The fundamentals of structural building codes

Partial Factor Design is nowadays a generally accepted design method for building and civil engineering structures. For most engineers the general philosophy that the safety factors depend on the type of the load and on the limit state under consideration makes sense. However, the background, in particular the reliability aspect, seems to be vague and is only understood by a handful of specialists. Even a general notion and feeling has not been developed in the minds of most designers. This is a pity: reliability aspects are in the same way essential for the design as the mechanical aspects are, but the knowledge and appreciation of most engineers is quite unbalanced. The reliability aspect plays also a key role in the development of a prescriptive code to a performance based code. The paper intends to address and explain these fundamental aspects of the codification processes and will also consider them in an historic perspective. On the one side, the present day codes will be compared with the allowable stress and load factor methods of the past. On the other a look into future developments like full probabilistic assessment, system approach, risk analysis and the inclusion of durability and maintenance strategies will be give