Correspondence on The Global and Local Behaviour of Bridge Deck Slabs by Dr. P.A. Jackson

Potential for catastrophe in building alterations The above topic, raised by Peter Mawer in our column for 20 March, attracted numerous responses, published in the journal for 15 May. Predictably, further correspondence has been received. Mr M. J. Foxton, from St. Helens, Merseyside, writes: The situation described by Mr Mawer will be very familiar to anyone engaged in local authority building control in the appraisal of submissions made for compliance with the requirements of the current Building Regulations and Part A of Schedule 1, in paticular. The local authority will, normally, require, in support, the production of such calculations and details as are necessary to demonstrate structural adequacy, including overall stability. Verulam

This paper outlines the philosophy and objectives of structural evaluation and describes how the IStructE report Appraisal of existing structures can be used and interpreted to provide a practical basis for decisions concerning the current and future use of buildings for which the original design and construction information is incomplete or unavailable, or where a change of use is envisaged. R.J. Currie

A method is presented for the derivation of structural forms for vaults and sails which are to be designed to carry one dominant load case-dead load in the case of a heavy vault or wind load in the case of a sail. A stress function is used to describe the state of stress in the vault or sail. The stress function is derived from the Biot-Savart law used in electromagnetic theory. C.J.K. Williams