TABLE OF CONTENTS Risk analysis is normally based on identification and probabilistic evaluation of failure scenarios. Ideally, one would like to identify all of them in a complete and systematic way. A failure scenario can be described by a sequence of events, some of them external (e.g. fire spreading from a neighbouring building) and some of them internal to the system (e.g. failure of a valve to open). These events can be displayed in different graphical forms. One convenient structure to encompass a family of scenarios is the structure of a tree representing a sequential progression of branching points at which several possibilities can be envisioned. Two particular structures of tree are of interest in risk analysis: event trees and fault trees.
A loss scenario represents the sequence of events that can result in a fire. The scenario development process must be:
Sequentially structured in a time-related manner
Credible in terms of realistic incident outcomes
Contain sufficient information to allow the risk analysis team to quantify the scenario.
The identification of the scenario sequences should be done by using event trees.
The general modelling approach for exposure assessment involves the following steps:
Determine the vulnerable targets. Vulnerability is defined in terms of the potential failure limits of the target subsystems or components when exposed to the considered fire scenario. The main targets in building fires are the occupants, the structure and the property stored in...
