This issue contains four varied and significant technical papers with authors from six different countries and three different continents. The first, by Setareh (2012), considers the evaluation and assessment of vibrations owing to human activity. This, like other issues of serviceability, is often considered to be becoming of greater importance as the combination of material strengths increasing and more refined analysis for strength makes structures of a given design strength less stiff. It is therefore interesting that the susceptible structure considered as an example was built in the 1920s. The paper concentrates on acceptability criteria rather than analysis and gives good insight into this subject showing that a more sophisticated criterion than simple peak acceleration is needed to get an accurate representation of acceptability. The paper proposes a new frequency weighted ‘VDV'. Tests reported include getting groups of volunteers to bounce up and down at predetermined frequencies: a rather different activity from conventional structural research.
The paper by Castel et al. (2012) considers the behaviour and strength of prestressed beams with bonded corroded strands. The paper considers tests in which actual corrosion was induced artificially leading to wire breaks and analyses behaviour by two different approaches, one a full non-linear finite-element approach and the other closer to traditional methods using ‘macro finite elements'. The paper contributes to the understanding of behaviour of this particular type of deteriorated structure and it is found wire breaks typically arise when the stress is close to yield. The paper finds that rebonding either side of the breaks after failure is not significant although it acknowledges that this may not apply to longer beams found in practice.
The paper by Cuadrado et al. (2012) considers sustainability of buildings. This has been a topical subject in recent years but this paper is unusual in considering specifically industrial buildings which it notes were traditionally ‘seen as no more than four walls and a roof under which a specific production activity took place'. The paper gives emphasis to design and construction, functionality, employee safety throughout all phases of the building's life-cycle, and the external image projected by the firm as a marketing component making the point that sustainability is not just about environmental issues.
The last paper by Zheng et al. (2012) considers the local strength of bridge deck slabs that fail in punching with strength much enhanced by compressive membrane action. I was particularly interested in this paper having done some research on the subject in the 1980s at the then C&CA. Then as now, non-linear analysis was the only way to really understand or predict the behaviour not only in terms of understanding the local behaviour in the area that is loaded and that fails but also in determining the restraint available. The tests reported use specimens that have relatively little surrounding structure to provide the restraint. The software and hardware available now for the analysis is much more advanced than when I was investigating the subject. However, perhaps the most significant change in terms of the direct applicability of the work is that then we used specialist programs developed in research institutions for the purpose as indeed did Castel, Coronelli and François in their paper on beams with corroded tendons. In contrast, the authors here use a publically available commercial program. This shows that the analysis can be done with software readily available to ordinary engineers. On the other hand, the paper also shows that some understanding is needed to get reliable results. Realistic modern bridges, typically without intermediate diaphragms, would also require larger computer models to predict behaviour and it will be interesting to see if engineers start using compressive membrane action more in design, over a century after it was first observed and mentioned in a paper.
Mention of ancient papers reminds me that on many occasions in my career, often when working on existing structures, I have had occasion to read Proceedings of the Institution from the 1960s and earlier. I have been struck by the greater and often more critical discussion than in more recent times. All the papers in this issue raise significant issues and your contribution to the discussion would be welcome.
