Dynamic Behavior of UHPC-FST Under Close-In Explosions with Large Charge Weight

UHPC-FST pier columns are highly suitable for use in bridge engineering due to their exceptional structural and constructional capabilities. However, they are vulnerable to car bomb assaults when located in close proximity. This chapter intends to analyze the dynamic behavior of UHPC-FST specimens under close-in explosion with a significant charge weight, using both field explosion tests and numerical modelling. The initial step was conducting a field explosion test on five UHPC-FST specimens that were scaled down to 1/4 of their original size. The specimens were subjected to a TNT charge weighing 25 kg, and the test was carried out at scaled distances ranging from 0.10 to 0.17 m/kg1/3. The objective of the test was to evaluate the effects of standoff distance and burst height. The UHPC-FST demonstrates exceptional blast resistance as the specimens were able to preserve their structural integrity despite intense blast loads. Furthermore, a comparison was made between the distinct dynamic characteristics of UHPC-FST samples acquired from current and past explosion experiments using both high and low charge weights. Additionally, in order to carry out the necessary numerical simulation, the parameters of the K&C model were thoroughly calibrated for UHPC. Furthermore, the FE models of the field explosion test on UHPC-FST specimens were established using the commercial software LS-DYNA. Ultimately, the calibrated K&C model parameters and the established FE model were thoroughly validated by comparing the predicted damage mechanism and global deflection of UHPC-FST specimens with the test findings. This chapter can offer valuable resources for the design and assessment of the blast resistance of UHPC-FST.