Issue 6

A review is presented of data concerning the occurrence of abnormally heavy highway loads and of severe temperature difference loading on bridges. The probabilities of these loads occurring simultaneously during the design life of a bridge are considered. It is concluded that there is a high probability of combined loading occurring on about 1% of UK trunk-road bridges during their design lives. The probability of the remaining trunk-road bridges experiencing combined loading during their design lives is about 3%. It is almost certain that severe temperature difference loading will occur under dead load conditions. Finally, reduced design loads, based on a nominal ‘permanent’ load, are suggested. J.G. Church and L.A. Clark

Significant efforts have been made in recent years to develop an engineering basis for the design of masonry (brickwork and blockwork). Much testing and some analytical work have been carried out, and important advances have been made in this direction. Many aspects, however, still require mostly engineering judgment. This is particularly true of damage criteria. Cracks and deflections in brickwork are common and decisions have often to be made without benefit of conclusive evidence. Professor Iain MacLeod

Introduction: Mr Armitage The structural engineer practices his art in a continually changing world. In recent years, the pace of change has quickened dramatically with the emergence of new techniques and with increased awareness of the contribution the engineer can make to the protection and improvement of the environment and to the economic use of resources.

At their meeting in April last, Council reviewed a plan for the future development of Institution activities and services; the plan, reproduced below, was adopted as a discussion document and has been circulated to all Branch Committees and Overseas Representatives.

The author is indebted to Mr Jackson for a valuable response to the original ‘Viewpoint’ article; it is gratifying that at least one person felt sufficiently moved by the question posed in the title of the article, and in its content, to take the trouble to compose a reply. Mr. D. McQuillan

Raft foundations for low-rise buildings In October last year, Mr J. O’Rourke described some methods adopted in the Wrekin District for the construction of raft foundations to counter the effects of mining subsidence. Some amendments to these were suggested by Mr T. Holden Brown in February, but Mr D. R. Robinson, who is with the Poole Borough Council, has now written to express his disagreement with these suggested amendments. He continues: If the cavity is closed by the additional 150mm-thick mass concrete, water running down the cavity will build up on the mass concrete and cause dampness on the inner blockwork and the screed. Verulam