Some Comments on Internal Pressures and Dominant Openings

Settlement cracks and cavity wall insulation Andrew Shaw, from Wakefield, W Yorks., writes: My practice investigates inter alia building movement, frequently subsidence-related. I wonder whether the pages of Verulam can be used to air a matter that somewhat perplexes me?

The Bann River Bridge is located on the M1 Motorway in Northern Ireland. The bridge was assessed as part of the National Assessment Programme. Localised durability problems were identified in the areas of the expansion joints, which had failed, allowing deicing salt contamination to parts of the bridge soffit and parts of the substructure. The bridge fniled the loading requirements of the National Assessment Programme, achieving 45% of the required HA loading. The preferred repair and strengthening option involved the repair of the contaminated areas. However concrete replacement repairs could not be applied economically to some of the contaminated areas owing to access problems and the extent of the contamination. Electrochemical repair techniques were therefore regarded us the only viable repair option. The Department of the Environment Roads Service (NI) decided to carry out an electrochemical chloride extraction demonstration on purt of the bridge, to ascertain the effectiveness of the technique. The University of Ulster was commissioned to provide independent assessment of the success of the treatment. During the autumn of 1997 the demonstration was carried out by Martech Services Ltd, and the range of tests performed by the team from the Universily of Ulster proved its success. J.A. Cromie, A.I. Abu-Tair and J.F. Lyness

This viewpoint is written on a wholly personal basis and may not reflect the views of the trade and professional associations with which I am associated, or those of my employer. I write after a decade of concern, discussion, meetings and seminars in connection with EC 3, the proposed European Steel Structures Design Code, and with a current feeling of complete frustration and despair. Joe Locke