The mitigation of blast hazards on critical reinforced concrete structures has become a major concern in regards to the safety of people and the integrity of buildings. Recent terrorist incidents and accidental explosions have demonstrated the need to study the effects of such threats on structures in order to develop effective methods of reducing the overall impact of blast loads. With the arrival of innovative materials such as steel fibre reinforced concrete (SFRC), ultra-high performance fibre reinforced concrete (UHPFRC) and high strength steel reinforcement, research is required in order to successfully adapt these new materials in blast-resistant structures. Hence, the objective of this thesis to conduct an experimental parametric study with the purpose of investigating the implementation of these innovative materials in reinforced concrete slabs and panels. As part of the study, a total of fourteen one-way slab specimens with different combinations of concrete, steel fibres and steel reinforcement are tested under simulated blast loads using the University of Ottawa Shock-Tube Facility. The test program includes three slabs constructed with normal-strength concrete, five slabs constructed with SFRC and six slabs constructed with UHPFRC. Among these specimens, four are reinforced with high-performance steel reinforcement. The specimens are subjected to repeated blast loading with gradually increasing reflected pressure and reflected impulse until failure. The performance of the slabs is studied using various criteria such as failure load and mode, maximum and residual deflections, as well as tensile cracking, spalling and secondary fragmentation control. The behaviour of all specimens is compared in different categories to determine the effects of concrete type, steel reinforcement type, steel fibre content and steel fibre type on blast performance. As part of the analytical study the response of the slab specimens is predicted using dynamic inelastic single-degree-of-freedom (SDOF) analysis. The dynamic analysis is conducted by generating load-deformation resistance functions for the slabs incorporating dynamic material properties.

Corrosion of reinforcing steel embedded in concrete due to the presence of moisture, aggressive chemicals, inadequate cover, and other factors can lead to deterioration that substantially reduces the strength and serviceability of the affected structure. Accounting for corrosion degradation is critical for evaluation and assessment of the load carrying capacity of existing reinforced concrete (RC) structures. However, little is known about the relationship between high strain rate blast loading and the degradation effects that govern corrosion damaged structures such as concrete cover cracking, reduction in reinforcement areas, and deterioration of bond between concrete and steel. Ten identical RC beams were constructed and tested, half under blast loading conditions produced using the Virginia Tech Shock Tube Research Facility and the other half under quasi-static loading. The blast tests were conducted to investigate how increasing blast pressure and impulse affect the global displacement response and damage modes of beams subjected to blast loads. The quasi-static tests were performed to establish fundamental data on the load-deflection characteristics of corroded RC beams. One beam from each testing group served as a control specimen and was not corroded while the remaining beams were subjected to varying levels of corrosion (5%, 10%, 15%, and 20%) of the longitudinal reinforcement along the midspan region. The specimens were corroded using an accelerated corrosion technique in a tank of 3% sodium chloride solution and a constant electrical current, creating a controlled environment for varying levels of corrosion. An analytical model was also created using a single degree of freedom (SDOF) approach which predicted the performance of corroded RC beams under blast loading. The results of the quasi-static tests revealed that as corrosion levels increased, the load to cause yielding decreased, the yield displacements decreased, and failure occurred earlier for all specimens. This was accompanied by increased damage to the concrete cover and the addition of longitudinal corrosion induced cracking. For the blast loaded specimens, the results demonstrated that the maximum displacements and residual displacements increased beyond the expected response limits for corrosion levels greater than 5%, but at corrosion levels less than 5% there was no significant change in displacements. Damage levels increased by one or more categories with the introduction of even small levels of corrosion of less than 5%. At corrosion levels greater than 5%, before loading was applied, the specimens exhibited moderate damage due to the introduction of corrosion induced cracking. After loading, the specimens sustained hazardous damage at progressively lower blast volumes. The failure mode changed from ductile to sudden and brittle failure at corrosion levels greater than 5% but remained ductile with flexural failures at low corrosion levels below 5%. The experimental results could be predicted with a high level of accuracy using the SDOF approach, provided that the degraded strength of corroded concrete cover, degraded mechanical properties of corroded steel, length of the corroded region, and determination of either uniform or pitting corrosion are accounted for. Overall, the introduction of corrosion to an RC beam subjected to blast loading resulted in decreased strength and ductility across all specimens but with most disastrous effects occurring at corrosion levels of 5% or greater. A recommendation is made to adjust the response limits in ASCE/SEI 59 to account for corrosion in RC beams. / Master of Science / The threat of blast loads, resulting from either terrorist attacks or accidental explosions, poses a significant threat to the structural integrity of buildings, life safety of occupants, and the functionality of the structure. Corrosion of reinforcing steel embedded in concrete, due to the presence of moisture, aggressive chemicals, and other factors, can lead to deterioration that substantially weakens the affected structure. Accounting for corrosion degradation is critical for evaluation and assessment of the strength of existing reinforced concrete structures. However, little is known about the effects of blast loading on the adverse nature that governs corrosion damaged structures. Ten identical reinforced concrete beams were constructed and tested, half under blast loading and the other half under quasi-static loading. The blast loaded beams were subjected to a series of increasing blast volumes until failure was reached. Five identical beams were tested under quasi-static loading to provide a baseline comparison against the blast loaded beams. One beam from each testing group served as a control specimen and was not corroded while the remaining beams were subjected to varying levels of corrosion of the steel reinforcement. An analytical model was also created to predict the performance of corroded reinforced concrete beams under blast loading. The results of the study showed that as corrosion levels increased, the displacements increased beyond the expected response limits. Damage levels became increasingly more severe with the introduction of corrosion at all levels. The behavior changed from ductile to brittle at corrosion levels greater than 5% but remained ductile with flexural failures at corrosion levels below 5%. Overall, the introduction of corrosion to a concrete beam subjected to blast loading resulted in decreased strength and ductility across all specimens but with most disastrous effects occurring at corrosion levels of 5% or greater. A recommendation is made to adjust the response the limits in the code to account for corrosion in reinforced concrete beams.

Yes / Steel wire reinforced ultra-high performance concrete (SWRUHPC) offers exceptional resistance to impacts and blast, making it a promising construction material for infrastructure with blast-resistance demands. However, limited research has been conducted on the blast-resistance characteristics and design of SWRUHPC elements under blast loading, particularly in considering multiple influencing parameters and levels. Therefore, this study employed finite element simulation methods to investigate the influence of scaled distance (Z), reinforcement ratio (ρ) and slab thickness (D) as well as slab length (L) on the failure mode and maximum deflection of SWRUHPC slabs. Range analysis and variance analysis methods were used to quantitively analyze the effects of various factors on the blast resistance performance, culminating in the proposal of a design formula for SWRUHPC slabs. The results demonstrated that SWRUHPC exhibits superior blast resistance compared to ordinary concrete, effectively reducing the occurrence of concrete spalling and splashing, thus enhancing overall structural resilience in blast scenarios. Among the four factors analyzed, their influence on maximum deflection follows this order: D > Z > ρ > L. Notably, the maximum deflection decreases by 82% when the slab thickness increases from 40 mm to 90 mm. Additionally, the established design formula for SWRUHPC slabs under different scaled distances shows good agreement with the numerical simulation results, offering valuable design guidelines for SWRUHPC slabs in protective engineering structures. / National Science Foundation of China (52308236 and 52368031), and the Major Science and Technology Research Project of the China Building Materials Federation (2023JBGS10-02), Natural Science Joint Foundation of Liaoning Province (2023-BSBA-077), and the Fundamental Research Funds for the Central Universities (DUT24GJ202). / The full text will be available at the end of the publisher's embargo: 22nd July 2025

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<p>  </p> <p>The design of blast-resistant structures is critical for defense related facilities and industries. An emerging option for these applications is Steel-plate composite (SC) systems. SC systems include a steel module and concrete infill. Steel modules can include but are not limited to steel faceplates, tie bars, tie plates, diaphragm plates, and steel headed stud anchors. SC technologies have been adopted as a structural system in the design of nuclear powerplant containment vessels and high-rise buildings. These applications have benefitted from the inherent ductility and modular construction that SC systems provide.</p> <p>When designing structures to resist blast and impact, the desired behavior is for the structure to demonstrate ductility. Previous research has explored the behavior of a variety of SC elements; however, limited research on the behavior of L-joint connections exists. For L-joint connections to demonstrate ductile behavior, it is suggested that the joint that connects SC components- SC beams, columns, or slabs- be stronger than the connected elements. L-joint connections with joints stronger than the connected SC elements are considered full strength connections. As such, the connected elements reach their maximum bending moments and demonstrate ductile behavior. This study proposes a design philosophy for achieving full-strength L-joint connections using a diagonal steel reinforcing plate in the joint. This study evaluated the behavior of L-joint connections with joint reinforcement through large-scale experimental testing and subsequent benchmarked finite element analyses. The inclusion of a diagonal plate contributes to the L-joint connections ability to resist joint failure and develop a greater moment capacity in the SC members. This finding was also validated through finite element analyses comparing the specimen behavior with and without the joint reinforcement. The specimen without joint reinforcement experienced joint shear failure in the concrete while the experimental specimens were able to demonstrate ductile behavior prior to failure. </p>

The threat of terrorist bombings and accidental industrial explosions motivates the need for more economical and efficient blast-resistant construction techniques that offer enhanced levels of protection at reduced component damage levels. Despite having a high strength-to-weight ratio and being chemically inert, fiber reinforced polymer (FRP) reinforcing bars are not currently used in blast-resistant reinforced concrete due to their brittle nature and lack of ductility. However, the innovative use of blended mixtures of FRP and steel rebar as tensile reinforcement promises to address these limitations through self-centering behavior that provides reductions in residual damage and enhancements in flexural performance. This thesis presents the results of an experimental and analytical investigation on the effect of hybrid arrangements of glass fiber reinforced polymer (GFRP) and conventional mild steel reinforcement on the blast performance of reinforced concrete beams. Seven large-scale reinforced concrete beams with different combinations of tensile steel and GFRP rebar were designed, constructed, and tested under progressively increasing blast loading generated using the Virginia Tech Shock Tube Research Facility. The effect of hybrid reinforcing on the blast performance of the beams was evaluated based on the global response, failure mode, damage pattern, mid-span displacement, and support reactions of the tested beams. The results demonstrated several benefits in using hybrid arrangements of steel and GFRP reinforcement. Beams with hybrid reinforcing experienced reduced overall residual displacements compared with similar conventionally reinforced concrete members. This was attributed to the elastic nature of GFRP rebar which was found to produce a self-centering behavior that assisted in returning the hybrid members to their original undeformed position. This permitted the hybrid beams to safely experience larger maximum displacements at substantially less damage than all-steel construction. Furthermore, if the GFRP reinforcement did rupture, the presence of steel arrested hazardous component failure and provided additional energy dissipation and redundancy. Accompanying the experimental tests was an inelastic single-degree-of-freedom analysis to predict the displacement time-history response of the beams. Reasonably good predictions of response were obtained when the advanced material models and the effects of accumulated damage due to repeated blast testing were incorporated into the analytical predictions. Finally, a series of protective design recommendations and a new proposed response limit, that describes the level of damage achieved after a blast event, were established to encourage use of hybrid GFRP/steel reinforcement in blast-resistant construction. / Master of Science / The threat of terrorist bombings and accidental industrial explosions motivate the need for new blast resistant construction techniques. Despite having a high strength-to-weight ratio and being chemically inert, fiber reinforced polymer (FRP) reinforcing bars are not currently used in blast-resistant reinforced concrete due to their brittle nature and lack of ductility. However, the innovative use of blended mixtures of FRP and steel rebar as tensile reinforcement promises to address these limitations through self-centering behavior that provides reductions in residual damage and enhancements in flexural performance. Large-scale reinforced concrete beams with different combinations of steel and GFRP rebar were designed, constructed, and tested under progressively increasing blast loads, gen-erated by the Virginia Tech Shock Tube Research Facility. The results demonstrated that beams with hybrid reinforcing experienced reduced overall residual damage in comparison with similar conventionally reinforced concrete members. Additionally, if the GFRP rebar ruptured, the presence of steel prevented a brittle failure and provided additional energy dissipation and redundancy. The inelastic single degree of freedom model developed for this investigation resulted in an adequate prediction of the load-deflection characteristics record-ed from experimental testing. To encourage the use of hybrid FRP/steel reinforcement in blast-resistant construction, a series of protective design recommendations and a proposed response limit, that describes the level of damage achieved after a given blast event, were established.

It is important to ensure that vulnerable structures (federal and provincial offices, military structures, embassies, etc) are blast resistant to safeguard life and critical infrastructure. In the wake of recent malicious attacks and accidental explosions, it is becoming increasingly important to ensure that columns in structures are properly detailed to provide the ductility and continuity necessary to prevent progressive collapse. Research has shown that steel fibre reinforced concrete (SFRC) can enhance many of the properties of concrete, including improved post-cracking tensile capacity, enhanced shear resistance, and increased ductility. The enhanced properties of SFRC make it an ideal candidate for use in the blast resistant design of structures. There is limited research on the behaviour of SFRC under high strain rates, including impact and blast loading, and some of this data is conflicting, with some researchers showing that the additional ductility normally evident in SFRC is absent or reduced at high strain loading. On the other hand, other data indicates that SFRC can improve toughness and energy-absorption capacity under extreme loading conditions. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube. A total of 13 half-scale steel fibre reinforced concrete columns, 8 with normal strength steel fibre reinforced concrete (SFRC) and 5 with an ultra high performance fibre reinforced concrete (UHPFRC), were constructed and tested under simulated blast pressures. The columns were designed according to CSA A23.3 standards for both seismic and non-seismic regions, using various fibre amounts and types. Each column was exposed to similar shock wave loads in order to provide direct comparisons between seismic and non-seismically detailed columns, amount of steel fibres, type of steel fibres, and type of concrete. The dynamic response of the columns tested in the experimental program is predicted by generating dynamic load-deformation resistance functions for SFRC and UHPFRC columns and using single degree of freedom dynamic analysis software, RCBlast. The analytical results are compared to experimental data, and shown to accurately predict the maximum mid-span displacements of the fibre reinforced concrete columns under shock wave loading.

It is important to ensure that vulnerable structures (federal and provincial offices, military structures, embassies, etc) are blast resistant to safeguard life and critical infrastructure. In the wake of recent malicious attacks and accidental explosions, it is becoming increasingly important to ensure that columns in structures are properly detailed to provide the ductility and continuity necessary to prevent progressive collapse. Research has shown that steel fibre reinforced concrete (SFRC) can enhance many of the properties of concrete, including improved post-cracking tensile capacity, enhanced shear resistance, and increased ductility. The enhanced properties of SFRC make it an ideal candidate for use in the blast resistant design of structures. There is limited research on the behaviour of SFRC under high strain rates, including impact and blast loading, and some of this data is conflicting, with some researchers showing that the additional ductility normally evident in SFRC is absent or reduced at high strain loading. On the other hand, other data indicates that SFRC can improve toughness and energy-absorption capacity under extreme loading conditions. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube. A total of 13 half-scale steel fibre reinforced concrete columns, 8 with normal strength steel fibre reinforced concrete (SFRC) and 5 with an ultra high performance fibre reinforced concrete (UHPFRC), were constructed and tested under simulated blast pressures. The columns were designed according to CSA A23.3 standards for both seismic and non-seismic regions, using various fibre amounts and types. Each column was exposed to similar shock wave loads in order to provide direct comparisons between seismic and non-seismically detailed columns, amount of steel fibres, type of steel fibres, and type of concrete. The dynamic response of the columns tested in the experimental program is predicted by generating dynamic load-deformation resistance functions for SFRC and UHPFRC columns and using single degree of freedom dynamic analysis software, RCBlast. The analytical results are compared to experimental data, and shown to accurately predict the maximum mid-span displacements of the fibre reinforced concrete columns under shock wave loading.

It is important to ensure that vulnerable structures (federal and provincial offices, military structures, embassies, etc) are blast resistant to safeguard life and critical infrastructure. In the wake of recent malicious attacks and accidental explosions, it is becoming increasingly important to ensure that columns in structures are properly detailed to provide the ductility and continuity necessary to prevent progressive collapse. Research has shown that steel fibre reinforced concrete (SFRC) can enhance many of the properties of concrete, including improved post-cracking tensile capacity, enhanced shear resistance, and increased ductility. The enhanced properties of SFRC make it an ideal candidate for use in the blast resistant design of structures. There is limited research on the behaviour of SFRC under high strain rates, including impact and blast loading, and some of this data is conflicting, with some researchers showing that the additional ductility normally evident in SFRC is absent or reduced at high strain loading. On the other hand, other data indicates that SFRC can improve toughness and energy-absorption capacity under extreme loading conditions. This thesis presents the results of experimental research involving tests of scaled reinforced concrete columns exposed to shock wave induced impulsive loads using the University of Ottawa Shock Tube. A total of 13 half-scale steel fibre reinforced concrete columns, 8 with normal strength steel fibre reinforced concrete (SFRC) and 5 with an ultra high performance fibre reinforced concrete (UHPFRC), were constructed and tested under simulated blast pressures. The columns were designed according to CSA A23.3 standards for both seismic and non-seismic regions, using various fibre amounts and types. Each column was exposed to similar shock wave loads in order to provide direct comparisons between seismic and non-seismically detailed columns, amount of steel fibres, type of steel fibres, and type of concrete. The dynamic response of the columns tested in the experimental program is predicted by generating dynamic load-deformation resistance functions for SFRC and UHPFRC columns and using single degree of freedom dynamic analysis software, RCBlast. The analytical results are compared to experimental data, and shown to accurately predict the maximum mid-span displacements of the fibre reinforced concrete columns under shock wave loading.

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