Verulam

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

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

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