Conservation compendium. Part 18: Non-invasive quantitative appraisal of historic floor structures

James Miller brings this series to a close by looking back over ground covered and forward to a bright future in which conservation accreditation is increasingly valued and engineers are able to innovate through the application of emerging technologies.

The authors recently conducted a study into the elastic behaviour of thin (Kirchhoff ) plates using commercial finite-element (FE) software. In attempting to verify the FE solution, it was compared to results presented in Timoshenko’s Theory of Plates and Shells and a significant difference was observed. This article presents the work conducted to uncover the reason for this difference and reveals an error (probably typographical) in the text. The source of the error is identified and it is demonstrated how such errors might propagate into other texts on the subject of plates. The significance of the error to the practising engineer is also discussed.

Historic buildings and structures, like any other, move to some degree, whether due to thermal effects, changes in moisture levels in the structural fabric, influences on the founding subsoil, or environmental forces. The key question for the conservation engineer is to determine whether the movement is progressive and presents a risk to the structure. This article introduces engineers to the various techniques available to monitor movement in historic structures, from simple manual techniques which are less commonly used today, to sophisticated electronic systems. The form of monitoring will depend on the nature of the assumed movement, the funds available, and the possible consequences if the movement is progressive.