Recent terrorist attacks and accidental explosions have prompted increased interest in the blast resistant design of high-risk facilities, including government offices, private sector buildings, transportation terminals, sporting venues, and military facilities. Current blast resistant design standards prioritize the protection of the primary structural system, such as walls, columns, and beams, to prevent a disproportionate collapse of the entire structure. Secondary structural systems and non-structural components, such as blast resistant doors, are typically outside the focus of standard building design. Components such as blast resistant doors are designed and manufactured by private sector entities, and their details are confidential and considered proprietary business information. For this reason, scientific research on blast resistant doors is sparse and most test results are unavailable for public consumption. Nevertheless, the performance of blast doors is crucial to the survival of building occupants as they are relied upon to contain blast pressures and remain operable after a blast event to allow ingress/egress. These important roles highlight the critical need for further research and development to enhance the level of protection provided by components that are often not considered in any detail by protective design practice. This thesis presents a combined experimental and analytical research program intended to support the development of blast resistant hollow metal doors. A total of 18 static beam-assembly tests were conducted, which consisted of the flexural four-point bending of door segments, to inform on the performance characteristics of full-sized blast resistant doors. Six tests were conducted to evaluate the effectiveness of three skin-core construction methodologies, which consisted of one epoxy and two weld attachment specifications, between door skins and their internal reinforcing structures. The remaining 12 tests were performed to evaluate the in-situ performance of hinge hardware typically installed on blast resistant door assemblies. The results of the skin-core construction tests demonstrated that closely spaced weld patterns would provide the best blast performance. The results of the hinge hardware tests demonstrated that hinges which provided a continuous load-path directly into the primary ii structural core elements of the door frame and door were ideal; furthermore, robust hinges with fully-welded or continuous knuckles were best suited for limiting undesirable deformations. A semi-empirical analytical methodology was developed to predict the global deformation response of full-sized hollow metal doors subjected to blast loading in the seated direction. The goal was to provide practicing engineers who are competent but non-expert users of high fidelity simulations with the flexibility to conduct in-house evaluation of the blast resistance of hollow metal doors without having to conduct live explosive or simulated blast tests. A finite element analysis was first performed to compute the door resistance function. Hollow metal door construction was idealized using a bulk material sandwiched between sheet metal skins and internally stiffened by stringers. The properties of the bulk material were calibrated such that the deformability of the idealized core reasonably approximated the global load-deformation behavior which occurs due to loss of composite action when welds fail. The resistance curves were then used in a singledegree-of-freedom dynamic analysis to predict the displacement response of the door subjected to blast loading. The proposed methodology was first validated against the static beam-assembly flexural tests. It was then extended to the case of a full-sized door subjected to shock tube blast testing using results published in the literature. The proposed methodology was found to reasonably approximate the out-of-plane load-deformation response of beam-assemblies and full-size doors, provided the bulk material properties of the idealized core are calibrated against experimental data. Finally, the new Virginia Tech Shock Tube Testing Facility was introduced. A description of the facility, including an overview of the shock tube's location, construction, main components, instrumentation, and key operating principles, were discussed. Operating guidelines and procedures were outlined to ensure safe, controlled, and repeated blast testing operations. A detailed calibration plan was proposed, and future work pertaining to the development of blast resistant hollow metal doors was presented. / Master of Science / Recent terrorist attacks and accidental explosions have motivated an increase in the demand for blast protection of critical infrastructure. Secondary components, such as doors, play a pivotal role in the protection of occupants as they ensure blast pressures are contained and ingress/egress is possible after a blast event. Experiments have been conducted to characterize the performance of several door construction methodologies (i.e., epoxy, reduced weld requirements) and the in-situ performance of hinge hardware through quasi-static testing of beams whose construction closely mimics that of a full-size door. Results of door construction testing indicated that, whenever possible, blast resistant doors should be constructed with full weld attachment (maximum specification with weld spaced every 3”) as these doors were found to provide the greatest resistance. Due to inconsistent and sudden failure mode, epoxy skin-core construction is not recommended for use in blast resistant doors at this time. Hinge testing determined that hinge mounting plates (which hinge hardware leaves are attached to) should be integrally connected to the frame and door internal reinforcing elements to provide adequate strength and that hinges with fully welded knuckles should be used for blast applications to limit deformation and facilitate post-blast operability. An ABAQUS finite element analysis methodology utilizing a “skins and stringers” approach to generate a beam-assembly model resulted in an adequate prediction of load deflection results recorded during beam-assembly testing after calibration of the model. An extension of this modeling approach was used to model full-size doors and adequately captured their dynamic performance when subjected to blast loading. Finally, preparation of the Virginia Tech Shock Tube Testing Facility, which is currently in progress, is summarized with regards to its calibration and the first round of testing which will focus on providing more data for comparison with the analysis methodology developed in this research.

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.

Ground-motion data processing is a necessity for most earthquake engineering related studies. Important engineering parameters such as the peak values of ground motion and the ordinates of the response spectra are determined from the strong ground-motion data recorded by accelerometers. However, the raw data needs to be processed since the recorded data always contains high- and low-frequency noise from different sources. Low-cut filters are the most popular ground-motion data processing scheme for removing long-period noise. Removing long-period noise from the raw accelogram is important since the displacement spectrum that provides primary information about deformation demands on structural systems is highly sensitive to the long-period noise. The objective of this study is to investigate the effect of low-cut filtering period on linear and nonlinear deformation demands. A large number of strong ground motions from Europe and the Middle East representing different site classes as well as different magnitude and distance ranges are used to conduct statistical analysis. The statistical results are used to investigate the influence of low-cut filter period on spectral displacements. The results of the study are believed to be useful for future generation ground-motion prediction equations on deformation demands that are of great importance in performance-based earthquake engineering.

La prédiction de la réduction passive du bruit nécessite l’utilisation de modèles d’impédance acoustique fiables. La proposition de tels modèles en présence d’écoulement est un problème qui reste ouvert. Les travaux réalisés dans cette thèse sont consacrés à la mise en place d’une méthode expérimentale et numérique permettant de tester la validité de modèles d’impédance acoustique de traitements SDOF en présence d’écoulement. Cette approche repose sur la comparaison de résultats expérimentaux issus d’un banc aéroacoustique, et de résultats numériques issus d’un modèle FEM-PML axisymétrique basé sur l’équation de Galbrun. Ainsi, dans la première partie de cette thèse, le modèle FEM-PML utilisé est présenté. Dans la seconde partie, des modèles d’impédance acoustique de SDOF tenant compte de l’écoulement sont exposés, ainsi que la méthode de validation de ces modèles et les résultats de ces validations. / Prediction of noise reduction requires reliable acoustic impedance models. The proposal of such models in the presence of a mean flow is a problem which remains open. This thesis is devoted to the development of an experimental and a numerical method to test the validity of SDOF treatments acoustic impedance models in the presence of mean flow. This approach is based on the comparison of experimental results from an aeroacoustical duct, and numerical results from a FEM-PML axisymmetric model based on Galbrun’s equation. Thus, in the first part of this thesis, the FEM-PML model is presented. In the second part, some acoustic impedance models are exposed, and the validation method and the results of these validations are presented.

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.

Windows in building façade are vulnerable to blast pressures. When subjected to blast shock waves, glass windows may suffer failures, potentially causing serious injuries and casualties to the building occupants due to the flying glass shards and other projectiles. Protective films and laminated glass are widely used to protect windows against blast loads. These techniques have proven to reduce or prevent hazards associated with glass breakage. The use of steel or strengthened aluminum frames also reduce window blast hazards associated with frame failures. However, such measures are not always sufficient to mitigate the blast hazard if window retention anchors do not have sufficient resistance to blast pressures. Research on blast resistant windows is scarce in the literature. Therefore, a comprehensive research project was undertaken to address the behaviour, analysis, and design of window retention anchors. The research program consisted of combined experimental and analytical components. Three main phases were pursued, comprising of: i) Experimental research using a shock tube as blast simulator, ii) Numerical investigation based on three-dimensional finite element method (FEM) of analysis, and iii) Non-linear dynamic analysis of window systems based on a single-degree-of-freedom (SDOF) simplification. The experimental phase consisted of tests of 23 punched windows mounted on four different types of substrates consisting of structural steel, reinforced concrete, concrete block masonry, and stone masonry. The experimental parameters included window size and aspect ratio, glazing type, protective film thickness, substrate type, as well as the number and pattern of window retention anchors. Two levels of blast pressure-impulse combinations were used as per the recommendations of the U.S General Services Administration (GSA).The numerical phase involved FEM modelling and analysis of selected test windows. The FEM models were first validated against test results. The validated models were then employed to conduct an analytical parametric study. The parameters in this phase consisted of; substrate type, window frame rigidity, anchor fixity level in the substrate, window aspect ratio and size, anchor spacing, and blast pressure-impulse combination. The results demonstrated the significance of design parameters on window response, while also defining anchor force distribution along the window frame. A simplified SDOF method of analysis was developed for window systems, including the effects of anchor flexibility and substrate rigidity on non-linear response. The analysis approach includes the construction of window resistance functions in pre-break and post-break phases of response, where the latter stage of response is dominated by the membrane action of protective film. The analysis leads to the computation of anchor design forces, which have been validated against anchor shear and axial tension forces recorded experimentally. The SDOF analysis is recommended for use in designing blast-resistant window retention anchors on different substrates.

<p> A numerical algorithm has been developed to solve the sloshing motion of liquid in a Tuned Liquid Damper (TLD) outfitted by slat screens under large and random amplitude of excitation. It is based on the finite-difference method. The free surface has been reconstructed using volume of fluid method. Donor-acceptor technique has been used for tracking the volume fraction field. The effect of slat screen has been included and modeled using the partial cell treatment method. </p> <p> The algorithm is an integrated fluid-structure model where the response of the structure is determined considering the effects of TLD. The structure is assumed as a single degree of freedom system (SDOF) and its response is calculated using the Duhamel integral method. </p> <p> The algorithm has been validated against experimental data for the cases with and without screens. An excellent agreement was obtained between numerical and experimental results. </p> <p> An extensive parametric study has been carried out investigating the effect of slat screens and screen pattern on the TLD performance and on the structure response. A new parameter termed as slat ratio was introduced to characterize the slat screens based on their pattern. Results indicated that screen pattern has a significant effect on the TLD performance and it could lead up to 33 % reduction in structure response. It was found that decreasing the slat ratio will increase the damping effect of a TLD outfitted by slat screen. </p> <p> The validity of the most commonly used approach, Baines and Peterson model, to calculate pressure drop of slat screens has been investigated. A conelation factor as a function of Reynolds number and solidity ratio of screen has been proposed to improve the results of this model. A new concept termed as effective solidity ratio has been proposed to account for the physical significant of screen pattern on TLD performance. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.