Dynamic Response Characteristics that Lead to Direct Shear Failure in Blast-Loaded Columns

Blast-loaded structures respond dynamically to impulsive loads generated by an explosion. Individual components must possess adequate flexural and sectional shear capacity to survive such extreme loads. Unlike static loads, blasts can cause a unique limit state known as direct shear failure, which occurs early in the response history of a blast-loaded member. While various researchers have observed this phenomenon in past testing, the fundamental mechanics underlying this behavior are not completely understood. Multiple analysis approaches for capturing direct shear behavior of blast-loaded members have been proposed in the research literature, suggesting that further study is needed to understand this phenomenon. In this paper, direct shear response is explored in detail, demonstrating that this behavior originates from high-frequency contributions that are often neglected in modal analyses or misrepresented as a feature of traditional flexural response in single-degree-of-freedom analyses.