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SUMMARY

Partially confined vapour cloud explosions will generate pressure loading onto wall and deck elements. The pressure rise time and duration will be relatively long compared to the natural period of the structural elements. The response of the structure is therefore usually in the quasi-static or dynamic regime and rarely in the impulsive regime.

A severe explosion is a low probability, accidental event which can be permitted to cause plastic deformation and large deflections. However, it should not lead to progressive collapse. The required analysis capability should therefore include a non-linear material behaviour and large deflection analysis capability. For problems that are neither impulsive or quasi-static, a non-linear time history response capability is also required.

Finite element packages with the necessary capabilities have been identified. They have been evaluated by the use of standard test cases. small differences in solution were observed between the various programs. However, these differences are relatively minor when compared with the accuracy to which the loads can be defined.

User experience is identified as a major factor in achieving accurate results. For the analysis of Blast Resistance, only engineers with the appropriate experience should be used. At present, there is no formal way of identifying people with the relevant experience (e.g. an Institute of FE Analysts).

Further development of some of the FE packages is desirable. However, there are a number of programs with sufficient features already available commercially. Rigorous analysis of Blast Resistance is therefore feasible, although in many circumstances the extra "accuracy" compared to simplified techniques will not be warranted.

The full report is publicly available from the HSE Website at www.hse.gov.uk/research/otipdf/oti92601.pdf.