Study of blast effects on structures

Engineers have a duty to the public to preserve life and protect the community and occupants within structure that we build and use. All practicing engineers are obligated to foster the health, safety and wellbeing of the community and the environment. This involves acting on the basis of adequate knowledge and foreseeable risks that pose a potential hazard towards the built environment. The terrorism threat has evolved rapidly in scale and occurrences in recent history and with that the need to create resilient structures. This dissertation endeavours to undertake a study of the global blast loading effects on structures and identify techniques for improved structural resilience of critical elements. Blasts can be delivered by explosive events either deliberate, accidental or through indirect action. A historical review of case studies and blast incidents was undertaken to identify susceptible structures to blast and development of a structural model in order to simulate a credible scenario and understand the blast effects and predicting the design loading. The scope of the dissertation is restricted to the blast pressure disturbance effects interacting with a structure delivered by an external air blast and not considering the secondary effects of a blast incident including thermal and high velocity fragments. Common structural members and materials were used to devise a Finite Element model and simulate against the blast loading cases derived from empirical methods. Since the nature of blast load only lasting for a short time and undergoes constant change Non-Linear Transient Dynamic Analysis approach was well suited to undertaking this type of analysis. Some of the findings include whipping effects due to inertia as the structure accelerating from its initial position to develop resistance against the applied loading even after the applied load has ceased. The global response of a structure due to blast pressure, is generally a consequence of lateral or out-of-plane loading. Longer pressure phase durations tend to result in bending failures while impulsive loads (short pressure phase duration) lead to shear responses. Resilience techniques including steel UC encased in concrete, RC steel plate wraps and RC shear reinforcement lacing have the potential to improve the robustness of structural elements reducing overall displacements and stress responses