<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>

Recently, numerous flexible structures have been employed in various fields of industry. Loading conditions sustained by these flexible structures are often not described well enough for engineering analyses even though these conditions are important. Here, a flexible tent with an interior Collective Protection System, which is subjected to an explosion, is analyzed. The tent protects personnel from biological and chemical agents with a pressurized liner inside the tent as an environmental barrier. Field tests showed unexpected damage to the liner, and most of the damage occurred on tent's leeward side. To solve this problem, various tests and analyses have been performed, involving material characteristics of the liner, canvas, and zip seals, modeling of the blast loading over the tent and inside the tent, and structural response of the tent to the blast loading as collaborative research works with others. It was found that the blast loading and the structural response can not be analyzed separately due to the interaction between the flexible structure and the dynamic pressure loading. In this dissertation, the dynamic loadings imposed on both the interior and the exterior sides of the tent structure due to the airblasts and the resulting dynamic responses were studied. First, the blast loadings were obtained by a newly proposed theoretical method of analytical/empirical models which was developed into a FORTRAN program. Then, a numerical method of an iterative Fluid-Structure Interaction using Computational Fluid Dynamics and Computational Structural Dynamics was employed to simulate the blast wave propagation inside and outside the flexible structure and to calculate the dynamic loads on it. All the results were compared with the field test data conducted by the Air Force Research Laboratory. The experimental pressure data were gathered from pressure gauges attached to the tent surfaces at different locations. The comparison showed that the proposed methods can be a good design tool to analyze the loading conditions for rigid or flexible structures under explosive loads. In particular, the causes of the failure of the liner on the leeward were explained. Also, the results showed that the effect of fluid-structure interaction should be considered in the pressure load calculation on the structure where the structural deflection rate can influence the solution of the flow field surrounding the structure. / Ph. D.

<p>The focus of this study is on evaluating the performance of nine, one-third scale, arching, reinforced masonry (RM) walls subjected to blast loads and three, one-third scale arching, RM walls subjected to out-of-plane static airbag loads. These RM walls were supported on four sides to enforce two-way arching allowing the ability to monitor individual response to varying levels of blast loads and standoff distances. The uniformity of the blast pressure and impulse were ensured by a specifically designed test enclosure, diminishing the wrap-around and clearing effects, allowing valuable data to be documented. The damage levels noted, ranged from Superficial to Blowout compared directly to the CSA S850-12 performance limits. The outcome of this experiment demonstrates the beneficial effect of two-way arching on the flexural behaviour of RM walls under impulsive loading. The use of two-way arching RM walls significantly reduces structural damage and increases out-of-plane resistance, which in turn enhances the overall structural integrity and building preservation. Further, when subjected to blast, two-way arching RM walls considerably reduces debris and their dispersal, thus increasing public safety and minimizing hazard levels. When using the experimental test data results to calibrate finite element models (FEM), more analytical data points can be obtained and therefore getting a larger range of scaled distances and trials. The validation of the LS-DYNA model can be used as an alternative to the costly experimental data, as the information collected concluded that the FEM gave damage patterns and failure modes that were comparable with experimental results. The test data collected provides a better understanding of RM wall response to blast loads and to the ongoing Masonry Blast Performance Database (MBPD) project at McMaster University. The generated MBPD will in turn contribute to masonry design clauses in the future editions of the recently introduced Canadian Standards CSA S850-12 “Design and Assessment of Buildings Subjected to Blast Loads”.</p> / Master of Applied Science (MASc)

There has always been a challenge for designing structures against extreme dynamic loads. Blast loading falls under these loads category and blast resistant design has been gaining more interest during the past decade. Among different types of structures, Reinforced Concrete (RC) structures are usually recommended to be used for blast resistant design. However, the nonlinearities associated with these structures make their accurate analysis complicated. Therefore, simplified techniques have been introduced for nonlinear dynamic analysis of these structures. This study focuses on developing simplified computational strategies for the dynamic analysis of blast loaded RC elements including beams, panels/slabs and columns. For RC beams, the basis for commonly used Single-Degree-of-Freedom (SDOF) models has been outlined. A Multi-Degrees-of-Freedom (MDOF) model which takes into account the concrete nonlinear properties has been developed and the effect of varying the number of degrees-of-freedom (DOF) on response has been studied. Results showed that increasing the number of DOF affects the pressure-impulse (P-I) diagrams, especially in the impulsive regime, as the extent of damage increased. In addition, the model was compared with the experimental data and showed good agreement. For RC panels, a SDOF technique, based on the US Army Technical Manual TMS-1300 instructions, was constructed and results were compared with the ones obtained from explicit Finite Element (FE) analysis. Compared to the FE results, SDOF model yielded conservative predictions for deflection but it usually underestimated the dynamic reactions. A modification for reaction calculation was proposed which resulted in significantly better prediction of the reaction for the impulsive range of loading. Finally, considering the important role of columns in providing the overall stability of the structure, a MDOF model was developed for RC columns and the load carrying capacity of the columns was investigated for different levels of axial load, strain rate and damage. Increasing the strain rate enhanced the column's cross section properties whereas increasing the levels of axial load reduced the cross section curvature and the column deflection capacities. Results also showed that good detailing at the supports can significantly improve the load carrying capacity of RC columns. / Thesis / Master of Applied Science (MASc)

The response of submerged structures subject to loading by underwater blast waves is governed by complex interactions between the moving or deforming structure and the surrounding fluid and these phenomena need to be thoroughly understood in order to design structural components against underwater blast. This thesis has addressed the response of simple structural systems to blast loading in shallow or deep water environment. Analytical models have been developed to examine the one-dimensional response of both water-backed and air-backed submerged rigid plates, supported by linear springs and loaded by underwater shock waves. Cavitation phenomena as well as the effect of initial static fluid pressure are explicitly included in the models and their predictions were found in excellent agreement with detailed FE simulations. Then, a novel experimental apparatus has been developed, to reproduce controlled blast loading in initially pressurised liquids. It consists of a transparent water shock tube and allows observing the structural response as well as the propagation of cavitation fronts initiated by fluid-structure interaction in a blast event. This experimental technique was then employed to explore the one-dimensional response of monolithic plates, sandwich panels and double-walled structures subject to loading by underwater shock waves. The performed experiments provide great visual insight into the cavitation process and the experimental measurements were found to be in good agreement with analytical predictions and dynamic FE results. Finally, underwater blast loading of circular elastic plates has been investigated by theoretically modelling the main phenomena of dynamic plate deformation and fluid-structure interaction. In addition, underwater shock experiments have been performed on circular composite plates and the obtained measurements were found in good correlation with the corresponding analytical predictions. The validated analytical models were then used to determine the optimal designs of circular elastic plates which maximise the resistance to underwater blast.

Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.

Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.

This thesis recounts the experimental study of the dynamic response of polycarbonate blast resistant glazing systems to explosive loading through the use of triaxial load cells, pressure sensors, and a laser displacement gauge. This instrumentation captured the response of the glazing systems to blast loading over three phases of testing. The first phase of testing characterizes the load distribution around the perimeter and the second phase examines the repeatability of the results. The final phase of testing pushes the samples to failure. The results are then compared to HazL, a commonly used blast resistant glazing system analysis software tool. The experimental data is also compared to data available characterizing the response of laminated glass.

Unreinforced masonry walls subjected to blast loading are vulnerable to collapse and fragmentation. The objective of this thesis is to conduct experimental and analytical research for developing a blast retrofit methodology that utilizes polyurea. A total of four unreinforced masonry walls were constructed and tested under various shock tube induced blast pressures at the University of Ottawa Shock Tube Testing Facility. Two of the retrofitted walls had surface-sprayed polyurea. The results indicate that the use of polyurea effectively controlled fragmentation while significantly increased the load capacity and stiffness of masonry walls. Polyurea proved to be an excellent retrofit material for dissipating blast induced energy by providing ductility to the system and changing the failure mode from brittle to ductile. Single degree of freedom (SDOF) dynamic analyses were conducted as part of the analytical investigation. The results show that the analytical model provides reasonably accurate predictions of the specimen response.

Recent events including deliberate terrorist attacks and accidental explosions have highlighted the need for comprehensive research in the area of structural response to blast loading. Research in this area has recently received significant attention by the civil engineering community. Reinforced Concrete (RC) water reservoir tanks are an integral part of the critical infrastructure network of urban centers and are vulnerable to blast loading. However, there is a lack of research and knowledge on the performance of RC reservoir walls under blast loading. The objective of this research study is to experimentally investigate the performance of reinforced concrete reservoir walls subjected to blast loading and to analyze the structural response. This study provides experimental test data on the performance of reinforced concrete reservoir walls under blast loading and complementary analytical predictions using the Singe-Degree-Of-Freedom (SDOF) analysis method. The reservoir walls in this study were designed according to the water volume capacity using the Portland Cement Association (PCA 1993) methodology. The design was validated using software SAP 2000. The experimental program involved the construction and simulated blast testing of two RC reservoir wall specimens with different support conditions: (1) two opposite lateral edges fixed, bottom edge pinned and top edge free; and (2) two opposite lateral edges fixed, and bottom and top edges free. The first boundary condition was intended to promote two-way bending action, while the second was dominated by one-way bending. The two specimens were each subjected to a total of six consecutive incrementally increasing blast tests. The experimental program was conducted in the shock tube testing facility that is housed in the University of Ottawa. Wall displacements, reinforcement strains, and reflected pressures and impulses were measured during testing. Analytical calculations were conducted using the equivalent SDOF method to simulate the dynamic response of the RC reservoir wall specimens under different blast loadings. Published tables, charts and coefficients contained in Biggs (1964) and UFC 3-340-02 (2008) were adopted in the equivalent SDOF calculations. The analytical results were compared against the ii experimental data. The SDOF method predicted smaller displacements than those recorded during testing. The approximate nature of the parameters and tables used in the equivalent SDOF calculations contributed to the discrepancy between the analytical and experimental results. Furthermore, assumptions regarding the support conditions and neglecting residual damage from previous blast tests contributed to the underestimation of the displacements.