The principles of conservation are not rocket science. They are based on an understanding of natural materials, structural behaviour and of prevailing building techniques. If intervention is required, it should be based on observation, study and reflection. Early deliberations on the approach to conservation were outlined by John Ruskin and William Morris in the 19th century. The first international attempt to address the principles of conservation were set out in 1931 in the Athens Charter under the auspices of the League of Nations. This batten has since been taken up by many international organisations, and this is not the place to go into detail, but further information is available in Technical Advice Notes published by Historic Scotland, and no doubt similar documents area available from English Heritage. A useful document has recently been published by ICOMOS (International Council on Monuments and Sites), entitled The principles for the analysis, conservation and structural restoration of architectural heritage. This outlines general criteria for such works. All engineers involved in older buildings should endeavour to adopt these principles. It is not a long document and should be to hand when carrying out such work and used with other design disciplines and clients. We have been involved in a number of Conservation Plans, which if nothing else allows the owner and designers to understand the cultural significance of the project in hand. But please, when you get the chance, fight for the integrity of the structure behind the finishes. Since the advent of the Heritage Lottery Fund, the issues highlighted by ICOMOS are invariably required as part of a Conservation Plan, and in the near future there will be a requirement for an appropriately registered professional to be involved in these works. The scheme for engineers has been running for nearly a year under the auspices of IStructE and ICE in the form of the Conservation Accreditation Register of Engineers, (CARE). In order to elaborate and illustrate a number of these issues, I will describe aspects of a number of projects with which we have been involved in over the last 15 years. Peter Elliott, BSc, CEng, FIStructE, FSA Scot
The application of fracture mechanics to predict the cracking damage in masonry buildings subjected to ground movement by tunnelling activity is presented in this paper. It describes the computational approach employed to capture the failure mechanism of a selected historical masonry façade. Both uncoupled and coupled soil-structure analyses are performed. Various continuum crack models are tested in largescale fracture analyses. The results indicate the need for reliable numerical techniques for large-scale fracture analysis of highly brittle material. M. Boonpichetvong Faculty of Architecture, Delft University of Technology, The Netherlands J.G. Rots Faculty of Architecture, Delft University of Technology, The Netherlands