Hybrid modelling of blast vibration uses the signal produced from a single hole test shot to simulate the vibration that would be produced by a full-scale production blast. This simulation can be used to determine optimum hole timings to minimise the vibration generated at a point of interest. This thesis studies the assumptions that are made to facilitate the use of hybrid modelling with emphasis placed on near to mid field applications. A highly accurate seismograph is developed and used to monitor a series of test blasts carried out in limestone and chalk. The repeatability of single hole test shots is investigated. It is shown that in the near field single holes are generally highly repeatable even with relatively major differences in design. It is also shown that an inversion of the radial and transverse vibration traces may occur. The factors which affect the vibration magnitude are also explored, showing that the level of confinement can have a large effect on the magnitude of vibration. Two, three and five hole production blasts are examined to determine the signal generated by each hole in the blast. It is shown that in a two hole blast the second hole can produce an inverted signal in the radial and transverse components. The three and five hole are disassembled by using a computer program to test every possible combination of convolved single holes and select the best. It is concluded that the complex interaction of the vibration generated by each blast hole makes it very difficult to model the vibration generated by a production blast in the near field.

Modern day structures are reaching higher, spanning longer and undergoing new design methods. In addition to regular loads, it is becoming increasingly important to consider the potential risks of intentional and accidental explosions on structures. In the case of reinforced concrete buildings, critical elements such as beams and columns must de designed with sufficient strength and ductility to mitigate against the effects of blast loads to safekeep the public and prevent progressive structural collapse. Recent advancements in structural materials have led to the development of ultra-high-performance concrete (UHPC) with high compressive strength, tensile resistance, toughness and energy absorption capacity, properties which are ideal for blast protection of structures. Combining UHPC with high-performance steels, such as and high strength reinforcement is another potential solution to enhance the blast resilience of structures. This experimental and analytical research program investigates the advantages of combining high performance materials to increase the blast capacity of reinforced concrete beams. The experimental program includes tests on 21 beam specimens, fourteen of which are subjected to extreme blast loading using the University of Ottawa shock-tube, with seven companion specimens tested statically. Parameters investigated include: effect of concrete type (NSC vs. UHPC), effect of steel reinforcement type (NSR vs. HSR), effect of longitudinal reinforcement ratio, effect of fiber type/content and effect of transverse reinforcement on structural performance under static and dynamic loads. The experimental study includes three series having specified material combinations as follows: series 1 (NSC & NSR), series 2 (UHPC & NSR) and series 3 (UHPC & HSR). Each dynamically tested beam specimen is subjected to gradually increasing blast shockwaves until reaching failure. Performance assessment criteria included; maximum and residual displacements, overall blast resistance and resistance to secondary fragmentation. Results show that the specimens detailed with UHPC can resist greater blast loads with reduced mid-span displacement and debris generation when compared to beams built with conventional concrete. The combination of UHPC and high strength reinforcement further enhances blast performance and delays failure as both high strength materials balance themselves for optimum efficiency. Similarly, for specimens subjected to static loading, the use of UHPC increased the maximum load resisted by the beams, although failure mode alters from concrete crushing to rebar rupture. The combination of UHPC and high strength reinforcement further heightens beam resistance, at the expense of reduced specimen ductility. The analytical component of this thesis presents an analysis program called UO Resistance which is capable of predicting structural element resistance curves and conducting a dynamic inelastic single degree of freedom (SDOF) analysis of members subjected to blast loads. Resistance curves generated using UO Resistance were compared to data obtained through static testing and were found to effectively predict specimen response. Similarly, dynamic analysis methods implemented in UO Resistance prove to be effective at predicting specimen response under blast load. Additionally, a sensitivity analysis was performed to evaluate the effect of various modeling parameters on the static and SDOF dynamic predictions of specimen response.

This thesis focuses on the dynamic and static behavior of steel fiber-reinforced concrete (SRFC) beams. As part of this study a total of eighteen (18) beams are tested, including fourteen (14) SFRC beams, and a companion set of four (4) beams built without fibers. Seven (7) of the beams are tested under quasi-static (slowly applied) loading with the remaining eleven (11) beams tested under simulated blast loading using the University of Ottawa shock-tube. The variables considered in this study include: concrete type (SFRC vs. conventional concrete), fiber content, fiber type, as well as the effect of transverse reinforcement. The criteria used to evaluate the blast performance of the beams includes: overall blast capacity, maximum and residual mid-span displacement, secondary fragmentation and damage control. Static results confirm the beneficial effect of fibers on improving the shear and flexural capacity of beams. Dynamic results show that use of steel fibers at a sufficient content can increase shear capacity and effectively replace transverse reinforcement in beams tested under blast loads. The results also show that increasing fiber content can improve the blast response of the beams by reducing maximum and residual mid-span displacement, improving damage tolerance and minimizing secondary blast fragments. However, at high fiber contents, problems with workability of the concrete mix can occur, resulting in a reduction of improvements when compared to SFRC specimens with lower fiber content. The analytical research program aimed at predicting the response of the test beams using dynamic inelastic single-degree-of-freedom (SDOF) analysis. Overall the analytical results demonstrate that SDOF analysis can be used to predict the blast response of beams built with SFRC.

The influence of coking conditions, with respect to position in a commercial coke-oven, on the mechanical behaviour of blast furnace coke has been studied. This involved the determination of density, porosity, the characterization of microstructure and assessing the influence of all three on the compressive strength of coke. The plastic flow properties were also investigated at temperatures greater than 1000°C. Three coke batches, originating in a 5m commercial coke-oven at three different positions with respect to height (0.8m, 3.3m and 5m below the coal line), along with three coke batches produced in a 460mm test-oven, were supplied by Energy, Mines and Resources (CANMET) in Ottawa. A warf coke batch was also provided as a control sample. Several hundred core-drilled specimens (≃1.3cm diameter and 1.3cm length) were produced from the seven coke batches. The bulk density of each cylindrical coke specimen was determined. Also, a detailed microstructural analysis, using a Leitz Image Analyzer, of the flat faces of the coke cylinders was performed to quantitatively characterize the pore and cell wall size, and the pore geometry. The compressive strength of each coke cylinder was determined both at ambient temperature and at 1400°C. In addition, the plastic flow behaviour of the commercially produced coke batches was studied. Results indicate that the coke product bulk density was affected by the coke-oven pressure (static load). Studies of the test-oven coke batches revealed that coke bulk density increased with higher oven pressure. Furthermore, the pore size was found to be larger for cokes produced at lower oven pressures. The cell wall size did not appear to be affected by coke-oven pressure. The bulk density of the commercially produced samples increased with depth below the coal line. This was attributed to a higher temperature and static load that existed at the bottom of the battery. The pore size was larger in cokes extracted from higher regions. No correlation of cell wall size with depth below the coal line was found. However, an oven size effect on the pore and wall size was noticed. Both the pore and wall size was smaller in the test-oven coke batches. The compressive strength of coke was higher in batches subjected to higher coke-oven pressures. Similarly,' the compressive strength of commercial coke batches was higher for coke batches extracted from regions near the sole of the coke-oven, than that for coke batches extracted from higher regions. It was concluded that high oven pressures resulted in cokes exhibiting a lower porosity and small pores which had the combined effect of producing stronger coke. Coke strength was generally shown to be higher at 1400°C than at room temperature. The test-oven cokes were always stronger than cokes produced in the 5m commercial coke-oven. Constant load tests revealed that coke exhibited plastic flow behaviour at temperatures above 1000°C. The time dependent strain data was described using an interactive-double-Kelvin element visco-elastic model. / Applied Science, Faculty of / Materials Engineering, Department of / Graduate

The impact of improvised explosive devices (IEDs) on the safety of civilians can be devastating, especially when solid objects are inserted into the explosives. These inserts are propelled at high speed and increase the lethality of an IED detonation. Due to the wide range of possible IED configurations, a fundamental understanding of momentum transfer from explosives to the solid inserts is required. This project investigated the influence of charge geometry on the velocity of a 5 mm diameter stainless steel ball bearing. The ball bearing was half-buried and centrally placed on the at face of a cylindrical charge which was detonated centrally on the opposite face. The geometric parameters of interest were the charge diameter and the charge aspect ratio (length/diameter). Investigations were carried out in the project through blast and impact experiments as well as numerical simulations. The impact velocity of the explosively driven ball bearing was inferred using the impact crater depth on a witness plate. The correlation between crater depth and the impact velocity was determined using impact experiments which was performed using a gas gun. The average velocity (between detonation and impact) was captured by tracking the time of detonation and impact. The time of impact was recorded through a Hopkinson Pressure Bar (HPB) behind the witness plate. Additionally, the total axial impulse and the localised impulse, over the face of the HPB, were recorded by a ballistic pendulum and the HPB. Numerical simulations were conducted using a commercial software, Ansys Autodyn 18.0. The blast arrangement was simulated using a two-dimensional, axisymmetric model. The maximum velocity, average velocity, impact velocity, total axial impulse and localised impulse were 'extracted' from the simulations. The simulated velocities agreed well with experimental measurements, showing less than 2% variation. The deformed shape of the blasted ball bearings displayed similar characteristics to the model predictions. There were differences in the simulated impulse, with the numerical model predicting higher magnitudes but a less localised distribution. For a constant charge diameter, the bearing velocity increased in a nearly logarithmic manner with the increase in aspect ratio until a critical aspect ratio of <math><msqrt><mi>3</mi></msqrt></math>/2 was reached. At a constant charge mass, the bearing velocity decreased with the increase in charge diameter. The numerical model suggested that the influence of charge geometry on the bearing velocity was likely caused by the shape of the detonation pressure waves. The detonation pressure profile is sensitive to the charge aspect ratio and the diameter.

Unreinforced masonry (URM) walls are commonly found in existing and heritage buildings in Canada, either as infill or load-bearing walls. Such walls are vulnerable to sudden and brittle failure under blast loads due to their insufficient out-of-plane strength. The failure of such walls under blast pressures can also result in fragmentation and wall debris which can injure building occupants. Over the years, researchers have conducted experimental tests to evaluate the structural behaviour of unreinforced masonry walls under out-of-plane loading. Various strengthening methods have been proposed, including the use of concrete overlays, polyurea coatings and advanced fiber-reinforced polymer (FRP) composites. Fabric-reinforced cementitious matrix (FRCM) is an emerging material which can also be used to strengthen and remove the deficiencies in unreinforced masonry walls. This composite material consists of a sequence of one or multiple layers of cement-based mortar reinforced with an open mesh of dry fibers (fabric). This thesis presents an experimental and analytical study which investigates the effectiveness of using FRCM composites to improve the out-of-plane resistance of URM walls when subjected to blast loading. As part of the experimental program, two large-scale URM masonry walls were constructed and strengthened with the 3-plies of unidirectional carbon FRCM retrofit. The specimens included one infill concrete masonry (CMU) wall, and one load-bearing stone wall. The University of Ottawa Shock Tube was used to test the walls under gradually increasing blast pressures until failure, and the results were compared to those of control (un-retrofitted) walls tested in previous research. Overall, the FRCM strengthening method was found to be a promising retrofit technique to increase the blast resistance of unreinforced masonry walls. In particular, the retrofit was effective in increasing the out-of-plane strength, stiffness and ultimate blast capacity of the walls, while delaying brittle failure and reducing fragmentation. As part of the analytical research, Single Degree of Freedom (SDOF) analysis was performed to predict the blast behaviour of the stone load-bearing retrofit wall. This was done by computing wall flexural strength using Plane Section Analysis, and developing an idealized resistance curve for use in the SDOF analysis. Overall, the dynamic analysis results were found to be in reasonable agreement with the experimental maximum displacements.

Simulation of fracture in ductile materials is a challenging problem, since it typically occurs at length scales that are orders of magnitude smaller than that of the structures in which the fracture is occurring and, hence, difficult to resolve . One approach is to avoid modelling the micro-mechanics of ductile fracture by describing the macroscopic effects of fracture using damage parameters. Damage in metals can be defined as a measure of discontinuous deformation of a body. Many numerical models include some measure of damage to predict when a material will fracture under certain conditions, however there is little consensus as to what measures and parameters will accurately predict the onset of fracture. Most notably, the effect of strain rate at the point of fracture is significant and must be taken into account. The literature indicates that in the quasistatic regime where inertial effects are negligible, an increase in strain rate increases the strain at fracture. However, the research conducted in this dissertation suggests the opposite is true. The aim of this research is to conduct further high strain rate ductile damage experiments so as to extend the available data set, and develop a pragmatic damage model to relate the plastic strain at fracture to material parameters such as triaxiality, lode angle and strain rate in a specimen, which is verified using experiments performed under various loading conditions and strain rates.

Bibliography: pages 68-69. / This work describes what is primarily an investigation into methods for estimating the maximum permanent deformation of a circular cylindrical shell subjected to internal explosive loadings. A complete rigid-plastic analysis of the transient response is performed. Subsequently the effects of material properties are included. Finally the theoretical predictions are compared with the experimental results obtained from a series of tests on aluminium shell specimens.

Includes bibliographical references (leaves 131-134). / An investigation into the deformation and tearing of stiffened quadrangular plates subjected to a uniform blast load is presented. A series of experimental results and numerical modelling using the finite element package; ABAQUS, on built-in quadrangular mild steel plates of different stiffener configurations and sizes subjected to a uniform blast load are reported. The main objectives of this investigation are to determine the dynamic response of stiffened quadrangular plates subjected to uniform blast loads, to assess the effect of the stiffener configuration and size on plate failure and to use a new approach that uses material properties that include temperature dependency to model the plate response. The experimental procedure consists of creating an impulsive load with the use of plastic explosive and measuring the resulting impulse using a ballistic pendulum. Explosive is centrally laid out in two concentric rectangular annuli on quadrangular plates of thickness 1.6mm with stiffeners of sizes; 3x3mm, 3x7mm, 4x3mm and 4x7mm; and configurations; none, single, double, cross and double cross; to provide the impulse required to give deformations up to plate tearing. In all the tests of Mode I category of large inelastic deformation, the plate profiles are characterised by a uniform global dome. The results of mid-point deflection versus impulse for the various stiffener sizes and configurations for Mode I show a generally linear relationship. In all the experiments, thinning mechanisms at the boundary are observed for all plates despite different stiffener sizes and configurations. Thinning, however, is not consistent all around the boundary. Thinning is also observed at the stiffener side closest to the boundary for double and double cross stiffened plates. There is, furthermore, a reduction in the stiffener width where two stiffeners cross each other perpendicularly.

This thesis presents a damage model developed for the rapid prediction of the vulnerability of a ship concept design to AIREX weapon effects. The model uses simplified physics-based and empirical equations, threat charge size, geometry of the design, and the structure of the design as inputs. The damage volumes are customized to the design being assessed instead using of a single volume defined only by the threat charge size as in previous damage ellipsoid methods. This methodology is validated against a range of charge sizes and a library of notional threats is created. The model uses a randomized hit distribution that is generated using notional threat targeting and the geometry of the design. A Preliminary Arrangement and Vulnerability (PAandV) model is updated with this methodology and used to calculate an Overall Measure of Vulnerability (OMOV) by determining equipment failures and calculating the resulting loss of mission capabilities. A selection of baseline designs from a large design space search in a Concept and Requirements Exploration (CandRE) are assessed using this methodology. / Master of Science