Manuel Campidelli

Experimental Performance of Steel Beams under Blast Loading

In this study, the dynamic response of typical wide-flange steel beams was experimentally evaluated under blast loading. A total of 13 beams were field tested using live explosives, where the charge size ranged from 50 to 250 kg of ammonium nitrate-fuel oil mixture, and the ground stand-off distance was from 7.0 to 10.3 m. Blast wave characteristics, including incident and reflected pressures, were recorded. In addition, time-dependent displacements, accelerations, and strains at different locations along the steel members were measured, and the postblast damage and mode of failure of the test specimens were observed. The blast load characteristics were compared with those obtained using the Technical Manual UFC 3-340-02 results. The displacement response results were used to validate the results obtained from a nonlinear dynamic analysis based on a single degree-of-freedom (SDOF) model. Results showed that the UFC 3-340-02 pressure predictions compare reasonably well with the measured pressure in the positive phase in terms of both the peak pressure and overall time variations. The SDOF model predicted the maximum displacements of beams in the elastic range reasonably well, but it overestimated them in the plastic range.

Inference of Blast Wavefront Parameter Uncertainty for Probabilistic Risk Assessment

AbstractProbabilistic risk assessment methodologies are typically employed to optimize resource allocations for blast risk mitigation schemes, which may be necessary for the design of new blast resistant facilities as well as the hardening of existing construction. A key aspect of any blast risk assessment methodology is the quantification of uncertainty inherent in the prediction of shock wave parameters. In this study, a blast pressure database that was generated from arena testing using live explosives is used to infer the probability distributions that best represent the model error affecting the prediction of four key wavefront parameters, namely: the peak pressure, specific impulse, duration, and waveform coefficient of the positive pressure phase. Confidence intervals are given for the descriptors of each distribution and their percentiles. In addition, two sets of partial factors are developed for the blast-resistant design of structures requiring high level of protection (LOP) based on a simplifi...

Resilience-based design of urban centres: application to blast risk assessment

Abstract Current standards for the blast protection of buildings are primarily focused on the response of single components and do not provide adequate tools to quantify the overall performance of complex structural systems. Methodologies that can translate structural damage into information actionable by policy-makers are greatly needed to support the risk management process. The best efforts produced to date towards a comprehensive analysis of the built environment under blast threats can be classified under the umbrella of probabilistic risk assessment, which can provide the public with projections of casualties and economic loss. However, additional metrics are needed in order to capture the post-blast resilience of target facilities. The current study addresses the need of a unified risk and resilience framework, wherein new design criteria – the functionality loss index and the resilience indicator – are proposed as instrumental to the assessment of a building’s post-blast functionality and resilience in an integrated fashion.

Blast Resilient Design of Infrastructure Subjected to Ground Threats

The growing number of terrorist attacks in the past decade has focused the public’s attention on the severity of such a man–made hazard. The rising threat of improvised explosive devices — one of the most successful attack strategies — has significantly increased the number of threats on the ground, in the form of suicide–bombs, vehicle–bombs, etc., thereby requiring the development of more effective blast risk mitigation measures. However, the modern proliferation of such measures poses the problem of evaluating their cost–effectiveness, which prompts the need for a comprehensive optimization methodology — capable of maximizing the resilience of the built environment. The aim of this paper is to lay out the foundations of a resilience–based framework for quantifying the performance of different infrastructure elements incurring blast threats, by means of functionality and resilience indicators. The proposed framework can quantify the consequences of multiple outdoor explosions typified by the emblematic car–bomb scenario. The level of localized damage is evaluated via pressure–impulse diagrams; local failures are then aggregated into the definition of resilience and functionality indicators, designed to provide the analyst with a comprehensive picture of global damage, residual functionality, and downtime of the structural system.Copyright