Assessment of Existing Structures—Approaches and Research Needs

The possibility of safely extending the life of existing infrastructure is a matter that has become of increasing importance for the work of structural engineers, particularly when seen in the widest context of structural engineering. This paper proposes the view that the profession must be able to provide defendable estimates of the safety of individuals and of the safety and performance of existing structural systems. It will be argued that to do so requires prediction of future structural behavior at a level of detail and accuracy not hitherto required from the profession. Meeting this challenge opens up very extensive basic and applied research needs in structural engineering. These include better understanding and modeling of load processes and their rational combination; better understanding of structural system behavior and the influences of largely unknowable boundary and construction conditions; and much better understanding and modeling of processes such as fatigue, corrosion, deterioration of paint, and other protection systems. Moreover, it is argued that assessment procedures still require fundamentally acceptable and rational decision frameworks able to justify structural adequacy in terms increasingly being demanded by safety and environmental regulators.