The advancement in manufacturing technologies to produce high-performing engineered wood products (EWP) has allowed wood to be utilized beyond the traditional low-rise light-frame structures and to become a viable material option for much larger structures. Although glued-laminated timber (glulam) is included as a material option in the current blast code (CSA, 2012), its response to blast loading is not yet well documented. An experimental program investigating the behaviour of seventy glulam beams and columns was developed with focus on establishing the dynamic characteristics of glulam beams and columns with and without the effect of FRP reinforcement. A shock tube capable of simulating high strain rates similar to those experienced during blast was used. Thirty-eight beams with three different cross-sections were tested statically and dynamically to establish the high strain rate effects (dynamic increase factor). Six columns were also tested dynamically with axial load levels ranging from 15 to 75 % of the columns’ compression design capacity. Different retrofit configurations varying from simple tension reinforcement to U-shaped tension reinforcement with confinement using both unidirectional and bi-directional FRP were investigated on a total of twenty-six beams. A procedure capturing the strain-rate effects, variable axial load and FRP, was developed and found to be capable of predicting the flexural behaviour of the beams up to maximum resistance with reasonable accuracy when compared to experimentally obtained static and dynamic resistance curves. Implications on the design of both retrofitted and unretrofitted specimens are also discussed.

The experimental investigations performed on the behaviour of reinforce concrete elements subjected to blast loading have revealed that the shear mechanisms and ductility play important roles in the overall response and failure mode of such structures. The main aim of this master thesis is to study the possibility of using finite element method as a tool for predicting the dynamic response of blast loaded reinforced concrete beams and evaluation of their shear strength. In this study, the commercial software, ABAQUS/Explicit has been used by implementing appropriate constitutive material models in order to consider the material nonlinearity, stiffness degradation and strain rate effects. The results of some blast loaded tested beams have been used for verification and calibration of the model. As a secondary objective, the calibrated model used to study the influence of some important factors on the shear strength of reinforced concrete beams and investigate their effects on the failure mode. The results used as a reference and compared with the calculations according to some design codes for blast resistance design. The results of the present research show that the implemented nonlinear finite element model successfully simulates the dynamic responses including displacement/reaction force time histories and induced damage patterns of blast tested beams with reasonable accuracy. The results of performed parametric study confirm that the ductility play important role in the failure behaviour of studied beams. The numerical simulations show that dynamic response of a soft element is more ductile than the stiffer one and the shear forces are thereby limited. Thus, although a soft element fails by large deformations in flexure, a stiff element may experience a brittle shear failure mode for the same load intensity. The comparison between the results of numerical analysis and design codes calculation show that the American approach in shear design of reinforced concrete elements subjected to blast loading is relatively conservative, similar to static design approach and do not consider the effect of ductility in the shear design procedure. On the contrary, the procedure that Swedish guideline implemented somehow considers the effect of ductility on the shear strength of reinforced concrete elements subjected to impulsive loads. Further research should involve the using the developed finite element model as a tool in order to theoretically study the dynamic response of blast loaded reinforced concrete elements and their failure modes. The results of numerical simulations can be used as a reference to derive simplified computational methods for practical design purposes.

Deliberate and accidental explosions along with the heightened risk of loss of life and property damage during such events have highlighted the need for research in the behaviour of materials under high strain rates. Where an extensive body of research is available on steel and concrete structures, little to no details on how to address the design or retrofitting of wood structures subjected to a blast threat are available. Studies reported in the literature that focused on full scale light-frame wood structures did not quantify the increase in capacity due to the dynamic loading while the studies that did quantify the increase mostly stems from small clear specimens that are not representative of the behaviour of structural size members with defects. Tests on larger-scale specimens have mostly focused on the material properties and not the structural behaviour of subsystems. Advancements in design and construction techniques have greatly contributed to the emergence of taller and safer wood structures which increase potential for blast threat. This thesis presents results on the flexural behaviour of light-frame wood stud walls subjected to shock wave loading using the University of Ottawa shock tube. The emphasis is on the overall behaviour of the wall subsystem, especially the interaction between the sheathing and the studs through the nailed connection. The approach employed in this experimental program was holistic, where the specimens were investigated at the component and the subsystem levels. Twenty walls consisting of 38 mm x 140 mm machine stress-rated (MSR) studs spaced 406 mm on center and sheathed with two different types and sheathing thicknesses were tested to failure under static and dynamic loads. The experimental results were used to determine dynamic increase factors (DIFs) and a material predictive model was validated using experimental data. The implications of the code are also discussed and compared to the experimental data. Once validated, an equivalent single-degree-of-freedom (SDOF) model incorporating partial composite action was used to evaluate current analysis and design assumptions. The results showed that a shock tube can effectively be used to generate high strain-rate flexural response in wood members and that the material predictive model was found suitable to effectively predict the displacement resulting from shock wave loading. Furthermore, it was found that current analysis and design approaches overestimated the wall displacements.

Deliberate and accidental explosions along with the heightened risk of loss of life and property damage during such events have highlighted the need for research in the behaviour of materials under high strain rates. Where an extensive body of research is available on steel and concrete structures, little to no details on how to address the design or retrofitting of wood structures subjected to a blast threat are available. Studies reported in the literature that focused on full scale light-frame wood structures did not quantify the increase in capacity due to the dynamic loading while the studies that did quantify the increase mostly stems from small clear specimens that are not representative of the behaviour of structural size members with defects. Tests on larger-scale specimens have mostly focused on the material properties and not the structural behaviour of subsystems. Advancements in design and construction techniques have greatly contributed to the emergence of taller and safer wood structures which increase potential for blast threat. This thesis presents results on the flexural behaviour of light-frame wood stud walls subjected to shock wave loading using the University of Ottawa shock tube. The emphasis is on the overall behaviour of the wall subsystem, especially the interaction between the sheathing and the studs through the nailed connection. The approach employed in this experimental program was holistic, where the specimens were investigated at the component and the subsystem levels. Twenty walls consisting of 38 mm x 140 mm machine stress-rated (MSR) studs spaced 406 mm on center and sheathed with two different types and sheathing thicknesses were tested to failure under static and dynamic loads. The experimental results were used to determine dynamic increase factors (DIFs) and a material predictive model was validated using experimental data. The implications of the code are also discussed and compared to the experimental data. Once validated, an equivalent single-degree-of-freedom (SDOF) model incorporating partial composite action was used to evaluate current analysis and design assumptions. The results showed that a shock tube can effectively be used to generate high strain-rate flexural response in wood members and that the material predictive model was found suitable to effectively predict the displacement resulting from shock wave loading. Furthermore, it was found that current analysis and design approaches overestimated the wall displacements.

Indiana University-Purdue University Indianapolis (IUPUI) / Structural optimization of vehicle components for blast mitigation seeks to counteract the damaging effects of an impulsive threat on occupants and critical components. The strong and urgent need for improved protection from blast events has made blast mitigating component design an active research subject. Standard up-armoring of ground vehicles can significantly increase the mass of the vehicle. Without concurrent modifications to the power train, suspension, braking and steering components, the up-armored vehicles suffer from degraded stability and mobility. For these reasons, there is a critical need for effective methods to generate lightweight components for blast mitigation. The overall objective of this research is to make advances in structural design methods for the optimization of lightweight blast-mitigating systems. This thesis investigates the automated design process of isotropic plates to mitigate the effects of blast loading by addressing the design of blast-protective structures from a design optimization perspective. The general design problem is stated as finding the optimum shape of a protective shell of minimum mass satisfying deformation and envelops constraints. This research was conducted in terms of three primary research projects. The first project was to investigate the design of lightweight structures under deterministic loading conditions and subject to the same objective function and constraints, in order to compare feasible design methodologies through the expansion of the problem dimension in order to reach the limits of performance. The second research project involved the investigation of recently developed uncertainty quantification methods, the univariate dimensional reduction method and the performance moment integration method, to structures under stochastic loading conditions. The third research project involved application of these uncertainty quantification methods to problems of design optimization under uncertainty, in order to develop a methodology for the generation of lightweight reliable structures. This research has resulted in the construction of a computational framework, incorporating uncertainty quantification methods and various optimization techniques, which can be used for the generation of lightweight structures for blast mitigation under uncertainty. Applied to practical structural design problems, the results demonstrate that the methodologies provide a practical tool to aid the design engineer in generating design concepts for blast-mitigating structures. These methods can be used to advance research into the generation of reliable structures under uncertain loading conditions inherent to blast events.