When subjected to blast loading, brittle building components such as glass and masonry tend to break into fragments that are propelled at hazardous high velocities. There has been copious research on defining the design resistance of structures subjected to extreme dynamic loading, but research that relates the loading characteristics to fragmentation velocity and lethality is lacking in some areas. A review of research concerning fragmentation of brittle materials in dynamic loading scenarios, concentrating on far-field blast loading, was conducted. Fragmentation principles and their application in, analytical, statistical, numerical, and other varied modeling approaches were examined. Special attention was given to research evaluating fragment generation and velocity calculation above the level required for design of structural members and suitable for occupant hazard calculation. By surveying fragmentation research key factors that affect fragmentation behavior, velocity, and hazard across modeling efforts are developed and discussed.
Very few methods are available for predicting the secondary fragment velocity and secondary fragment production of ungrouted and nonreinforced concrete masonry unit (UGNR CMU) walls when subjected to blast loading. Existing approaches often require large computational resources or fail to predict secondary fragment velocity accurately. This paper presents an engineering-level analysis methodology that can be rapidly implemented to predict the velocity of fragments from UGNR CMU walls subjected to blast loading. The theoretical background and need for the methodology are discussed. Results from the analytical methodology are compared to results from two full-scale experiments and four quarter-scale experiments. A strong correlation is demonstrated between the experimental results and the analytical methodology.
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