Although the title of this book embraces ‘structures' in a general sense, the emphasis in this collection of papers by international authors is very much on aspects of the structural condition assessment of steel ships and offshore structures. Only four papers (out of 17) look at land-based structures. The content also deals with – as the preface confirms – ageing (existing) structures rather than aged (in the sense of historical).
Different aspects of the topic covered include the reliability of aged structures, their residual strength and mathematical models of age-related deterioration.
For all structures, the need for condition assessment – and within this there is coverage of inspection, repair and maintenance – is driven not only by considerations of safety but also increasingly by economics and environmental issues. ‘Structural integrity management' is seen as being of importance to the management of ships and offshore structures, but it is increasingly recognised as being equally important to those on land also.
There is a strong regulatory environment for ships and offshore structures — closer to that which exists in the aviation and nuclear industries, as well as dams and bridges, than to more general building structures. The experience from such regulation provides some useful lessons, and there is obvious commonality as to how structural assessment is carried out.
The constraints for inspection of the non-land-based structures are self-evident. What is of particular use here is the material covering the different types of inspection and a risk-based approach to both extent and timing, together with discussion of the various regimes and techniques used. Health and safety aspects of inspection encourage development of more remote monitoring methods, and there are a number of techniques – either in use or being developed – which not only collect data remotely, without the need for repeated physical access, but also allow some prediction of associated deterioration. There is some description of intelligent monitoring techniques in the paper on ‘Inspection of aged ships and offshore structures', but without subsequent discussion of possible application to land-based structures, perhaps surprisingly as this is an area where work is currently taking place.
In the papers related to land-based structures there is extensive coverage of concrete, its mechanisms of deterioration, testing and the generally recognised repair methods available, with comparatively abbreviated reference to steel and masonry structures. Much of this latter category is focused on ‘brick growth', that is irreversible volumetric expansion. Steel structures and their deterioration mechanisms, however, are given extensive review in the various papers on ships and offshore structures where the topics of corrosion and fatigue are examined in some depth. In looking at the reliability of aged land-based structures it is suggested that all the materials used – structural steel, concrete, masonry and stone (sic), also timber and fibre-reinforced plastics to a lesser extent – ‘tend to exhibit similar deterioration behaviour'. This appears to be a very broad generalisation and, while some more discussion might have been enlightening, no further elaboration is provided.
The topic of risk-based methods is looked at in some detail in the final paper. Although the paper focuses on ships and offshore structures, and in particular the problem of steel degradation, it is of more general use and applicability to all structures. While these methods have been more commonly used for mechanical and electrical systems, their use for structural systems, especially marine and offshore applications, is at a much earlier stage. Some work has been done on the integration of risk-based approaches into software, but for more general [land-based] structural application this would be harder because of non-standardised designs and lack of common environmental conditions.
Overall, this is a useful source of information for those involved with the inspection and maintenance of all structures. For those concerned with ‘land-based' structures, there is a significant body of useful information gained from the regulated industries beyond the coastline, and opportunities exist for common development of remote monitoring techniques. This area perhaps might usefully have been explored briefly in the preface.
