Issue 2

The Panel was established in December 1977, with Dr. Wm. Henderson (Vice-president) as Convener. The first report has been adopted by the Structural Codes Advisory Committee and Council, and the Panel has been requested to proceed with the preparation of the second report mentioned in the final paragraph.

Dr. L. A. Clark has discussed (The Structural Engineer, Vol. 56A, Sept. 1978, p. 244) the complexity introduced into concrete bridge design by the temperature changes and differences specified in BS 5400: Part 2: 1978. Similar problems arise in the design of composite bridge decks. An appropriate method of analysis and several worked examples have therefore been given in a Commentary on BS 5400: Part 5: Composite bridges. R.P. Johnson

New investment is being made in coalmining. Existing mines are being re-equipped to exploit further reserves, and new ones are being planned to open up newly discovered coalfields-in the case of Selby, sinking has commenced. Reference is made to previous papers which describe and illustrate post-1945 colliery reconstruction works: this paper deals with changes that have taken place since then. A.R. Taylor

The paper is concerned with the problem of predicting theoretically the strength of square thin-walled steel box columns that are pinended and loaded centrally at the ends. Interaction between yielding, local buckling (possible in all four component plates), and overall buckling makes this a difficult problem to solve rigorously. An approximate, and correspondingly economical, method of solution is presented and is used to analyse a range of cases. Local buckling of the plate elements is allowed for by the technique of using an appropriate average compressive stress-strain curve. G.H. Little

An appeal for better support On several occasions, we have had letters giving account of problems with the bearings for precast units of various kinds. Mr. A. Tydeman is concerned in this respect about the provisions made for precast floor slabs; essentially an appeal from the manufacturing side of the industry to the designer, Mr. Tydeman's letter was written on behalf of the Federation of Concrete Specialists: We would be grateful if we could use your columns to put forward a plea on behalf of the manufacturers of precast concrete floor slabs for more thought to be given to bearings on shelf angles. The problems that are arising with ever increasing frequency are, firstly, that the units have inadequate bearings and, secondly, that the ends of the units have to be reduced to an unsatisfactory degree in order to be placed at all. The first problem can be easily overcome by ensuring that the shelf angle projects sufficiently beyond the flange of the steel beam. When the end of the unit will slip between the top flange of the beam and the shelf angle, the amount of this projection can be obtained by using the formula (b/4) + 80 for the minimum length of the horizontal leg of the shelf angle, where b is the breadth of the top flange of the beam. Verulam