Dynamic analysis of multihazard-resistant bridge piers having concrete-filled steel tube under blast loading

Research was conducted to analytically investigate the blast-response and behavior of multihazard-resistant bridge piers having circular-shaped, concrete-filled steel tube (CFST) columns. Two different analysis methods, namely a single-degree-of-freedom (SDOF) dynamic analysis and a fiber-based dynamic analysis, were used for this purpose and calibrated with the maximum residual deformations obtained from 1/4 scale blast tests of CFST columns. It was noted that the structural response of SDOF dynamic analyses is sensitive to assumptions made in the load-mass factors needed to model structural components as an equivalent SDOF system. Fiber-based dynamic analyses showed that high-frequency modes of vibration have some influence on the structural response when subjected to blast loading. This study shows that different values of the shape factors, (which reduces blast pressures when applied to a circular column), must be used with different analytical methods, along with assumptions and conditions behind these different analytical methods.