Probabilistic Damage Analysis of Offshore Installations
Sirous Yasseri KBR
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ABSTRACT
This paper presents a probabilistic method for generating explosion fragility curves for structures. Uncertainties in explosion loading and structure are quantified by varying parameters that define the loading and the structure. The uncertainty in each parameter is characterised by several representative values which are selected considering the uncertainty range of that parameter and its engineering implication. This gives a number of samples for the structure sample. Five loading conditions representing five return periods are defined, and by varying the defining parameters a number of sample were generated for loads. Performance requirement varies from, no damage to prevention of total collapse. The state of damage of the structure is defined by five limit states representing various degrees of damage. This allows the statistics of the structural capacity corresponding to each limit state to be determined.
Pairs of structures and explosion loading are then constructed from these selections. For each structure-explosion pair, a non-linear explosion analysis is performed to determine the ductility demand, these are then statistically analysed.
The fragility curve is generated by evaluating the limit state probabilities at different levels of explosion loading intensity. As an example, the fragility curves of an offshore blast wall are constructed.
The elements of the analysis methods are: (a) defining five loading levels and changing parameters for each loading to represent uncertainties; (b) varying parameters controlling the structural behaviour to represent the range of its response; (c) Pairing structure and loading for each load level and performing non-linear finite element analysis and categorising the response into five limit states; (d) constructing the fragility curves using statistical calculation.
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Tags: analysis of, element analysis, damage, sirous, offshore, analysis, installations, yasseri, probabilistic