Probabilistic blast load model for domes under external surface burst explosions

摘要

The increasing threat of terrorist attacks and the risk of accidental explosions has raised the alarm on structural design, and consequently, the dome structure as the classical building configuration model for public buildings requires safe and reliable defence capabilities against blast loads for the duration of its lifespan. Some de-terministic blast load models for specific blast loading scenarios are unable to take the risk of damage into consideration. Therefore, the variability and uncertainty of blast loads need to be studied and quantified. In this study, a probabilistic blast load model is proposed based on a series of repeated field trials. The repeatability of explosive mass and size, detonator type and location, stand-off distance, field condition, data acquisition device and the structure were ensured to realise consistency and standardisation. The experimental results reveal a high degree of variability and uncertainty in the impulse, reflected overpressure and decay coefficient distributed on the studied dome under the effect of external surface explosions. The decay coefficient of a blast wave on the dome has a large variability with a coefficient of variation of 55% when the impulse is less than 8%, which demonstrates that the impulse distributed on the dome has higher precision than other blast load parameters. Furthermore, statistical analysis shows that the normal distribution is the best-fit probability blast load model in an anti-explosion protection design. Furthermore, the accuracy of some blast load predictive methods was also assessed. It was found that the semi-empirical CONWEP air blast code is not an appropriate blast load model for the dome. However, the Arbitrary Lagrangian-Eulerian model is a safer and relatively more accurate method for describing the distribution and variation characteristics of a blast wave distributed on the dome, which can serve as an approximate mean blast load.