The term robustness is used rather loosely in the context of structural engineering. Some consider it to be synonymous to redundancy and reserve system capacity, others consider it to be the opposite of vulnerability (which it self is also subject to various interpretations) to specific hazards, and yet others point out that robustness is critically related to the chain of consequences and decisions triggered by changes or deviations of the system characteristics. In this paper, we identify and examine the essential attributes of a robustness analysis: the careful system definition, definition of a set of desirable system characteristics and risk...