between the responses under static and extreme dynamic loads arises from inertia and wave propagation effects, which tend to increase as the load duration decreases relative to the fundamental period of the element.   This thesis investigated the occurrence of shear failures in reinforced concrete elements subjected to impulsive loads, both experimentally and numerically, and evaluated to what extent current analysis methods for impulse-loaded structures can predict shear failure. Furthermore, the study examined the influence of crucial parameters on the energy absorption capacity during flexural failure modes when shear failure was inhibited.   The results demonstrated that shear-plug damage, prevalent during impact loads, may lead to premature shear failure during sequential impact testing. This occurred for a statically flexure-critical beam with a significantly larger static flexural-shear capacity relative to its flexural capacity. Similar conclusions applied to the residual static capacity after an initial impact introduced shear-plug damage. These findings indicate potentially severe consequences of shear-plug damage, which should be considered when assessing structures damaged by impact loads.   The energy absorption capacity of reinforced concrete elements is closely related to the plastic work capacity of the reinforcement. The experimental study showed how the plastic work capacity varied with reinforcement properties, concrete properties, and impact velocity using static and dynamic four-point flexural tests. The results revealed that the reinforcement type, specifically whether the steel is mild or stiff, governs the strain distribution during static and low-velocity impact testing. Generally, stiff steels result in strain localization before rupturing, indicating a lower plastic work capacity. Factors such as stress and strain capacity also proved significant. However, as the impact velocity increased, wave propagation effects governed strain distribution rather than reinforcement type.    Numerical studies comparing results with outcomes using proposed design methods indicated agreement for support reactions used to verify the shear capacity in the later stages of the response. However, this agreement decreased in the initial stages of the response. This may be because the dynamic equilibrium method only considers a global response, while the local response due to wave propagation is influential in the initial stages of the response. Today, resources such as Biggs [8] and the Swedish Fortifications Agency [86] recommend using two stages of the response to determine the internal forces; an elastic global response and a later elastoplastic global response. From the observations in the papers, it is suggested to add a third initial stage of the response considering wave propagation effects. However, it is deemed that this response stage only has a significant effect for high-intensity blast loads with short rise times relative to the shear wave velocity. / Impulsiva laster har i litteraturen visats leda till spröda skjuvbrott for armerade betongelement designade for mjuka brott under statiska laster. Spröda brottmoder påvisar sämre energiupptagande förmågor jämfört med mjuka böjbrott på grund av dess lägre deformationskapacitet, vilket resulterar i tidigt brott. Skillnaden i respons under statisk och dynamisk belastning kommer från tröghetskrafter och vågutbredningseffekter, där effekten av båda ökar med en minskande lastvaraktighet i relation till fundamentala perioden av elementet.   Det här arbetet undersöker förekomsten av skjuvbrott under impulsiva laster experimentellt och med numeriska analyser. Hur väl befintliga beräkningsmetoder kan förutspå skjuvbrott utvärderas aven. Dessutom studeras effekten av viktiga parametrar på den energiupptagande förmågan när skjuvbrott hämmas.   Resultaten påvisade att skjuv-plugg-skada, allmänt förekommande under stötbelastning, kan leda till tidigt skjuvbrott under sekventiell stötbelastning. Detta förekom for en statiskt böj-kritisk balk med en markant högre skjuvkapacitet relativt till dess böjkapacitet. Liknande slutsatser kunde dras vid provning av den statiska residualhållfastheten efter att ett initiellt fallviktsförsök introducerade skjuv-plugg-skada. Dessa resultat indikerar potentiellt allvarliga konsekvenser av skjuv-plugg-skada, vilket bör beaktas vid bedömning av element skadade från stötbelastning.   Den energiupptagande förmågan hos armerade betongelement är nära relaterat till det plastiska arbetet som armeringen kan utföra. Den experimentella studien visade hur kapaciteten for plastiskt arbete hos armeringen berodde på armeringsegenskaperna, betongegenskaperna samt anslagshastigheten hos massan vid statisk och dynamisk fyrpunktsbelastning. Resultaten visade att armeringstypen, mer specifikt ifall stålet var mjukt eller styvt, styrde töjningslokaliseringen under statisk belastning samt dynamisk belastning med låg anslagshastighet. Generellt sett resulterade styvare stål i töjningslokalisering när stålet slets av, vilket ledde till en mindre kapacitet for plastiskt arbete hos armeringsstången. Faktorer som töjnings- och spänningskapaciteten visades även vara betydande. Däremot indikerade resultaten att allt eftersom anslagshastigheten ökade så var vågutbredningseffekter det som bestämde grad av töjningslokalisering, och inte styvheten hos stålet.   Numeriska studier där resultat jämfördes mot resultat från rekommenderade designmetoder indikerade överenskommelse för stödreaktioner som används för att verifiera skjuvkapaciteten i ett senare skede av responsen. Däremot så var överenskommelsen sämre i ett tidigare skede av responsen. Detta kan möjligen förklaras av att den dynamiska jämviktsmodellen endast tar hänsyn till den globala responsen, medans lokal respons från vågutbredning är dominerande tidigt. Idag använder referenser som Biggs [8] och Fortifikationsverket [86] två stadium av responsen for att bestämma interna krafter; ett globalt elastiskt stadie och ett globalt elasiskt-plastiskt stadie. Från observationer i artiklarna så rekommenderas det att ett tredje initiellt stadie som beaktar vågutbredningseffekter bör inkluderas. Detta stadie anses dock bara visa markant effekt for intensiva stötvågsbelastningar med kort stegtid relativt till skjuvvågshastigheten i materialet. / <p>QC 230828</p>

High-strength steel (HSS) conforming to ASTM A1035 is becoming increasingly used in various structural applications, including in high-rise buildings and bridges. Due to their chemistry and manufacturing process, ASTM A1035 steel bars result in a combination of high tensile strength to yield ratio and varying levels of corrosion resistance. One potential application of ASTM A1035 bars is in the blast-resistant design of concrete structures, where their use can allow for reduced steel congestion, and increased blast resistance. Despite their high initial cost, stainless steel (SS) reinforcing bars are also seeing increased use in concrete construction. Solid stainless steel bars are referenced in ASTM A955, which is applicable to various stainless steel alloys. In addition to their inherent corrosion resistance, most stainless steel bars possess greater tensile strength, and importantly, exceptional ductility, when compared to ordinary steel reinforcement. This unique combination of strength and ductility makes SS bars well-suited for blast design applications. The overarching aim of this thesis is to gain better understanding of the blast behavior of RC flexural members designed with high-strength (HSS) and stainless steel (SS) reinforcement. This objective is achieved through a combined experimental and numerical research program. As part of the experimental research, a large set of beams, subdivided into three series, are tested under either quasi-static bending or simulated blast loads using the University of Ottawa shock-tube. Series 1 (HSC-HSS) and Series 2 (HSC-SS) aim at examining the effects of blast detailing (as recommended in modern blast codes,) on the quasi-static, blast and post-blast behaviour of high-strength concrete (HSC) beams reinforced with either ASTM A1035 high-strength bars (8 beams) or ASTM A955 stainless steel bars (16 beams). In addition to the influence of detailing, the effects of steel grade/type, steel ratio and steel fibers are also studied. Series 3 further studies the benefits of combining higher grade or higher ductility reinforcement, with more advanced ultra-high performance concrete (UHPC). This series includes 20 UHPC beams built with either ordinary, HSS or SS reinforcing bars (UHPC-NSS, UHPC-HSS and UHPC-SS). In addition to the effect of steel grade/type, concrete type, steel ratio and steel detailing are also studied. The results from Series 1 and 2 demonstrate the benefits of implementing high-strength and stainless steel reinforcement in HSC beams subjected to blast loads, where their use leads to increased blast capacity, reduced support rotations, and higher damage tolerance. The results further demonstrate the benefits of “blast detailing” on the ductility and resilience of such beams, under both static and blast loads. The results also show that the use of steel fibers can be used to relax blast detailing in the beams with high-strength or stainless steel by increasing the required tie spacing from d/4 to d/2. The results from Series 3 confirm that the use of UHPC in beams enhances flexural response (in terms of strength and stiffness), which in turn results in superior blast resistance. Conversely, the high bond capacity of UHPC makes such beams more vulnerable to bar fracture. Increasing the steel ratio is found to effectively increase the failure displacement and ductility of the UHPC beams. The use of high-strength steel is found to increase load capacity and blast resistance, while the use of stainless steel results in remarkable ductility, which further enhances beam response under blast loading. As part of the numerical research program, the static and blast responses of the test beams are simulated using either 2D or 3D finite element (FE) modelling, using software VecTor2 and LS-DYNA. The numerical results show that the 2D FE modelling using software VecTor2 can provide reliable predictions of the static and blast responses of the HSS or SS reinforced HSC beams built with varying detailing, in terms of load-deflection response, cracking patterns, failure mode, displacement time histories and dynamic reactions. Likewise, the 3D FE modelling using software LS-DYNA with appropriate modelling of UHPC (using the Winfrith Concrete or CSCM models) can well predict the blast responses of UHPC beams with ordinary, high-strength and stainless steel, in terms of displacement/load-time histories, damage and failure modes.

yes / Test results of thirty six ground granulated blast-furnace slag (GGBS)-based mortars and eighteen fly ash (FA)-based mortars activated by sodium silicate and/or sodium hydroxide powders are presented. The main variables investigated were the mixing ratio of sodium oxide (Na2O) of the activators to source materials, water-to-binder ratio, and fine aggregate-to-binder ratio. Test results showed that GGBS based alkali-activated (AA) mortars exhibited much higher compressive strength but slightly less flow than FA based AA mortars for the same mixing condition. Feed-forward neural networks and simplified equations developed from nonlinear multiple regression analysis were proposed to evaluate the initial flow and 28-day compressive strength of AA mortars. The training and testing of neural networks, and calibration of the simplified equations were achieved using a comprehensive database of 82 test results of mortars activated by sodium silicate and sodium hydroxide powders. Compressive strength development of GGBS-based alkali-activated mortars was also estimated using the formula specified in ACI 209 calibrated against the collected database. Predictions obtained from the trained neural network or developed simplified equations were in good agreement with test results, though early strength of GGBS-based alkali-activated mortars was slightly overestimated by the proposed simplified equations.

No description available.

The steel industry is aiming to reduce CO2 emissions by different means; in the short-term, by replacing fossil coal with highly reactive carbonaceous material like bio-coal (pretreated biomass) and, in the longer term, by using hydrogen. The use of bio-coal as part of top charged briquettes also containing iron oxide has the potential to lower the thermal reserve zone temperature of the Blast furnace (BF) and, due to improved gas efficiency, thereby give a high replacement ratio to coke. In order to select a suitable bio-coal to be contained in agglomerates with iron oxide, the current study aims at investigating the devolatilization behavior and related kinetics of different types of bio-coals. In addition, the aim is to investigate the self-reduction behavior of bio-coal-containing iron ore composite under inert condition and simulated blast furnace thermal profile. In the BF the temperature of the top-charged material will increase rather quickly during the descent in the upper part. Ideally, all the carbon and hydrogen contained in the top-charged bio-coal should contribute to the reduction. The devolatilization of bio-coal is thus important to understand and to compare between different types of bio-coal. To explore the devolatilization behavior for different materials, a thermogravimetric analyzer equipped with a quadrupole mass spectrometer was used to monitor the weight loss and off-gases during non-isothermal tests for bio-coals having different contents of volatile matter. The samples were heated in an inert atmosphere up to 1200°C at three different heating rates: 5, 10 and 15°C/min. The thermogravimetric data were evaluated by using the Kissinger–Akahira–Sonuse (KAS) iso-conversational model and the activation energy was determined as a function of the conversion degree. Bio-coals with both low and high content of volatile matter can produce reducing gases that can contribute to the reduction of iron oxide in bio-agglomerates. Bio-coals containing a higher content of catalyzing components such as CaO and K2O will enhance the devolatilization and release of volatile matter at a lower temperature.  The self–reduction of composites was investigated by thermogravimetric analyses in argon atmosphere up to 1100°C and evolved gases were monitored by means of quadrupole mass spectroscopy. Composites with and without 10% bio-coal and sufficient coke breeze to keep the C/O molar ratio equal to one were mixed and Portland cement was used as a binder. To explore the effect of added bio-coals, interrupted vertical tube furnace tests were conducted in a nitrogen atmosphere at temperatures selected based on thermogravimetric results, using a similar thermal profile as for the thermogravimetric analyzer. The variation between fixed carbon, volatile matter contents and ash composition for different types of bio-coal influences the reduction of iron oxide. The results showed that the self-reduction proceeds more rapidly in the bio-coal-containing composite and that the volatile matter could have contributed to the reduction. The self-reduction of bio-coal-containing composites started at 500°C, while it started at 740°C with coke as the only carbon source. The hematite was successfully reduced to metallic iron at 850°C with bio-coal present as a reducing agent, but not until 1100°C when using coke. Use of bio-coal with high content of volatile matter but low content of catalyzing elements as potassium, sodium and calcium in bio-agglomerates for the BF can be recommended because it enhances the self-reduction of iron oxide, e.g., wustite was detected by XRD analysis in samples treated up to 680°C. Bio-coal with low content of volatile matter, low alkalis, low phosphorous and high content of fixed carbon will also be suitable to use in the BF.

<p> This study deals with a method of analysis and the associated computer program that can capture the full nonlinear response of twodimensional reinforced concrete and steel plane frames subjected to dynamic loads, including blast and impact. Most of the relevant parameters that are normally neglected by similar available analysis tools have been considered in the present study. These include tension stiffening and concrete cracking, confinement effect and strain rate effect. Interaction between axial and bending deformations has also been accounted for. Four different constitutive models for concrete have been used and compared to each other together with multiple formulae accounting for the strain rate effect. The proposed analysis procedure was verified against other sophisticated software and experimental results and has proven to be a reliable means of analysis. </p> <p> The strain rate effect is shown to be a key parameter that plays an important role in the overall behaviour of structures under blast loads. Neglecting this effect does not necessarily lead to a more conservative design because it increases the overall stiffness of the structure which causes it to attract higher forces. This increase is proportional to the strain rate, which makes it particularly important in the case of blast loading where the strain rate can reach up to 1000 sec⁻¹. </p> / Thesis / Master of Applied Science (MASc)

<p dir="ltr">SC walls have emerged as an advantageous alternative to reinforced concrete (RC) construction for blast resistant structures. SC walls typically consist of shop fabricated steel modules which can be erected on site and filled with concrete, without additional formwork setup or removal. The steel modules typically consist of steel faceplates, tie bars between faceplates, and optional shear studs. SC members offer advantages in strength, ductility, constructability, and construction schedule when compared with RC. The behavior of SC structures have been previously demonstrated and adopted into many building design codes, but there is a knowledge gap on the post-elastic behavior of SC members in two-way bending. The desire to use SC walls for blast resistant design motivates the need to study this behavior for SC walls and slabs. In this study, the behavior of SC panels in two-way bending was evaluated by using analytical, experimental, and numerical methods.</p><p dir="ltr">Structural mechanics was used to develop simple predictions for the static behavior of rectangular, two-way SC panels under a uniform pressure loading. These predictions include the inelastic cross-section flexural capacity, the member static resistance function, the load-mass transformation factor for SDOF analysis, out-of-plane shear demands, and rotation demands. A quick-running SDOF computer algorithm was created to conduct blast load analysis incorporating the nonlinear member behavior predicted by mechanics.</p><p dir="ltr">The two-way bending behavior of a SC panel was experimentally investigated. A SC panel was fabricated and experimentally loaded in two-way bending until flexural failure of the panel was reached. A series of concentrated loads applied to the panel was designed to simulate the yield line pattern of a panel under a uniform applied pressure. The experimental test demonstrated the deformed shape, inelastic capacity, and progression of yield lines throughout a SC panel in two-way bending. A 2D, layered composite shell finite element analysis was benchmarked to the experimental results. The finite element modeled the inelastic flexural behavior of the SC panel, closely matching the capacity, deformed shape, and development of yield lines throughout the panel.</p><p dir="ltr">The finite element modeling approach was used to validate the SDOF predictions of two-way SC panel behavior under static and blast pressure loadings through a parametric study. Detailed comparisons of the two modeling results were made. Iso-damage pressure-impulse diagrams for multiple SC panel geometries were developed.</p>

Military-related blast-exposure and sports-related closed-head impact-injury are associated with traumatic brain injury (TBI) and chronic traumatic encephalopathy (CTE), a tau protein neurodegenerative disease. Despite growing awareness of links between TBI and CTE, the mechanisms underpinning this association, and relationship to concussive and subconcussive head injury, are poorly understood. This dissertation addresses the hypothesis that blast-exposure and impact-injury induce traumatic acceleration of the head and injurious forces in the brain that led to structural brain damage (TBI) and chronic sequelae, including CTE. This hypothesis was addressed in five specific aims: 1) develop a blast shock tube instrument and impact instrument to deliver relevant blast-exposure and impact-injury to mice, 2) validate a mouse model of single blast-exposure that recapitulates brain pathology in blast-exposed military veterans diagnosed with CTE, 3) validate a mouse model of single-repeat closed-head impact-injury that recapitulates brain pathology in contact sport athletes diagnosed with CTE, 4) match kinematics of blast and impact models using high-speed videography, 5) deploy kinematically-matched mouse models of single blast-exposure and single-repeat closed-head impact-injury to investigate mechanisms that trigger experimental concussion and post-traumatic sequelae. Blast and impact injuries were shown to cause similar CTE-linked brain pathologies, including microvasculopathy, neuroinflammation, astrogliosis, and phosphorylated tauopathy. Despite similarities in chronic consequences, blast-exposure and impact-injury produced different acute neurological responses. Surprisingly, impact-injured mice demonstrated signs of experimental concussion, whereas blast-exposed mice with comparable head kinematics did not. Computational modeling indicated that point loading of forces during impact, as opposed to distributed loading in blast, caused ipsilateral spikes in cortical shear stress which we conclude to be responsible for experimental concussion. The blast-exposure and impact-injury models have been and will continue to be invaluable tools for elucidating the mechanisms of and relationships between concussion, TBI, and CTE. / 2019-07-09T00:00:00Z