Author: J. Avent (Conservation Accreditation Register for Engineers)
1 October 2015
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J. Avent (Conservation Accreditation Register for Engineers)
The yield-line method of analysis provides a powerful means of identifying the ultimate load-carrying capacity of reinforced concrete slabs. Benefits of the yield-line method are that it will often identify additional reserves of strength when applied to the analysis of existing slabs, and to highly economic slabs when used in design. Traditionally a hand-based method, the yield-line method is easy to apply to problems involving simple slab geometries and loading regimes. However, when these become more complex it can be difficult to identify the critical yield-line pattern. To address this, the method has now been systematically automated. The automated method quickly identifies the critical mechanism (or a close approximation of this) and corresponding load-carrying capacity, providing engineers with a powerful new computer-based tool for the analysis and design of concrete slabs. In this article, the discontinuity layout optimisation (DLO) procedure which has been used to automate the yield-line method is briefly described and then applied to various example problems.
In Timber Engineering Notebook (TEN) No. 11, a detailed introduction to the applications and use of cross-laminated timber (CLT) as a structural timber product was provided. This article provides further information on the manufacture, detailing and erection of CLT constructions.
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.