Managing safety and hazard through dependability

Abstract

There is an implied view, at the root of current techniques for dealing with structural safety, that safety factors or probabilities of failure exist objectively. An analogy between truth and safety is used in a critical analysis of the essential incompleteness of theoretical models. Theories are seen as social constructs which depend on the culture and objectives of those who build them. Theoretical models are dependable if they are highly tested. Dependability, it is argued, is a measure of truth content of a statement or of safety content of a structure. It is argued that it is necessary to move away from the idea that structural safety should be concerned with the prediction of a ‘true’ factor of safety, or probability of failure, to the idea of management of hazard as a process. It is argued that factors of safety and probabilities of failure are features of theoretical models to be used in the management of hazard. A hazard is a set of preconditions to failure. Hazard engineering should be concerned with hazard auditing and hazard management. A structure earns dependability through the process of hazard auditing based on critical tests of the design, construction and operation of the structure. Measures of dependability can be used in management of hazard. A conceptual model, which is an extension of the limit state hypervolume, is described and the requirements of a computer tool for the management of hazard outlined.