Logical Analysis of Structural Failure

In engineering only the product, the hardware, is a physical system; the system which designs it, produces it and uses it is human and therefore complex and vulnerable. Human error of one form or another is a major cause of failures. One way of attempting to reduce this is to find ways of distilling conclusions from past performance by a logical analysis of available information. This analysis may then be stored as a computer data structure and used as a basis for predictions regarding future projects. The vehicle for this process, the handling of rather imprecise information, is fuzzy logic. A logical hierarchy of simple deductions has been set up to represent the three main influences on structural safety—human error, random hazards as well as the system uncertainty of reliability theory. The hierarchy is used to obtain measures of safety for two famous bridge failures.