Abass Braimah

Near-field Explosion Effects on the Behaviour of Reinforced Concrete Columns: A Numerical Investigation

The high incidence of global terrorism and accidental explosions have highlighted the vulnerability of built infrastructure to blast loading. Thus, owners of iconic structures are looking for ways to protect their critical assets from the effects of explosions. Many of the research efforts, in this light, have been devoted to the effects of far-field explosions on structural elements. The effects of near-field explosions on structural elements, especially columns, have not been as widely investigated. This paper presents the results of a comprehensive research program designed to investigate the effects of near-field explosions on the behaviour of reinforced concrete columns designed and detailed for regions of different levels of seismicity. The numerical study shows that reinforced concrete columns subjected to blast loading from higher explosive charge masses have higher deflections than those subjected to blast loading from lower charge masses, but at the same scaled distance. Also, the effect of closely spaced transverse reinforcement is significant at smaller scaled distances. Thus, reinforced concrete columns designed and detailed for areas of high seismicity have an inherently high blast resistance.

Experimental Investigation of Aluminum Foam Lined Suppressive Shield Containment Vessels

Manufacture, transport, and storage of dangerous goods, especially energetic materials, in Canada and around the world pose serious challenges to explosives regulators and inspectors. Currently siting of manufacturing and storage facilities are in accordance with quantity-distance principles designed to mitigate effects of accidental explosions. The land requirements to satisfy these principles are imposing financial burdens on the explosives sector. This paper presents an experimental program designed to investigate the effectiveness of suppressive shield containers in reducing the blast pressure outside of the container while eliminating fragments thus reducing the distance requirement for the stored amount of explosives. Several suppressive shield panels including aluminium foam-lined panels were tested to study their effect on blast pressure and impulse. In addition computational fluid dynamics techniques were used to study suppressive shields effects on blast environment. The results show reduction of the incident peak blast pressure by 60% and the incident impulse by 58%. The aluminium foam-lined suppressive shield panels attenuated the peak incident pressure and impulse by 80%.

Computational Method for Calculation of Blast Pressure Outside Vented Suppressive Shield Containers

Vented suppressive shield (VSS) containers have traditionally been used to store hazardous materials, especially explosives, and to attenuate the blast pressure and impulse outside the shield. VSS containers also eliminate the primary fragment hazard associated with accidental explosions. Most VSS containers are designed from experience and observations of container test programs. This design process, however, limits the designers ability to economize on materials or use suppressive shield configurations other than those used in the test programs. The aim of this study is to investigate the interaction between the blast waves and the structural steel elements used in VSSs. This paper investigates the effect of different VSS sections (configurations) in the attenuation of blast pressure outside the container and develops semiempirical equations that can be used to predict blast pressure and impulse outside VSS containers. AUTODYN, a commercial software package, was used to model the explosive detonation process and the evolution of the blast wave and its interaction with the VSS. Different VSS configurations, which ranged in complexity and included single- and multilayer shields, were studied. The single- and multilayer VSSs were compared and used to develop semiempirical equations to predict the pressure and impulse outside the VSS container. The proposed equations were compared with the results obtained from a previous experimental test program and showed a very good correlation.

Dynamic behavior of ribbon floating bridges

Floating bridges are economical means for crossing water bodies, especially in times of emergency or war. A special type of floating bridge, a ribbon pontoon floating bridge, is designed, built, and stocked by the military and emergency management organizations to be deployed in times of need. Lightweight and quickly erected, such bridges use the buoyancy of water to support their weight and imposed traffic loads. With increasing vehicular weights and the need for fast traversing times, analytical tools capable of designing and analyzing floating bridges are necessary. This development is ideal for optimizing vehicle weights and spacing to achieve greater economic efficiency. An analytical and experimental research program designed to study the dynamic behavior of ribbon pontoon floating bridges under two-axle vehicular loading is presented. This analytical method yielded maximum bridge displacements comparable to the experimental results. In most cases, analytical results were higher than experimental results; this difference provided a level of conservatism for design. Midspan displacements were accurately predicted as the vehicle traversed the floating bridge. However, at heavier vehicle weights, the analytical model failed to predict midspan displacement accurately at axle locations beyond midspan.

Aluminum foam-lined suppressive shields for safe transport of explosives

The manufacture, transportation, and storage of explosives in Canada and around the world pose serious challenges to explosives regulators and inspectors tasked with ensuring the safety of nearby populations. Explosives are routinely transported through, and manufacturing and storage facilities are often located close to, populated areas and traffic routes. This proximity increases the risk of severe casualties and infrastructure damage if there is an accidental or deliberate explosion. Even though an explosion is unlikely, the consequences can be severe. Several accidents that have involved explosives are discussed in the literature. These accidents highlight the devastation likely to result from an explosion and underscore the importance of finding cost-effective solutions to mitigate the effects on the population and infrastructure. This paper presents a research program designed to investigate the effectiveness of suppressive shield containers in reducing the blast pressure outside the container and eliminating fragment hazards from an explosion. Several types of suppressive shield panels, including panels lined with aluminum foam, were tested in a blast chamber. The results show reduced peak blast pressure outside the container by as much as 60% and in the incident impulse by about 58%. When the suppressive shield was lined with aluminum foam, a further reduction in peak incident pressure (up to 80%) was achieved.